Brett Neilan

Advances in genomics, transcriptomics and proteomics of toxin‐producing cyanobacteria

Publisher: Wiley

Date: 22-01-2016

DOI: 10.1111/1758-2229.12366

Abstract: A common misconception persists that the genomes of toxic and non-toxic cyanobacterial strains are largely conserved with the exception of the presence or absence of the genes responsible for toxin production. Implementation of -omics era technologies has challenged this paradigm, with comparative analyses providing increased insight into the differences between strains of the same species. The implementation of genomic, transcriptomic and proteomic approaches has revealed distinct profiles between toxin-producing and non-toxic strains. Further, metagenomics and metaproteomics highlight the genomic potential and functional state of toxic bloom events over time. In this review, we highlight how these technologies have shaped our understanding of the complex relationship between these molecules, their producers and the environment at large within which they persist.

An investigation into the detoxification of microcystin-LR by the glutathione pathway in Balb/c mice

Publisher: Elsevier BV

Date: 05-2004

DOI: 10.1016/J.BIOCEL.2003.10.012

Detection of Toxigenicity by a Probe for the Microcystin Synthetase a Gene (mcyA) of the Cyanobacterial Genus Microcystis: Comparison of Toxicities with 16S rRNa and Phycocyanin Operon (Phycocyanin Intergenic Spacer) Phylogenies

Publisher: American Society for Microbiology

Date: 06-2001

DOI: 10.1128/AEM.67.6.2810-2818.2001

Abstract: The relationship between toxigenicity and phylogeny within the cyanobacterial genus Microcystis is unclear. To investigate this issue, we have designed PCR primers for the N -methyltransferase (NMT) domain of the microcystin synthetase gene mcyA and have probed 37 Microcystis sp. cultures as well as several field s les. The NMT region was present in all 18 laboratory strains that gave positive reactions in the protein phosphatase inhibition assay for microcystin but was absent in 17 nontoxic strains. Two other nontoxic strains, one of which had previously been reported to produce microcystin, possessed the NMT region. Detection of NMT-specific DNA in field s les corresponded to periods of toxicity as assessed by protein phosphatase inhibition. The Microcystis strains formed a monophyletic cluster based on 16S rRNA gene sequences but comprised two groups with respect to phycocyanin intergenic spacer (PC-IGS) sequences. Toxic and nontoxic strains appeared to be erratically distributed within the PC-IGS and 16S rRNA trees. Sequence analysis of the NMT domain revealed two coherent groups. The genomic region immediately downstream of the mcyABC cluster in all 20 NMT-positive strains contained an open reading frame of unknown function ( uma1 ) at a conserved distance from mcyC . All nontoxic strains also contained uma1 , which is not cotranscribed with mcyABC . The consistent linkage of mcyC to uma1 suggests that mcyC has not been frequently transferred into nontoxic strains via any mechanism involving insertion at random chromosomal locations. These results are discussed with respect to various mechanisms that could explain the patchy distribution of toxigenicity among the various Microcystis clades.

Insights into the distribution and abundance of the ubiquitous candidatus Saccharibacteria phylum following tag pyrosequencing

Publisher: Springer Science and Business Media LLC

Date: 04-02-2014

DOI: 10.1038/SREP03957

Nodularin, a cyanobacterial toxin, is synthesized in planta by symbiotic Nostoc sp.

Publisher: Springer Science and Business Media LLC

Date: 29-03-2012

DOI: 10.1038/ISMEJ.2012.25

Comparative protein expression in different strains of the bloom-forming cyanobacterium Microcystis aeruginosa

Publisher: Elsevier BV

Date: 09-2011

DOI: 10.1074/MCP.M110.003749

Geographical segregation of the neurotoxin-producing cyanobacterium Anabaena circinalis

Publisher: American Society for Microbiology

Date: 10-2000

DOI: 10.1128/AEM.66.10.4468-4474.2000

Abstract: Blooms of the cyanobacterium Anabaena circinalis are a major worldwide problem due to their production of a range of toxins, in particular the neurotoxins anatoxin-a and paralytic shellfish poisons (PSPs). Although there is a worldwide distribution of A. circinalis , there is a geographical segregation of neurotoxin production. American and European isolates of A. circinalis produce only anatoxin-a, while Australian isolates exclusively produce PSPs. The reason for this geographical segregation of neurotoxin production by A. circinalis is unknown. The phylogenetic structure of A. circinalis was determined by analyzing 16S rRNA gene sequences. A. circinalis was found to form a monophyletic group of international distribution. However, the PSP- and non-PSP-producing A. circinalis formed two distinct 16S rRNA gene clusters. A molecular probe was designed, allowing the identification of A. circinalis from cultured and uncultured environmental s les. In addition, probes targeting the predominantly PSP-producing or non-PSP-producing clusters were designed for the characterization of A. circinalis isolates as potential PSP producers.

Comparative gene expression of PSP-toxin producing and non-toxic Anabaena circinalis strains

Publisher: Elsevier BV

Date: 08-2006

DOI: 10.1016/J.ENVINT.2006.03.010

Abstract: Blooms of the freshwater cyanobacterium Anabaena circinalis are recognised as an important health risk worldwide due to the production of a range of toxins such as saxitoxin (STX) and its derivatives, also known as paralytic shellfish poisoning (PSP) toxins. In this study the transcriptional profile of PSP toxin-producing and non-toxic strains of A. circinalis was investigated by means of a DNA microarray approach. Additionally, gene expression was studied after exposure of toxic A. circinalis cultures to lidocaine hydrochloride at 1 microM for 2 h. Under standard growth conditions, a limited number of putative toxic-strain distinctive DNA fragments, identified in previous studies, were preferentially expressed in toxic versus non-toxic strains. The same genes did not significantly change their expression after exposure to 1 microM lidocaine, conditions previously shown to induce STX production in the cyanobacterium Cylindrospermopsis raciborskii T3. Lidocaine supplementation, however, enhanced the transcription of genes involved in physiological adaptive responses and bloom formation in cyanobacteria, such as the gas vesicle structural protein A and phycocyanin. The heat shock protein HSP-70 and the chlorophyll-a binding protein isiA were significantly repressed by lidocaine exposure. Stress response proteins and genes implicated in secondary metabolism were repressed, including phosphopantetheinyl transferases. The BGGM1 DNA microarray, used in this study, was shown to be suitable for gene expression studies in cultured toxic cyanobacteria and allowed the analysis of gene transcripts associated with surface scum formation by toxic A. circinalis.

Increased methane production in cyanobacteria and methanogenic microbe co-cultures

Publisher: Elsevier BV

Date: 11-2017

DOI: 10.1016/J.BIORTECH.2017.06.126

Abstract: A novel light-to-bioenergy system produced 3.5 times the baseline methane output using a co-culture of cyanobacteria (Oscillatoria sp.) and a methanogenic microbial community. Analysis of micronutrients in the system during the growth phase indicated that cobalt, iron, nickel and zinc were not appreciably consumed. The stable consumption and return of macronutrients calcium and magnesium were also observed. Essential macronutrients nitrogen, in the form of nitrate, and phosphorus showed no cycling during the growth phase and were depleted at rates of 0.35mg/L/day and 0.40µg/L/day, respectively. Biofilm formation increased the resilience of biomass to bacterial degradation in an anaerobic digester, as shown by viability assays of cyanobacterial biofilms in the co-culture.

Excitotoxic potential of the cyanotoxin β-methyl-amino-L-alanine (BMAA) in primary human neurons

Publisher: Elsevier BV

Date: 11-2012

DOI: 10.1016/J.TOXICON.2012.07.169

Abstract: The toxicity of the cyanobacterial modified amino acid, BMAA, has been described in rat, mouse and leech neurons. Particular emphasis has been placed on the potential ability of BMAA to induce neuronal damage via excitotoxic mechanisms. Here we present data indicating that the effects observed on lower organisms are also evident in a human model. Our data indicates that BMAA induces increased intracellular Ca²⁺ influx, DNA damage, mitochondrial activity, lactate dehydrogenase (LDH) release and generation of reactive oxygen species (ROS). The amelioration of LDH release in the presence of the N-methyl-D-aspartate (NMDA) receptor antagonist MK801 indicates that the neurotoxic effects of BMAA are mediated via NMDA receptor activation. Additionally, we have shown that BMAA induces the expression of neuronal nitric oxide synthase (nNOS) and caspase-3 indicating that it can stimulate apoptosis in human neurons, presumably via activation of NMDA receptors.

Expression of Cyanobacterial Biosynthetic Gene Clusters in Escherichia coli

Publisher: Springer US

Date: 2022

DOI: 10.1007/978-1-0716-2273-5_17

Abstract: Cyanobacteria represent an attractive source of natural bioactive compounds, ranging from sunscreens to cancer treatments. While many biosynthetic gene clusters (BGCs) that encode cyanobacterial natural products are known, the slow growth and lack of genetic tools in the native producers h ers their modification, characterization, and large-scale production. By engineering heterologous hosts for the expression of cyanobacterial BGCs, sufficient material can be produced for research or industry. Although several hosts have been evaluated for the expression of cyanobacterial natural products, this work details the process of expressing BGCs in Escherichia coli via promoter exchange.

Comparative genomics of Cylindrospermopsis raciborskii strains with differential toxicities

Publisher: Springer Science and Business Media LLC

Date: 29-01-2014

DOI: 10.1186/1471-2164-15-83

Molecular identification and evolution of the cyclic peptide hepatotoxins, microcystin and nodularin, synthetase genes in three orders of cyanobacteria

Publisher: Springer Science and Business Media LLC

Date: 10-01-2006

DOI: 10.1007/S00203-005-0073-5

Abstract: The cyanobacterial hepatotoxins, microcystin and nodularin, are produced by a wide range of cyanobacteria. Microcystin production has been reported in the four cyanobacterial orders: Oscillatoriales, Chroococcales, Stigonematales, and Nostocales. The production of nodularin is a distinct characteristic of the Nostocales genus Nodularia. A single rapid method is needed to reliably detect cyanobacteria that are potentially capable of producing these hepatotoxins. To this end, a PCR was designed to detect all potential microcystin and nodularin-producing cyanobacteria from laboratory cultures as well as in harmful algal blooms. The aminotransferase (AMT) domain, which is located on the modules mcyE and ndaF of the microcystin and nodularin synthetase enzyme complexes, respectively, was chosen as the target sequence because of its essential function in the synthesis of all microcystins as well as nodularins. Using the described PCR, it was possible to lify a 472 bp PCR product from the AMT domains of all tested hepatotoxic species and bloom s les. Sequence data provided further insight into the evolution of the microcystin and nodularin synthetases through bioinformatic analyses of the AMT in microcystin and nodularin synthetases, with congruence between the evolution of 16S rRNA and the AMT domain.

Carotenoid analysis of halophilic archaea by resonance Raman spectroscopy

Publisher: Mary Ann Liebert Inc

Date: 08-2007

DOI: 10.1089/AST.2006.0097

Abstract: Recently, halite and sulfate evaporate rocks have been discovered on Mars by the NASA rovers, Spirit and Opportunity. It is reasonable to propose that halophilic microorganisms could have potentially flourished in these settings. If so, biomolecules found in microorganisms adapted to high salinity and basic pH environments on Earth may be reliable biomarkers for detecting life on Mars. Therefore, we investigated the potential of Resonance Raman (RR) spectroscopy to detect biomarkers derived from microorganisms adapted to hypersaline environments. RR spectra were acquired using 488.0 and 514.5 nm excitation from a variety of halophilic archaea, including Halobacterium salinarum NRC-1, Halococcus morrhuae, and Natrinema pallidum. It was clearly demonstrated that RR spectra enhance the chromophore carotenoid molecules in the cell membrane with respect to the various protein and lipid cellular components. RR spectra acquired from all halophilic archaea investigated contained major features at approximately 1000, 1152, and 1505 cm(-1). The bands at 1505 cm(-1) and 1152 cm(-1) are due to in-phase C=C (nu(1) ) and C-C stretching ( nu(2) ) vibrations of the polyene chain in carotenoids. Additionally, in-plane rocking modes of CH(3) groups attached to the polyene chain coupled with C-C bonds occur in the 1000 cm(-1) region. We also investigated the RR spectral differences between bacterioruberin and bacteriorhodopsin as another potential biomarker for hypersaline environments. By comparison, the RR spectrum acquired from bacteriorhodopsin is much more complex and contains modes that can be ided into four groups: the C=C stretches (1600-1500 cm(-1)), the CCH in-plane rocks (1400-1250 cm(-1)), the C-C stretches (1250-1100 cm(-1)), and the hydrogen out-of-plane wags (1000-700 cm(-1)). RR spectroscopy was shown to be a useful tool for the analysis and remote in situ detection of carotenoids from halophilic archaea without the need for large s le sizes and complicated extractions, which are required by analytical techniques such as high performance liquid chromatography and mass spectrometry.

Enzyme-Free Cloning of PCR Products and Fusion Protein Expression

Publisher: Humana Press

Date: 2002

DOI: 10.1385/1-59259-177-9:125

Demonstration of the use of Scenedesmus and Carteria biomass to drive bacterial sulfate reduction by Desulfovibrio alcoholovorans isolated from an artificial wetland

Publisher: Elsevier BV

Date: 10-2003

DOI: 10.1016/S0304-386X(03)00160-9

Exploring cyanobacterial genomes for natural product biosynthesis pathways

Publisher: Elsevier BV

Date: 06-2015

DOI: 10.1016/J.MARGEN.2014.11.009

Abstract: Cyanobacteria produce a vast array of natural products, some of which are toxic to human health, while others possess potential pharmaceutical activities. Genome mining enables the identification and characterisation of natural product gene clusters however, the current number of cyanobacterial genomes remains low compared to other phyla. There has been a recent effort to rectify this issue by increasing the number of sequenced cyanobacterial genomes. This has enabled the identification of biosynthetic gene clusters for structurally erse metabolites, including non-ribosomal peptides, polyketides, ribosomal peptides, UV-absorbing compounds, alkaloids, terpenes and fatty acids. While some of the identified biosynthetic gene clusters correlate with known metabolites, genome mining also highlights the number and ersity of clusters for which the product is unknown (referred to as orphan gene clusters). A number of bioinformatic tools have recently been developed in order to predict the products of orphan gene clusters however, in some cases the complexity of the cyanobacterial pathways makes the prediction problematic. This can be overcome by the use of mass spectrometry-guided natural product genome mining, or heterologous expression. Application of these techniques to cyanobacterial natural product gene clusters will be explored.

Molecular characterization and the effect of salinity on cyanobacterial diversity in the rice fields of Eastern Uttar Pradesh, India

Publisher: Springer Science and Business Media LLC

Date: 06-04-2009

DOI: 10.1186/1746-1448-5-4

Abstract: Salinity is known to affect almost half of the world's irrigated lands, especially rice fields. Furthermore, cyanobacteria, one of the critical inhabitants of rice fields have been characterized at molecular level from many different geographical locations. This study, for the first time, has examined the molecular ersity of cyanobacteria inhabiting Indian rice fields which experience various levels of salinity. Ten physicochemical parameters were analyzed for s les collected from twenty experimental sites. Electrical conductivity data were used to classify the soils and to investigate relationship between soil salinity and cyanobacterial ersity. The cyanobacterial communities were analyzed using semi-nested 16S rRNA gene PCR and denaturing gradient gel electrophoresis. Out of 51 DGGE bands selected for sequencing only 31 which showed difference in sequences were subjected to further analysis. BLAST analysis revealed highest similarity for twenty nine of the sequences with cyanobacteria, and the other two to plant plastids. Clusters obtained based on morphological and molecular attributes of cyanobacteria were correlated to soil salinity. Among six different clades, clades 1, 2, 4 and 6 contained cyanobacteria inhabiting normal or low saline (having EC 4.0 ds m -1 ) to (high) saline soils (having EC 4.0 ds m -1 ), however, clade 5 represented the cyanobacteria inhabiting only saline soils. Whilst, clade 3 contained cyanobacteria from normal soils. The presence of DGGE band corresponding to Aulosira strains were present in large number of soil indicating its wide distribution over a range of salinities, as were Nostoc , Anabaena , and Hapalosiphon although to a lesser extent in the sites studied. Low salinity favored the presence of heterocystous cyanobacteria, while very high salinity mainly supported the growth of non-heterocystous genera. High nitrogen content in the low salt soils is proposed to be a result of reduced ammonia volatilization compared to the high salt soils. Although many environmental factors could potentially determine the microbial community present in these multidimensional ecosystems, changes in the ersity of cyanobacteria in rice fields was correlated to salinity.

Cost-Effectiveness Analysis of Risk-Factor Guided and Birth-Cohort Screening for Chronic Hepatitis C Infection in the United States

Publisher: Public Library of Science (PLoS)

Date: 22-03-2013

DOI: 10.1371/JOURNAL.PONE.0058975

Phylogeography of the invasive cyanobacterium Cylindrospermopsis raciborskii

Publisher: Wiley

Date: 19-12-2003

DOI: 10.1046/J.1365-294X.2003.01709.X

Abstract: Cylindrospermopsis raciborskii is a planktonic freshwater cyanobacterium that has become increasingly prevalent in tropical and temperate water bodies world-wide. This species is of concern from a water-quality perspective because of its known ability to produce toxins that can affect the health of humans and other animals. This study investigates genetic variation between strains of C. raciborskii isolated from freshwater rivers and reservoirs in Australia, Brazil, Germany, Hungary, Portugal and the USA. Strains were first characterized by analysis of their 16S rRNA gene nucleotide sequences and were found to have a sequence ergence of 99.1%. A phylogenetic tree, constructed using the 16S rRNA gene sequences showed that strains grouped into Australian, European and North/South American phylotypes. To investigate further the observed separation of strains into geographically distinct groups, we applied a cyanobacterium-specific short tandem repeat sequence technique, HIP1. An electrophoretic comparison of the HIP1 polymerase chain reaction products showed clear distinctions between the C. raciborskii strains. A phylogenetic tree, based on the repeat element banding patterns, also revealed three distinct groups of C. raciborskii strains. The first group consisted of strains from the USA and Brazil the second comprised European strains from Germany, Hungary and Portugal and the third were strains from Australia. In general, between-country variation was greater than within-country variation, indicating that this fingerprinting technique can successfully distinguish C. raciborskii strains taken from different global locations. The relationship between toxicity and the observed HIP1 polymerase chain reaction fingerprint profiles was less clear, although it is interesting to note that of the strains analysed in this study, only Australian strains are known to produce cylindrospermopsin and only Brazilian strains have been reported to produce paralytic shellfish poisoning toxins.

The phosphopantetheinyl transferase superfamily: Phylogenetic analysis and functional implications in cyanobacteria

Publisher: American Society for Microbiology

Date: 04-2006

DOI: 10.1128/AEM.72.4.2298-2305.2006

Abstract: Phosphopantetheinyl transferases (PPTs) are a superfamily of essential enzymes required for the synthesis of a wide range of compounds including fatty acid, polyketide, and nonribosomal peptide metabolites. These enzymes activate carrier proteins in specific biosynthetic pathways by the transfer of a phosphopantetheinyl moiety to an invariant serine residue. PPTs display low levels of sequence similarity but can be classified into two major families based on several short motifs. The prototype of the first family is the broad-substrate-range PPT Sfp, which is required for biosynthesis of surfactin in Bacillus subtilis . The second family is typified by the Escherichia coli acyl carrier protein synthase (AcpS). Facilitated by the growing number of genome sequences available for analyses, large-scale phylogenetic studies were utilized in this research to reveal novel subfamily groupings, including two subfamilies within the Sfp-like family. In the present study degenerate oligonucleotide primers were designed for lification of cyanobacterial PPT gene fragments. Subsequent phylogenetic analyses suggested a unique, function-based PPT type, defined by the PPTs involved in heterocyst differentiation. Evidence supporting this hypothesis was obtained by sequencing the region surrounding the partial Nodularia spumigena PPT gene. The ability to genetically classify PPT function is critical for the engineering of novel compounds utilizing combinatorial biosynthesis techniques. Information regarding cyanobacterial PPTs has important ramifications for the ex situ production of cyanobacterial natural products.

Structural organization of microcystin biosynthesis in Microcystis aeruginosa PCC7806: An integrated peptide-polyketide synthetase system

Publisher: Elsevier BV

Date: 10-2000

DOI: 10.1016/S1074-5521(00)00021-1

Abstract: Blooms of toxic cyanobacteria (blue-green algae) have become increasingly common in the surface waters of the world. Of the known toxins produced by cyanobacteria, the microcystins are the most significant threat to human and animal health. These cyclic peptides are potent inhibitors of eukaryotic protein phosphatases type 1 and 2A. Synthesized nonribosomally, the microcystins contain a number of unusual amino acid residues including the beta-amino polyketide moiety Adda (3-amino-9-methoxy-2,6, 8-trimethyl-10-phenyl-4,6-decadienoic acid). We have characterized the microcystin biosynthetic gene cluster from Microcystis aeruginosa PCC7806. A cluster spanning 55 kb, composed of 10 bidirectionally transcribed open reading frames arranged in two putative operons (mcyA-C and mcyD-J), has been correlated with microcystin formation by gene disruption and mutant analysis. Of the 48 sequential catalytic reactions involved in microcystin synthesis, 45 have been assigned to catalytic domains within six large multienzyme synthases/synthetases (McyA-E, G), which incorporate the precursors phenylacetate, malonyl-CoA, S-adenosyl-L-methionine, glutamate, serine, alanine, leucine, D-methyl-isoaspartate, and arginine. The additional four monofunctional proteins are putatively involved in O-methylation (McyJ), epimerization (McyF), dehydration (McyI), and localization (McyH). The unusual polyketide amino acid Adda is formed by transamination of a polyketide precursor as enzyme-bound intermediate, and not released during the process. This report is the first complete description of the biosynthesis pathway of a complex cyanobacterial metabolite. The enzymatic organization of the microcystin assembly represents an integrated polyketide-peptide biosynthetic pathway with a number of unusual structural and enzymatic features. These include the integrated synthesis of a beta-amino-pentaketide precursor and the formation of beta- and gamma-carboxyl-peptide bonds, respectively. Other features of this complex system also observed in erse related biosynthetic clusters are integrated C- and N-methyltransferases, an integrated aminotransferase, and an associated O-methyltransferase and a racemase acting on acidic amino acids.

Unravelling core microbial metabolisms in the hypersaline microbial mats of Shark Bay using high-throughput metagenomics

Publisher: Springer Science and Business Media LLC

Date: 29-05-2016

DOI: 10.1038/ISMEJ.2015.87

Zinc Homeostasis in Cyanobacteria

Publisher: CRC Press

Date: 03-2013

DOI: 10.1201/B13853-14

The Synechocystis sp. PCC6803 Sfp-type phosphopantetheinyl transferase does not possess characteristic broad-range activity

Publisher: Wiley

Date: 13-07-2009

DOI: 10.1002/CBIC.200900095

Abstract: The cyanobacterium Synechocystis sp. PCC6803 harbours one phosphopantetheinyl transferase (PPTase), Sppt. Protein modelling supported previous bioinformatics analyses, which suggested that Sppt is a Sfp-type PPTase with the potential to phosphopantetheinylate a broad range of carrier proteins from both primary and secondary metabolism. However, no natural products are synthesised by this species, which raises interesting evolutionary and functional questions. Phosphopantetheinylation assays and kinetic data demonstrate that Sppt was able to activate its cognate fatty acid synthesis carrier protein, SACP, but was unable to effectively activate various cyanobacterial carrier proteins from secondary metabolism or glycolipid biosynthesis pathways. To our knowledge, this is the first ex le of a PPTase with a Sfp-type structure, but with activity more closely resembling AcpS-type enzymes. The broad-range PPTase from Nodularia spumigena NSOR10 was introduced into Synechocystis sp. PCC6803 and was shown to activate a noncognate carrier protein, in vivo. This engineered strain could provide a future biotechnological platform for the heterologous expression of cyanobacterial biosynthetic gene clusters.

Functional renormalization group for commensurate antiferromagnets: Beyond the mean-field picture

Publisher: American Physical Society (APS)

Date: 29-07-2014

DOI: 10.1103/PHYSREVB.90.035140

Radioreceptor assays for sensitive detection and quantitation of saxitoxin and its analogues from strains of the freshwater cyanobacterium, Anabaena circinalis

Publisher: American Chemical Society (ACS)

Date: 03-03-2001

DOI: 10.1021/ES001575Z

Abstract: Toxic freshwater cyanobacteria can contaminate water supplies and adversely effect humans, agricultural livestock, and wildlife. Toxicity is strain-specific so morphological observations alone cannot predict the hazard level. Two microtiter plate based bioassays have emerged for measuring saxitoxin (STX) and its derivatives, commonly found in the freshwater cyanobacteria Anabaena and Aphanizomenon. They use radioactively labeled STX binding by sodium channels, STX's pharmacological target, or an unrelated protein, saxiphilin. These bioassays were challenged with extracts of toxic and nontoxic strains of Anabaena circinalis, and the results were compared with HPLC analysis. Both radioreceptor assays had detection limits of 2 microg STX equivalents (STXeq)/L, which is belowthe concentration proposed for a health alert, namely 3 microg STXeq/L. In all cases, statistically significant correlations existed between all toxicity measurements of the same extracts with the methods used herein. Sodium channel and saxiphilin assays however predicted less toxicity relative to HPLC analysis. The only exception to this was the equivalency observed between saxiphilin measurement and HPLC quantitation corrected for mammalian toxicity. Saxiphilin assay predicted toxicity in one strain was 3 orders of magnitude more than by sodium channel assay, and no STX was detected by HPLC. Lack of acetylcholinesterase inhibition showed this bioactivity was not anatoxin-a(S), a toxin also produced by this A. circinalis with some resemblance to the region of STX bound by saxiphilin. Presence of anatoxin-a(S) was predicted for another strain by this same acetylcholinesterase assay that, if confirmed by chemical analysis, would be the first report of anatoxin-a(S) in an Australian cyanobacterium.

A multiplex qPCR targeting hepato- and neurotoxigenic cyanobacteria of global significance

Publisher: Elsevier BV

Date: 03-2012

DOI: 10.1016/J.HAL.2011.11.001

Genome-Guided Discovery of Natural Products and Biosynthetic Pathways from Australia's Untapped Microbial Megadiversity

Publisher: CSIRO Publishing

Date: 2016

DOI: 10.1071/CH15601

Abstract: Historically microbial natural product biosynthesis pathways were elucidated mainly by isotope labelled precursor directed feeding studies. Now the genetics underpinning the assembly of microbial natural products biosynthesis is so well understood that some pathways and their products can be predicted from DNA sequences alone. The association between microbial natural products and their biosynthesis gene clusters is now driving the field of ‘genetics guided natural product discovery’. This account overviews our research into cyanotoxin biosynthesis before the genome sequencing era through to some recent discoveries resulting from the mining of Australian biota for natural product biosynthesis pathways.

Cyanobacteria as a critical reservoir of the environmental antimicrobial resistome

Publisher: Wiley

Date: 26-06-2023

DOI: 10.1111/1462-2920.16453

Abstract: Antimicrobial resistance (AMR) is predicted to cause a worldwide annual toll of 10 million deaths by 2050. This looming public health threat has been linked to antibiotic overuse and pollution, which places selective pressures on AMR maintenance and transfer in and between microbial populations. We examined the distribution, ersity and potential mobility of AMR genes in cyanobacteria. While cyanobacteria are not pathogenic, we hypothesised that they could be a major environmental reservoir for AMR genes. Genes encoding AMR to seven antimicrobial drug classes were found in 10% of cyanobacterial genomes. AMR genes were found in 13% of freshwater, 19% of terrestrial, 34% of symbiotic, 2% of thermal spring, and 3% of marine genomes. AMR genes were found in five cyanobacterial orders with 23% of Nostocales and 8% of Oscillatoriales strains containing AMR genes. The most frequently observed alleles were ansamycin resistance genes, which were present in 7% of strains. AMR genes responsible for resistance to broad‐spectrum β‐lactams, chlor henicols, tetracyclines, macrolides, and aminoglycosides were associated with mobile genetic elements or plasmid replicons or both. These results suggest that cyanobacteria are an extensive reservoir, and potential vector, for AMR genes in erse terrestrial and aquatic habitats.

Gene expression profiling of Helicobacter pylori reveals a growth-phase-dependent switch in virulence gene expression

Publisher: American Society for Microbiology

Date: 05-2003

DOI: 10.1128/IAI.71.5.2643-2655.2003

Abstract: The global pattern of growth-phase-dependent gene expression of Helicobacter pylori during in vitro culture was analyzed by using a high-density DNA microarray. To detect consistent coordinated gene expression in this bacterium, temporal changes in transcription were assessed in two independent time courses. Cluster analysis of the expression profiles highlighted a major switch in gene expression during the late log-to-stationary phase transition that we have termed the Log-Stat switch. Statistical analysis of the genes that were significantly induced or repressed during the Log-Stat switch revealed that many of these genes were related to virulence. Among these, expression of the genes for the neutrophil activating protein ( napA ) and the major flagellin subunit ( flaA ) were significantly induced. Additionally, the expression of a number of genes involved in iron homeostasis changed dramatically at this switch the gene for the iron-storage protein, pfr , was induced, while the genes for two putative iron uptake proteins, fecA and frpB , were significantly repressed. These data suggest that the late log phase may correspond to the most virulent phase of growth in H. pylori and may be intimately related to its pathogenesis. The use of microarrays to analyze the kinetics of the transcriptional response of a bacterial pathogen to a changing environment has enabled the discovery of previously unappreciated relationships between genes by elucidation of coordinated gene expression profiles.

On the origins and biosynthesis of tetrodotoxin

Publisher: Elsevier BV

Date: 07-2011

DOI: 10.1016/J.AQUATOX.2011.04.001

Abstract: The potent neurotoxin tetrodotoxin (TTX) has been identified from taxonomically erse marine organisms. TTX possesses a unique cage-like structure, however, its biosynthesis has yet to be elucidated. Biosynthetic studies in the TTX-producing newt Taricha torosa, and in bacterial genera, including Vibrio, have proven inconclusive. Indeed, very few studies have been performed that address the cellular production of TTX. Here we review the sources of TTX described to date and provide evidence for the biosynthesis of TTX by symbiotic microorganisms in higher taxa. Chemical and genetic based biosynthesis studies of TTX undertaken thus far are discussed and we outline approaches which may be useful for expanding upon the current body of knowledge. The complex biosynthesis of structurally similar toxins, that reveal clues into the biosynthetic pathway of TTX, is also presented.

Lipid biomarkers in Hamelin Pool microbial mats and stromatolites

Publisher: Elsevier BV

Date: 11-2010

DOI: 10.1016/J.ORGGEOCHEM.2010.07.007

Effects of synthetic local anaesthetics on the growth of the cyanobacterium Synechococcus leopoliensis

Publisher: Springer Science and Business Media LLC

Date: 03-2004

DOI: 10.1023/B:JAPH.0000044776.04977.00

Lipid biomarker analysis of cyanobacteria-dominated microbial mats in meltwater ponds on the McMurdo Ice Shelf, Antarctica

Publisher: Elsevier BV

Date: 02-2009

DOI: 10.1016/J.ORGGEOCHEM.2008.10.002

Cereulide, the emetic toxin of Bacillus cereus, is putatively a product of nonribosomal peptide synthesis

Publisher: Oxford University Press (OUP)

Date: 11-2004

DOI: 10.1111/J.1365-2672.2004.02381.X

Abstract: To determine if cereulide, the emetic toxin produced by Bacillus cereus, is produced by a nonribosomal peptide synthetase (NRPS). NC Y, an emetic strain of Bacillus cereus, was examined for a NRPS gene using PCR with primers recognizing a fragment of a NRPS gene from the cyanobacterium Microcystis. The licon was sequenced and compared with other gene sequences using BLAST analysis, which showed that the licon from strain NC Y was similar in sequence to peptide synthetase genes in other micro-organisms, including Bacillus subtilis and B. brevis, while no such sequence was found in the complete genome sequence of a nonemetic strain of B. cereus. Specific PCR primers were then designed and used to screen 40 B. cereus isolates previously implicated in outbreaks of foodborne illness. The isolates were also screened for toxin production using the MTT cell cytotoxicity assay. PCR and MTT assay screening of the B. cereus isolates revealed a high correlation between the presence of the NRPS gene and cereulide production. The results indicate that cereulide is produced by a NRPS complex. This is the first study to provide evidence identifying the mechanism of production of cereulide, the emetic toxin of B. cereus. The PCR primers developed in the study allow determination of the potential for cereulide production among isolates of B. cereus.

Pseudoalteromonas tunicata sp. nov., a bacterium that produces antifouling agents

Publisher: Microbiology Society

Date: 10-1998

DOI: 10.1099/00207713-48-4-1205

Abstract: A dark-green-pigmented marine bacterium, previously designated D2, which produces components that are inhibitory to common marine fouling organisms has been characterized and assessed for taxonomic assignment. Based on direct double-stranded sequencing of the 16S rRNA gene, D2T was found to show the highest similarity (93%) to members of the genus Pseudoalteromonas. The G + C content of D2T is 42 mol%, and it is a facultatively anaerobic rod and oxidase-positive. D2T is motile by a sheathed polar flagellum, exhibited non-fermentative metabolism and required sodium ions for growth. The strain was not capable of using citrate, fructose, sucrose, sorbitol and glycerol but it utilizes mannose and maltose and hydrolyses gelatin. The molecular evidence, together with phenotypic characteristics, showed that this bacterium which produces an antifouling agent constitutes a new species of the genus Pseudoalteromonas. The name Pseudoalteromonas tunicata is proposed for this bacterium, and the type strain is D2T (= CCUG 26757T).

A multidrug efflux response to methyl viologen and acriflavine toxicity in the cyanobacterium Synechocystis sp. PCC6803

Publisher: Springer Science and Business Media LLC

Date: 25-02-2016

DOI: 10.1007/S10811-016-0816-5

Microbial Communities of Stromatolites

Publisher: Springer Netherlands

DOI: 10.1007/978-1-4020-8837-7_7

Investigation of the Biosynthetic Potential of Endophytes in Traditional Chinese Anticancer Herbs

Publisher: Public Library of Science (PLoS)

Date: 22-05-2012

DOI: 10.1371/JOURNAL.PONE.0035953

Identification of two residues essential for the stringent substrate specificity and active site stability of the prokaryotic l‐arginine:glycine amidinotransferase CyrA

Publisher: Wiley

Date: 02-2012

DOI: 10.1111/J.1742-4658.2012.08472.X

Abstract: A novel prokaryotic l-arginine:glycine amidinotransferase (CyrA EC2.1.4.1) is involved in the biosynthesis of the polyketide-derived cytotoxin cylindrospermopsin in the cyanobacterium Cylindrospermopsis raciborskii AWT250, and was previously characterized with regard to kinetic mechanism and substrate specificity [Muenchhoff J et al. (2010) FEBS J277, 3844-3860]. In order to elucidate the structure-function-stability relationship of this enzyme, two residues in its active site were replaced with the residues that occur in the human l-arginine:glycine amidinotransferase (h-AGAT) at the corresponding positions (F245N and S247M), and a double variant carrying both substitutions was also created. In h-AGAT, both of these residues are critical for the function of this enzyme with regard to substrate binding, ligand-induced structural changes, and stability of the active site. In this study, we demonstrated that both single residue replacements resulted in a dramatic broadening of substrate specificity, but did not affect the kinetic mechanism. Experiments with substrate analogues indicate that donor substrates require a carboxylate group for binding. Evidence from initial velocity studies suggests that CyrA undergoes ligand-induced structural changes that involve Phe245. Stability parameters (T(opt) and T(max) ) of the CyrA variants differed from those of wild-type CyrA. Structural flexibilities of the wild type and all three variants were comparable on the basis of dynamic fluorescence quenching, indicating that changes in T(opt) are most likely attributable to localized effects within the active site. Overall, the results indicated that these two residues are essential for both stringent substrate specificity and the active site stability and flexibility of this unique cyanobacterial enzyme.

sxtA -Based Quantitative Molecular Assay To Identify Saxitoxin-Producing Harmful Algal Blooms in Marine Waters

Publisher: American Society for Microbiology

Date: 10-2011

DOI: 10.1128/AEM.05308-11

Abstract: The recent identification of genes involved in the production of the potent neurotoxin and keystone metabolite saxitoxin (STX) in marine eukaryotic phytoplankton has allowed us for the first time to develop molecular genetic methods to investigate the chemical ecology of harmful algal blooms in situ . We present a novel method for detecting and quantifying the potential for STX production in marine environmental s les. Our assay detects a domain of the gene sxtA that encodes a unique enzyme putatively involved in the sxt pathway in marine dinoflagellates, sxtA4 . A product of the correct size was recovered from nine strains of four species of STX-producing Alexandrium and Gymnodinium catenatum and was not detected in the non-STX-producing Alexandrium species, other dinoflagellate cultures, or an environmental s le that did not contain known STX-producing species. However, sxtA4 was also detected in the non-STX-producing strain of Alexandrium tamarense , Tasmanian ribotype. We investigated the copy number of sxtA4 in three strains of Alexandrium catenella and found it to be relatively constant among strains. Using our novel method, we detected and quantified sxtA4 in three environmental blooms of Alexandrium catenella that led to STX uptake in oysters. We conclude that this method shows promise as an accurate, fast, and cost-effective means of quantifying the potential for STX production in marine s les and will be useful for biological oceanographic research and harmful algal bloom monitoring.

A Pseudoalteromonas Clade with Remarkable Biosynthetic Potential

Publisher: American Society for Microbiology

Date: 26-02-2021

DOI: 10.1128/AEM.02604-20

Abstract: This study demonstrates that the Pseudoalteromonas strain HM-SA03, isolated from the venomous blue-ringed octopus, Hapalochalaena sp., is a biosynthetically talented organism, capable of producing alterochromides and potentially six other specialized metabolites. We identified a pseudoalterobactin biosynthesis gene cluster and proposed a pathway for the production of the associated siderophore.

Absence of detectable levels of the cyanobacterial toxin (microcystin-LR) carry-over into milk

Publisher: Elsevier BV

Date: 08-2002

DOI: 10.1016/S0041-0101(02)00123-X

Abstract: The potential for the carry-over of the cyanobacterial toxin, microcystin-LR, from feed to milk was assessed using four Holstein-Friesian cows in a 4 week feeding trial. Two cows were used as control and the other two dosed daily at increasing weekly concentrations of microcystins from zero to a maximum dosage of 13 microg toxin kg x (-1) d x (-1) (or 7.4 mg toxin day(-1)). The absence of any deviation from the control in terms of physiological response and plasma indicators (total bilirubin, gamma-glutamyl transpeptidase and alkaline phosphatase) suggests that the microcystin-LR dosage did not have a detrimental effect on cattle liver function or milk yield during the course of the study. While the milk production did decrease over the period of the trial, no difference was observed between control and dosed cattle. Protein phosphatase inhibition assays were successfully used to determine the presence of microcystin-LR in prepared milk s les with an average recovery of 88% for s les spiked with 0.6 microg x l(-1) microcystin-LR. The level of microcystin-LR in all milk s les during the trial was less than 0.2 microg x l(-1). This suggests that after digestion, microcystin--LR is either not present in milk or sufficiently modified to render it non-toxic.

Molecular and morphological survey of saxitoxin-producing cyanobacterium Dolichospermum circinale (Anabaena circinalis) isolated from geographically distinct regions of Australia

Publisher: Elsevier BV

Date: 11-2017

DOI: 10.1016/J.TOXICON.2017.08.006

Abstract: The cyanobacterium Dolichospermum circinale (formerly Anabaena circinalis) is responsible for neurotoxic saxitoxin-producing blooms in Australia. Previous studies have reported distinct isolates of toxic D. circinale producing different saxitoxin analogues at varying amounts, but the mechanisms responsible remain poorly understood. To assess the characteristics that may be responsible for this variance, a morphological, molecular and chemical survey of 28 Anabaena isolates was conducted. Morphological characteristics, presence or absence of saxitoxin biosynthetic genes and toxin amount and profile were assessed. The 28 isolates were collected from 16 locations. A correlation between the size of the isolates and its reported toxicity or geographical location could not be found. Molecular screening for the presence of several sxt genes revealed eight out of the 28 strains harboured the sxt gene cluster and all tailoring genes except sxtX. Furthermore, the presence of PSTs was correlated with the presence of the sxt cluster using quantitative pre-column oxidation high performance liquid chromatography with fluorescence detection (HPLC-FLD) and LC-MS/MS. Interestingly, isolates differed in the amount and type of toxins produced, with the eight toxic strains containing the core and tailoring biosynthetic genes while non-toxic strains were devoid of these genes. Moreover, the presence of sxt tailoring genes in toxic strains correlated with the biosynthesis of analogues. A greater understanding of toxin profile/quantity from distinct sites around Australia will aid the management of these at-risk areas and provide information on the molecular control or physiological characteristics responsible for toxin production.

Comparative profiling and discovery of novel glycosylated mycosporine-like amino acids in two strains of the cyanobacterium Scytonema cf. crispum

Publisher: American Society for Microbiology

Date: 10-2016

DOI: 10.1128/AEM.01633-16

Abstract: The mycosporine-like amino acids (MAAs) are a group of small molecules with a erse ecological distribution among microorganisms. MAAs have a range of physiological functions, including protection against UV radiation, making them important from a biotechnological perspective. In the present study, we identified a putative MAA ( mys ) gene cluster in two New Zealand isolates of Scytonema cf. crispum (UCFS10 and UCFS15). Homology to “ Anabaena -type” mys clusters suggested that this cluster was likely to be involved in shinorine biosynthesis. Surprisingly, high-performance liquid chromatography analysis of S . cf. crispum cell extracts revealed a complex MAA profile, including shinorine, palythine-serine, and their hexose-bound variants. It was hypothesized that a short-chain dehydrogenase (UCFS15_00405) encoded by a gene adjacent to the S . cf. crispum mys cluster was responsible for the conversion of shinorine to palythine-serine. Heterologous expression of MysABCE and UCFS15_00405 in Escherichia coli resulted in the exclusive production of the parent compound shinorine. Taken together, these results suggest that shinorine biosynthesis in S . cf. crispum proceeds via an Anabaena -type mechanism and that the genes responsible for the production of other MAA analogues, including palythine-serine and glycosylated analogues, may be located elsewhere in the genome. IMPORTANCE Recently, New Zealand isolates of S . cf. crispum were linked to the production of paralytic shellfish toxins for the first time, but no other natural products from this species have been reported. Thus, the species was screened for important natural product biosynthesis. The mycosporine-like amino acids (MAAs) are among the strongest absorbers of UV radiation produced in nature. The identification of novel MAAs is important from a biotechnology perspective, as these molecules are able to be utilized as sunscreens. This study has identified two novel MAAs that have provided several new avenues of future research related to MAA genetics and biosynthesis. Further, we have revealed that the genetic basis of MAA biosynthesis may not be clustered on the genome. The identification of the genes responsible for MAA biosynthesis is vital for future genetic engineering.

Deteriogenic cyanobacteria on historic buildings in Brazil detected by culture and molecular techniques

Publisher: Elsevier BV

Date: 06-2006

DOI: 10.1016/J.IBIOD.2006.03.001

Molecular identification and characterization of three isoforms of tachykinin NK1-like receptors in the cane toad Bufo marinus

Publisher: American Physiological Society

Date: 09-2004

DOI: 10.1152/AJPREGU.00051.2004

Abstract: The tachykinin peptide bufokinin, isolated from the cane toad intestine, is important in intestinal and cardiovascular regulation in the toad. In this study, three tachykinin NK 1 -like receptor isoforms, bNK 1 -A, bNK 1 -B, and bNK 1 -C, encoding proteins of 309, 390, and 371 amino acids, respectively, were cloned from the toad brain and intestine. These isoforms differ only at the intracellular COOH terminus. The bNK 1 -A and bNK 1 -B isoforms are similar to the truncated and full-length forms of the mammalian NK 1 receptor, whereas bNK 1 -C is unique and does not correspond to any previously described receptor. RT-PCR studies demonstrated that three isoform transcripts are widely distributed in the toad with high expression in gut, spinal cord, brain, lung, and skeletal muscle. When expressed in COS-7 cells, bufokinin showed similar high affinity (IC 50 0.6–0.8 nM) in competing for 125 I-labeled Bolton-Hunter bufokinin binding at all receptors, but the binding affinities of substance P (SP) and neurokinin A (NKA) were very different at each isoform. When expressed in Xenopus oocytes, the truncated isoform, bNK 1 -A, was inactive, whereas bNK 1 -B and bNK 1 -C produced changes in chloride current when stimulated by tachykinins (minimum concentrations: bufokinin, 0.1 nM SP, 1 nM and NKA, 10 nM). A marked desensitization of the response was seen to subsequent applications of tachykinins, as experienced by the mammalian NK 1 receptor. In summary, our study describing three isoforms of NK 1 -like receptor from the toad suggests that the alternative splicing of NK 1 receptor is a physiologically conserved mechanism and raises a fundamental question as to the physiological role of each isoform.

The freshwater cyanobacterium Planktothrix sp. FP1: Molecular identification and detection of paralytic shellfish poisoning toxins

Publisher: Wiley

Date: 06-2000

DOI: 10.1046/J.1529-8817.2000.99181.X

Abstract: A filamentous cyanobacterium, belonging to the Order of Oscillatoriales, was found to be responsible for a toxic algal bloom in Lake Varese, Italy, during the summer of 1997. Morphological characters, as well as near complete 16S rRNA gene sequencing, revealed that the dominant species of the bloom was most closely related to the genus Planktothrix. In addition, genetic analysis of the phycocyanin operon of Planktothrix sp. FP1 revealed a novel primary structure, previously undescribed within the cyanobacteria, which was used as a genetic marker for rapid detection and identification of this toxic strain. The occurrence of saxitoxin (STX), a principal toxin in paralytic shellfish poisoning (PSP), was confirmed in the natural bloom s le by both pre-column and post-column derivatization high-performance liquid chromatography (HPLC) analyses, and eventually by liquid chromatography/mass spectrometry (LC/MS). The toxicity of this field s le was also revealed by electrophysiological assays in which the extract inhibited 90% of the voltage-dependent Na

The Molecular Evolution and DNA Profiling of Toxic Cyanobacteria

Publisher: MDPI AG

Date: 2002

DOI: 10.21775/CIMB.004.001

Uranium Binding Mechanisms of the Acid-Tolerant Fungus Coniochaeta fodinicola

Publisher: American Chemical Society (ACS)

Date: 09-07-2015

DOI: 10.1021/ACS.EST.5B01342

Abstract: The uptake and binding of uranium [as (UO2)(2+)] by a moderately acidophilic fungus, Coniochaeta fodinicola, recently isolated from a uranium mine site, is examined in this work in order to better understand the potential impact of organisms such as this on uranium sequestration in hydrometallurgical systems. Our results show that the viability of the fungal biomass is critical to their capacity to remove uranium from solution. Indeed, live biomass (viable cells based on vital staining) were capable of removing ∼16 mg U/g dry weight in contrast with dead biomass (autoclaved) which removed ∼45 mg U/g dry weight after 2 h. Furthermore, the uranium binds with different strength, with a fraction ranging from ∼20-50% being easily leached from the exposed biomass by a 10 min acid wash. Results from X-ray absorption spectroscopy measurements show that the strength of uranium binding is strongly influenced by cell viability, with live cells showing a more well-ordered uranium bonding environment, while the distance to carbon or phosphorus second neighbors is similar in all s les. When coupled with time-resolved laser fluorescence and Fourier transformed infrared measurements, the importance of organic acids, phosphates, and polysaccharides, likely released with fungal cell death, appear to be the primary determinants of uranium binding in this system. These results provide an important progression to our understanding with regard to uranium sequestration in hydrometallurgical applications with implications to the unwanted retention of uranium in biofilms and/or its mobility in a remediation context.

Contrasting effects of two mammalian soil engineers on microbial communities

Publisher: Wiley

Date: 24-11-2017

DOI: 10.1111/AEC.12467

Temporal variations in microcystin-producing cells and microcystin concentrations in two fresh water ponds

Publisher: Elsevier BV

Date: 02-2015

DOI: 10.1016/J.WATRES.2014.11.015

Abstract: The relationship between microcystin production, microcystin-producing cyanobacteria, including Microcystis spp., and various biological and physicochemical parameters in Sankuldhara and Lakshmikund, situated in the same geographical area was studied over a period of 1.5 years. Seasonal variation in cyanobacterial 16S rRNA, Microcystis spp. 16S rRNA, mcyA and mcyB genes were quantitatively determined by real-time PCR. Microcystis was the dominant microcystin producer in both study sites constituting 67% and 97% of the total microcystin-producing cyanobacteria at Sankuldhara and Lakshmikund, respectively. Microcystin concentrations were 2.19-39.60 μg/L and 15.22-128.14 μg/L at Sankuldhara and Lakshmikund, respectively, as determined by LC-MS. Principal component analysis revealed a strong positive correlation between microcystin concentration and the copy number of mcyA and mcyB, chlorophyll a and cyanobacterial biomass at both sites. The higher microcystin concentrations in Lakshmikund pond were attributed to the high copy number of mcy genes present coupled with the pond's eutrophication status, as indicated by high total algal biomass, high chlorophyll a content, high nutrient load and low DO. Therefore, a significant difference in microcystin concentrations, correlating with these various biological and physicochemical parameters, confirms the importance of local environmental variables in the overall regulation of microcystins production.

Tailoring Enzyme Stringency Masks the Multispecificity of a Lyngbyatoxin (Indolactam Alkaloid) Nonribosomal Peptide Synthetase

Publisher: Wiley

Date: 10-12-2021

DOI: 10.1002/CBIC.202100574

Abstract: Indolactam alkaloids are activators of protein kinase C (PKC) and are of pharmacological interest for the treatment of pathologies involving PKC dysregulation. The marine cyanobacterial nonribosomal peptide synthetase (NRPS) pathway for lyngbyatoxin biosynthesis, which we previously expressed in E. coli , was studied for its amenability towards the biosynthesis of indolactam variants. Modification of culture conditions for our E. coli heterologous expression host and analysis of pathway products suggested the native lyngbyatoxin pathway NRPS does possess a degree of relaxed specificity. Site‐directed mutagenesis of two positions within the adenylation domain (A‐domain) substrate‐binding pocket was performed, resulting in an alteration of substrate preference between valine, isoleucine, and leucine. We observed relative congruence of in vitro substrate activation by the LtxA NRPS to in vivo product formation. While there was a preference for isoleucine over leucine, the substitution of alternative tailoring domains may unveil the true in vivo effects of the mutations introduced herein.

Vitamin B₁₂ biosynthesis gene diversity in the Ross Sea: the identification of a new group of putative polar B₁₂ biosynthesizers

Publisher: Wiley

Date: 16-03-2011

DOI: 10.1111/J.1462-2920.2011.02428.X

Abstract: Vitamin B₁₂, a cobalt-containing micronutrient, has been shown to limit phytoplankton growth in the Ross Sea of the Southern Ocean. However, B₁₂ biosynthesis potential in this environment remains uncharacterized. Select bacteria and archaea synthesize B₁₂ while many phytoplankton require it for growth. Low ratios of bacterial biomass production to primary productivity and high concentrations of labile cobalt in Antarctic surface water suggest that factors controlling bacterial growth rather than cobalt availability may determine vitamin production rates here. In order to assess B₁₂ biosynthesis potential, degenerate polymerase chain reaction primers were designed to target the genetic locus cbiA/cobB, encoding cobyrinic acid a,c-diamide synthase, a B₁₂ biosynthesis protein. Sequencing the DNA compliment of Ross Sea 16S rRNA (see Supporting information) allowed targeting of cbiA/cobB probes to dominant bacterial groups. CbiA/cobB DNA sequences were successfully identified in clone libraries from the Ross Sea. To our knowledge, this study represents the first targeted molecular characterization of environmental B₁₂ biosynthesis potential. A newly identified group of cbiA/cobB sequences dominated the ersity of the sequences retrieved their expression was confirmed via mass spectrometry-based peptide detection. These sequences seem to have originated from a previously undescribed group of bacteria that could dominate the B₁₂ biosynthesizing community in polar systems.

Enhancement of intracellular saxitoxin accumulation by lidocaine hydrochloride in the cyanobacterium Cylindrospermopsis raciborskii T3 (Nostocales)

Publisher: Wiley

Date: 27-05-2003

DOI: 10.1046/J.1529-8817.2003.02122.X

The competence gene, comF, from Synechocystis sp. strain PCC 6803 is involved in natural transformation, phototactic motility and piliation

Publisher: Microbiology Society

Date: 12-2006

DOI: 10.1099/MIC.0.29189-0

Abstract: The gene slr0388 was previously annotated to encode a hypothetical protein in Synechocystis sp. strain PCC 6803. When a positively phototactic strain of this cyanobacterium was insertionally inactivated at slr0388 , the mutants were not transformable, and appeared to aggregate as a result of increased bundling of type IV pili. Also, these mutants were rendered non-phototactic compared to the wild-type. Quantitative real-time PCR revealed a 3.5-fold increase in pilA1 transcript levels in the mutant over wild-type cells, while there were no changes in the level of pilT1 and comA transcripts. Supernatant from mutant liquid culture contained more PilA1 protein, confirmed by mass spectrometric analysis, compared to the wild-type cells, which corresponded to the increase in pilA1 transcripts. The increase in PilA1 subunits may contribute to the bundling morphology of pili that was observed, which in turn may act to retard DNA uptake by hindering the retraction of pili. This gene is therefore proposed to be designated comF , as it possesses a phosphoribosyltransferase domain, a distinguishing feature of other ComF proteins of naturally transformable heterotrophic bacteria. This report is the second of a competence-related gene from Synechocystis sp. strain PCC 6803, the product of which does not show homology to other well-studied type IV pili proteins.

Microbial diversity and diazotrophy associated with the freshwater non-heterocyst forming cyanobacterium Lyngbya robusta

Publisher: Springer Science and Business Media LLC

Date: 25-09-2013

DOI: 10.1007/S10811-012-9909-Y

Assessment of salinity-induced photorespiratory glycolate metabolism in Anabaena sp. PCC 7120

Publisher: Microbiology Society

Date: 03-2011

DOI: 10.1099/MIC.0.045682-0

Abstract: This paper reports an investigation of salinity-induced glycolate metabolism in the cyanobacterium Anabaena sp. PCC 7120 (hereafter Anabaena PCC 7120). Quantitative analysis of transcripts for the photosynthesis-associated genes encoding ribulose-1,5-bisphosphate carboxylase oxygenase (Rubisco), phosphoribulokinase and transketolase, as well as those involved in glycolate metabolism (phosphoglycolate phosphatase, glycolate oxidase, alanine-glyoxylate aminotransferase and serine hydroxymethyltransferase) was performed. The expression of all investigated photosynthesis-associated genes except Rubisco was downregulated after 24 h NaCl treatment. However, under the same conditions, the transcripts encoding enzymes involved in glycolate metabolism were overexpressed. This was further confirmed by the quantitative analysis of the intermediates involved in glycolate metabolism. The intracellular levels of organic acids (glyceric, glycolic and glyoxylic acids) and amino acids (glycine and serine) were elevated in salt-treated cells as compared to those in the control cells. Transcriptional inhibition of photosynthesis-associated genes, and upregulation of genes and enhanced synthesis of intermediates associated with glycolate metabolism, indicate the occurrence of this photorespiratory metabolic pathway metabolism in Anabaena PCC 7120 under salt stress.

Neurotoxic Alkaloids: Saxitoxin and Its Analogs

Publisher: MDPI AG

Date: 20-07-2010

DOI: 10.3390/MD8072185

Algicide production by the filamentous cyanobacterium Fischerella sp. CENA 19

Publisher: Springer Science and Business Media LLC

Date: 06-2004

DOI: 10.1023/B:JAPH.0000048509.77816.5E

Erratum: Identification of a saxitoxin biosynthesis gene with a history of frequent horizontal gene transfers (Journal of Molecular Evolution (2008) 67 (526-538) DOI: 10.1007/s00239-008-9169-2)

Publisher: Springer Science and Business Media LLC

Date: 21-02-2009

DOI: 10.1007/S00239-009-9210-0

Alexandrium diversaporum sp. nov., a new non-saxitoxin producing species: Phylogeny, morphology and sxtA genes

Publisher: Elsevier BV

Date: 2014

DOI: 10.1016/J.HAL.2013.09.005

Abstract: Species of the PST producing planktonic marine dinoflagellate genus Alexandrium have been intensively scrutinised, and it is therefore surprising that new taxa can still be found. Here we report a new species, Alexandrium ersaporum nov. sp., isolated from spherical cysts found at two sites in Tasmania, Australia. This species differs in its morphology from all previously reported Alexandrium species, possessing a unique combination of morphological features: the presence of 2 size classes of thecal pores on the cell surface, a medium cell size, the size and shape of the 6″, 1', 2⁗ and Sp plates, the lack of a ventral pore, a lack of anterior and posterior connecting pores, and a lack of chain formation. We determined the relationship of the two strains to other species of Alexandrium based on an alignment of concatenated SSU-ITS1, 5.8S, ITS2 and partial LSU ribosomal RNA sequences, and found A. ersaporum to be a sister group to Alexandrium leei with high support. A. leei shares several morphological features, including the relative size and shapes of the 6″, 1', 2⁗ and Sp plates and the fact that some strains of A. leei have two size classes of thecal pores. We examined A. ersaporum strains for saxitoxin production and found them to be non-toxic. The species lacked sequences for the domain A4 of sxtA, as has been previously found for non-saxitoxin producing species of Alexandrium.

Uranium extraction from a low-grade, stockpiled, non-sulfidic ore: Impact of added iron and the native microbial consortia

Publisher: Elsevier BV

Date: 2017

DOI: 10.1016/J.HYDROMET.2016.11.002

Characteristics of a Microcystin-Degrading Bacterium under Alkaline Environmental Conditions

Publisher: Hindawi Limited

Date: 2009

DOI: 10.1155/2009/954291

Abstract: The pH of the water associated with toxic blooms of cyanobacteria is typically in the alkaline range however, previously only microcystin-degrading bacteria growing in neutral pH conditions have been isolated. Therefore, we sought to isolate and characterize an alkali-tolerant microcystin-degrading bacterium from a water bloom using microcystin-LR. Analysis of the 16S rRNA gene sequence revealed that the isolated bacterium belonged to the genus Sphingopyxis , and the strain was named C-1. Sphingopyxis sp. C-1 can grow at pH 11.0 however, the optimum pH for growth was pH 7.0. The microcystin degradation activity of the bacterium was the greatest between pH 6.52 and pH 8.45 but was also detected at pH 10.0. The mlrA homolog encoding the microcystin-degrading enzyme in the C-1 strain was conserved. We concluded that alkali-tolerant microcystin-degrading bacterium played a key role in triggering the rapid degradation of microcystin, leading to the disappearance of toxic water blooms in aquatic environments.

Insertions within the Saxitoxin Biosynthetic Gene Cluster Result in Differential Toxin Profiles

Publisher: American Chemical Society (ACS)

Date: 08-10-2018

DOI: 10.1021/ACSCHEMBIO.8B00608

Abstract: The neurotoxin saxitoxin and related paralytic shellfish toxins are produced by multiple species of cyanobacteria and dinoflagellates. This study investigates the two saxitoxin-producing strains of Scytonema crispum, CAWBG524 and CAWBG72, isolated in New Zealand. Each strain was previously reported to have a distinct paralytic shellfish toxin profile, a rare observation between strains within the same species. Sequencing of the saxitoxin biosynthetic clusters ( sxt) from S. crispum CAWBG524 and S. crispum CAWBG72 revealed the largest sxt gene clusters described to date. The distinct toxin profiles of each strain were correlated to genetic differences in sxt tailoring enzymes, specifically the open-reading frame disruption of the N-21 sulfotransferase sxtN, adenylylsulfate kinase sxtO, and the C-11 dioxygenase sxtDIOX within S. crispum CAWBG524 via genetic insertions. Heterologous overexpression of SxtN allowed for the proposal of saxitoxin and 3'-phosphoadenosine 5'-phosphosulfate as substrate and cofactor, respectively, using florescence binding assays. Further, catalytic activity of SxtN was confirmed by the in vitro conversion of saxitoxin to the N-21 sulfonated analog gonyautoxin 5, making this the first known report to biochemically confirm the function of a sxt tailoring enzyme. Further, SxtN could not convert neosaxitoxin to its N-21 sulfonated analog gonyautoxin 6, indicating paralytic shellfish toxin biosynthesis most likely occurs along a predefined route. In this study, we identified key steps toward the biosynthetic conversation of saxitoxin to other paralytic shellfish toxins.

Combined genetic and bioactivity-based prioritization leads to the isolation of an endophyte-derived antimycobacterial compound

Publisher: Oxford University Press (OUP)

Date: 04-04-2016

DOI: 10.1111/JAM.13062

Abstract: To initiate a genetic and bioactivity-based screening programme of culturable endophytes to identify micro-organisms capable of producing bioactive polyketides and peptides. Fungal endophytes were isolated from flowers, leaves and roots of Rhoeo spathacea, revealing a community consisting of Colletotrichum sp., Fusarium sp., Guignardia sp., Phomopsis sp., Phoma sp. and Microdochium sp. Genetic screening showed that all isolates had polyketide synthase (PKS) genes and most had nonribosomal peptide synthetase (NRPS) genes. Ethyl acetate extracts of the fungal isolates exhibited antiproliferative activity against at least one of the seven bacterial and mycobacterial test strains. Nuclear Magnetic Resonance -guided fractionation of the crude extract from a Fusarium sp. strain which exhibited strong antiproliferative activity against Mycobacterium tuberculosis resulted in the isolation of the polyketide javanicin. This compound was active against Myco. tuberculosis (MIC = 25 μg ml(-1)) and Mycobacterium phlei (MIC = 50 μg ml(-1)). The medicinal plant R. spathacea hosts a variety of fungal endophytes capable of producing antibacterial and antimycobacterial compounds. There is a positive correlation between the presence of PKS and/or NRPS encoding genes in endophytes and the bioactivity of their respective organic extracts. This is the first report on the fungal endophytic ersity of R. spathacea, and the isolation of an antimycobacterial compound from the plant which has been traditionally used for the treatment of tuberculosis symptoms.

Global cellular responses to β-methyl-amino-l-alanine (BMAA) by olfactory ensheathing glial cells (OEC)

Publisher: Elsevier BV

Date: 06-2015

DOI: 10.1016/J.TOXICON.2015.03.009

Abstract: This study utilised a proteomics approach to identify any differential protein expression in a glial cell line, rat olfactory ensheathing cells (OECs), treated with the cyanotoxin β-methylamino-l-alanine (BMAA). Five proteins of interest were identified, namely Rho GDP-dissociation inhibitor 1 (RhoGDP1), Nck-associated protein 1 (NCKAP1), voltage-dependent anion-selective channel protein 1 (VDAC1), 3-hydroxyacyl-CoA dehydrogenase type-2 (3hCoAdh2), and ubiquilin-4 (UBQLN4). Four of these candidates, nuclear receptor subfamily 4 group A member 1 (Nur77), cyclophilin A (CyPA), RhoGDP1 and VDAC1, have been reported to be involved in cell growth. A microarray identified UBQLN4, palladin and CyPA, which have been implicated to have roles in excitotoxicity. Moreover, the NCKAP1, UBQLN4, CyPA and 3hCoAdh2 genes have been associated with abnormal protein aggregation. Differential expression of genes involved in mitochondrial activity, Nur77, 3hCoAdh2, VDAC1 and UBQLN4, were also identified. Confirmatory reverse transcription quantitative PCR (RT-qPCR) analysis of transcripts generated from the genes of interest corroborated the differential expression trends identified in the global protein analysis. BMAA induced cell cycle arrest in the G2/M phase of OEC and apoptosis after 48 h at concentrations of 250 μM and 500 μM. Collectively, this work advances our understanding of the mechanism of BMAA-mediated glial-toxicity in vitro.

Understanding the winning strategies used by the bloom-forming cyanobacterium Cylindrospermopsis raciborskii

Publisher: Elsevier BV

Date: 04-2016

DOI: 10.1016/J.HAL.2015.10.012

Abstract: The cyanobacterium Cylindrospermopsis raciborskii is a widespread species increasingly being recorded in freshwater systems around the world. It is of particular concern because strains in some geographic areas are capable of producing toxins with implications for human and animal health. Studies of this species have increased rapidly in the last two decades, especially in the southern hemisphere where toxic strains are prevalent. A clearer picture is emerging of the strategies adopted by this species to bloom and out-compete other species. This species has a high level of flexibility with respect to light and nutrients, with higher temperatures and carbon dioxide also promoting growth. There are two types of toxins produced by C. raciborskii: cylindrospermopsins (CYNs) and saxitoxins (STXs). The toxins CYNs are constitutively produced irrespective of environmental conditions and the ecological or physiological role is unclear, while STXs appear to serve as protection against high salinity and/or water hardness. It is also apparent that strains of this species can vary substantially in their physiological responses to environmental conditions, including CYNs production, and this may explain discrepancies in findings from studies in different geographical areas. The combination of a flexible strategy with respect to environmental conditions, and variability in strain response makes it a challenging species to manage. Our ability to improve bloom prediction will rely on a more detailed understanding of the complex physiology of this species.

NifHgene diversity and expression in a microbial mat community on the McMurdo Ice Shelf, Antarctica

Publisher: Cambridge University Press (CUP)

Date: 18-09-2009

DOI: 10.1017/S0954102009990514

Abstract: N 2 -fixation is an important mechanism in microbial mats of the McMurdo Ice Shelf as nitrogen sources are limited. Here we applied molecular analyses of the N 2 -fixing ersity in cyanobacterial dominated microbial mats in a meltwater pond, known as Orange Pond, on the McMurdo Ice Shelf. Phylogenetic analyses of nifH genes and nifH gene transcripts were performed in association with acetylene reduction assay measurements. Eighteen phylotypes with the highest similarities to cyanobacteria, firmicutes, beta-, gamma- and deltaproteobacteria, spirochaetes and verrumicrobia were identified. All cyanobacterial nifH phylotypes grouped solely in the genus Nostoc spp. Clone-library analysis of nifH gene transcripts only identified sequences with a highest match to Nostoc spp. and acetylene reduction activity was identified in the presence of light and absence of 3-(3,4-dichlorophenyl)-1,1-dimethyl urea. These molecular results indicate that a variety of bacterial phyla possess the ability to fix nitrogen. However, under the tested conditions the only organisms actively transcribing nifH genes were Nostoc spp. This underlines the importance of Nostoc for the nitrogen budget on the McMurdo Ice Shelf.

Cyanobacteria from Brazilian building walls are distant relatives of aquatic genera

Publisher: Mary Ann Liebert Inc

Date: 03-2005

DOI: 10.1089/OMI.2005.9.30

Abstract: The 16S-rDNA from 22 cyanobacteria isolated from biofilms on walls of modern and historic buildings in Brazil was partially sequenced (approximately 350 bp) using specific primers. The cyanobacteria with the closest matching sequences were found using the BLAST tool. The sequences were combined with 52 other cyanobacterial sequences already deposited in public data banks and a dendrogram constructed, after deletion from each sequence of one of the variable 16S rDNA regions (VI). The newly sequenced organisms fitted well within their respective families, but their similarities to other members of the groups were generally low, less than 96%. Close matches were found only with one other terrestrial (hot dry desert) cyanobacterium, Microcoleus sociatus, and with Anabaena variabilis. Phylogenetic analysis suggested that the deletion of the hypervariable regions in the RNA structure is essential for meaningful evolutionary studies. The results support the standard phylogenetic tree based on morphology, but suggest that these terrestrial cyanobacteria are distant relatives of their equivalent aquatic genera and are, indeed, a distinct population.

Polyphasic detection of cyanobacteria in terrestrial biofilms

Publisher: Informa UK Limited

Date: 04-2004

DOI: 10.1080/08927010410001681237

Identification of genes implicated in toxin production in the cyanobacterium Cylindrospermosis raciborskii

Publisher: Wiley

Date: 10-2001

DOI: 10.1002/TOX.1051

Abstract: Cylindrospermopsis raciborskii is a bloom-forming cyanobacterium found in both tropical and temperate climates which produces cylindrospermopsin, a potent hepatotoxic secondary metabolite. This organism is notorious for its association with a significant human poisoning incident on Palm Island, Australia, which resulted in the hospitalization of 148 people. We have screened 13 C. raciborskii isolates from various regions of Australia and shown that both toxic and nontoxic strains exist within this species. No association was observed between geographical origin and toxin production. Polyketide synthases (PKSs) and peptide synthetases (PSs) are enzymes involved in secondary metabolite biosynthesis in cyanobacteria. Putative PKS and PS genes from C. raciborskii strains AWT205 and CYP020B were identified by PCR using degenerate primers based on conserved regions within each gene. Examination of the strain-specific distribution of the PKS and PS genes in C. raciborskii isolates demonstrated a direct link between the presence of these two genes and the ability to produce cylindrospermopsin. Interestingly, the possession of these two genes was also linked. They were also identified in an Anabaena bergii isolate that was demonstrated to produce cylindrospermopsin. Taken together, these data suggest a likely role for these determinants in secondary metabolite and toxin production by C. raciborskii.

Australian bush medicines harbour diverse microbial endophytes with broad‐spectrum antibacterial activity

Publisher: Oxford University Press (OUP)

Date: 11-06-2021

DOI: 10.1111/JAM.15122

DNA restriction-modification systems in the ethanologen, Zymomonas mobilis ZM4

Publisher: Springer Science and Business Media LLC

Date: 19-10-2010

DOI: 10.1007/S00253-010-2936-1

Abstract: To better understand the DNA restriction-modification (R-M) systems for more amenable strain development of the alternative industrial ethanologen, Zymomonas mobilis, three gene knockout mutants were constructed. The gene knockout mutants were tested for their DNA restriction activities by the determination of transformation efficiency using methylated and unmethylated foreign plasmid DNAs. Inactivation of a putative mrr gene encoded by ZMO0028 (zmrr) resulted in a 60-fold increase in the transformation efficiency when unmethylated plasmid DNA was used. This indicated that the putative mrr gene may serve as a type IV restriction-modification system in Z. mobilis ZM4. To assign the function of a putative type I DNA methyltransferase encoded by ZMO1933 (putative S subunit) and ZMO1934 (putative M subunit), the putative S subunit was inactivated. The gene inactivation of ZMO1933 resulted in a 30-fold increase in the transformation efficiency when methylated plasmid DNA was introduced, indicating that the putative S subunit possibly serves as a part of functional type I R-M system(s). Growth studies performed on the mutant strains indicate inactivation of the type I S subunit resulted in a lower maximum specific glucose consumption rate and biomass yield, while inactivation of the type IV Zmrr had the opposite effect, with an increase in the maximum specific growth rate and biomass yield.

Genetic diversity, morphological uniformity and polyketide production in dinoflagellates (Amphidinium, Dinoflagellata)

Publisher: Public Library of Science (PLoS)

Date: 04-06-2012

DOI: 10.1371/JOURNAL.PONE.0038253

Cyanobacterial Protease Inhibitor Microviridin J Causes a Lethal Molting Disruption in Daphnia pulicaria

Publisher: American Society for Microbiology

Date: 08-2004

DOI: 10.1128/AEM.70.8.5047-5050.2004

Abstract: Laboratory experiments identified microviridin J as the source of a fatal molting disruption in Daphnia species organisms feeding on Microcystis cells. The molting disruption was presumably linked to the inhibitory effect of microviridin J on daphnid proteases, suggesting that hundreds of further cyanobacterial protease inhibitors must be considered potentially toxic to zooplankton.

Monitoring changing toxigenicity of a cyanobacterial bloom by molecular methods

Publisher: American Society for Microbiology

Date: 12-2014

DOI: 10.1128/AEM.68.12.6070-6076.2002

Abstract: Cyanobacterial blooms are potential health hazards in water supply reservoirs. This paper reports analyses of a cyanobacterial bloom by use of PCR-based methods for direct detection and identification of strains present and determination of their toxigenicity. Serial s les from Malpas Dam, in the New England region of Australia, were analyzed during a prolonged, mixed cyanobacterial bloom in the summer of 2000 to 2001. Malpas Dam has been shown in the past to have toxic blooms of Microcystis aeruginosa that have caused liver damage in the human population drinking from this water supply reservoir. Cyanobacterial genera were detected at low cell numbers by PCR lification of the phycocyanin intergenic spacer region between the genes for the β and α subunits. The potential for microcystin production was determined by PCR lification of a gene in the microcystin biosynthesis pathway. The potential for saxitoxin production was determined by PCR lification of a region of the 16S rRNA gene of Anabaena circinalis strains. Toxicity of s les was established by mouse bioassay and high-pressure liquid chromatography. We show that bloom components can be identified and monitored for toxigenicity by PCR more effectively than by other methods such as microscopy and mouse bioassay. We also show that toxigenic strains of Anabaena and Microcystis spp. occur at this site and that, over the course of the bloom, the cell types and toxicity changed. This work demonstrates that PCR detection of potential toxicity can enhance the management of a significant public health hazard.

Genetic Variation of the Bloom-Forming Cyanobacterium Microcystis aeruginosa within and among Lakes: Implications for Harmful Algal Blooms

Publisher: American Society for Microbiology

Date: 10-2005

DOI: 10.1128/AEM.71.10.6126-6133.2005

Abstract: To measure genetic variation within and among populations of the bloom-forming cyanobacterium Microcystis aeruginosa , we surveyed a suite of lakes in the southern peninsula of Michigan that vary in productivity (total phosphorus concentrations of ∼10 to 100 μg liter −1 ). Survival of M. aeruginosa isolates from lakes was relatively low (i.e., mean of 7% and maximum of 30%) and positively related to lake total phosphorus concentration ( P = 0.014, r 2 = 0.407, n = 14). In another study (D. F. Raikow, O. Sarnelle, A. E. Wilson, and S. K. Hamilton, Limnol. Oceanogr. 49:482-487, 2004), survival rates of M. aeruginosa isolates collected from an oligotrophic lake (total phosphorus of ∼10 μg liter −1 and dissolved inorganic nitrogen:total phosphorus ratio of 12.75) differed among five different medium types ( G test, P of .001), with higher survival ( P = 0.003) in low-nutrient media (28 to 37% survival) than in high-nutrient media. Even with the relatively low isolate survivorship that could select against detecting the full range of genetic variation, populations of M. aeruginosa were genetically erse within and among lakes (by analysis of molecular variance, Φ sc = 0.412 [Φ sc is an F-statistic derivative which evaluates the correlation of haplotypic ersity within populations relative to the haplotypic ersity among all s led populations], P = 0.001), with most clones being distantly related to clones collected from lakes directly attached to Lake Michigan (a Laurentian Great Lake) and culture collection strains collected from Canada, Scotland, and South Africa. Ninety-one percent of the 53 genetically unique M. aeruginosa clones contained the microcystin toxin gene ( mcyA ). Genotypes with the toxin gene were found in all lakes, while four lakes harbored both genotypes possessing and genotypes lacking the toxin gene.

Constitutive cylindrospermopsin pool size in Cylindrospermopsis raciborskii under different light and CO<inf>2</inf> partial pressure conditions

Publisher: American Society for Microbiology

Date: 05-2015

DOI: 10.1128/AEM.03556-14

Abstract: Cylindrospermopsin (CYN) and 7-deoxy-cylindrospermopsin (dCYN) are potent hepatotoxic alkaloids produced by numerous species of cyanobacteria, including the freshwater Cylindrospermopsis raciborskii . C. raciborskii is an invasive cyanobacterium, and the study of how environmental parameters drive CYN production has received significant interest from water managers and health authorities. Light and CO 2 affect cell growth and physiology in photoautotrophs, and these are potential regulators of cyanotoxin biosynthesis. In this study, we investigated how light and CO 2 affect CYN and dCYN pool size as well as the expression of the key genes, cyrA and cyrK , involved in CYN biosynthesis in a toxic C. raciborskii strain. For cells growing at different light intensities (10 and 100 μmol photons m −2 s −1 ), we observed that the rate of CYN pool size production (μ CYN ) was coupled to the cell ision rate (μ c ) during batch culture. This indicated that CYN pool size under our experimental conditions is constant and cell quotas of CYN (Q CYN ) and dCYN (Q dCYN ) are fixed. Moreover, a lack of correlation between expression of cyrA and total CYN cell quotas (Q CYNs ) suggests that the CYN biosynthesis is regulated posttranscriptionally. Under elevated CO 2 (1,300 ppm), we observed minor effects on Q CYN and no effects on expression of cyrA and cyrK . We conclude that the CYN pool size is constitutive and not affected by light and CO 2 conditions. Thus, C. raciborskii bloom toxicity is determined by the absolute abundance of C. raciborskii cells within the water column and the relative abundance of toxic and nontoxic strains.

Extant Analogues of the Microbial Origins of Life

Publisher: CRC Press

Date: 19-04-2016

DOI: 10.1201/B10193-9

Detection of microcystin synthetase genes in health food supplements containing the freshwater cyanobacterium Aphanizomenon flos-aquae

Publisher: Elsevier BV

Date: 10-2005

DOI: 10.1016/J.TOXICON.2005.06.021

Abstract: In this study we investigated the presence of toxin-producing cyanobacterial contaminants in food supplements manufactured from blooms of the non-toxic freshwater cyanobacterium Aphanizomenon flos-aquae. Previous reports investigating the contamination of health food supplements with toxin-producing cyanobacteria have used chemical and or biochemical methods such as HPLC, ELISA and protein phosphatase assays. Whilst these studies have drawn attention to the presence of hepatotoxic microcystins in some commercially available food supplements, the methods used do not provide any information on the source of the contaminant. Such information would be useful for the quality control of food supplements produced for human consumption. In this study we applied a molecular technique, involving the lification of the 16s rRNA gene, the phycocyanin operon, and two genes of the microcystin synthetase gene cluster to show that all 12 food supplement s les, sourced from various internet distributors and containing non-toxic A. flos-aquae, also contained toxigenic cyanobacteria. Sequencing of the microcystin synthetase genes detected in all of the food supplements showed that M. aeruginosa was the organism responsible for the production of microcystins in the s les. The presence of microcystins in the food supplements was confirmed by ELISA, with concentrations within the range of 0.1--4.72 microgg(-1) (microcystin-LR equivalents). Given that the molecular methods applied here are highly sensitive, and show good agreement with the results obtained from ELISA, we believe that they could potentially be used as a quality control technique for food products that contain cyanobacteria.

Characterization, differentiation and identification of wild-type cellulose-synthesizing Acetobacter strains involved in Nata de Coco production

Publisher: Elsevier BV

Date: 12-1998

DOI: 10.1016/S0723-2020(98)80073-8

Bioactive natural products from Papua New Guinea marine sponges

Publisher: Wiley

Date: 10-2012

DOI: 10.1002/CBDV.201100292

Abstract: The discovery of novel natural products for drug development relies heavily upon a rich bio ersity, of which the marine environment is an obvious ex le. Marine natural product research has spawned several drugs and many other candidates, some of which are the focus of current clinical trials. The sponge mega ersity of Papua New Guinea is a rich but underexplored source of bioactive natural products. Here, we review some of the many natural products derived from PNG sponges with an emphasis on those with interesting biological activity and, therefore, drug potential. Many bioactive natural products discussed here appear to be derived from non‐ribosomal peptide and polyketide biosynthesis pathways, strongly suggesting a microbial origin of these compounds. With this in mind, we also explore the notion of sponge‐symbiont biosynthesis of these bioactive compounds and present ex les to support the working hypothesis.

The genetics, biosynthesis and regulation of toxic specialized metabolites of cyanobacteria

Publisher: Elsevier BV

Date: 04-2016

DOI: 10.1016/J.HAL.2015.11.002

Abstract: The production of toxic metabolites by cyanobacterial blooms represents a significant threat to the health of humans and ecosystems worldwide. Here we summarize the current state of the knowledge regarding the genetics, biosynthesis and regulation of well-characterized cyanotoxins, including the microcystins, nodularin, cylindrospermopsin, saxitoxins and anatoxins, as well as the lesser-known marine toxins (e.g. lyngbyatoxin, aplysiatoxin, jamaicamides, barbamide, curacin, hectochlorin and apratoxins).

Cytotoxic Effects of Environmental Toxins on Human Glial Cells

Publisher: Springer Science and Business Media LLC

Date: 29-10-2017

DOI: 10.1007/S12640-016-9678-5

Abstract: Toxins produced by cyanobacteria and dinoflagellates have increasingly become a public health concern due to their degenerative effects on mammalian tissue and cells. In particular, emerging evidence has called attention to the neurodegenerative effects of the cyanobacterial toxin β-N-methylamino-L-alanine (BMAA). Other toxins such as the neurotoxins saxitoxin and ciguatoxin, as well as the hepatotoxic microcystin, have been previously shown to have a range of effects upon the nervous system. However, the capacity of these toxins to cause neurodegeneration in human cells has not, to our knowledge, been previously investigated. This study aimed to examine the cytotoxic effects of BMAA, microcystin-LR (MC-LR), saxitoxin (STX) and ciguatoxin (CTX-1B) on primary adult human astrocytes. We also demonstrated that α-lipoate attenuated MC-LR toxicity in primary astrocytes and characterised changes in gene expression which could potentially be caused by these toxins in primary astrocytes. Herein, we are the first to show that all of these toxins are capable of causing physiological changes consistent with neurodegeneration in glial cells, via oxidative stress and excitotoxicity, leading to a reduction in cell proliferation culminating in cell death. In addition, MC-LR toxicity was reduced significantly in astrocytes-treated α-lipoic acid. While there were no significant changes in gene expression, many of the probes that were altered were associated with neurodegenerative disease pathogenesis. Overall, this is important in advancing our current understanding of the mechanism of toxicity of MC-LR on human brain function in vitro, particularly in the context of neurodegeneration.

Biochemical characterization of paralytic shellfish toxin biosynthesis in vitro

Publisher: Wiley

Date: 16-05-2007

DOI: 10.1111/J.1529-8817.2007.00351.X

Elevated nutrients change bacterial community composition and connectivity: high throughput sequencing of young marine biofilms

Publisher: Informa UK Limited

Date: 02-01-2016

DOI: 10.1080/08927014.2015.1126581

Abstract: Biofilms are integral to many marine processes but their formation and function may be affected by anthropogenic inputs that alter environmental conditions, including fertilisers that increase nutrients. Density composition and connectivity of biofilms developed in situ (under ambient and elevated nutrients) were compared using 454-pyrosequencing of the 16S gene. Elevated nutrients shifted community composition from bacteria involved in higher processes (eg Pseudoalteromonas spp. invertebrate recruitment) towards more nutrient-tolerant bacterial species (eg Terendinibacter sp.). This may enable the persistence of biofilm communities by increasing resistance to nutrient inputs. A core biofilm microbiome was identified (predominantly Alteromonadales and Oceanospirillales) and revealed shifts in abundances of core microbes that could indicate enrichment by fertilisers. Fertiliser decreased density and connectivity within biofilms indicating that associations were disrupted perhaps via changes to energetic allocations within the core microbiome. Density composition and connectivity changes suggest nutrients can affect the stability and function of these important marine communities.

Hive Transplantation Has Minimal Impact on the Core Gut Microbiome of the Australian Stingless Bee, Tetragonula carbonaria

Publisher: Springer Science and Business Media LLC

Date: 24-04-2023

DOI: 10.1007/S00248-023-02222-W

Abstract: Bacteria residing in the guts of pollinating insects play a key role in nutrient acquisition, digestion, and resistance to pests and diseases. Imbalances in microbial flora in response to environmental change and stress can therefore impact insect health and resilience. This study is aimed at defining the core gut microbiome of the Australian native stingless bee, Tetragonula carbonaria , and exploring the impact of colony transplantation on gut health. The gut microbiomes of nine forager bees from natural (log) and manufactured (box) hives were examined via 16S rRNA gene licon sequencing. Some differences were observed at the ASV level between the microbiomes of log and box hive bees. However, a core microbiome, dominated by Lactobacillus spp., unclassified Acetobacteraceae spp., and Bombella spp., was maintained. Further, the inferred functional potential of the microbiomes was consistent across all in iduals. This study highlights that although hive transplantation has an impact on the overall ersity of stingless bee gut microbiomes, it is unlikely to have a significant negative impact on the overall health and resilience of the colony.

The molecular genetics of cyanobacterial toxicity as a basis for monitoring water quality and public health risk

Publisher: Elsevier BV

Date: 06-2008

DOI: 10.1016/J.COPBIO.2008.03.002

Abstract: Toxic cyanobacteria pose a significant hazard to human health and the environment. The recent characterisation of cyanotoxin synthetase gene clusters has resulted in an explosion of molecular detection methods for these organisms and their toxins. Conventional polymerase chain reaction (PCR) tests targeting cyanotoxin biosynthesis genes provide a rapid and sensitive means for detecting potentially toxic populations of cyanobacteria in water supplies. The adaptation of these simple PCR tests into quantitative methods has additionally enabled the monitoring of dynamic bloom populations and the identification of particularly problematic species. More recently, DNA microarray technology has been applied to cyanobacterial diagnostics offering a high-throughput option for detecting and differentiating toxic genotypes in complex s les. Together, these molecular methods are proving increasingly important for monitoring water quality.

The molecular genetics and regulation of cyanobacterial peptide hepatotoxin biosynthesis

Publisher: Informa UK Limited

Date: 2008

DOI: 10.1080/10408440802291513

Abstract: Over the last 10 years, we have witnessed major advances in our understanding of natural product biosynthesis, including the genetic basis for toxin production by numerous groups of cyanobacteria. Cyanobacteria produce an unparalleled array of bioactive secondary metabolites, including alkaloids, polyketides and non-ribosomal peptides, some of which are potent toxins. This review addresses the molecular genetics underlying the production of hepatotoxins, microcystin and nodularin in fresh and brackish water. These toxins pose a serious threat to human health and their occurrence in water supplies is increasing, because of the prevalence of toxic algal blooms worldwide. Toxin biosynthesis gene-cluster-associated transposition and the natural transformability of certain species suggest a broader distribution of toxic cyanobacterial taxa. The information gained from the discovery of these toxin biosynthetic pathways has enabled the genetic screening of various environments for drinking-water quality management. Understanding the role of cyanotoxins in the producing microorganisms and the environmental regulation of their biosynthesis genes may also suggest the means of controlling toxic-bloom events.

Functional analysis of PilT from the toxic cyanobacterium Microcystis aeruginosa PCC 7806

Publisher: American Society for Microbiology

Date: 03-2007

DOI: 10.1128/JB.01640-06

Abstract: The evolution of the microcystin toxin gene cluster in phylogenetically distant cyanobacteria has been attributed to recombination, inactivation, and deletion events, although gene transfer may also be involved. Since the microcystin-producing Microcystis aeruginosa PCC 7806 is naturally transformable, we have initiated the characterization of its type IV pilus system, involved in DNA uptake in many bacteria, to provide a physiological focus for the influence of gene transfer in microcystin evolution. The type IV pilus genes pilA , pilB , pilC , and pilT were shown to be expressed in M. aeruginosa PCC 7806. The purified PilT protein yielded a maximal ATPase activity of 37.5 ± 1.8 nmol P i min −1 mg protein −1 , with a requirement for Mg 2+ . Heterologous expression indicated that it could complement the pilT mutant of Pseudomonas aeruginosa , but not that of the cyanobacterium Synechocystis sp. strain PCC 6803, which was unexpected. Differences in two critical residues between the M. aeruginosa PCC 7806 PilT (7806 PilT) and the Synechocystis sp. strain PCC 6803 PilT proteins affected their theoretical structural models, which may explain the nonfunctionality of 7806 PilT in its cyanobacterial counterpart. Screening of the pilT gene in toxic and nontoxic strains of Microcystis was also performed.

Chromera velia is Endosymbiotic in Larvae of the Reef Corals Acropora digitifera and A. tenuis

Publisher: Elsevier BV

Date: 03-2013

DOI: 10.1016/J.PROTIS.2012.08.003

Abstract: Scleractinian corals occur in symbiosis with a range of organisms including the dinoflagellate alga, Symbiodinium, an association that is mutualistic. However, not all symbionts benefit the host. In particular, many organisms within the microbial mucus layer that covers the coral epithelium can cause disease and death. Other organisms in symbiosis with corals include the recently described Chromera velia, a photosynthetic relative of the apicomplexan parasites that shares a common ancestor with Symbiodinium. To explore the nature of the association between C. velia and corals we first isolated C. velia from the coral Montipora digitata and then exposed aposymbiotic Acropora digitifera and A. tenuis larvae to these cultures. Three C. velia cultures were isolated, and symbiosis was established in coral larvae of both these species exposed to all three clones. Histology verified that C. velia was located in the larval endoderm and ectoderm. These results indicate that C. velia has the potential to be endosymbiotic with coral larvae.

Benthic cyanobacteria (Oscillatoriaceae) that produce microcystin-LR, isolated from four reservoirs in southern California

Publisher: Elsevier BV

Date: 2007

DOI: 10.1016/J.WATRES.2006.10.012

Abstract: Cyanobacteria that produce the toxin microcystin have been isolated from many parts of the world. Most of these organisms are planktonic however, we report on several microcystin-producing benthic filamentous cyanobacterial isolates from four drinking-water reservoirs in southern California (USA): Lake Mathews, Lake Skinner, Diamond Valley Lake (DVL), and Lake Perris. Some s les of benthic material from these reservoirs tested positive for microcystin by an ELISA tube assay, and all the positive s les had in common a green filamentous cyanobacterium 10-15microm in diameter. Seventeen unialgal strains of the organism were isolated and tested positive by ELISA, and 11 cultures of these strains were found to contain high concentrations of microcystin-LR (90-432microgL(-1)). The cultures were analyzed by protein phosphatase inhibition assay (PPIA) and HPLC with photodiode array detector (PDA) or liquid chromatography/mass spectrometry (LC/MS). Microcystin per unit carbon was determined for six cultures and ranged from 1.15 to 4.15microgmg(-1) C. Phylogenetic analysis of four cultures from Lake Skinner and DVL using cyanobacterial-specific PCR and sequencing of the partial 16S rRNA gene suggested the highest similarity to an unidentified cyanobacterium in the oscillatoriales, and to a Phormidium sp. Morphologically, some of the isolates were similar to Oscillatoria, and others resembled Lyngbya. The significance of these organisms lies in the relative scarcity of known toxin producers among freshwater benthic cyanobacteria, and also as a source of cell-bound microcystin in these reservoirs.

Environmental conditions that influence toxin biosynthesis in cyanobacteria

Publisher: Wiley

Date: 20-03-2013

DOI: 10.1111/J.1462-2920.2012.02729.X

Abstract: Over the past 15 years, the genetic basis for production of many cyanobacterial bioactive compounds has been described. This knowledge has enabled investigations into the environmental factors that regulate the production of these toxins at the molecular level. Such molecular or systems level studies are also likely to reveal the physiological role of the toxin and contribute to effective water resource management. This review focuses on the environmental regulation of some of the most relevant cyanotoxins, namely the microcystins, nodularin, cylindrospermopsin, saxitoxins, anatoxins and jamaicamides.

Peroxide reduction by a metal-dependent catalase in Nostoc punctiforme (cyanobacteria)

Publisher: Springer Science and Business Media LLC

Date: 02-02-2017

DOI: 10.1007/S00253-017-8130-Y

Abstract: This study investigated the role of a novel metal-dependent catalase (Npun_R4582) that reduces hydrogen peroxide in the cyanobacterium Nostoc punctiforme. Quantitative real-time PCR showed that npun_R4582 relative mRNA levels were upregulated by over 16-fold in cells treated with either 2 μM added Co, 0.5 μM added Cu, 500 μM Mn, 1 μM Ni, or 18 μM Zn. For cells treated with 60 μM H

Novel homologs of the multiple resistance regulator marA in antibiotic-contaminated environments

Publisher: Elsevier BV

Date: 10-2008

DOI: 10.1016/J.WATRES.2008.07.004

Abstract: Antibiotics are commonly detected in the environment as contaminants. Exposure to antibiotics may induce antimicrobial-resistance, as well as the horizontal transfer of resistance genes in bacterial populations. We selected the resistance gene marA, mediating resistance to multiple antibiotics, and explored its distribution in sediment and water s les from surface and sewage treatment waters. Ciprofloxacin and ofloxacin (fluoroquinolones), sulphamethoxazole (sulphonamide), erythromycin, clarythromycin, and spiramycin (macrolides), lincomycin (lincosamide), and oxytetracycline (tetracycline) were measured in the same s les to determine antibiotic contamination. Bacterial populations from environmental s les were challenged with antibiotics to identify resistant isolates. The gene marA was found in almost all environmental s les and was confirmed by PCR lification in antibiotic-resistant colonies. 16S rDNA sequencing revealed that the majority of resistant isolates belonged to the Gram-positive genus Bacillus, not previously known to possess the regulator marA. We assayed the incidence of marA in environmental bacterial populations of Escherichia coli and Bacillus by quantitative real-time PCR in correlation with the levels of antibiotics. Phylogenetic analysis indicated the possible lateral acquisition of marA by Bacillus from Gram-negative Enterobacteriaceae revealing a novel marA homolog in Bacillus. Quantitative PCR assays indicate that the frequency of this gene in antropised environments seems to be related to bacterial exposure to water-borne antibiotics.

Genome Sequence of the Halophilic Archaeon Halococcus hamelinensis

Publisher: American Society for Microbiology

Date: 15-04-2012

DOI: 10.1128/JB.06599-11

Abstract: Halococcus hamelinensis was isolated from hypersaline stromatolites in Shark Bay, Australia. Here we report the genome sequence (3,133,046 bp) of H. hamelinensis , which provides insights into the ecology, evolution, and adaptation of this novel microorganism.

Heterologous expression and biochemical characterisation of cyanotoxin biosynthesis pathways

Publisher: Royal Society of Chemistry (RSC)

Date: 2019

DOI: 10.1039/C8NP00063H

Abstract: This review discusses cyanotoxin biosynthetic pathways and highlights the heterologous expression and biochemical studies used to characterise them.

Comparative proteomics reveals that a saxitoxin-producing and a nontoxic strain of Anabaena circinalis are two different ecotypes

Publisher: American Chemical Society (ACS)

Date: 02-0100

DOI: 10.1021/PR401007K

Abstract: In Australia, saxitoxin production is restricted to the cyanobacterial species Anabaena circinalis and is strain-dependent. We aimed to characterize a saxitoxin-producing and nontoxic strain of A. circinalis at the proteomic level using iTRAQ. Seven proteins putatively involved in saxitoxin biosynthesis were identified within our iTRAQ experiment for the first time. The proteomic profile of the toxic A. circinalis was significantly different from the nontoxic strain, indicating that each is likely to inhabit a unique ecological niche. Under control growth conditions, the saxitoxin-producing A. circinalis displayed a higher abundance of photosynthetic, carbon fixation and nitrogen metabolic proteins. Differential abundance of these proteins suggests a higher intracellular C:N ratio and a higher concentration of intracellular 2-oxoglutarate in our toxic strain compared with the nontoxic strain. This may be a novel site for posttranslational regulation because saxitoxin biosynthesis putatively requires a 2-oxoglutarate-dependent dioxygenase. The nontoxic A. circinalis was more abundant in proteins, indicating cellular stress. Overall, our study has provided the first insight into fundamental differences between a toxic and nontoxic strain of A. circinalis, indicating that they are distinct ecotypes.

Directing the Heterologous Production of Specific Cyanobacterial Toxin Variants

Publisher: American Chemical Society (ACS)

Date: 07-06-2017

DOI: 10.1021/ACSCHEMBIO.7B00181

Abstract: Microcystins are globally the most commonly occurring freshwater cyanotoxins, causing acute poisoning and chronically inducing hepatocellular carcinoma. However, the detection and toxicological study of microcystins is h ered by the limited availability and high cost of pure toxin standards. Biosynthesis of microcystin variants in a fast-growing heterologous host offers a promising method of achieving reliable and economically viable alternative to isolating toxin from slow-growing cyanobacterial cultures. Here, we report the heterologous expression of recombinant microcystin synthetases in Escherichia coli to produce [d-Asp

A universal procedure for primer labelling of amplicons

Publisher: Oxford University Press (OUP)

Date: 15-07-1997

DOI: 10.1093/NAR/25.14.2938

Abstract: Detection and visualisation of nucleic acids is integral to genome analyses. Exponential lification procedures have provided the means for the manipulation of nucleic acid sequences, which were otherwise inaccessible. We describe the development and application of a universal method for the labelling of any PCR product using a single end-labelled primer. Amplification was performed in a single reaction with the resulting licon labelled to a high specific activity. The method was adapted to a wide range of PCRs and significantly reduced the expense of such analyses.

Characterization of microcystin production in an Antarctic cyanobacterial mat community

Publisher: Elsevier BV

Date: 03-2006

DOI: 10.1016/J.TOXICON.2005.11.002

Abstract: Cyanobacteria are well known for their production of non-ribosomal cyclic peptide toxins, including microcystin, in temperate and tropical regions, however, the production of these compounds in extremely cold environments is still largely unexplored. Therefore, we investigated the production of protein phosphatase inhibiting microcystins by Antarctic cyanobacteria. We have identified microcystin-LR and for the first time [D-Asp3] microcystin-LR by mass spectrometric analysis in Antarctic cyanobacteria. The microcystins were extracted from a benthic microbial community that was s led from a meltwater pond (Fresh Pond, McMurdo Ice Shelf, Antarctica). The extracted cyanobacterial cyclic peptides were equivalent to 11.4 ng MC-LR per mg dry weight by semi-quantitative analyses using HPLC-DAD and the protein phosphatase inhibition assay. Furthermore, we were able to identify the presence of cyanobacterial non-ribosomal peptide synthetase (NRPS) and polyketide synthase (PKS) genes in total DNA extracts from the mat community.

Characterization of the Gene Cluster Responsible for Cylindrospermopsin Biosynthesis

Publisher: American Society for Microbiology

Date: 02-2007

DOI: 10.1128/AEM.01988-07

Abstract: Toxic cyanobacterial blooms cause economic losses and pose significant public health threats on a global scale. Characterization of the gene cluster for the biosynthesis of the cyanobacterial toxin cylindrospermopsin ( cyr ) in Cylindrospermopsis raciborskii AWT205 is described, and the complete biosynthetic pathway is proposed. The cyr gene cluster spans 43 kb and is comprised of 15 open reading frames containing genes required for the biosynthesis, regulation, and export of the toxin. Biosynthesis is initiated via an amidinotransfer onto glycine followed by five polyketide extensions and subsequent reductions, and rings are formed via Michael additions in a stepwise manner. The uracil ring is formed by a novel pyrimidine biosynthesis mechanism and tailoring reactions, including sulfation and hydroxylation that complete biosynthesis. These findings enable the design of toxic strain-specific probes and allow the future study of the regulation and biological role of cylindrospermopsin.

Detection, Isolation, and Characterization of Helicobacter Species from the Gastrointestinal Tract of the Brushtail Possum

Publisher: American Society for Microbiology

Date: 03-2011

DOI: 10.1128/AEM.01960-10

Abstract: The presence of Helicobacter species in Australian marsupials was examined systematically using microscopy, culture, and PCR in different regions of the gastrointestinal tract (GIT) and in the liver of brushtail possums (BTPs) ( Trichosurus vulpecula ), a common Australian marsupial that feeds on eucalyptus leaves. The spatial distribution of Helicobacter species in the GIT sections also was examined microscopically in silver-stained sections and by fluorescent in situ hybridization (FISH) using a Helicobacter genus-specific probe. Helicobacter species were found colonizing the lower bowel of all BTPs studied. Good agreement was observed between the detection of Helicobacter species using culture and PCR, which was supported by the microscopic examination of silver-stained sections and FISH. The lower bowel of BTPs were colonized by one to three morphologically different (a comma-shaped species with no apparent flagella, a fusiform-shaped species entwined with periplasmic fibers and a bipolar sheathed flagella, and an S-shaped species with bipolar sheathed flagella) and potentially novel Helicobacter species, as well as in one case with a potentially novel C ylobacter species, which was a tightly coiled rod with bipolar unsheathed flagella. The isolation and characterization of these Helicobacter species in BTPs provides important information regarding the specific natural niche of these bacteria and their corelationship within their host, and it increases our understanding of the ecology of Helicobacter species.

Diversity within cyanobacterial mat communities in variable salinity meltwater ponds of McMurdo Ice Shelf, Antarctica

Publisher: Wiley

Date: 28-01-2005

DOI: 10.1111/J.1462-2920.2005.00717.X

Abstract: This study investigated the ersity of cyanobacterial mat communities of three meltwater ponds--Fresh, Orange and Salt Ponds, south of Bratina Island, McMurdo Ice Shelf, Antarctica. A combined morphological and genetic approach using clone libraries was used to investigate the influence of salinity on cyanobacterial ersity within these ecosystems without prior cultivation or isolation of cyanobacteria. We were able to identify 22 phylotypes belonging to Phormidium sp., Oscillatoria sp. and Lyngbya sp. In addition, we identified Antarctic Nostoc sp., Nodularia sp. and Anabaena sp. from the clone libraries. Fresh (17 phylotypes) and Orange (nine phylotypes) Ponds showed a similar ersity in contrast to that of the hypersaline Salt Pond (five phylotypes), where the ersity within cyanobacterial mats was reduced. Using the comparison of identified phylotypes with existing Antarctic sequence data, it was possible to gain further insight into the different levels of distribution of phylotypes identified in the investigated cyanobacterial mat communities of McMurdo Ice Shelf.

Cyclooxygenase-2-Linked Attenuation of Hypoxia-Induced Pulmonary Hypertension and Intravascular Thrombosis

Publisher: American Society for Pharmacology & Experimental Therapeutics (ASPET)

Date: 28-03-2008

DOI: 10.1124/JPET.107.134221

Abstract: Exogenous prostacyclin is effective in reducing pulmonary vascular resistance in some forms of human pulmonary hypertension (PH). To explore whether endogenous prostaglandins played a similar role in pulmonary hypertension, we examined the effect of deleting cyclooxygenase (COX)-gene isoforms in a chronic hypoxia model of PH. Pulmonary hypertension, examined by direct measurement of right ventricular end systolic pressure (RVESP), right ventricular hypertrophy (n = 8), and hematocrit (n = 3), was induced by 3 weeks of hypobaric-hypoxia in wild-type and COX-knockout (KO) mice. RVESP was increased in wild-type hypoxic mice compared with normoxic controls (24.4 +/- 1.4 versus 13.8 +/- 1.9 mm Hg n = 8 p < 0.05). COX-2 KO mice showed a greater increase in RVESP following hypoxia (36.8 +/- 2.7 mm Hg p < 0.05). Urinary thromboxane (TX)B(2) excretion increased following hypoxia (44.6 +/- 11.1 versus 14.7 +/- 1.8 ng/ml n = 6 p < 0.05), an effect that was exacerbated by COX-2 gene disruption (54.5 +/- 10.8 ng/ml n = 6). In contrast, the increase in 6-keto-prostacyclin(1alpha) excretion following hypoxia was reduced by COX-2 gene disruption (29 +/- 3 versus 52 +/- 4.6 ng/ml p < 0.01). Tail cut bleed times were lower following hypoxia, and there was evidence of intravascular thrombosis in lung vessels that was exacerbated by disruption of COX-2 and reduced by deletion of COX-1. The TXA(2)/endoperoxide receptor antagonist ifetroban (50 mg/kg/day) offset the effect of deleting the COX-2 gene, attenuating the hypoxia-induced rise in RVESP and intravascular thrombosis. COX-2 gene deletion exacerbates pulmonary hypertension, enhances sensitivity to TXA(2), and induces intravascular thrombosis in response to hypoxia. The data provide evidence that endogenous prostaglandins modulate the pulmonary response to hypoxia.

Comparative genomics between human and animal associated subspecies of the Mycobacterium avium complex: A basis for pathogenicity

Publisher: Springer Science and Business Media LLC

Date: 15-09-2015

DOI: 10.1186/S12864-015-1889-2

Evolutionary affiliations within the superfamily of ketosynthases reflect complex pathway associations

Publisher: Springer Science and Business Media LLC

Date: 04-2003

DOI: 10.1007/S00239-002-2415-0

Abstract: Type I polyketide synthases are known to produce a wide range of medically and industrially important polyketides. The ketosynthase (KS) domain is required for the condensation of an extender unit onto the growing polyketide chain during polyketide biosynthesis. KSs represent a superfamily of complex biosynthetic pathway-associated enzymes found in prokaryotes, fungi, and plants. Although themselves functionally conserved, KSs are involved in the production of a structurally erse range of metabolites. Degenerate oligonucleotide primers, designed for the lification of KS domains, lified KS domains from a range of organisms including cyanobacterial and dinoflagellates. KS domains detected in dinoflagellate cultures appear to have been lified from the less than 3- micro m filtrate of the nonaxenic culture. Phylogenetic analysis of sequences obtained during this study enabled the specific identification of KS domains of hybrid or mixed polyketide synthase eptide synthetase complexes, required for the condensation of an extender unit onto an amino acid starter unit. The primer sets described in this study were also used for the detection of novel KS domains directly from environmental s les. The ability to predict function based on primary molecular structure will be critical for future discovery and rational engineering of polyketides.

Nonribosomal Peptides

Publisher: CRC Press

Date: 23-04-2009

DOI: 10.1201/9781420061161-C13

Industrial robustness linked to the gluconolactonase from Zymomonas mobilis

Publisher: Springer Science and Business Media LLC

Date: 24-03-2017

DOI: 10.1007/S00253-017-8248-Y

Abstract: The physiological characteristics and the potential gluconolactone production of the gluconolactonase-deficient strain, Zymomonas mobilis ZM4 gnlΔ, were investigated via growth inhibitory assay and biotransformation of glucose and fructose into gluconolactone and sorbitol, respectively. The results of ethanol fermentation studies performed in the presence of high concentration of glucose (>200 g l

Cyanobacterial toxins: biosynthetic routes and evolutionary roots

Publisher: Oxford University Press (OUP)

Date: 2013

DOI: 10.1111/J.1574-6976.2012.12000.X

Abstract: Cyanobacteria produce an unparalleled variety of toxins that can cause severe health problems or even death in humans, and wild or domestic animals. In the last decade, biosynthetic pathways have been assigned to the majority of the known toxin families. This review summarizes current knowledge about the enzymatic basis for the production of the hepatotoxins microcystin and nodularin, the cytotoxin cylindrospermopsin, the neurotoxins anatoxin and saxitoxin, and the dermatotoxin lyngbyatoxin. Elucidation of the biosynthetic pathways of the toxins has paved the way for the development of molecular techniques for the detection and quantification of the producing cyanobacteria in different environments. Phylogenetic analyses of related clusters from a large number of strains has also allowed for the reconstruction of the evolutionary scenarios that have led to the emergence, ersification, and loss of such gene clusters in different strains and genera of cyanobacteria. Advances in the understanding of toxin biosynthesis and evolution have provided new methods for drinking-water quality control and may inspire the development of techniques for the management of bloom formation in the future.

A Red-Shifted Chlorophyll: Fig. 1

Publisher: American Association for the Advancement of Science (AAAS)

Date: 10-09-2010

DOI: 10.1126/SCIENCE.1191127

Abstract: Among the first facts students learn about the natural world is that plants owe their green color to the pigment chlorophyll. There have actually been a handful of slightly different chlorophyll variants uncovered over the years, and Chen et al. (p. 1318 , published online 19 August) have found another in bacteria from Shark Bay, Australia. The chlorophyll variant displayed a red-shifted absorption spectrum, which extended into the near-infrared region due to the insertion of a formyl group on the molecule's periphery. The precise cellular function of the pigment awaits further study.

High abundance of the potentially maitotoxic dinoflagellate Gambierdiscus carpenteri in temperate waters of New South Wales, Australia

Publisher: Elsevier BV

Date: 10-2014

DOI: 10.1016/J.HAL.2014.07.007

An improved method for the purification of large DNA fragments from agarose gels using Wizard Plus SV columns

Publisher: Elsevier BV

Date: 04-1999

DOI: 10.1006/ABIO.1999.4006

Cob gene pyrosequencing enables characterization of benthic dinoflagellate diversity and biogeography

Publisher: Wiley

Date: 21-10-2014

DOI: 10.1111/1462-2920.12275

Abstract: Dinoflagellates in marine benthic habitats living epiphytically on macroalgae are an important but highly understudied group of protists. Many produce toxins that can have severe economic impacts on marine-based economies, and improved monitoring tools are required to enhance the management of toxin-related hazards. We analysed the distribution and ersity of epibenthic dinoflagellates inhabiting eight sites in Cocos (Keeling) Islands, Papua New Guinea, and Broome and Exmouth, Western Australia. We used pyrosequencing approaches based on two DNA barcoding marker genes - 18S ribosomal RNA (rRNA) and mitochondrial cytochrome b (cob) - and compared these to an approach based on clone libraries (197 sequences) using the cob gene. Dinoflagellate sequences accounted for 133 [64 unique operational taxonomic units (OTU)] out of 10 529 18S rRNA gene sequences obtained from all s les. However, using the dinoflagellate specific assay targeting the cob gene marker, we obtained 9748 (1217 unique OTU) dinoflagellate sequences from the same environmental s les, providing the largest, to date, set of dinoflagellate cob gene sequences and reliable estimates of total dinoflagellate richness within the s les and biogeographic comparisons between s les. This study also reports the presence of potentially toxic species of the genera Gambierdiscus, Ostreopsis, Coolia, Prorocentrum and Amphidinium from the above-mentioned geographical regions.

Altered expression of two light-dependent genes in a microcystin-lacking mutant of Microcystis aeruginosa PCC 7806

Publisher: Microbiology Society

Date: 11-2001

DOI: 10.1099/00221287-147-11-3113

Abstract: Microcystin is a potent inhibitor of eukaryotic protein phosphatases and has been implicated in causing hepatotoxicity to humans and animals worldwide. It is produced primarily by the bloom-forming cyanobacterium Microcystis aeruginosa, although the function of the peptide in this micro-organism is unknown. In this study, a microcystin-related protein, MrpA, was identified using a microcystin-lacking mutant of M. aeruginosa, PCC 7806. Comparative two-dimensional protein electrophoresis showed that MrpA was strongly expressed in wild-type PCC 7806, but was not detectable in the mcyB mutant. MrpA showed similarity to the RhiA protein from Rhizobium leguminosarum, which is encoded by the rhiABC operon and controlled by quorum-sensing mediators. Sequencing of mrpA flanking regions in M. aeruginosa PCC 7806 revealed the presence of a rhiB homologue, mrpB, directly downstream of mrpA. Northern blot analyses of mrpA expression in cells exposed to different light conditions revealed a rapid decline of transcription under high light conditions. Most striking was a strong increase in transcript levels from cultures irradiated with blue light. The mrpA transcription level was strongly reduced in two independent microcystin-lacking mutants under all light conditions investigated.

A novel prokaryotic l‐arginine:glycine amidinotransferase is involved in cylindrospermopsin biosynthesis

Publisher: Wiley

Date: 16-08-2010

DOI: 10.1111/J.1742-4658.2010.07788.X

Abstract: We report the first characterization of an L-arginine:glycine amidinotransferase from a prokaryote. The enzyme, CyrA, is involved in the pathway for biosynthesis of the polyketide-derived hepatotoxin cylindrospermopsin from Cylindrospermopsis raciborskii AWT205. CyrA is phylogenetically distinct from other amidinotransferases, and structural alignment shows differences between the active site residues of CyrA and the well-characterized human L-arginine:glycine amidinotransferase (AGAT). Overexpression of recombinant CyrA in Escherichia coli enabled biochemical characterization of the enzyme, and we confirmed the predicted function of CyrA as an L-arginine:glycine amidinotransferase by (1) H NMR. As compared with AGAT, CyrA showed narrow substrate specificity when presented with substrate analogs, and deviated from regular Michaelis-Menten kinetics in the presence of the non-natural substrate hydroxylamine. Studies of initial reaction velocities and product inhibition, and identification of intermediate reaction products, were used to probe the kinetic mechanism of CyrA, which is best described as a hybrid of ping-pong and sequential mechanisms. Differences in the active site residues of CyrA and AGAT are discussed in relation to the different properties of both enzymes. The enzyme had maximum activity and maximum stability at pH 8.5 and 6.5, respectively, and an optimum temperature of 32 °C. Investigations into the stability of the enzyme revealed that an inactivated form of this enzyme retained an appreciable amount of secondary structure elements even on heating to 94 °C, but lost its tertiary structure at low temperature (T(max) of 44.5 °C), resulting in a state reminiscent of a molten globule. CyrA represents a novel group of prokaryotic amidinotransferases that utilize arginine and glycine as substrates with a complex kinetic mechanism and substrate specificity that differs from that of the eukaryotic L-arginine:glycine amidinotransferases.

An In Vitro and In Vivo Study of Broad-Range Phosphopantetheinyl Transferases for Heterologous Expression of Cyanobacterial Natural Products

Publisher: American Chemical Society (ACS)

Date: 21-03-2018

DOI: 10.1021/ACSSYNBIO.8B00091

Abstract: Phosphopantetheinyl transferases catalyze the post-translational modification of carrier proteins involved in both primary and secondary metabolism. The functional expression of polyketide synthases and nonribosomal peptide synthetases requires the activation of all carrier protein domains by phosphopantetheinyl transferases. Here we describe the characterization of five bacterial phosphopantetheinyl transferases by their substrate specificity and catalytic efficiency of four cyanobacterial carrier proteins. Comparative in vitro phosphopantetheinylation analysis showed Sfp possesses the highest catalytic efficiency over various carrier proteins. In vivo coexpression of phosphopantetheinyl transferases with carrier proteins revealed a broad range substrate specificity of phosphopantetheinyl transferases all studied phosphopantetheinyl transferases were capable of converting apo- carrier proteins, sourced from erse biosynthetic enzymes, to their active holo form. Phosphopantetheinyl transferase coexpression with the hybrid nonribosomal peptide synthetases olyketide synthases responsible for microcystin biosynthesis confirmed that the higher in vitro activity of Sfp translated in vivo to a higher yield of production.

Use of ion-channel modulating agents to study cyanobacterial Na⁺-K⁺ fluxes

Publisher: Springer Science and Business Media LLC

Date: 2004

DOI: 10.1251/BPO82

Rapid, multiplex-tandem PCR assay for automated detection and differentiation of toxigenic cyanobacterial blooms

Publisher: Elsevier BV

Date: 10-2013

DOI: 10.1016/J.MCP.2013.07.001

Abstract: Cyanobacterial blooms are a major water quality issue and potential public health risk in freshwater, marine and estuarine ecosystems globally, because of their potential to produce cyanotoxins. To date, a significant challenge in the effective management of cyanobacterial has been an inability of classical microscopy-based approaches to consistently and reliably detect and differentiate toxic from non-toxic blooms. The potential of cyanobacteria to produce toxins has been linked to the presence of specific biosynthetic gene clusters. Here, we describe the application of a robotic PCR-based assay for the semi-automated and simultaneous detection of toxin biosynthesis genes of each of the toxin classes characterized to date for cyanobacteria [i.e., microcystins (MCYs), nodularins (NODs), cylindrospermopsins (CYNs) and paralytic shellfish toxins (PSTs)/saxitoxins (SXTs)]. We demonstrated high sensitivity and specificity for each assay using well-characterized, cultured isolates, and establish its utility as a quantitative PCR using DNA, clone and cell-based dilution series. In addition, we used 206 field-collected s les and 100 known negative controls to compare the performance of each assay with conventional PCR and direct toxin detection. We report a diagnostic specificity of 100% and a sensitivity of ≥97.7% for each assay.

Inactivation of an ABC transporter gene, mcyH, results in loss of microcystin production in the cyanobacterium Microcystis aeruginosa PCC 7806

Publisher: American Society for Microbiology

Date: 08-2016

DOI: 10.1128/AEM.70.11.6370-6378.2004

Abstract: The cyanobacterium Microcystis aeruginosa is widely known for its production of the potent hepatotoxin microcystin. Microcystin is synthesized nonribosomally by the thiotemplate function of a large, modular enzyme complex encoded within the 55-kb microcystin synthetase ( mcy ) gene cluster. Also encoded within the mcy gene cluster is a putative ATP binding cassette (ABC) transporter, McyH. This study details the bioinformatic and mutational analyses of McyH and offers functional predictions for the hypothetical protein. The transporter is putatively comprised of two homodimers, each with an N-terminal hydrophobic domain and a C-terminal ATPase. Phylogenetically, McyH was found to cluster with members of the ABC-A 1 subgroup of ABC ATPases, suggesting an export function for the protein. Two mcyH null mutant (Δ mcyH ) strains were constructed by partial deletion of the mcyH gene. Microcystin production was completely absent in these strains. While the mcyH deletion had no apparent effect on the transcription of other mcy genes, the complete microcystin biosynthesis enzyme complex could not be detected in Δ mcyH mutant strains. Finally, expression levels of McyH in the wild type and in Δ mcyA , Δ mcyB , and Δ mcyH mutants were investigated by using immunoblotting with an anti-McyH antibody. Expression of McyH was found to be reduced in Δ mcyA and Δ mcyB mutants and completely absent in the Δ mcyH mutant. By virtue of its association with the mcy gene cluster and the bioinformatic and experimental data presented in this study, we predict that McyH functions as a microcystin exporter and is, in addition, intimately associated with the microcystin biosynthesis pathway.

Characterization of PPTNs, a cyanobacterial phosphopantetheinyl transferase from Nodularia spumigena NSOR10

Publisher: American Society for Microbiology

Date: 15-04-2007

DOI: 10.1128/JB.01850-06

Abstract: The phosphopantetheinyl transferases (PPTs) are a superfamily of essential enzymes required for the synthesis of a wide range of compounds, including fatty acids, polyketides, and nonribosomal peptide metabolites. These enzymes activate carrier proteins in specific biosynthetic pathways by transfer of a phosphopantetheinyl moiety. The erse PPT superfamily can be ided into two families based on specificity and conserved sequence motifs. The first family is typified by the Escherichia coli acyl carrier protein synthase (AcpS), which is involved in fatty acid synthesis. The prototype of the second family is the broad-substrate-range PPT Sfp, which is required for surfactin biosynthesis in Bacillus subtilis . Most cyanobacteria do not encode an AcpS-like PPT, and furthermore, some of their Sfp-like PPTs belong to a unique phylogenetic subgroup defined by the PPTs involved in heterocyst differentiation. Here, we describe the first functional characterization of a cyanobacterial PPT based on a structural analysis and subsequent functional analysis of the Nodularia spumigena NSOR10 PPT. Southern hybridizations suggested that this enzyme may be the only PPT encoded in the N. spumigena NSOR10 genome. Expression and enzyme characterization showed that this PPT was capable of modifying carrier proteins resulting from both heterocyst glycoplipid synthesis and nodularin toxin synthesis. Cyanobacteria are a unique and vast source of bioactive metabolites therefore, an understanding of cyanobacterial PPTs is important in order to harness the biotechnological potential of cyanobacterial natural products.

Physiological metal uptake by Nostoc punctiforme

Publisher: Springer Science and Business Media LLC

Date: 17-05-2012

DOI: 10.1007/S10534-012-9556-4

Abstract: Trace metals are required for many cellular processes. The acquisition of trace elements from the environment includes a rapid adsorption of metals to the cell surface, followed by a slower internalization. We investigated the uptake of the trace elements Co(2+), Cu(2+), Mn(2+), Ni(2+), and Zn(2+) and the non-essential alent cation Cd(2+) in the cyanobacterium Nostoc punctiforme. For each metal, a dose response study based on cell viability showed that the highest non-toxic concentrations were: 0.5 μM Cd(2+), 2 μM Co(2+), 0.5 μM Cu(2+), 500 μM Mn(2+), 1 μM Ni(2+), and 18 μM Zn(2+). Cells exposed to these non-toxic concentrations with combinations of Zn(2+) and Cd(2+), Zn(2+) and Co(2+), Zn(2+) and Cu(2+) or Zn(2+) and Ni(2+), had reduced growth in comparison to controls. Cells exposed to metal combinations with the addition of 500 μM Mn(2+) showed similar growth compared to the untreated controls. Metal levels were measured after one and 72 h for whole cells and absorbed (EDTA-resistant) fractions and used to calculate differential uptake rates for each metal. The differences in binding and internalisation between different metals indicate different uptake processes exist for each metal. For each metal, competitive uptake experiments using (65)Zn showed that after 72 h of exposure Zn(2+) uptake was reduced by most metals particularly 0.5 μM Cd(2+), while 2 μM Co(2+) increased Zn(2+) uptake. This study demonstrates that N. punctiforme discriminates between different metals and favourably substitutes their uptake to avoid the toxic effects of particular metals.

Ecological and molecular investigations of cyanotoxin production

Publisher: Oxford University Press (OUP)

Date: 03-2001

DOI: 10.1111/J.1574-6941.2001.TB00782.X

Alternariol 9-O-methyl ether

Publisher: International Union of Crystallography (IUCr)

Date: 21-04-2012

DOI: 10.1107/S1600536812015000

Increased incidence of Cylindrospermopsis raciborskii in temperate zones – Is climate change responsible?

Publisher: Elsevier BV

Date: 04-2012

DOI: 10.1016/J.WATRES.2011.12.019

Abstract: The bloom-forming, toxic cyanobacterium, Cylindrospermopsis raciborskii exhibits global distribution. In recent years both the occurrence and dominance of this species, particularly in temperate regions, has increased. Whilst this may be due to increased sensitivity of analytical detection methods or more rigorous s ling routines, it is possible that this expansion has been assisted by a number of changing conditions in these environments. The geographical expansion of both the organism and toxin production can be attributed to phenomena such as eutrophication and climate change. In this review, we discuss the occurrence of C. raciborskii with respect to current literature against the backdrop of increasing global temperatures. Critically, we identify a concerning trend between the geographical spread of this organism and global climate change.

Cyanotoxins Workgroup report

Publisher: Springer New York

Date: 2008

DOI: 10.1007/978-0-387-75865-7_15

Biocrust morphology is linked to marked differences in microbial community composition

Publisher: Springer Science and Business Media LLC

Date: 04-10-2017

DOI: 10.1007/S11104-017-3442-3

The genetics and genomics of cyanobacterial toxicity

Publisher: Springer New York

Date: 2008

DOI: 10.1007/978-0-387-75865-7_17

Multiple origins of the ascidian-Prochloron symbiosis: Molecular phylogeny of photosymbiotic and non-symbiotic colonial ascidians inferred from 18S rDNA sequences

Publisher: Elsevier BV

Date: 07-2006

DOI: 10.1016/J.YMPEV.2005.11.025

Abstract: In the tropics, certain didemnid ascidians harbor the prokaryotic photosymbiont Prochloron. To date, this photosymbiosis has been found in four didemnid genera that include non-symbiotic species. Here, we report the molecular phylogeny of symbiotic and non-symbiotic didemnids based on their 18S rDNA sequences. The data cover all four genera containing symbiotic species and one other genus comprised of only non-symbiotic species. Near-complete nucleotide sequences of 18S rDNAs were determined for four non-didemnid species and 52 didemnid s les (five genera), including 48 photosymbiotic s les collected from the Ryukyu Archipelago, the Great Barrier Reef, Hawaii, and Bali. Our phylogenetic trees indicated a monophyletic origin of the family Didemnidae, as well as each of the didemnid genera. The results strongly support the hypothesis that establishment of the ascidian-Prochloron symbiosis occurred independently in the Didemnidae lineage at least once in each of the genera that possess symbiotic species.

Localization of symbiotic cyanobacteria in the colonial ascidian Trididemnum miniatum (Didemnidae, Ascidiacea)

Publisher: Zoological Society of Japan

Date: 05-2006

DOI: 10.2108/ZSJ.23.435

Abstract: Trididemnum miniatum is a colonial ascidian harboring the photosymbiotic prokaryote Prochloron sp. These bacterial cells are located in the tunic of the host animal. The present study revealed, by ultrastructural analysis, that the Prochloron cells were exclusively distributed and proliferated in the tunic. They were shown to be embedded in the tunic matrix and to have no direct contact with ascidian cells. Some tunic cells of the ascidians, however, did phagocytize and digest the symbiont. Round cell masses were sometimes found in the tunic and appeared to consist of disintegrating cyanobacterial cells. The thoracic epidermis of ascidian zooids was often digitated, and the epidermal cells extended microvilli into the tunic. Since there were no Prochloron cells in the alimentary tract of the ascidian zooids, the photosymbionts would not be considered part of the typical diet of the host ascidians. Thin layer chromatography showed that the symbionts possessed both chlorophyll a and b, while a 16S rRNA gene phylogeny supported the identification of the photosymbiont of T. miniatum as Prochloron sp.

Genome mining of a fungal endophyte of Taxus yunnanensis (Chinese yew) leads to the discovery of a novel azaphilone polyketide, lijiquinone

Publisher: Wiley

Date: 26-05-0012

DOI: 10.1111/1751-7915.13568

Towards a molecular taxonomy for the bloom-forming cyanobacteria

Publisher: CSIRO Publishing

Date: 1994

DOI: 10.1071/MF9940869

Abstract: Regions of the 16s subunit of the ribosomal RNA gene of the bloom-associated cyanobacterial genera Microcystis and Anabaena have been sequenced and found to provide strain-specific sequence information. Comparisons of the DNA sequence of these cyanobacteria indicated that the strains examined are related and that probes diagnostic for bloom-forming and toxigenic strains in water s les can be designed.

Exploring the potential of endophytes from medicinal plants as sources of antimycobacterial compounds

Publisher: Elsevier BV

Date: 07-2014

DOI: 10.1016/J.MICRES.2013.12.009

Effective three-particle interactions in low-energy models for multiband systems

Publisher: American Physical Society (APS)

Date: 27-02-2012

DOI: 10.1103/PHYSREVB.85.064520

Nutrient-related changes in the toxicity of field blooms of the cyanobacterium, Cylindrospermopsis raciborskii

Publisher: Oxford University Press (OUP)

Date: 12-05-2014

DOI: 10.1111/1574-6941.12341

Abstract: Nutrients have the capacity to change cyanobacterial toxin loads via growth-related toxin production, or shifts in the dominance of toxic and nontoxic strains. This study examined the effect of nitrogen (N) and phosphorus on cell ision and strain-related changes in production of the toxins, cylindrospermopsins (CYNs) by the cyanobacterium, Cylindrospermopsis raciborskii. Two short-term experiments were conducted with mixed phytoplankton populations dominated by C. raciborskii in a subtropical reservoir where treatments had nitrate (NO3 ), urea (U) and inorganic phosphorus (P) added alone or in combination. Cell ision rates of C. raciborskii were only statistically higher than the control on day 5 when U and P were co-supplied. In contrast, cell quotas of CYNs (QCYNS ) increased significantly in treatments where P was supplied, irrespective of whether N was supplied, and this increase was not necessarily related to cell ision rates. Increased QCYNS did correlate with an increase in the proportion of the cyrA toxin gene to 16S genes in the C. raciborskii-dominated cyanobacterial population. Therefore, changes in strain dominance are the most likely factor driving differences in toxin production between treatments. Our study has demonstrated differential effects of nutrients on cell ision and strain dominance reflecting a C. raciborskii population with a range of strategies in response to environmental conditions.

Cyanotoxins

Publisher: Wiley

Date: 30-11-2013

DOI: 10.1002/9781118402238.CH16

Characterization of nitrogen-fixing cyanobacteria in the Brazilian Amazon floodplain

Publisher: Elsevier BV

Date: 12-2005

DOI: 10.1016/J.WATRES.2005.10.002

Abstract: The ersity of the free-living nitrogen-fixing cyanobacterial community in the floodplain sediments along the Solimões and Amazon Rivers and some of their tributaries (Japurá, Negro and Madeira) was investigated. Five cyanobacterial genera were morphologically identified, four of which (Nostoc, Calothrix, Cylindrospermum and Fischerella) have not previously been isolated from the Brazilian Amazon floodplain. Nostoc strains were the most commonly found heterocyst-forming cyanobacteria. Five strains (N. muscorum CENA18 and CENA61, N. piscinale CENA21, Cylindrospermum sp. CENA33 and Fischerella sp. CENA19) were selected for growth measurement, ability to fix N2 and phylogenetic analysis, based on their widespread distribution and morphological distinction. Molecular analyses employing 16S rRNA sequences indicated that some of the isolates may represent novel cyanobacterial species. Dinitrogen fixed by these strains was measured indirectly as acetylene reduction activity and ranged from 11.5 to 22.2 nmol C2H4 microg Chl a(-1) h(-1). These results provide evidence of widespread and importance of nitrogen-fixing cyanobacteria as a source of N inputs in the Amazonian ecosystem.

Alternariol 9-O-methyl ether dimethyl sulfoxide monosolvate

Publisher: International Union of Crystallography (IUCr)

Date: 11-05-2013

DOI: 10.1107/S1600536813012294

Host Selection of Symbiotic Cyanobacteria in 31 Species of the Australian Cycad Genus: Macrozamia (Zamiaceae)

Publisher: Scientific Societies

Date: 06-2010

DOI: 10.1094/MPMI-23-6-0811

Abstract: The nitrogen-fixing cyanobacterium Nostoc is a commonly occurring terrestrial and aquatic cyanobacterium often found in symbiosis with a wide range of plant, algal, and fungal species. We investigated the ersity of cyanobacterial species occurring within the coralloid roots of different Macrozamia cycad species at erse locations throughout Australia. In all, 74 coralloid root s les were processed and 56 endosymbiotic cyanobacteria were cultured. DNA was isolated from unialgal cultures and a segment of the 16S rRNA gene was lified and sequenced. Microscopic analysis was performed on representative isolates. Twenty-two cyanobacterial species were identified, comprising mostly Nostoc spp. and a Calothrix sp. No correlation was observed between a cycad species and its resident cyanobiont species. The predominant cyanobacterium isolated from 18 root s les occurred over a erse range of environmental conditions and within 14 different Macrozamia spp. Phylogenetic analysis indicated that endosymbionts were not restricted to previously described terrestrial species. An isolate clustering with Nostoc PCC7120, an aquatic strain, was identified. This is the first comprehensive study to identify the endosymbionts within a cycad genus using s les obtained from their natural habitats. These results indicate that there is negligible host specialization of cyanobacterial endosymbionts within the cycad genus Macrozamia in the wild.

Optimisation of DNA extraction and validation of PCR assays to detect Mycobacterium avium subsp. paratuberculosis

Publisher: Elsevier BV

Date: 05-2015

DOI: 10.1016/J.MIMET.2015.03.016

Abstract: The aim of this study was to investigate DNA extraction methods and PCR assays suitable for the detection of Mycobacterium paratuberculosis in bovine tissue. The majority of methods currently used to detect M. paratuberculosis have been developed using bovine s les, such as faeces, blood or tissue and, in many cases, have been based on detection from pooled s les from a herd. However most studies have not compared PCR results to culture results. In order to address this problem, four DNA extraction protocols and three PCR assays were employed to detect M. paratuberculosis in bovine tissue. Given that culture is reliable from cows, the results were then compared with the known M. paratuberculosis culture status. The following DNA extractions were included, two commercial kits, a boiling method, an in house extraction based on a published method and enrichment by sonication. The three PCR assays used included single round IS900 and f57 assays and a nested IS900 assay. In addition, another PCR assay was validated for the detection of any Mycobacterial species and a universal bacterial 16S rRNA gene assay was used to detect s le inhibition. The in-house DNA extraction was the most consistent in extracting good quality DNA compared to all other methods. The use of two PCR markers, IS900 and f57, and a universal PCR enabled the correct s les to be identified as M. paratuberculosis positive. In addition, when compared to the culture result, false-positives did not occur and PCR inhibition was readily identified. Using an in house DNA extraction coupled with the IS900 and f57 PCR markers, this study provides a reliable and simple method to detect M. paratuberculosis in both veterinary and spill over infections.

Diversity and biosynthetic potential of culturable microbes associated with toxic marine animals

Publisher: MDPI AG

Date: 02-08-2013

DOI: 10.3390/MD11082695

Mutagenesis of the Microcystin Tailoring and Transport Proteins in a Heterologous Cyanotoxin Expression System

Publisher: American Chemical Society (ACS)

Date: 05-2019

DOI: 10.1021/ACSSYNBIO.9B00068

Abstract: The microcystins are a large group of cyclic peptide hepatotoxins produced by several genera of freshwater cyanobacteria. The genes responsible for microcystin biosynthesis are encoded within a large (∼55 kbp) gene cluster, mcyA-J. The recent establishment of a cyanotoxin heterologous expression system in Escherichia coli has provided the means to study microcystin biosynthesis in a genetically tractable, rapidly growing host. Using this system, we demonstrate that deletion of the ABC-transporter, mcyH, and dehydrogenase, mcyI, abolishes microcystin production, while deletion of the O-methyltransferase, mcyJ, results in the production of the demethylated (DM) toxin [d-Asp

Deep sequencing of non-ribosomal peptide synthetases and polyketide synthases from the microbiomes of Australian marine sponges

Publisher: Springer Science and Business Media LLC

Date: 18-04-2013

DOI: 10.1038/ISMEJ.2013.65

Multiorbital effects in the functional renormalization group: A weak-coupling study of the Emery model

Publisher: American Physical Society (APS)

Date: 10-12-2015

DOI: 10.1103/PHYSREVB.88.235112

Isolation, characterization, and quantitative analysis of Microviridin J, a new Microcystis metabolite toxic to Daphnia.

Publisher: Springer Science and Business Media LLC

Date: 2003

DOI: 10.1023/A:1024889925732

Abstract: This paper describes the purification and characterization of microviridin J. a newly discovered metabolite of Microcystis that causes a lethal molting disruption in Daphnia spp., upon ingestion of living cyanobacterial cells. Microviridin J consists of an acetylated chain of 13 amino acids arranged in three rings and two side chains. Unlike other known isoforms of microviridin, microviridin J contains arginine that imparts a unique solution conformation characterized by proximal hydrophobic interactions between Arg and other regions of the molecule. This eventually results in the formation and stabilization of an additional ring system. Microviridin J potently inhibits porcine trypsin, bovine chymotrypsin, and daphnid trypsin-like proteases. The activity against trypsin is most likely due to Arg and its distinctive conformational interactions. Overall, the data presented for microviridin J emphasize once again the ability of cyanobacteria to produce numerous and potent environmental toxins.

Interactions between intracellular Na+ levels and saxitoxin production in Cylindrospermopsis raciborskii T3

Publisher: Microbiology Society

Date: 02-2004

DOI: 10.1099/MIC.0.26350-0

Abstract: Saxitoxin (STX) is the most potent representative among the paralytic shellfish poisoning (PSP) toxins, which are highly selective Na + channel-blocking alkaloids. This study investigated, in cultures of the cyanobacterium Cylindrospermopsis raciborskii T3, the effects of pH, salt, amiloride and lidocaine hydrochloride on total cellular levels of Na + and K + ions and STX accumulation. Both Na + levels and intracellular STX concentrations increased exponentially in response to rising alkalinity. NaCl inhibited cyanobacterial growth at a concentration of 10 mM. In comparison with osmotically stressed controls, however, NaCl promoted STX accumulation in a dose-dependent manner. A correlation was seen in the time-course of both total cellular Na + levels and intracellular STX for NaCl, amiloride and lidocaine exposure. The increase in cellular Na + induced by NaCl at 10 mM was coupled with a proportional accumulation of STX. The two Na + channel-blocking agents amiloride and lidocaine had opposing effects on both cellular Na + levels and STX accumulation. Amiloride at 1 mM reduced ion and toxin concentrations, while lidocaine at 1 μM increased the total cellular Na + and STX levels. The effects of the channel-blockers were antagonistic and dependent on an alkaline pH. The results presented suggest that, in C. raciborskii T3, STX is responsive to cellular Na + levels. This may indicate that either STX metabolism or the toxin itself could be linked to the maintenance of cyanobacterial homeostasis. The results also enhance the understanding of STX production and the ecology of PSP toxin-producing cyanobacteria.

The Helicobacter pylori pyrB gene encoding aspartate carbamoyltransferase is essential for bacterial survival

Publisher: Elsevier BV

Date: 08-2000

DOI: 10.1006/ABBI.2000.1920

Session 18. Functional Complexity of Modern Stromatolites and Microbial Mats

Publisher: Mary Ann Liebert Inc

Date: 04-2008

DOI: 10.1089/AST.2008.1242

Development of taxol and other endophyte produced anti-cancer agents

Publisher: Bentham Science Publishers Ltd.

Date: 18-01-2021

DOI: 10.2174/157489208783478685

Abstract: Taxol is a powerful and complex anti-cancer compound that was first isolated from the bark of the Pacific yew Taxus brevifolia. Although it offered huge potential as an anti-cancer agent, it experienced a long development period, attributed to by its low availability from its traditional source. Research into alternate sources and methods of production for Taxol have been crucial in meeting with demand for the drug. Three main avenues of research have resulted. Firstly, chemical syntheses of this complex diterpene consist of multiple steps and are not economically feasible due to their low yield. Developments have therefore concentrated on enhancing production in vivo. Efforts have been made to understand the enzymatic steps involved in the synthesis within the yew and innovations to produce Taxol and Taxol-like substances in high yield from cell cultures of Taxus species. An alternative stream of research focuses on endophytes as the producer of Taxol. Endophytes can be isolated from the yew tree and produce Taxol in culture. Encouraging findings with endophytes resulted in much interest in the prospect of using endophytes as the producer of Taxol and Taxol-like substances. This review also discusses patents and the future prospects of each of the main streams of production.

A new quantitative PCR assay for the detection of hepatotoxigenic cyanobacteria

Publisher: Elsevier BV

Date: 03-2011

DOI: 10.1016/J.TOXICON.2010.12.018

Abstract: Toxin-producing cyanobacteria are a worldwide threat to both human and animal health. The hepatotoxins microcystin and nodularin are the most commonly occurring toxins produced by bloom-forming cyanobacteria. They are cyclic peptides that are synthesized nonribosomally by a multienzyme complexes encoded within the microcystin (mcyS) and nodularin (ndaS) synthetase gene clusters. Early detection of potentially toxic blooms would allow for pre-emptive action to reduce consumer exposure to cyanotoxins. We have developed a quantitative PCR (qPCR) assay based on SYBR-green chemistry for the detection of potentially hepatotoxic cyanobacteria spanning all known microcystin and nodularin producing taxa using primers specifically targeting mcyE and ndaF. The qPCR assay was validated against previously analyzed cyanobacterial bloom s les. Whole cell qPCR using cultured M. aeruginosa PCC7806 and non-toxic M. aeruginosa UTEX2386 had a sensitivity of 1000 cells ml⁻¹. In summary, we have developed a robust and sensitive molecular method for the detection and quantification of hepatotoxigenic cyanobacteria in bloom s les. This technology offers several advantages over traditional and contemporary testing protocols currently used to assess water quality.

2‐Methylhopanoids in geographically distinct, arid biological soil crusts are primarily cyanobacterial in origin

Publisher: Wiley

Date: 12-12-2021

DOI: 10.1111/1758-2229.13037

Abstract: Microbial palaeontology is largely reliant on the interpretation of geologically stable biomarkers or molecular fossils. Biomolecules that are both specific to particular groups of organisms and stable on a geological scale are invaluable for tracing the emergence and ersification of lifeforms, particularly in cases where mineral fossils are lacking. 2‐Methylhopanoids and their diagenic product, 2‐methylhopanes, are highly abundant bacterial membrane lipids, recoverable from s les in excess of a billion years old. In this work we used degenerate PCR, targeting 2‐methylhopanoid biosynthesis genes, and sequencing to show that the ability to produce these molecules in arid biological soil crusts from deserts in erse geographical locations (Utah, USA, and the Pilbara, Australia) is largely confined to cyanobacteria. These data suggest that 2‐methylhopanes can be used as a proxy for cyanobacterial presence within these environments, contributing to our understanding of the emergence of terrestrial life on Earth.

Identification of cyanobacteria and their toxigenicity in environmental samples by rapid molecular analysis

Publisher: Wiley

Date: 2001

DOI: 10.1002/TOX.10010

Abstract: We report molecular analyses which identify cyanobacterial strains present in environmental s les. These analyses do not require the isolation and culture of strains. Identification of cyanobacteria used the polymerase chain reaction (PCR), based on the phycocyanin operon. Differentiation was either by restriction endonuclease digestion (restriction fragment length polymorphisms) or sequencing of the PCR products. Identification was based on sequence homology of the intergenic spacer region (IGS) between the beta- and alpha-phycocyanin subunits (PC-IGS) with database records. We have found that the length and sequence of the PC-IGS is capable of predicting the genus accurately, but not the species. Toxigenicity was determined with oligonucleotide probes for key steps in the microcystin toxin synthesis pathway. We have shown that it is possible to easily and routinely obtain PCR lification products and differentiate the strains in bloom s les. The methods can detect even minor components in bloom s les, which may not be apparent on microscopic examination. Genetic probes for microcystin toxigenicity are effective on environmental s les, eliminating the need for isolation and culture of the organisms. The use of a suite of tests described here will allow water managers to determine the presence and the type of cyanobacteria and their microcystin toxigenicity.

Discovery of Nuclear-Encoded Genes for the Neurotoxin Saxitoxin in Dinoflagellates

Publisher: Public Library of Science (PLoS)

Date: 18-05-2011

DOI: 10.1371/JOURNAL.PONE.0020096

Iron uptake and toxin synthesis in the bloom-forming Microcystis aeruginosa under iron limitation

Publisher: Wiley

Date: 20-01-2011

DOI: 10.1111/J.1462-2920.2010.02412.X

Abstract: Toxin production during cyanobacterial blooms poses a significant public health threat in water bodies globally and requires the development of effective bloom management strategies. Previously, synthesis of the hepatotoxin microcystin has been proposed to be regulated by iron availability, but the contribution of the toxin to the adaptation of cyanobacteria to environmental stresses, such as changing light intensity and nutrient limitation, remains unclear. The aim of this study was to compare the iron stress response in toxic and non-toxic strains of Microcystis aeruginosa subjected to moderate and severe iron limitation. The transcription of a number of genes involved in iron uptake, oxidative stress response, toxin synthesis and transcriptional control of these processes was accessed by quantitative real-time PCR (qRT-PCR). The process of adaptation of M. aeruginosa to iron stress was found to be highly dynamic and strain-specific. Toxin production in PCC 7806 increased in an iron-dependent manner and appeared to be regulated by FurA. The inability to produce microcystin, either due to natural mutations in the mcy gene cluster or due to insertional inactivation of mcyH, affected the remodelling of the photosynthetic machinery in iron-stressed cells, the transport of Fe(II) and transcription of the Fur family of transcriptional regulators. The presence of the toxin appears to give an advantage to microcystin-producing cyanobacteria in the early stages of exposure to severe iron stress and may protect the cell from reactive oxygen species-induced damage.

Functional modeling and phylogenetic distribution of putative cylindrospermopsin biosynthesis enzymes

Publisher: Springer Science and Business Media LLC

Date: 25-02-2006

DOI: 10.1007/S00239-005-0030-6

Abstract: The alkaloid cylindrospermopsin is the most recently discovered cyanotoxin and has caused epidemic outbreaks of human poisoning. Cylindrospermopsin producing cyanobacteria have in recent times appeared in countries all over the world where they had not been observed previously and, thus, represent a global public health concern. Three putative cylindrospermopsin biosynthesis genes, encoding an amidinotransferase (aoaA), a nonribosomal peptide synthetase (aoaB), and a polyketide synthase (aoaC), have been described. Most cyanotoxins are the product of nonribosomal peptide and polyketide synthesis, but the involvement of an amidinotransferase is novel. In the present study, functional modeling was carried out to gain insight into the mechanism of precursor recruitment in cylindrospermopsin biosynthesis. In addition, the molecular phylogenies of putative cylindrospermopsin biosynthesis genes and producer organisms were determined. The model indicated that AoaA may catalyze the formation of guanidino acetate from glycine and arginine. The catalytic site of the AoaB adenylation domain provided two aspartate residues, instead of the usual one, which may be involved in the binding of the guanidino moiety of guanidino acetate. Molecular phylogenetic analysis grouped cylindrospermopsin producing cyanobacteria into two ergent groups. Although the phylogeny of the cylindrospermopsin biosynthesis genes followed that of the producer organisms, they were less ergent, which may indicate the recent horizontal transfer of these genes.

Phenotype-Based Identification of Host Genes Required for Replication of African Swine Fever Virus

Publisher: American Society for Microbiology

Date: 09-2006

DOI: 10.1128/JVI.00475-06

Abstract: African swine fever virus (ASFV) produces a fatal acute hemorrhagic fever in domesticated pigs that potentially is a worldwide economic threat. Using an expressed sequence tag (EST) library-based antisense method of random gene inactivation and a phenotypic screen for limitation of ASFV replication in cultured human cells, we identified six host genes whose cellular functions are required by ASFV. These included three loci, BAT3 (HLA-B-associated transcript 3), C1qTNF (C1q and tumor necrosis factor-related protein 6), and TOM40 (translocase of outer mitochondrial membrane 40), for which antisense expression from a tetracycline-regulated promoter resulted in reversible inhibition of ASFV production by %. The effects of antisense transcription of the BAT3 EST and also of expression in the sense orientation of this EST, which encodes amino acid residues 450 to 518 of the mature BAT3 protein, were investigated more extensively. Sense expression of the BAT3 peptide, which appears to reversibly interfere with BAT3 function by a dominant negative mechanism, resulted in decreased synthesis of viral DNA and proteins early after ASFV infection, altered transcription of apoptosis-related genes as determined by cDNA microarray analysis, and increased cellular sensitivity to staurosporine-induced apoptosis. Antisense transcription of BAT3 reduced ASFV production without affecting abundance of the virus macromolecules we assayed. Our results, which demonstrate the utility of EST-based functional screens for the detection of host genes exploited by pathogenic viruses, reveal a novel collection of cellular genes previously not known to be required for ASFV infection.

Light and the transcriptional response of the microcystin biosynthesis gene cluster

Publisher: American Society for Microbiology

Date: 08-2000

DOI: 10.1128/AEM.66.8.3387-3392.2000

Abstract: Microcystin, a hepatotoxin known to be the cause of animal and human deaths, is produced by the bloom-forming cyanobacterium Microcystis aeruginosa in freshwater bodies worldwide. The toxin is produced nonribosomally via a multifunctional enzyme complex, consisting of both peptide synthetase and polyketide synthase modules coded for by the mcy gene cluster. The recent identification of the mcy genes in the production of microcystin synthetase for the first time provides an avenue to study the regulation of microcystin production at a genetic level. In this study, M. aeruginosa PCC7806 was grown either under continuous light of various intensities or under low light with subsequent short-term exposure to different light intensities and qualities and various stress factors. RNase protection assays were employed to observe the level of mcyB and mcyD transcription under each condition. Both mcyB and mcyD transcript levels were increased under high light intensities and red light. Blue light and certain artificial stress factors (methylviologen and NaCl) led to reduced transcript amounts. There appeared to be two light thresholds, between dark and low light (16 μmol of photons m −2 s −1 ), and medium (31 μmol of photons m −2 s −1 ) and high light (68 μmol of photons m −2 s −1 ), at which a significant increase in transcription occurred. Our findings show that the effect of light on microcystin synthetase production is due to light quality and is initiated at certain threshold intensities, which are not necessarily reflected by observed intracellular toxin bioactivity.

The Gallipoli campaign: History and legend

Publisher: Cambridge University Press

Date: 05-01-2016

DOI: 10.1017/CBO9781316278291.005

Direct PCR Sequencing of Dystrophin Polymorphic CACA Alleles after Purification to Remove Shadow Bands

Publisher: Mary Ann Liebert Inc

Date: 10-1992

DOI: 10.1089/DNA.1992.11.637

Abstract: A method is described that allows the sequencing of polymerase chain reaction (PCR) products containing CACA repeats. The method was tested using a DNA polymorphism that exists at the 3' end of the dystrophin gene. This polymorphism consists of a variation in the length of a CACA dinucleotide repeat. Four alleles from a total of 16 in iduals were sequenced at this locus after the DNA sequence had been lified by the PCR. Five ex les of each of the common alleles were sequenced. For each allele all five sequences were the same. The only ex le of a rare allele was also sequenced. The PCR products of DNA sequences containing dinucleotide repeats consist of a number of bands differing by 2 bp below the most intense main band. Previously, direct sequencing of the PCR products lead to ambiguities and smearing at and above the CACA repeat. In this paper, the main PCR band was cut out of a sequencing gel and directly sequenced to give a clear DNA sequence. Our results indicate that for a particular allele, all in iduals had exactly the same DNA sequence. This implies that with the appropriate choice of oligonucleotide primers, polymorphisms could be detected without electrophoresis.

Recent advances in the heterologous expression of microbial natural product biosynthetic pathways

Publisher: Royal Society of Chemistry (RSC)

Date: 2013

DOI: 10.1039/C3NP70034H

Abstract: The heterologous expression of microbial natural product biosynthetic pathways coupled with advanced DNA engineering enables optimisation of product yields, functional elucidation of cryptic gene clusters, and generation of novel derivatives. This review summarises the recent advances in cloning and maintenance of natural product biosynthetic gene clusters for heterologous expression and the efforts fundamental for discovering novel natural products in the post-genomics era, with a focus on polyketide synthases (PKSs) and non-ribosomal polypeptide synthetases (NRPS).

Renormalization group flow for fermions into antiferromagnetically ordered phases: Method and mean-field models

Publisher: American Physical Society (APS)

Date: 09-10-2012

DOI: 10.1103/PHYSREVB.86.134404

Differential accumulation of paralytic shellfish toxins from Alexandrium minutum in the pearl oyster, Pinctada imbricata

Publisher: Elsevier BV

Date: 09-2009

DOI: 10.1016/J.TOXICON.2009.04.005

Abstract: To investigate the potential for differential accumulation of paralytic shellfish toxins (PSTs) in various tissues of the akoya pearl oyster, Pinctada imbricata, two feeding trials were carried out using the PST-producing dinoflagellate, Alexandrium minutum. When fed with A. minutum at concentrations between 100 and 1300 cells ml(-1), the maximum clearance by P. imbricata was shown to occur at a density of 300 cells ml(-1). When fed twice daily at this rate for up 12 days, P. imbricata accumulated analogues of gonyautoxins (GTXs): GTXs 1,4 and 2,3. The levels of GTXs in the viscera increased progressively on days 4, 8 and 12 to peak at 17.9+/-4.47 microg STX-equivalent 100 g(-1) biomass. Following 12 days of depuration, in the absence of A. minutum, GTX levels fell by approximately 65% to 6.0+/-2.20 microg STX-equivalent 100 g(-1) biomass. No GTX was found in the oysters at the start of the trial or in untreated controls. The accumulation of GTX was found to be tissue specific. No GTX was detected in the muscle tissue of P. imbricata during the feeding trial.

Insertion of an E. coli lacZ gene in Acetobacter xylinus for the production of cellulose in whey

Publisher: Oxford University Press (OUP)

Date: 02-2004

DOI: 10.1016/S0378-1097(04)00007-2

Culturable Endophytes of Medicinal Plants and the Genetic Basis for Their Bioactivity

Publisher: Springer Science and Business Media LLC

Date: 21-03-2012

DOI: 10.1007/S00248-012-0044-8

Abstract: The bioactive compounds of medicinal plants are products of the plant itself or of endophytes living inside the plant. Endophytes isolated from eight different anticancer plants collected in Yunnan, China, were characterized by erse 16S and 18S rRNA gene phylogenies. A functional gene-based molecular screening strategy was used to target nonribosomal peptide synthetase (NRPS) and type I polyketide synthase (PKS) genes in endophytes. Bioinformatic analysis of these biosynthetic pathways facilitated inference of the potential bioactivity of endophyte natural products, suggesting that the isolated endophytes are capable of producing a plethora of secondary metabolites. All of the endophyte culture broth extracts demonstrated antiproliferative effects in at least one test assay, either cytotoxic, antibacterial or antifungal. From the perspective of natural product discovery, this study confirms the potential for endophytes from medicinal plants to produce anticancer, antibacterial and antifungal compounds. In addition, PKS and NRPS gene screening is a valuable method for screening isolates of biosynthetic potential.

An Immortalized Myocyte Cell Line, HL-1, Expresses a Functional δ -Opioid Receptor

Publisher: Elsevier BV

Date: 12-2000

DOI: 10.1006/JMCC.2000.1241

Extraordinary Conservation, Gene Loss, and Positive Selection in the Evolution of an Ancient Neurotoxin

Publisher: Oxford University Press (OUP)

Date: 13-11-2010

DOI: 10.1093/MOLBEV/MSQ295

Abstract: The recent determination of the genetic basis for the biosynthesis of the neurotoxin, saxitoxin, produced by cyanobacteria, has revealed a highly complex sequence of reactions, involving over 30 biosynthetic steps encoded by up to 26 genes clustered at one genomic locus, sxt. Insights into evolutionary-ecological processes have been found through the study of such secondary metabolites because they consist of a measurable phenotype with clear ecological consequences, synthesized by known genes in a small number of species. However, the processes involved in and timing of the ergence of prokaryotic secondary metabolites have been difficult to determine due to their antiquity and the possible frequency of horizontal gene transfer and homologous recombination. Through analyses of gene synteny, phylogenies of in idual genes, and analyses of recombination and selection, we identified the evolutionary processes of this cluster in five species of cyanobacteria. Here, we provide evidence that the sxt cluster appears to have been largely vertically inherited and was therefore likely present early in the ergence of the Nostocales, at least 2,100 Ma, the earliest reliably dated appearance of a secondary metabolite. The sxt cluster has been extraordinarily conserved through stabilizing selection. Genes have been lost and rearranged, have undergone intra- and interspecific recombination, and have been subject to duplication followed by positive selection along the duplicated lineage, with likely consequences for the toxin analogues produced. Several hypotheses exist as to the ecophysiological role of saxitoxin: as a method of chemical defense, cellular nitrogen storage, DNA metabolism, or chemical signaling. The antiquity of this gene cluster indicates that potassium channels, not sodium channels, may have been the original targets of this compound. The extraordinary conservation of the machinery for saxitoxin synthesis, under radically changing environmental conditions, shows that it has continued to play an important adaptive role in some cyanobacteria.

Comparative genomics for understanding intraspecific diversity: a case study of the cyanobacterium Raphidiopsis raciborskii

Publisher: Elsevier

Date: 2022

DOI: 10.1016/B978-0-12-822861-6.00021-2

rRNA sequences reflect the ecophysiology and define the toxic cyanobacteria of the genus Nodularia

Publisher: Microbiology Society

Date: 03-2001

DOI: 10.1099/00207713-51-2-505

Abstract: Nodularia, a member of the order Nostocales, is a bloom-forming filamentous cyanobacterium that possesses the ability to form toxic blooms. The toxin produced by Nodularia, nodularin, is a hepatotoxin, similar in structure to the heptapeptide toxin microcystin. Twenty-one strains of Nodularia, representing the species Nodularia spumigena, Nodularia harveyana and Nodularia sphaerocarpa, were analysed for toxin production by protein phosphatase inhibition assay and sequenced over the 16S rDNA region. Phylogenetic analysis of Nodularia 16S rDNA sequences found that Nodularia clustered into two main groups. An N. spumigena cluster was distinct from the benthic species N. harveyana and N. sphaerocarpa. There was no distinction between strains isolated from globally erse locations. Nodularin-producing species were restricted to the single, evolutionally distinct cluster of N. spumigena. This observation has enabled the design of a specific 16S rRNA PCR for the rapid detection of nodularin-producing strains. Alignment of 16S rDNA sequences from toxic and non-toxic Nodularia with other members of the cyanobacteria allowed the design of both Nodularia generic and toxic N. spumigena-specific primers.

Rashba spin-orbit coupling in the square-lattice Hubbard model: A truncated-unity functional renormalization group study

Publisher: American Physical Society (APS)

Date: 07-03-2023

DOI: 10.1103/PHYSREVB.107.125115

Cover Feature: Heterologous Expression of an Unusual Ketosynthase, SxtA, Leads to Production of Saxitoxin Intermediates in Escherichia coli (5/2021)

Publisher: Wiley

Date: 15-02-2021

DOI: 10.1002/CBIC.202100062

Characterization of the nodularin synthetase gene cluster and proposed theory of the evolution of cyanobacterial hepatotoxins

Publisher: American Society for Microbiology

Date: 11-2004

DOI: 10.1128/AEM.70.11.6353-6362.2004

Abstract: Nodularia spumigena is a bloom-forming cyanobacterium which produces the hepatotoxin nodularin. The complete gene cluster encoding the enzymatic machinery required for the biosynthesis of nodularin in N. spumigena strain NSOR10 was sequenced and characterized. The 48-kb gene cluster consists of nine open reading frames (ORFs), ndaA to ndaI , which are transcribed from a bidirectional regulatory promoter region and encode nonribosomal peptide synthetase modules, polyketide synthase modules, and tailoring enzymes. The ORFs flanking the nda gene cluster in the genome of N. spumigena strain NSOR10 were identified, and one of them was found to encode a protein with homology to previously characterized transposases. Putative transposases are also associated with the structurally related microcystin synthetase ( mcy ) gene clusters derived from three cyanobacterial strains, indicating a possible mechanism for the distribution of these biosynthetic gene clusters between various cyanobacterial genera. We propose an alternative hypothesis for hepatotoxin evolution in cyanobacteria based on the results of comparative and phylogenetic analyses of the nda and mcy gene clusters. These analyses suggested that nodularin synthetase evolved from a microcystin synthetase progenitor. The identification of the nodularin biosynthetic gene cluster and evolution of hepatotoxicity in cyanobacteria reported in this study may be valuable for future studies on toxic cyanobacterial bloom formation. In addition, an appreciation of the natural evolution of nonribosomal biosynthetic pathways will be vital for future combinatorial engineering and rational design of novel metabolites and pharmaceuticals.

Nostoc, Microcoleus and Leptolyngbya inoculums are detrimental to the growth of wheat (Triticum aestivum L.) under salt stress

Publisher: Springer Science and Business Media LLC

Date: 17-02-2013

DOI: 10.1007/S11104-013-1607-2

Molecular Mechanisms to Cellular Responses

Publisher: CRC Press

Date: 03-2013

DOI: 10.1201/B13853

A Putative Gene Cluster from a Lyngbya wollei Bloom that Encodes Paralytic Shellfish Toxin Biosynthesis

Publisher: Public Library of Science (PLoS)

Date: 10-02-2011

DOI: 10.1371/JOURNAL.PONE.0014657

Detection of Saxitoxin-Producing Cyanobacteria and Anabaena circinalis in Environmental Water Blooms by Quantitative PCR

Publisher: American Society for Microbiology

Date: 12-2010

DOI: 10.1128/AEM.00174-10

Abstract: Saxitoxins (STXs) are carbamate alkaloid neurotoxins produced by marine “red tide” dinoflagellates and several species of freshwater filamentous cyanobacteria, including Anabaena circinalis , Aphanizomenon spp., Lyngbya wollei , and Cylindrospermopsis raciborskii . A specific quantitative PCR (qPCR) method based on SYBR green chemistry was developed to quantify saxitoxin-producing Anabaena circinalis cyanobacteria, which are major bloom-forming freshwater cyanobacteria. The aim of this study was to infer the potential toxigenicity of s les by determining the copy number of a unique and unusual polyketide synthase (PKS) sequence ( sxtA ) in the STX biosynthesis gene cluster identified in cyanobacteria. Our qPCR approach was applied to water s les collected from different Australian lakes, dams, and rivers. The STX concentration and cyanobacterial cell density of these blooms were also determined by high-pressure liquid chromatography (HPLC) and microscopic cell counting, respectively. STX concentrations correlated positively with STX gene copy numbers, indicating that the latter can be used as a measure of potential toxigenicity in Anabaena circinalis and possibly other cyanobacterial blooms. The qPCR method targeting STX genes can also be employed for both monitoring and ecophysiological studies of toxic Anabaena circinalis blooms and potentially several other STX-producing cyanobacteria.

Mutations in UVSSA cause UV-sensitive syndrome and destabilize ERCC6 in transcription-coupled DNA repair

Publisher: Springer Science and Business Media LLC

Date: 04-2012

DOI: 10.1038/NG.2228

Abstract: UV-sensitive syndrome (UV(S)S) is an autosomal recessive disorder characterized by photosensitivity and deficiency in transcription-coupled repair (TCR), a subpathway of nucleotide-excision repair that rapidly removes transcription-blocking DNA damage. Cockayne syndrome is a related disorder with defective TCR and consists of two complementation groups, Cockayne syndrome (CS)-A and CS-B, which are caused by mutations in ERCC8 (CSA) and ERCC6 (CSB), respectively. UV(S)S comprises three groups, UV(S)S/CS-A, UV(S)S/CS-B and UV(S)S-A, caused by mutations in ERCC8, ERCC6 and an unidentified gene, respectively. Here, we report the cloning of the gene mutated in UV(S)S-A by microcell-mediated chromosome transfer. The predicted human gene UVSSA (formerly known as KIAA1530)(7) corrects defective TCR in UV(S)S-A cells. We identify three nonsense and frameshift UVSSA mutations in in iduals with UV(S)S-A, indicating that UVSSA is the causative gene for this syndrome. The UVSSA protein forms a complex with USP7 (ref. 8), stabilizes ERCC6 and restores the hypophosphorylated form of RNA polymerase II after UV irradiation.

Description of 'Candidatus Helicobacter heilmannii' based on DNA sequence analysis of 16S rRNA and urease genes

Publisher: Microbiology Society

Date: 11-2004

DOI: 10.1099/IJS.0.63117-0

Abstract: While Helicobacter pylori is accepted as the major bacterial agent of gastric disease in humans, some patients and many animals are infected with a larger, tightly helical-shaped bacterium previously referred to as ‘ Helicobacter heilmannii ’ or ‘ Gastrospirillum hominis ’. Taxonomic classification of these bacteria has been h ered by the inability to cultivate them in vitro and by the inadequate discriminatory power of 16S rRNA gene sequence analysis. This study describes the detection and phylogenetic analysis of 26 different gastrospirillum isolates from humans and animals, which incorporates sequence data based on the 16S rRNA and urease genes. Fifteen gastrospirilla detected in humans, primates and pigs clustered with ‘ Candidatus Helicobacter suis’, thus expanding the host range for this organism. By comparison, based on 16S rRNA data, the remaining 11 gastrospirilla could not be differentiated from Helicobacter felis , Helicobacter bizzozeronii and Helicobacter salomonis . However, urease gene sequence analysis allowed for the discrimination of this latter group into four discrete clusters, three of which contained the above recognized species. The fourth cluster contained isolates from human and feline hosts, and should provisionally be considered a unique bacterial species, for which the name ‘ Candidatus Helicobacter heilmannii’ is proposed.

NtcA from Microcystis aeruginosa PCC 7806 Is Autoregulatory and Binds to the Microcystin Promoter

Publisher: American Society for Microbiology

Date: 07-2010

DOI: 10.1128/AEM.01862-09

Abstract: NtcA is a transcription factor that has been found in a erse range of cyanobacteria. This nitrogen-controlled factor was focused on as a key component in the yet-to-be-deciphered regulatory network controlling microcystin production. Adaptor-mediated PCR was utilized to isolate the ntcA gene from Microcystis aeruginosa PCC 7806. This gene was cloned, and the recombinant (His-tagged) protein was overexpressed and purified for use in mobility shift assays to analyze NtcA binding to putative sites identified in the microcystin mcyA / D promoter region. Autoregulation of NtcA in M. aeruginosa was shown via NtcA binding in the upstream ntcA promoter region. The observation of binding of NtcA to the mcyA / D promoter region has direct relevance for the regulation of microcystin biosynthesis, as transcription of the mcyABCDEFGHIJ gene cluster appears to be under direct control of nitrogen.

A new species of cryptic cyanobacteria isolated from the epidermis of a bottlenose dolphin and as a bioaerosol

Publisher: Informa UK Limited

Date: 29-09-2021

DOI: 10.1080/00318884.2021.1968173

Mucispirillum schaedleri gen. nov., sp. nov., a spiral-shaped bacterium colonizing the mucus layer of the gastrointestinal tract of laboratory rodents

Publisher: Microbiology Society

Date: 05-2005

DOI: 10.1099/IJS.0.63472-0

Abstract: The mammalian gastrointestinal tract is covered by a layer of mucus that can harbour a range of bacterial species specifically adapted to colonize this ecological niche. Examination of 110 bacterial isolates cultivated from the gastrointestinal tract of 23 mice revealed the presence of a subgroup of 30 isolates that did not correspond genetically with genera commonly associated with this site, i.e. members of the ε - Proteobacteria such as Helicobacter and C ylobacter species. Instead this group of isolates was found to lie within the phylum Deferribacteres , a completely distinct lineage in the domain Bacteria . There was a high level of consensus in results obtained from the phenotypic and genotypic characterization of a number of the isolates, which showed they were distinct from other members of the Deferribacteres . As such, they are proposed to constitute a new genus and species, Mucispirillum schaedleri gen. nov., sp. nov. These organisms are anaerobic, Gram-negative, spiral-shaped rods with bipolar flagella. The type strain is HRI I17 T (=ATCC BAA-1009 T =ACM 5223 T ).

Global protein-level responses of halobacterium salinarum NRC-1 to prolonged changes in external sodium chloride concentrations

Publisher: American Chemical Society (ACS)

Date: 23-03-2009

DOI: 10.1021/PR800663C

Abstract: Responses to changes in external salinity were examined in Halobacterium salinarum NRC-1. H. salinarum NRC-1 grows optimally at 4.3 M NaCl and is capable of growth between 2.6 and 5.1 M NaCl. Physiological changes following incubation at 2.6 M NaCl were investigated with respect to growth behavior and proteomic changes. Initial observations indicated delayed growth at low NaCl concentrations (2.6 M NaCl), and supplementation with different sugars, amino acids, or KCl to increase external osmotic pressure did not reverse these growth perturbations. To gain a more detailed insight into the adaptive responses of H. salinarum NRC-1 to changes in salinity, the proteome was characterized using iTRAQ (amine specific isobaric tagging reagents). Three hundred and nine differentially expressed proteins were shown to be associated with changes in the external sodium chloride concentration, with proteins associated with metabolism revealing the greatest response.

Biosynthetic Intermediate Analysis and Functional Homology Reveal a Saxitoxin Gene Cluster in Cyanobacteria

Publisher: American Society for Microbiology

Date: 07-2008

DOI: 10.1128/AEM.00353-08

Abstract: Saxitoxin (STX) and its analogues cause the paralytic shellfish poisoning (PSP) syndrome, which afflicts human health and impacts coastal shellfish economies worldwide. PSP toxins are unique alkaloids, being produced by both prokaryotes and eukaryotes. Here we describe a candidate PSP toxin biosynthesis gene cluster ( sxt ) from Cylindrospermopsis raciborskii T3. The saxitoxin biosynthetic pathway is encoded by more than 35 kb, and comparative sequence analysis assigns 30 catalytic functions to 26 proteins. STX biosynthesis is initiated with arginine, S -adenosylmethionine, and acetate by a new type of polyketide synthase, which can putatively perform a methylation of acetate, and a Claisen condensation reaction between propionate and arginine. Further steps involve enzymes catalyzing three heterocyclizations and various tailoring reactions that result in the numerous isoforms of saxitoxin. In the absence of a gene transfer system in these microorganisms, we have revised the description of the known STX biosynthetic pathway, with in silico functional inferences based on sxt open reading frames combined with liquid chromatography-tandem mass spectrometry analysis of the biosynthetic intermediates. Our results indicate the evolutionary origin for the production of PSP toxins in an ancestral cyanobacterium with genetic contributions from erse phylogenetic lineages of bacteria and provide a quantum addition to the catalytic collective available for future combinatorial biosyntheses. The distribution of these genes also supports the idea of the involvement of this gene cluster in STX production in various cyanobacteria.

The chemical composition and bacteria communities in acid and metalliferous drainage from the wet–dry tropics are dependent on season

Publisher: Elsevier BV

Date: 2013

DOI: 10.1016/J.SCITOTENV.2012.10.024

Abstract: Acid and metalliferous drainage (AMD) occurs when sulphidic minerals, such as arsenopyrite, chalcopyrite and pyrite, are exposed to oxygen and water. Climate, geology and mine site practices can have a significant impact on AMD composition. The elemental composition of the AMD can also affect the bacterial community. Our hypothesis was that in the dry season the AMD at two mine sites, Rum Jungle and Mt Todd, in the Northern Territory, Australia, has a higher concentration of dissolved metals because standing water evaporates during the extended dry period. Our second hypothesis was that the wet and dry season bacteria community in AMD at Rum Jungle and Mt Todd are different, and this difference is correlated to seasonally specific changes in physicochemistry. The first hypothesis was tested by measuring elemental concentrations in AMD during the wet and dry seasons at Mt Todd and Rum Jungle mine sites. The physicochemical properties such as temperature, pH and dissolved oxygen were also measured. To test the second hypothesis, we extracted DNA from AMD s les collected at Rum Jungle and Mt Todd during the wet and dry seasons. The hypervariable V6 region of the bacterial 16S rRNA gene was sequenced by 454 pyrosequencing. The bacterial community composition was examined and related to physiochemical variables. The elemental concentrations in Rum Jungle AMD were higher in the dry season compared to the wet season, but at Mt Todd the elemental composition of AMD changed with year, rather than season. The bacteria community in AMD at Rum Jungle changed between the wet and dry season while in Mt Todd AMD the bacteria community from year 1 was significantly different from year 2. The data showed that the elemental composition and bacteria communities of AMD at Rum Jungle and Mt Todd are influenced by season, mine site practices and geological characteristics of the ore body. In addition, the iron oxidising bacteria Leptospirillum and Acidithiobacillus typically associated with AMD in temperate regions were not prevalent at out tropical study sites.

Endolithic Phototrophs in Built and Natural Stone

Publisher: Springer Science and Business Media LLC

Date: 22-05-2012

DOI: 10.1007/S00284-012-0123-6

Abstract: Lichens, algae and cyanobacteria have been detected growing endolithically in natural rock and in stone buildings in various countries of Australasia, Europe and Latin America. Previously these organisms had mainly been described in natural carbonaceous rocks in aquatic environments, with some reports in siliceous rocks, principally from extremophilic regions. Using various culture and microscopy methods, we have detected endoliths in siliceous stone, both natural and cut, in humid temperate and subtropical climates. Such endolithic growth leads to degradation of the stone structure, not only by mechanical means, but also by metabolites liberated by the cells. Using in vitro culture, transmission, optical and fluorescence microscopy, and confocal laser scanning microscopy, both coccoid and filamentous cyanobacteria and algae, including Cyanidiales, have been identified growing endolithically in the facades of historic buildings built from limestone, sandstone, granite, basalt and soapstone, as well as in some natural rocks. Numerically, the most abundant are small, single-celled, colonial cyanobacteria. These small phototrophs are difficult to detect by standard microscope techniques and some of these species have not been previously reported within stone.

Effects of erythromycin, tetracycline and ibuprofen on the growth of Synechocystis sp. and Lemna minor

Publisher: Elsevier BV

Date: 05-2004

DOI: 10.1016/J.AQUATOX.2004.02.001

Evidence for differences in the metabolism of saxitoxin and C1+2 toxins in the freshwater cyanobacterium Cylindrospermopsis raciborskii T3

Publisher: Elsevier BV

Date: 09-2004

DOI: 10.1016/J.BBAGEN.2004.05.006

Gliotoxicity of the cyanotoxin, β-methyl-amino-L-alanine (BMAA)

Publisher: Springer Science and Business Media LLC

Date: 19-03-2013

DOI: 10.1038/SREP01482

Zorbamycin has a different DNA sequence selectivity compared with bleomycin and analogues

Publisher: Elsevier BV

Date: 11-2016

DOI: 10.1016/J.BMC.2016.09.072

Use of superoxide as an electron shuttle for iron acquasition by the marine cyanobacterium Lyngbya majuscula

Publisher: American Chemical Society (ACS)

Date: 09-04-2005

DOI: 10.1021/ES048766C

Abstract: Reduction of iron from the ferric state to the ferrous state is one strategy employed by microorganisms in nearneutral environments to increase its biological availability. In recent years, the existence of mobile reducing agents produced bymicroorganismsto promote iron reduction, known as electron shuttles, has been demonstrated. Production of electron shuttles has been shown for several organisms, employing a variety of mostly organic molecules as the electron carrier. Here we show that the coastal cyanobacterium Lyngbya majuscula produces iron-reducing superoxide radicals (02*-) and that this facilitates increased iron uptake. We suggest that superoxide is a useful electron shuttle because it reacts rapidly and almost indiscriminately with Fe(lll)-organic complexes and its precursor, dissolved oxygen, is ubiquitous in the photic zone. We further suggest that, for these reasons, the generation of superoxide by marine oxygenic photosynthetic microorganisms and its use in facilitating iron uptake may be a reasonably widespread process.

Microbial communities reflect temporal changes in cyanobacterial composition in a shallow ephemeral freshwater lake

Publisher: Springer Science and Business Media LLC

Date: 04-12-2016

DOI: 10.1038/ISMEJ.2015.218

Detection of Helicobacter species in the gastrointestinal tract of ringtail possum and koala: Possible influence of diet, on the gut microbiota

Publisher: Elsevier BV

Date: 10-2013

DOI: 10.1016/J.VETMIC.2013.06.026

Abstract: The presence of Helicobacter spp. was examined in the liver and in different regions of the gastrointestinal tract (GIT) including the stomach, 3 cm above ileum, ileum, caecum, colon and rectum of 10 ringtail possums (RTPs) and 3 koalas using a combination of microscopy, culture and PCR. Helicobacter was detected in the distal end of the GIT of 7 of 10 RTPs by direct PCR and in all (10/10) RTPs by nested PCR. Five 'S' shaped isolates with bipolar sheathed flagella were isolated from the lower bowel of 3 of the 10 RTPs. 16S rRNA sequence analysis of these 5 isolates confirmed them as potentially novel Helicobacter species. No Helicobacter species were cultured from the koalas, however Helicobacter DNA was detected, in the majority of liver and/or stomach s les of the three koalas and in the colonic region of one koala, using nested PCR. The 16S rRNA gene was sequenced directly from DNA extracted from the homogenised livers and mucus scrapings of the stomach from koala 1 and were confirmed to be Helicobacter species. Based on histopathological examination of sections from the liver and intestine no evidence of infection could be related to the presence of helicobacters in either the RTP or koala. Based on our results, it is possible that diet may influence the detection of Helicobacter species however this required further investigation.

Molecular Identification of Cyanobacteria Associated with Stromatolites from Distinct Geographical Locations

Publisher: Mary Ann Liebert Inc

Date: 08-2002

DOI: 10.1089/153110702762027853

Abstract: Modern stromatolites represent a significant resource for studying microbial ecology and evolution. A preliminary investigation was undertaken employing specific genetic probes to characterize the cyanobacteria responsible for stromatolite construction in a range of environments, including microbial mats found in Australia not previously examined with molecular methods. Isolates of cyanobacteria were collected from stromatolites in thermal springs, hypersaline lakes, and oceanic fringes on two continents. A polymerase chain reaction specific for DNA of cyanobacterial 16S rRNA was developed, the resulting products of the DNA lification reaction were sequenced, and the data were used to infer relatedness between the isolates studied and other members of the cyanobacterial radiation. Complete sequence was generated for the region from position 27 to 408 for 13 strains of cyanobacteria associated with stromatolites. All stromatolite-derived sequences were most closely related to cyanobacteria, as indicated by local sequence alignment. It was possible to correlate genetic identity with morphological nomenclatures and to expand the phylogeny of benthic cyanobacteria. These inferences were also expanded to temporal variation in the dominant resident cyanobacterial species based on s ling of surface and core sinter laminations. Under the methods employed, only one cyanobacterial strain was detected in each s le, suggesting the possible dominance of a specific clonal population of cyanobacteria at any one time in the biota of the s les tested. The data indicate that internal core s les of a stromatolite at least 10 years old can be successfully analyzed by DNA-based methods to identify preserved cyanobacteria.

Elevated Na⁺ and pH influence the production and transport of saxitoxin in the cyanobacteria Anabaena circinalisAWQC131C and Cylindrospermopsis raciborskiiT3

Publisher: Wiley

Date: 21-10-2016

DOI: 10.1111/1462-2920.13048

Abstract: Saxitoxins (STX), neurotoxic alkaloids, fall under the umbrella of paralytic shellfish toxins produced by marine dinoflagellates and freshwater cyanobacteria. The genes responsible for the production of STX have been proposed, but factors that influence their expression and induce toxin efflux remain unclear. Here we characterize the putative STX NorM-like MATE transporters SxtF and SxtM. Complementation of the antibiotic-sensitive strain Escherichia coli KAM32 with these transporters decreased fluoroquinolone sensitivity, indicating that while becoming evolutionary specialized for STX transport these transporters retain relaxed specificity typical of this class. The transcriptional response of STX biosynthesis (sxtA) along with that of the STX transporters (sxtM and sxtF from Cylindrospermopsis raciborskii T3, and sxtM from Anabaena circinalis AWQC131C) were assessed in response to ionic stress. These data, coupled with a measure of toxin intracellular to extracellular ratios, provide an insight into the physiology of STX export. Cylindrospermopsis raciborskii and Anabaena circinalis exhibited opposing responses under conditions of ionic stress. High Na(+) (10 mM) induced moderate alterations of transcription and STX localization, whereas high pH (pH 9) stimulated the greatest physiological response. Saxitoxin production and cellular localization are responsive to ionic strength, indicating a role of this molecule in the maintenance of cellular homeostasis.

Investigations into the taxonomy, toxicity and ecology of benthic cyanobacterial accumulations in Myall Lake, Australia

Publisher: CSIRO Publishing

Date: 2005

DOI: 10.1071/MF04195

Abstract: Large benthic accumulations of cyanobacteria occur in sheltered embayments within Myall Lake, New South Wales, Australia. The lake is shallow, with the entire bottom within the euphotic zone, and it is generally considered pristine, having low nutrient concentrations. The accumulations are highly organic and contain a mix of species mainly from the order Chroococcales, with two forms of Aphanothece being dominant. However polymerase chain reaction (PCR) analysis indicates a close similarity to Microcystis flos-aquae. The cells appear to lack aerotopes and form sticky mucilaginous amalgamations, which may enhance their benthic habit. Although Chroococcales also dominate the planktonic cyanobacterial community, the benthic species are seldom, if ever, found entrained within the water column. Some hepatotoxicity was indicated by mouse bioassay, protein phosphatase inhibition assay, enzyme-linked immuno-sorbent assay (ELISA) for microcystins, PCR and by chromatographic evidence for a microcystin. Ecological aspects of the distribution, gross morphology of the organisms and management implications for recreational water-users are discussed.

Lack of methylated hopanoids renders the cyanobacterium Nostoc punctiforme sensitive to osmotic and pH stress

Publisher: American Society for Microbiology

Date: 07-2017

DOI: 10.1128/AEM.00777-17

Abstract: To investigate the function of 2-methylhopanoids in modern cyanobacteria, the hpnP gene coding for the radical S -adenosyl methionine (SAM) methylase protein that acts on the C-2 position of hopanoids was deleted from the filamentous cyanobacterium Nostoc punctiforme ATCC 29133S. The resulting Δ hpnP mutant lacked all 2-methylhopanoids but was found to produce much higher levels of two bacteriohopanepentol isomers than the wild type. Growth rates of the Δ hpnP mutant cultures were not significantly different from those of the wild type under standard growth conditions. Akinete formation was also not impeded by the absence of 2-methylhopanoids. The relative abundances of the different hopanoid structures in akinete-dominated cultures of the wild-type and Δ hpnP mutant strains were similar to those of vegetative cell-dominated cultures. However, the Δ hpnP mutant was found to have decreased growth rates under both pH and osmotic stress, confirming a role for 2-methylhopanoids in stress tolerance. Evidence of elevated photosystem II yield and NAD(P)H-dependent oxidoreductase activity in the Δ hpnP mutant under stress conditions, compared to the wild type, suggested that the absence of 2-methylhopanoids increases cellular metabolic rates under stress conditions. IMPORTANCE As the first group of organisms to develop oxygenic photosynthesis, Cyanobacteria are central to the evolutionary history of life on Earth and the subsequent oxygenation of the atmosphere. To investigate the origin of cyanobacteria and the emergence of oxygenic photosynthesis, geobiologists use biomarkers, the remnants of lipids produced by different organisms that are found in geologic sediments. 2-Methylhopanes have been considered indicative of cyanobacteria in some environmental settings, with the parent lipids 2-methylhopanoids being present in many contemporary cyanobacteria. We have created a Nostoc punctiforme Δ hpnP mutant strain that does not produce 2-methylhopanoids to assess the influence of 2-methylhopanoids on stress tolerance. Increased metabolic activity in the mutant under stress indicates compensatory alterations in metabolism in the absence of 2-methylhopanoids.

Biosynthesis of toxic naturally-occurring seafood contaminants

Publisher: Elsevier BV

Date: 08-2010

DOI: 10.1016/J.TOXICON.2009.09.001

Abstract: Outbreaks of human illness caused by the consumption of contaminated seafood, continues to be a major problem particularly for the shellfish industry. Toxins from marine, brackish and freshwater environments, which are often produced as a result of harmful algal blooms, have been implicated as the causative agents of these poisonings. Commonly, poisoning events have been grouped into one of six classes, Paralytic Shellfish Poisoning (PSP), Diarrhetic Shellfish Poisoning (DSP), Neurotoxic Shellfish Poisoning (NSP), Ciguatera Fish Poisoning (CFP), Azaspiracid Shellfish Poisoning (AZP), and Amnesiac Shellfish Poisoning (ASP). The causative agents of these specific poisonings along with their biosyntheses are discussed in this review. The highly unusual and complex structures of most common seafood toxins have made them interesting targets for biosynthetic studies. Many of the toxins presented are biosynthesized via complex pathways that have been elucidated either through isotope labelled precursor feeding studies and/or characterization of the genes encoding the producing organism's biosynthetic machinery. Feeding studies key to our understanding of a particular toxin's biosynthesis, such as the incorporation of unusual precursors, as well as unique biosynthetic pathways and rare chemical mechanisms involved in the assembly process are highlighted. More recently, however, modern genomics-based techniques have been used for the elucidation of biosynthetic pathways and these are presented in the context of polyketide, non-ribosomal peptide, and hybrid pathway derived, toxin assembly.

Gene expression and molecular evolution of sxtA4 in a saxitoxin producing dinoflagellate Alexandrium catenella

Publisher: Elsevier BV

Date: 12-2014

DOI: 10.1016/J.TOXICON.2014.09.015

Abstract: Dinoflagellates of the genus Alexandrium produce the neurotoxin saxitoxin (STX), responsible for paralytic shellfish poisoning (PSP) and accumulates in marine invertebrates. The recent identification of STX biosynthesis genes allowed us to investigate the expression of sxtA4 at different growth stages in Alexandrium catenella Group IV. We found no significant differences in expression of sxtA4, despite significant differences in STX levels at different growth stages (P < 0.023). Three reference genes were tested for normalisation: actin, cytochrome b (cob), and the large subunit ribosomal RNA (LSU rDNA). cob was most stably expressed but the combination of two reference genes, actin and cob, resulted in the best stability factor. Most genomic sequences of sxtA4 from A. catenella were in a clade that included sequences from Alexandrium fundyense Group I, however, one paralogue was not related to the others, suggesting recombination or lateral transfer. A comparison of the sxtA4 cDNA sequences with genomic DNA sequences indicated the possibility of transcript editing and the preferential transcription of certain genomic DNA loci. The results show that, in dinoflagellates, post-transcriptional mechanisms play a major role in the regulation of saxitoxin biosynthesis.

Specific amplification and restriction polymorphisms of the cyanobacterial rRNA operon spacer region

Publisher: Elsevier BV

Date: 11-1997

DOI: 10.1016/S0723-2020(97)80033-1

Characterization of the V3 Region of HIV-1 Isolates from Sydney, Australia

Publisher: Mary Ann Liebert Inc

Date: 03-1995

DOI: 10.1089/AID.1995.11.423

Genetic Characterization of Cylindrospermopsis raciborskii (Cyanobacteria) Isolates from Diverse Geographic Origins Based on nifH and cpcBA-IGS Nucleotide Sequence Analysis

Publisher: American Society for Microbiology

Date: 05-2002

DOI: 10.1128/AEM.68.5.2567-2571.2002

Abstract: Isolates of the toxic, N 2 -fixing species Cylindrospermopsis raciborskii from various geographic locations were analyzed with respect to their genetic ersity based on the nifH and cpcBA -IGS genes. Gene sequences clustered according to their geographic origin, with the nifH sequences separating into European, Australian, and American groups and the cpcBA -IGS sequences separating into American and European or Australian groups. PCR primers for both genes were designed to exclusively lify DNA from Cylindrospermopsis species, and an additional primer set for cpcBA -IGS was designed to specifically lify the American C. raciborskii strains.

The association of mycobacterium avium subsp. paratuberculosis with inflammatory bowel disease

Publisher: Public Library of Science (PLoS)

Date: 05-02-2016

DOI: 10.1371/JOURNAL.PONE.0148731

Comparative analysis of cyanobacteria in the rhizosphere and as endosymbionts of cycads in drought-affected soils

Publisher: Oxford University Press (OUP)

Date: 30-01-2012

DOI: 10.1111/J.1574-6941.2011.01288.X

Abstract: Does the ersity of cyanobacteria in the cycad rhizosphere relate to the cyanobiont species found in the coralloid roots of these ancient plants? The aim of this study was to identify the ersity of soil cyanobacteria occurring in the immediate vicinity of 22 colonized coralloid roots belonging to members of the cycad genera: Macrozamia, Lepidozamia, Bowenia and Cycas. The majority of coralloid roots were s led at depths > 10 cm below the soil surface. A total of 32 cyanobacterial isolates were cultured and their 16S rRNA gene partially sequenced. Phylogenetic analysis revealed nine operational taxonomic units of soil cyanobacteria comprising 30 Nostoc spp., a Tolypothrix sp. and a Leptolyngbya sp. Microscopy indicated that all isolates were unialgal and confirmed their genus identity. Rhizospheric ersity was compared to existing data on cyanobionts isolated at the same time from the cycad coralloid root. The same isolate was present in both the cycad coralloid root and rhizosphere at only six sites. Phylogenetic evidence indicates that most rhizosphere isolates were distinct from root cyanobionts. This weak relationship between the soil cyanobacteria and cycad cyanobionts might indicate that changes in the soil community composition are due to environmental factors.

Intraspecific variation in growth, morphology and toxin quotas for the cyanobacterium, Cylindrospermopsis raciborskii

Publisher: Elsevier BV

Date: 09-2016

DOI: 10.1016/J.TOXICON.2016.07.005

Abstract: Cylindrospermopsis raciborskii is a bloom forming cyanobacterium with complex population dynamics and toxicity. In January of 2013 a single s le was collected from surface waters in Lake Wivenhoe, Australia, and twenty-four in idual trichomes were isolated. Each isolate exhibited differences in growth rate, toxin cell quota and morphology, in the absence of phylogenetic heterogeneity. This study demonstrates substantial intraspecific isolate variation within a small s le and this has implications for understanding the population dynamics of this species.

Xanthogenate nucleic acid isolation from cultured and environmental cyanobacteria

Publisher: Wiley

Date: 09-02-2000

DOI: 10.1046/J.1529-8817.2000.99079.X

The FeL model of iron acquisition: Nondissociative reduction of ferric complexes in the marine environment

Publisher: Wiley

Date: 07-2006

DOI: 10.4319/LO.2006.51.4.1744

A reinvestigation of saxitoxin production and sxtA in the 'non-toxic' Alexandrium tamarense Group V clade

Publisher: Elsevier BV

Date: 06-2012

DOI: 10.1016/J.HAL.2012.05.001

The ZntA-like NpunR4017 plays a key role in maintaining homeostatic levels of zinc in Nostoc punctiforme.

Publisher: Springer Science and Business Media LLC

Date: 20-08-2015

DOI: 10.1007/S00253-015-6922-5

Abstract: Analysis of cellular response to zinc exposure provides insights into how organisms maintain homeostatic levels of zinc that are essential, while avoiding potentially toxic cytosolic levels. Using the cyanobacterium Nostoc punctiforme as a model, qRT-PCR analyses established a profile of the changes in relative mRNA levels of the ZntA-like zinc efflux transporter NpunR4017 in response to extracellular zinc. In cells treated with 18 μM of zinc for 1 h, NpunR4017 mRNA levels increased by up to 1300 % above basal levels. The accumulation and retention of radiolabelled (65)Zn by NpunR4107-deficient and overexpressing strains were compared to wild-type levels. Disruption of NpunR4017 resulted in a significant increase in zinc accumulation up to 24 % greater than the wild type, while cells overexpressing NpunR4107 accumulated 22 % less than the wild type. Accumulation of (65)Zn in ZntA(-) Escherichia coli overexpressing NpunR4017 was reduced by up to 21 %, indicating the capacity for NpunR4017 to compensate for the loss of ZntA. These findings establish the newly identified NpunR4017 as a zinc efflux transporter and a key transporter for maintaining zinc homeostasis in N. punctiforme.

Detection and sequencing of the microcystin LR-degrading gene, mlrA, from new bacteria isolated from Japanese lakes

Publisher: Oxford University Press (OUP)

Date: 12-2003

DOI: 10.1016/S0378-1097(03)00847-4

16s ribosomal RNA gene sequence and phylogeny of toxic microcystis sp. (cyanobacteria)

Publisher: Informa UK Limited

Date: 1994

DOI: 10.3109/10425179409020861

Abstract: The toxigenic and bloom-forming cyanobacterial genus Microcystis contains several ill-defined species. The 16S rDNA for two strains of toxic M. aeruginosa were sequenced and compared to available cyanobacterial, bacterial, and chloroplast 16S rRNA gene information. Phylogeny and the validity of a molecular taxonomy for the genus Microcystis is presented.

Identification of an Na+-Dependent Transporter Associated with Saxitoxin-Producing Strains of the Cyanobacterium Anabaena circinalis

Publisher: American Society for Microbiology

Date: 08-2004

DOI: 10.1128/AEM.70.8.4711-4719.2004

Abstract: Blooms of the freshwater cyanobacterium Anabaena circinalis are recognized as an important health risk worldwide due to the production of a range of toxins such as saxitoxin (STX) and its derivatives. In this study we used HIP1 octameric-palindrome repeated-sequence PCR to compare the genomic structure of phylogenetically similar Australian isolates of A. circinalis . STX-producing and nontoxic cyanobacterial strains showed different HIP1 (highly iterated octameric palindrome 1) DNA patterns, and characteristic interrepeat licons for each group were identified. Suppression subtractive hybridization (SSH) was performed using HIP1 PCR-generated libraries to further identify toxic-strain-specific genes. An STX-producing strain and a nontoxic strain of A. circinalis were chosen as testers in two distinct experiments. The two categories of SSH putative tester-specific sequences were characterized by different families of encoded proteins that may be representative of the differences in metabolism between STX-producing and nontoxic A. circinalis strains. DNA-microarray hybridization and genomic screening revealed a toxic-strain-specific HIP1 fragment coding for a putative Na + -dependent transporter. Analysis of this gene demonstrated analogy to the mrpF gene of Bacillus subtilis , whose encoded protein is involved in Na + -specific pH homeostasis. The application of this gene as a molecular probe in laboratory and environmental screening for STX-producing A. circinalis strains was demonstrated. The possible role of this putative Na + -dependent transporter in the toxic cyanobacterial phenotype is also discussed, in light of recent physiological studies of STX-producing cyanobacteria.

A spontaneous mutant of microcystin biosynthesis: Genetic characterization and effect on Daphnia

Publisher: Wiley

Date: 11-2001

DOI: 10.1046/J.1462-2920.2001.00241.X

Abstract: Microcystis aeruginosa strain MRC is unique in its' possession of the mcyA-J gene cluster, which encodes microcystin synthetase, but its' inability to produce microcystins. M. aeruginosa strain MRD is genetically identical to MRC at numerous genomic loci examined, but produces a variety of microcystins, mainly with the amino acid tyrosine in the molecule. Zooplankton studies with Daphnia galeata and D. pulicaria, using the mutant (MRC) and its' wild type (MRD), showed for the first time that microcystins other than microcystin-LR can be responsible for the poisoning of Daphnia by Microcystis. Regardless of microcystin content, both Daphnia exhibited significantly reduced ingestion rates when fed with either strain of M. aeruginosa compared with the green alga Scenedesmus acutus. A disruption of the molting process in both Daphnia spp. was noted when these species were fed with MRC cells. Such symptoms on Daphnia have not been previously reported for cyanobacteria and may point to a bioactive compound, other than microcystin, which inhibits the hardening of protein-chitin complexes in Daphnia.

High-titer heterologous production in E. coli of lyngbyatoxin, a protein kinase C activator from an uncultured marine cyanobacterium

Publisher: American Chemical Society (ACS)

Date: 17-06-2013

DOI: 10.1021/CB400189J

How accurately can we detect Mycobacterium avium subsp. paratuberculosis infection?

Publisher: Elsevier BV

Date: 04-2011

DOI: 10.1016/J.MIMET.2011.01.026

Abstract: Mycobacteria have thwarted detection by scientists for centuries. Mycobacterium paratuberculosis is one of the most fastidious of the Mycobacteriaceae, and has been implicated in both animal and human diseases. In domestic livestock, M. paratuberculosis has been associated with Johne's disease, which given its increasing incidence, is currently a cause for concern, due to the potential for M. paratuberculosis to enter our food chain. In addition, a tenuous link has been reported between M. paratuberculosis and Crohn's disease, however evidence to support this link is h ered by the lack of accurate methodologies for detection of M. paratuberculosis in humans. This review compares the sensitivity and specificity of traditional and more recent techniques to the culture and molecular detection of M. paratuberculosis. While serology and culture are popular choices for the livestock industry they have not produced useful data for human infection. Although the advent of molecular biology has enabled faster diagnosis of M. paratuberculosis in human infection, there is currently no gold standard such as culture on which to validate these findings. Even with DNA/RNA detection methods, there is the ever present issue of the genetic relatedness of M. paratuberculosis to other mycobacteria of the Mycobacterium avium complex, some of which also infect humans with very different pathological outcomes. Recent developments in this field include more rapid methods of M. paratuberculosis culture as well as the development of more accurate and sensitive PCR assays. The application of these techniques should offer a greater insight as to the role of M. paratuberculosis in human gastrointestinal diseases.

Does α-Amino-β-methylaminopropionic Acid (BMAA) Play a Role in Neurodegeneration?

Publisher: MDPI AG

Date: 16-09-2011

DOI: 10.3390/IJERPH8093728

High-performance functional Renormalization Group calculations for interacting fermions

Publisher: Elsevier BV

Date: 04-2001

DOI: 10.1016/J.CPC.2016.12.013

Mammalian engineers drive soil microbial communities and ecosystem functions across a disturbance gradient

Publisher: Wiley

Date: 18-08-2016

DOI: 10.1111/1365-2656.12574

Abstract: The effects of mammalian ecosystem engineers on soil microbial communities and ecosystem functions in terrestrial ecosystems are poorly known. Disturbance from livestock has been widely reported to reduce soil function, but disturbance by animals that forage in the soil may partially offset these negative effects of livestock, directly and/or indirectly by shifting the composition and ersity of soil microbial communities. Understanding the role of disturbance from livestock and ecosystem engineers in driving soil microbes and functions is essential for formulating sustainable ecosystem management and conservation policies. We compared soil bacterial community composition and enzyme concentrations within four microsites: foraging pits of two vertebrates, the indigenous short-beaked echidna (Tachyglossus aculeatus) and the exotic European rabbit (Oryctolagus cuniculus), and surface and subsurface soils along a gradient in grazing-induced disturbance in an arid woodland. Microbial community composition varied little across the disturbance gradient, but there were substantial differences among the four microsites. Echidna pits supported a lower relative abundance of Acidobacteria and Cyanobacteria, but a higher relative abundance of Proteobacteria than rabbit pits and surface microsites. Moreover, these microsite differences varied with disturbance. Rabbit pits had a similar profile to the subsoil or the surface soils under moderate and high, but not low disturbance. Overall, echidna foraging pits had the greatest positive effect on function, assessed as mean enzyme concentrations, but rabbits had the least. The positive effects of echidna foraging on function were indirectly driven via microbial community composition. In particular, increasing activity was positively associated with increasing relative abundance of Proteobacteria, but decreasing Acidobacteria. Our study suggests that soil disturbance by animals may offset, to some degree, the oft-reported negative effects of grazing-induced disturbance on soil function. Further, our results suggest that most of this effect will be derived from echidnas, with little positive effects due to rabbits. Activities that enhance the habitat for echidnas or reduce rabbit populations are likely to have a positive effect on soil function in these systems.

Detection and identification of cyanobacteria associated with toxic blooms: DNA amplification protocols

Publisher: Informa UK Limited

Date: 11-1996

DOI: 10.2216/I0031-8884-35-6S-147.1

Multiple Alternate Transcripts Direct the Biosynthesis of Microcystin, a Cyanobacterial

Publisher: American Society for Microbiology

Date: 02-2002

DOI: 10.1128/AEM.68.2.449-455.2002

Abstract: The mcyABCDEFGHIJ gene cluster of Microcystis aeruginosa encodes the mixed polyketide synthase/nonribosomal peptide synthetase (microcystin synthetase) which is responsible for biosynthesis of the potent liver toxin microcystin. The sequence and orientation of the mcy genes have previously been reported, but no transcriptional analysis had been performed prior to this study. The mcyABCDEFGHIJ genes are transcribed as two polycistronic operons, mcyABC and mcyDEFGHIJ , from a central bidirectional promoter between mcyA and mcyD . Two transcription start sites were detected for both mcyA and mcyD when cells were exposed to light intensities of 68 and 16 μmol of photons m −2 s −1 . The start sites, located 206 and 254 bp upstream of the translational start for mcyD under high and low light conditions, respectively, indicate long untranslated leader regions. Putative transcription start sites were also identified for mcyE , mcyF , mcyG , mcyH , mcyI , and mcyJ but not for mcyB and mcyC . A combination of reverse transcription-PCR and rapid lification of cDNA ends was employed throughout this work, which may have been one of the first transcriptional analyses of a large nonribosomal polyketide gene cluster.

rRNA sequences and evolutionary relationships among toxic and nontoxic cyanobacteria of the genus Microcystis

Publisher: Microbiology Society

Date: 07-1997

DOI: 10.1099/00207713-47-3-693

Abstract: A primary-structure analysis of the 16S rRNA gene was performed with 10 strains representing five described and one unidentified species of the genus Microcystis. The phylogenies determined illustrate the evolutionary affiliations among Microcystis strains, other cyanobacteria, and related plastids and bacteria. A cluster of 10 strains that included hepatotoxic isolates identified as Microcystis aeruginosa formed a monophyletic group. However, the genus Microcystis appeared to be polyphyletic and contained two strains that clustered with unicellular cyanobacteria belonging to the genus Synechococcus. The clustering of related Microcystis strains, including strains involved in the production of the cyclic peptide toxin microcystin, was consistent with cell morphology, gas vacuolation, and the low G + C contents of the genomes. The Microcystis lineage was also distinct from the lineage containing the unicellular genus Synechocystis and the filamentous, heterocyst-forming genus Nostoc. The secondary structure of a Microcystis 16S rRNA molecule was determined, and genus-specific sequence signatures were used to design primers that permitted identification of the potentially toxic cyanobacteria belonging to the genus Microcystis via DNA lification.

Varied Diazotrophies, Morphologies, and Toxicities of Genetically Similar Isolates of Cylindrospermopsis raciborskii (Nostocales, Cyanophyceae) from Northern Australia

Publisher: American Society for Microbiology

Date: 04-2001

DOI: 10.1128/AEM.67.4.1839-1845.2001

Abstract: The potentially toxic freshwater cyanobacterium Cylindrospermopsis raciborskii has become increasingly prevalent in tropical and temperate water bodies worldwide. This paper investigates the effects of different nitrogen sources (NO 3 − , NH 4 + , and omission of a fixed form of nitrogen) on the growth rates, morphologies, and cylindrospermopsin (CYL) concentrations (expressed as a percentage of the freeze-dried weight) of seven C. raciborskii isolates obtained from a range of water bodies in northern Australia and grown in batch culture. In general, growth rates were lowest in the absence of a fixed-nitrogen source and highest with NH 4 + as the nitrogen source. Conversely, the highest concentrations of CYL were recorded in cultures grown in the absence of a fixed-nitrogen source and the lowest were found in cultures supplied with NH 4 + . Cultures supplied with NO 3 − were intermediate with respect to both CYL concentration and growth rate. Different nitrogen sources resulted in significant differences in the morphology of C. raciborskii trichomes. Most notable were the loss of heterocysts and the tapering of end cells in cultures supplied with NH 4 + and the statistically significant increase in vegetative cell length (nitrogen depleted NO 3 − NH 4 + ). The morphological changes induced by different nitrogen sources were consistent for all isolates, despite measurable differences in vegetative-cell and heterocyst dimensions among isolates. Such induced morphological variation has implications for Cylindrospermopsis taxonomy, given that distinctions between species are based on minor and overlapping differences in cell lengths and widths. The close phylogenetic association among all seven isolates was confirmed by the high level ( .8%) of similarity of their 16S rRNA gene sequences. Another genetic technique, analysis of the HIP1 octameric-palindrome repeated sequence, showed greater heterogeneity among the isolates and appears to be a useful method for distinguishing among isolates of C. raciborskii .

Non-ribosomal peptide antibiotics

Publisher: Informa Healthcare

Date: 10-2000

DOI: 10.1517/13543776.10.10.1583

Molecular detection of genes responsible for cyanobacterial toxin production in the genera Microcystis, Nodularia, and Cylindrospermopsis

Publisher: Humana Press

Date: 2004

DOI: 10.1385/1-59259-766-1:213

Abstract: Cyanobacteria are ubiquitous in the freshwater environment. Their success as a group in a wide range of aquatic habitats has been attributed to their unique physiological characteristics and their high adaptive ability over a wide range of environmental conditions. They are capable of reaching very high biomass levels, often dominating the other aquatic biota, and under some circumstances can accumulate near the water surface, producing scums. Such cyanobacterial "blooms" are of particular concern in reservoirs used to supply potable water. Dense aggregations of cyanobacterial cells may block water filters, and many species produce compounds that affect the taste and odor of water supplies. Of greatest concern, however, is the potential of many bloom-forming cyanobacteria to produce a wide range of toxic substances. These natural compounds, known as cyanotoxins, are chemically erse and are usually either neuro- or hepatotoxic in pathology.

A feeding study to probe the uptake of Maitotoxin by snapper (Pagrus auratus)

Publisher: Elsevier BV

Date: 07-2014

DOI: 10.1016/J.HAL.2014.05.018

Pseudovibrio denitrificans strain Z143-1, a heptylprodigiosin-producing bacterium isolated from a Philippine tunicate

Publisher: Oxford University Press (OUP)

Date: 12-2017

DOI: 10.1111/J.1574-6968.2007.00950.X

Abstract: Microbial isolate Z143-1 found to be associated with an unidentified tunicate was characterized due to its significant antimicrobial activity. Z143-1 is similar to Pseudovibrio ascidiaceicola and Pseudovibrio denitrificans in morphological, physiological and biochemical characteristics, except for its ability to ferment glucose and produce a characteristic red pigment. Fatty acid methyl ester analysis revealed a predominance of the fatty acid 18:1 omega7c at 80.55%, at levels slightly lower than the Pseudovibrio denitrificans type strain DN34(T) (87.7%). The mol% G+C of Z143-1 is 54.02, relatively higher than the Pseudovibrio denitrificans type strain DN34(T) and Pseudovibrio ascidiaceicola with mol% G+C of 51.7 and 51.4, respectively. However, phylogenetic analysis of the 16S rRNA gene sequence of Z143-1 showed 100% similarity with the Pseudovibrio denitrificans type strain DN34(T). In this study, the bacterium Z143-1 is reported as a new strain of Pseudovibrio denitrificans. While there is no report of a secondary metabolite for Pseudovibrio denitrificans, Z143-1 produces the red pigment heptylprodigiosin, also known as 16-methyl-15-heptyl-prodiginine, which shows anti-Staphylococcus aureus activity.

Neurotoxic alkaloids from cyanobacteria

Publisher: Springer Berlin Heidelberg

Date: 2013

DOI: 10.1007/978-3-642-22144-6_47

Molecular and cellular characterisation of the zinc uptake (Znu) system of Nostoc punctiforme.

Publisher: Oxford University Press (OUP)

Date: 19-06-2013

DOI: 10.1111/1574-6941.12153

Abstract: Metal homoeostasis in cyanobacteria is based on uptake and export systems that are controlled by their own regulators. This study characterises the zinc uptake (Znu) system in Nostoc punctiforme. The system was found to comprise of three subunits in an ACB operon: a Zn(2+)-binding protein (ZnuA18), a transmembrane domain (ZnuB) and an ATPase (ZnuC). These proteins are encoded within the znu operon regulated by a zinc uptake transcription repressor (Zur). Interestingly, a second Zn(2+)-binding protein (ZnuA08) was also identified at a distal genomic location. Interactions between components of the ZnuACB system were investigated using knockouts of the in idual genes. The znuA08(-), znuA18(-), znuB(-) and znuC(-) mutants displayed overall reduced znuACB transcript levels, suggesting that all system components are required for normal expression of znu genes. Zinc uptake assays in the Zn(2+)-binding protein mutant strains showed that the disruption of znuA18 had a greater negative effect on zinc uptake than disruption of znuA08. Complementation studies in Escherichia coli indicated that both znuA08 and znuA18 were able to restore zinc uptake in a znuA(-) mutant, with znuA18 permitting the highest zinc uptake rate. The N. punctiforme zur was also able to complement the E. coli zur(-) mutant.

Heterologous production of cyanobacterial mycosporine-like amino acids mycosporine-ornithine and mycosporine-lysine in Escherichia coli

Publisher: American Society for Microbiology

Date: 15-10-2016

DOI: 10.1128/AEM.01632-16

Abstract: Mycosporine-like amino acids (MAAs) are an important class of secondary metabolites known for their protection against UV radiation and other stress factors. Cyanobacteria produce a variety of MAAs, including shinorine, the active ingredient in many sunscreen creams. Bioinformatic analysis of the genome of the soil-dwelling cyanobacterium Cylindrospermum stagnale PCC 7417 revealed a new gene cluster with homology to MAA synthase from Nostoc punctiforme . This newly identified gene cluster is unusual because it has five biosynthesis genes ( mylA to mylE ), compared to the four found in other MAA gene clusters. Heterologous expression of mylA to mylE in Escherichia coli resulted in the production of mycosporine-lysine and the novel compound mycosporine-ornithine. To our knowledge, this is the first time these compounds have been heterologously produced in E. coli and structurally characterized via direct spectral guidance. This study offers insight into the ersity, biosynthesis, and structure of cyanobacterial MAAs and highlights their amenability to heterologous production methods. IMPORTANCE Mycosporine-like amino acids (MAAs) are significant from an environmental microbiological perspective as they offer microbes protection against a variety of stress factors, including UV radiation. The heterologous expression of MAAs in E. coli is also significant from a biotechnological perspective as MAAs are the active ingredient in next-generation sunscreens.

Fodinomyces uranophilus gen. nov. sp. nov. and Coniochaeta fodinicola sp. nov., two uranium mine-inhabiting Ascomycota fungi from northern Australia

Publisher: Informa UK Limited

Date: 11-2014

DOI: 10.3852/14-013

Abstract: Seven acidophilic/acidotolerant fungal strains were characterized from s les of process waters (raffinate) at one of Australia's largest uranium mines, the Ranger Mine in Northern Territory. They were isolated from raffinate, which typically were very acidic (pH 1.7-1.8) and contained high concentrations of total dissolved/colloidal salts (> 100 g/L). Five of the isolates correspond to two new acidotolerant Ascomycota fungi. The first is a member of a new genus, here described as Fodinomyces (Teratosphaeriaceae, Capnodiales, Dothideomycetes) and does not show clear close affiliation with any other described fungus in the scientific literature. The second belongs to the genus Coniochaeta (Coniochaetaceae, Coniochaetales, Sordariomycetes) and is closely related to Coniochaeta hansenii.

Comparative proteomics of the toxigenic diazotroph Raphidiopsis raciborskii (cyanobacteria) in response to iron

Publisher: Wiley

Date: 30-11-2020

DOI: 10.1111/1462-2920.15328

Abstract: Raphidiopsis raciborskii is an invasive bloom‐forming cyanobacteria with the flexibility to utilize atmospheric and fixed nitrogen. Since nitrogen‐fixation has a high requirement for iron as an ezyme cofactor, we hypothesize that iron availability would determine the success of the species under nitrogen‐fixing conditions. This study compares the proteomic response of cylindrospermopsin‐producing and non‐toxic strains of R. racibroskii to reduced iron concentrations, under nitrogen‐fixing conditions, to examine any strain‐specific adaptations that might increase fitness under these conditions. We also compared their proteomic responses at exponential and stationary growth phases to capture the changes throughout the growth cycle. Overall, the toxic strain was more competitive under Fe‐starved conditions during exponential phase, with upregulated growth and transport‐related proteins. The non‐toxic strain showed reduced protein expression across multiple primary metabolism pathways. We propose that the increased expression of porin proteins during the exponential growth phase enables toxic strains to persist under Fe‐starved conditions with this ability providing a potential explanation for the increased fitness of cylindrospermoipsin‐producing strains during unfavourable environmental conditions.

Characterization of two cation diffusion facilitators NpunF0707 and NpunF1794 in Nostoc punctiforme.

Publisher: Oxford University Press (OUP)

Date: 24-09-2015

DOI: 10.1111/JAM.12942

Abstract: To characterize genes involved in maintaining homeostatic levels of zinc in the cyanobacterium Nostoc punctiforme. Metal efflux transporters play a central role in maintaining homeostatic levels of trace elements such as zinc. Sequence analyses of the N. punctiforme genome identified two potential cation diffusion facilitator (CDF) metal efflux transporters, Npun_F0707 (Cdf31) and Npun_F1794 (Cdf33). Deletion of either Cdf31or Cdf33 resulted in increased zinc retention over 3 h. Interestingly, Cdf31(-) and Cdf33(-) mutants showed no change in sensitivity to zinc exposure in comparison with the wild type, suggesting some compensatory capacity for the loss of each other. Using qRT-PCR, a possible interaction was observed between the two cdf's, where the Cdf31(-) mutant had a more profound effect on cdf33 expression than Cdf33(-) did on cdf31. Over-expression of Cdf31 and Cdf33 in ZntA(-) - and ZitB(-) -deficient Escherichia coli revealed function similarities between the ZntA and ZitB of E. coli and the cyanobacterial transporters. The data presented shed light on the function of two important transporters that regulate zinc homeostasis in N. punctiforme. This study shows for the first time the functional characterization of two cyanobacterial zinc efflux proteins belonging to the CDF family.

The evolution of molecular analyses in forensic science

Publisher: Informa UK Limited

Date: 07-1994

DOI: 10.1080/00450619409411308

Functional characterization of the twin ZIP/SLC39 metal transporters, NpunF3111 and NpunF2202 in Nostoc punctiforme

Publisher: Springer Science and Business Media LLC

Date: 30-06-2013

DOI: 10.1007/S00253-013-5047-Y

Abstract: The ZIP family of metal transporters is involved in the transport of Zn(2+) and other metal cations from the extracellular environment and/or organelles into the cytoplasm of prokaryotes, eukaryotes and archaeotes. In the present study, we identified twin ZIP transporters, Zip11 (Npun_F3111) and Zip63 (Npun_F2202) encoded within the genome of the filamentous cyanobacterium, Nostoc punctiforme PCC73120. Sequence-based analyses and structural predictions confirmed that these cyanobacterial transporters belong to the SLC39 subfamily of metal transporters. Quantitative real-time (QRT)-PCR analyses suggested that the enzymes encoded by zip11 and zip63 have a broad allocrite range that includes zinc as well as cadmium, cobalt, copper, manganese and nickel. Inactivation of either zip11 or zip63 via insertional mutagenesis in N. punctiforme resulted in reduced expression of both genes, highlighting a possible co-regulation mechanism. Uptake experiments using (65)Zn demonstrated that both zip mutants had diminished zinc uptake capacity, with the deletion of zip11 resulting in the greatest overall reduction in (65)Zn uptake. Over-expression of Zip11 and Zip63 in an E. coli mutant strain (ZupT736::kan) restored alent metal cation uptake, providing further evidence that these transporters are involved in Zn uptake in N. punctiforme. Our findings show the functional role of these twin metal uptake transporters in N. punctiforme, which are independently expressed in the presence of an array of metals. Both Zip11 and Zip63 are required for the maintenance of homeostatic levels of intracellular zinc N. punctiforme, although Zip11 appears to be the primary zinc transporter in this cyanobacterium, both ZIP's may be part of a larger metal uptake system with shared regulatory elements.

Effects of Saxitoxin (STX) and Veratridine on Bacterial Na +-K+ Fluxes: A Prokaryote-Based STX Bioassay

Publisher: American Society for Microbiology

Date: 12-2003

DOI: 10.1128/AEM.69.12.7371-7376.2003

Abstract: Saxitoxin (STX) is a potent natural sodium channel blocker and represents a significant health concern worldwide. We describe here the antagonistic effects of STX and veratridine (VTD), an Na + channel activator, on three gram-negative bacteria and their application to an STX bioassay. STX reduced the total cellular levels of both Na + and K + , as measured by flame photometry, whereas VTD increased the cellular concentrations relative to control ion fluxes in the cyanobacterium Cylindrospermopsis raciborskii AWT205. Endogenous STX production in toxic cyanobacterial strains of C. raciborskii and Anabaena circinalis prevented cell lysis induced by VTD stress. Microscopic cell counts showed that non-STX producing cyanobacteria displayed complete cell lysis and trichome fragmentation 5 to 8 h after addition of VTD and vanadate (VAN), an inhibitor of sodium pumps. The addition of STX, or its analogue neoSTX, prior to treatment with VTD plus VAN prevented complete lysis in non-STX-producing cyanobacteria. VTD also affected cyanobacterial metabolism, and the presence of exogenous STX in the s le also ameliorated this decrease in metabolic activity, as measured by the cellular conversion of tetrazolium into formazan. Reduced primary metabolism was also recorded as a decrease in the light emissions of Vibrio fischeri exposed to VTD. Addition of STX prior to VTD resulted in a rapid and dose-dependent response to the presence of the channel blocker, with s les exhibiting resistance to the VTD effect. Our findings demonstrate that STX and VTD influence bacterial Na + and K + fluxes in opposite ways, and these principles can be applied to the development of a prokaryote-based STX bioassay.

Climate dictates microbial community composition and diversity in Australian biological soil crusts (biocrusts)

Publisher: Wiley

Date: 29-06-2022

DOI: 10.1111/1462-2920.16098

Abstract: The soil surface of drylands can typically be colonized by cyanobacteria and other microbes, forming biological soil crusts or ‘biocrusts’. Biocrusts provide critical benefits to ecosystems and are a common component of the largely arid and semi‐arid Australian continent. Yet, their distribution and the parameters that shape their microbial composition have not been investigated. We present here the first detailed description of Australia's biocrust microbiome assessed from 15 sites across the continent using 16S rRNA sequencing. The most abundant bacterial phyla from all sites were Cyanobacteria, Proteobacteria, Actinobacteria, Chloroflexi and Bacteroidetes. Cyanobacterial communities from northern regions were more erse and unclassified cyanobacteria were a noticeable feature of northern biocrusts. Segregation between northern and southern regions was largely due to the differential abundance of Microcoleus spp., with M . paludosus dominating in the north and M . vaginatus dominating in the south. The geographical shifts in bacterial composition and ersity were correlated to seasonal temperatures and summer rainfall. Our findings provide an initial reference for s ling strategies to maximize access to bacterial genetic ersity. As hubs for essential ecosystem services, further investigation into biocrusts in arid and semi‐arid regions may yield discoveries of genetic mechanisms that combat increases in warming due to climate change.

Screening, identification and kinetic characterization of a bacterium for Mn(II) uptake and oxidation

Publisher: Springer Science and Business Media LLC

Date: 2003

DOI: 10.1023/A:1025043326629

Abstract: Following s le collection and screening at a number of Mn-associated mine sites in Northern Australia, a microbial strain was selected for its enhanced rate of Mn uptake. The strain was identified by phylogenetic analysis as a Rhizobium sp. Kinetic studies of Mn(II) uptake and oxidation by this strain in glucose-based media established that the uptake of Mn(II) was much greater than the conversion of Mn(II) to Mn oxide. Chemical analysis and scanning electron microscopy confirmed the production of significant amounts of polysaccharides by this strain. These polysaccharides may play a role both in enhancing Mn(II) accumulation and in minimizing Mn oxide production.

Mechanisms and Effects Posed by Neurotoxic Products of Cyanobacteria/Microbial Eukaryotes/Dinoflagellates in Algae Blooms: a Review

Publisher: Springer Science and Business Media LLC

Date: 23-08-2018

DOI: 10.1007/S12640-017-9780-3

Abstract: Environmental toxins produced by cyanobacteria and dinoflagellates have increasingly become a public health concern due to their ability to damage several tissues in humans. In particular, emerging evidence has called attention to the neurodegenerative effects of the cyanobacterial toxin β-N-methylamino-L-alanine (BMAA). Furthermore, other toxins such as anatoxin, saxitoxin, microcystin, nodularin and ciguatoxin also have a different range of effects on human tissues, including hepatotoxicity, neurotoxicity and gastrointestinal irritation. However, the vast majority of known environmental toxins have not yet been examined in the context of neurodegenerative disease. This review aims to investigate whether neurotoxic mechanisms can be demonstrated in all aforementioned toxins, and whether there exists a link to neurodegeneration. Management of toxin exposure and potential neuroprotective compounds is also discussed. Collectively, all aforementioned microbial toxins are likely to exert some form of neuronal damage, with many of their modes of action consistent with neurodegeneration. This is important in advancing our current understanding of the cytotoxic potential of environmental toxins upon human brain function, particularly in the context of age-related neurodegenerative disease.

Mining cyanobacterial genomes for genes encoding complex biosynthetic pathways

Publisher: Royal Society of Chemistry (RSC)

Date: 2009

DOI: 10.1039/B817074F

Adaptation, ecology, and evolution of the halophilic stromatolite archaeon halococcus hamelinensis inferred through genome analyses

Publisher: Hindawi Limited

Date: 2015

DOI: 10.1155/2015/241608

Abstract: Halococcus hamelinensis was the first archaeon isolated from stromatolites. These geomicrobial ecosystems are thought to be some of the earliest known on Earth, yet, despite their evolutionary significance, the role of Archaea in these systems is still not well understood. Detailed here is the genome sequencing and analysis of an archaeon isolated from stromatolites. The genome of H. hamelinensis consisted of 3,133,046 base pairs with an average G+C content of 60.08% and contained 3,150 predicted coding sequences or ORFs, 2,196 (68.67%) of which were protein-coding genes with functional assignments and 954 (29.83%) of which were of unknown function. Codon usage of the H. hamelinensis genome was consistent with a highly acidic proteome, a major adaptive mechanism towards high salinity. Amino acid transport and metabolism, inorganic ion transport and metabolism, energy production and conversion, ribosomal structure, and unknown function COG genes were overrepresented. The genome of H. hamelinensis also revealed characteristics reflecting its survival in its extreme environment, including putative genes athways involved in osmoprotection, oxidative stress response, and UV damage repair. Finally, genome analyses indicated the presence of putative transposases as well as positive matches of genes of H. hamelinensis against various genomes of Bacteria, Archaea, and viruses, suggesting the potential for horizontal gene transfer.

Soil-foraging animals alter the composition and co-occurrence of microbial communities in a desert shrubland

Publisher: Springer Science and Business Media LLC

Date: 21-06-0011

DOI: 10.1038/ISMEJ.2015.70

PCR-based positive hybridization to detect genomic diversity associated with bacterial secondary metabolism

Publisher: Oxford University Press (OUP)

Date: 02-01-2004

DOI: 10.1093/NAR/GNH012

Elevation of myeloperoxidase in conjunction with cardiac-specific markers after marathon running

Publisher: Oxford University Press (OUP)

Date: 12-2006

DOI: 10.1309/1D62H6KRFTVQRJ0A

Characterisation of the paralytic shellfish toxin biosynthesis gene clusters in Anabaena circinalis AWQC131C and Aphanizomenon sp. NH-5

Publisher: Springer Science and Business Media LLC

Date: 30-03-2009

DOI: 10.1186/1471-2091-10-8

Abstract: Saxitoxin and its analogues collectively known as the paralytic shellfish toxins (PSTs) are neurotoxic alkaloids and are the cause of the syndrome named paralytic shellfish poisoning. PSTs are produced by a unique biosynthetic pathway, which involves reactions that are rare in microbial metabolic pathways. Nevertheless, distantly related organisms such as dinoflagellates and cyanobacteria appear to produce these toxins using the same pathway. Hypothesised explanations for such an unusual phylogenetic distribution of this shared uncommon metabolic pathway, include a polyphyletic origin, an involvement of symbiotic bacteria, and horizontal gene transfer. We describe the identification, annotation and bioinformatic characterisation of the putative paralytic shellfish toxin biosynthesis clusters in an Australian isolate of Anabaena circinalis and an American isolate of Aphanizomenon sp ., both members of the Nostocales . These putative PST gene clusters span approximately 28 kb and contain genes coding for the biosynthesis and export of the toxin. A putative insertion/excision site in the Australian Anabaena circinalis AWQC131C was identified, and the organization and evolution of the gene clusters are discussed. A biosynthetic pathway leading to the formation of saxitoxin and its analogues in these organisms is proposed. The PST biosynthesis gene cluster presents a mosaic structure, whereby genes have apparently transposed in segments of varying size, resulting in different gene arrangements in all three sxt clusters sequenced so far. The gene cluster organizational structure and sequence similarity seems to reflect the phylogeny of the producer organisms, indicating that the gene clusters have an ancient origin, or that their lateral transfer was also an ancient event. The knowledge we gain from the characterisation of the PST biosynthesis gene clusters, including the identity and sequence of the genes involved in the biosynthesis, may also afford the identification of these gene clusters in dinoflagellates, the cause of human mortalities and significant financial loss to the tourism and shellfish industries.

Physiological and Proteomic Responses of Continuous Cultures of Microcystis aeruginosa PCC 7806 to Changes in Iron Bioavailability and Growth Rate

Publisher: American Society for Microbiology

Date: 10-2016

DOI: 10.1128/AEM.01207-16

Abstract: The hepatotoxin microcystin (MCYST) is produced by a variety of freshwater cyanobacterial species, including Microcystis aeruginosa . Interestingly, MCYST-producing M. aeruginosa strains have been shown to outcompete their nontoxic counterparts under iron-limiting conditions. However, the reasons for this are unclear. Here we examined the proteomic response of M. aeruginosa PCC 7806 continuous cultures under different iron and growth regimes. Iron limitation was correlated with a global reduction in levels of proteins associated with energy metabolism and photosynthesis. These proteomic changes were consistent with physiological observations, including reduced chlorophyll a content and reduced cell size. While levels of MCYST biosynthesis proteins did not fluctuate during the study period, both intra- and extracellular toxin quotas were significantly higher under iron-limiting conditions. Our results support the hypothesis that intracellular MCYST plays a role in protecting the cell against oxidative stress. Further, we propose that extracellular MCYST may act as a signaling molecule, stimulating MCYST production under conditions of iron limitation and enhancing the fitness of bloom populations. IMPORTANCE Microcystin production in water supply reservoirs is a global public health problem. Understanding the ecophysiology of hepatotoxic cyanobacteria, including their responses to the presence of key micronutrient metals such as iron, is central to managing harmful blooms. To our knowledge, this was the first study to examine proteomic and physiological changes occurring in M. aeruginosa continuous cultures under conditions of iron limitation at different growth rates.

T‐RFLP Fingerprinting Analysis of Bacterial Communities in Debris Cones, Northern Victoria Land, Antarctica

Publisher: Wiley

Date: 07-2012

DOI: 10.1002/PPP.1749

Isolation and characterization of two novel ethanol-tolerant facultative-anaerobic thermophilic bacteria strains from waste compost

Publisher: Springer Science and Business Media LLC

Date: 11-03-2006

DOI: 10.1007/S00792-006-0507-2

Abstract: In a search for potential ethanologens, waste compost was screened for ethanol-tolerant thermophilic microorganisms. Two thermophilic bacterial strains, M5EXG and M10EXG, with tolerance of 5 and 10% (v/v) ethanol, respectively, were isolated. Both isolates are facultative anaerobic, non-spore forming, non-motile, catalase-positive, oxidase-negative, Gram-negative rods that are capable of utilizing a range of carbon sources including arabinose, galactose, mannose, glucose and xylose and produce low amounts of ethanol, acetate and lactate. Growth of both isolates was observed in fully defined minimal media within the temperature range 50-80 degrees C and pH 6.0-8.0. Phylogenetic analysis of the 16S rDNA sequences revealed that both isolates clustered with members of subgroup 5 of the genus Bacillus. G+C contents and DNA-DNA relatedness of M5EXG and M10EXG revealed that they are strains belonging to Geobacillus thermoglucosidasius. However, physiological and biochemical differences were evident when isolates M5EXG and M10EXG were compared with G. thermoglucosidasius type strain (DSM 2542(T)). The new thermophilic, ethanol-tolerant strains of G. thermoglucosidasius may be candidates for ethanol production at elevated temperatures.

Recent developments in quantitative PCR for monitoring harmful marine microalgae

Publisher: Elsevier BV

Date: 08-2021

DOI: 10.1016/J.HAL.2021.102096

Characterization of the 2-hydroxy-acid dehydrogenase Mcyl, encoded within the microcystin biosynthesis gene cluster of Microcystis aeruginosa PCC7806

Publisher: Elsevier BV

Date: 02-2007

DOI: 10.1074/JBC.M606986200

Proteogenomics of a saxitoxin-producing and non-toxic strain of Anabaena circinalis (cyanobacteria) in response to extracellular NaCl and phosphate depletion

Publisher: Wiley

Date: 18-01-2016

DOI: 10.1111/1462-2920.13131

Abstract: In Australia, saxitoxin production is strain dependent within the bloom-forming freshwater cyanobacterium Anabaena circinalis. Freshwater cyanobacteria are exposed to rapid fluctuations in environmental nutrient concentrations, and their adaption is vital for competition, succession and dominance. Two elements of environmental significance, phosphorus and sodium chloride, are proposed to play a role in bloom development and saxitoxin biosynthesis respectively. The aim of our study was to comparatively analyse the model saxitoxin-producing A. circinalis AWQC131C and non-toxic A. circinalis AWQC310F at the genomic level and proteomic level, in response to phosphate depletion and increased extracellular NaCl. When challenged, photosynthesis, carbon/nitrogen metabolisms, transcription/translation, oxidative stress and nutrient transport functional categories demonstrated the largest changes in protein abundance. In response to increased NaCl, SxtC, a protein conserved in all known saxitoxin biosynthetic pathways, was downregulated. Additionally, toxin quantification revealed a decrease in total saxitoxin and decarbomoyl-gonyautoxin2/3 content in response to the NaCl treatment. In response to phosphate depletion, the toxic and non-toxic strain displayed similar proteomic profiles, although the toxic strain did not alter the abundance of as many proteins as the non-toxic strain. These findings have important implications for the future, since response and adaption mechanisms are directly related to in situ dominance of cyanobacteria.

Functional renormalization group study of an eight-band model for the iron arsenides

Publisher: American Physical Society (APS)

Date: 26-06-2014

DOI: 10.1103/PHYSREVB.89.214514

Heterologous Expression and Biochemical Analysis Reveal a Schizokinen-Based Siderophore Pathway in Leptolyngbya (Cyanobacteria)

Publisher: American Society for Microbiology

Date: 12-04-2022

DOI: 10.1128/AEM.02373-21

Abstract: Iron availability limits the growth of many microorganisms, particularly those residing in high nutrient–low chlorophyll aquatic environments. Therefore, characterizing iron acquisition pathways in phytoplankton is essential for understanding nutrient cycling in our oceans.

Heterologous Expression of an Unusual Ketosynthase, SxtA, Leads to Production of Saxitoxin Intermediates in Escherichia coli

Publisher: Wiley

Date: 16-11-2020

DOI: 10.1002/CBIC.202000675

Abstract: Paralytic shellfish toxins (PSTs) are neurotoxic alkaloids produced by freshwater cyanobacteria and marine dinoflagellates. Due to their antagonism of voltage‐gated sodium channels in excitable cells, certain analogues are of significant pharmacological interest. The biosynthesis of the parent compound, saxitoxin, is initiated with the formation of 4‐amino‐3‐oxo‐guanidinoheptane (ethyl ketone) by an unusual polyketide synthase‐like enzyme, SxtA. We have heterologously expressed SxtA from Raphidiopsis raciborskii T3 in Escherichia coli and analysed its activity in vivo . Ethyl ketone and a truncated analogue, methyl ketone, were detected by HPLC‐ESI‐HRMS analysis, thus suggesting that SxtA has relaxed substrate specificity in vivo . The chemical structures of these products were further verified by tandem mass spectrometry and labelled‐precursor feeding with [guanidino‐ 15 N 2 ] arginine and [1,2‐ 13 C 2 ] acetate. These results indicate that the reactions catalysed by SxtA could give rise to multiple PST variants, including analogues of ecological and pharmacological significance.

Molecular assessment of UVC radiation-induced DNA damage repair in the stromatolitic halophilic archaeon, Halococcus hamelinensis

Publisher: Elsevier BV

Date: 02-2011

DOI: 10.1016/J.JPHOTOBIOL.2010.10.002

Abstract: The halophilic archaeon Halococcus hamelinensis was isolated from living stromatolites in Shark Bay, Western Australia, that are known to be exposed to extreme conditions of salinity, desiccation, and UV radiation. Modern stromatolites are considered analogues of very early life on Earth and thus inhabitants of modern stromatolites, and Hcc. hamelinensis in particular, are excellent candidates to examine responses to high UV radiation. This organism was exposed to high dosages (up to 500 J/m(2)) of standard germicidal UVC (254 nm) radiation and overall responses such as survival, thymine-thymine cyclobutane pyrimidine dimer formation, and DNA repair have been assessed. Results show that Hcc. hamelinensis is able to survive high UVC radiation dosages and that intact cells give an increased level of DNA protection over purified DNA. The organism was screened for the bacterial-like nucleotide excision repair (NER) genes uvrA, uvrB, uvrC, as well as for the photolyase phr2 gene. All four genes were discovered and changes in the expression levels of those genes during repair in either light or dark were investigated by means of quantitative Real-Time (qRT) PCR. The data obtained and presented in this study show that the uvrA, uvrB, and uvrC genes were up-regulated during both repair conditions. The photolyase phr2 was not induced during dark repair, yet showed a 20-fold increase during repair in light conditions. The data presented is the first molecular study of different repair mechanisms in the genus Halococcus following exposure to high UVC radiation levels.

Diversity of cyanobacterial biomarker genes from the stromatolites of Shark Bay, Western Australia

Publisher: Wiley

Date: 19-06-2013

DOI: 10.1111/J.1462-2920.2012.02809.X

Abstract: Families of closely related chemical compounds, which are relatively resistant to degradation, are often used as biomarkers to help trace the evolutionary history of early groups of organisms and the environments in which they lived. Biomarkers derived from hopanoid variations are particularly useful in determining bacterial community compositions. 2-Methylhopananoids have been thought to be diagnostic for cyanobacteria, and 2-methylhopanes in the geological record are taken as evidence for the presence of cyanobacteria-containing communities at the time of sediment deposition. Recently, however, doubt has been cast on the validity of 2-methylhopanes as cyanobacterial biomarkers, since non-cyanobacterial species have been shown to produce significant amounts of 2-methylhopanoids. This study examines the ersity of hpnP, the hopanoid biosynthesis gene coding for the enzyme that methylates hopanoids at the C2 position. Genomic DNA isolated from stromatolite-associated pustular and smooth microbial mat s les from Shark Bay, Western Australia, was analysed for bacterial ersity, and used to construct an hpnP clone library. A total of 117 partial hpnP clones were sequenced, representing 12 operational taxonomic units (OTUs). Phylogenetic analysis showed that 11 of these OTUs, representing 115 sequences, cluster within the cyanobacterial clade. We conclude that the dominant types of microorganisms with the detected capability of producing 2-methylhopanoids within pustular and smooth microbial mats in Shark Bay are cyanobacteria.

Identification of a Saxitoxin Biosynthesis Gene with a History of Frequent Horizontal Gene Transfers

Publisher: Springer Science and Business Media LLC

Date: 11-10-2008

DOI: 10.1007/S00239-008-9169-2

Abstract: The paralytic shellfish poisoning (PSP) toxins, saxitoxin, and its derivatives, are produced by a complex and unique biosynthetic pathway. It involves reactions that are rare in other metabolic pathways, however, distantly related organisms, such as dinoflagellates and cyanobacteria, produce these toxins by an identical pathway. Speculative explanations for the unusual phylogenetic distribution of this metabolic pathway have been proposed, including a polyphyletic origin, the involvement of symbiotic bacteria, and horizontal gene transfer. This study describes for the first time the identity of one gene, sxt1, that is involved in the biosynthesis of saxitoxin in cyanobacteria. It encoded an O-carbamoyltransferase (OCTASE) that was proposed to carbamoylate the hydroxymethyl side chain of saxitoxin precursor. Orthologues of sxt1 were exclusively present in PSP-toxic strains of cyanobacteria and had a high sequence similarity to each other. L. wollei had a naturally mutated sxt1 gene that encoded an inactive enzyme, and was incapable of producing carbamoylated PSP-toxin analogues, supporting the proposed function of Sxt1. Phylogenetic analysis revealed that OCATSE genes were present exclusively in prokaryotic organisms and were characterized by a high rate of horizontal gene transfer. OCTASE has most likely evolved from an ancestral O-sialoglycoprotein endopeptidase from proteobacteria, whereas the most likely phylogenetic origin of sxt1 was an ancestral alpha-proteobacterium. The phylogeny of sxt1 suggested that the entire set of genes required for saxitoxin biosynthesis may spread by horizontal gene transfer.

Specific global responses to N and Fe nutrition in toxic and non-toxic Microcystis aeruginosa

Publisher: Wiley

Date: 04-08-2016

DOI: 10.1111/1462-2920.12958

Abstract: The bloom-forming cyanobacteria species Microcystis aeruginosa includes toxic and non-toxic (microcystin-producing) strains. Certain stress conditions stimulate synthesis of microcystin (MCYST) and enhance the binding of the MCYST molecule to proteins. In this quantitative proteomic study, we compared the response of a wild-type toxic strain PCC 7806, an mcyH(-) knockout non-toxic strain, and a naturally occurring non-toxic strain, PCC 7005, after 8 days in low iron (Fe) and nitrogen (N) starvation in order to assess the benefit of MCYST synthesis in non-optimal conditions. Fe limitation increased MCYST synthesis and caused an accumulation of phycobilisome proteins and the ferric iron transporter FutA only in the toxic PCC 7806 but not the non-toxic strains. In N starvation, photosynthetic, C and N metabolism proteins were more abundant in the non-toxic strains, as were chaperones and proteases. Significant interaction between nutrient availability and toxicity existed for thioredoxin peroxidase and several thioredoxin-regulated proteins. We propose a competition of MCYST for binding sites in thioredoxin-regulated proteins during oxidative stress (low Fe) but not in growth-limiting conditions (low N). This then leads to differences in the regulation of C:N metabolism in toxic and non-toxic M. aeruginosa in nutrient-replete and nutrient-limited conditions.

On the Chemistry, Toxicology and Genetics of the Cyanobacterial Toxins, Microcystin, Nodularin, Saxitoxin and Cylindrospermopsin

Publisher: MDPI AG

Date: 10-05-2010

DOI: 10.3390/MD8051650

Heterologous expression of the alcohol dehydrogenase (adhI) gene from Geobacillus thermoglucosidasius strain M10EXG

Publisher: Elsevier BV

Date: 06-2008

DOI: 10.1016/J.JBIOTEC.2008.02.018

Abstract: A thermostable alcohol dehydrogenase (ADH-I) isolated from the potential thermophilic ethanologen Geobacillus thermoglucosidasius strain M10EXG has been characterised. Inverse PCR showed that the gene (adhI) was localised with 3-hexulose-6-phosphate synthase (HPS) and 6-phospho-3 hexuloisomerase (PHI) on its genome. The deduced peptide sequence of the 1020-bp M10EXG adhI, which corresponds to 340 amino acids, shows 96% and 89% similarity to ADH-hT and ADH-T from Geobacillus stearothermophilus strains LLD-R and NCA 1503, respectively. Over-expression of M10EXG ADH-I in Escherichia coli DH5alpha (pNF303) was confirmed using an ADH activity assay and SDS-PAGE analysis. The specific ADH activity in the extract from this recombinant strain was 9.7(+/-0.3) U mg(-1) protein, compared to 0.1(+/-0.01) U mg(-1) protein in the control strain. The recombinant E. coli showed enzymatic activity towards ethanol, 1-butanol, 1-pentanol, 1-heptanol, 1-hexanol, 1-octanol and 2-propanol, but not methanol. In silico analysis, including phylogenetic reconstruction and protein modeling, confirmed that the thermostable enzyme from G. thermoglucosidasius is likely to belong to the NAD-Zn-dependent family of alcohol dehydrogenases.

Bacterial community structure and metabolic potential in microbialite‐forming mats from South Australian saline lakes

Publisher: Wiley

Date: 21-03-2022

DOI: 10.1111/GBI.12489

Abstract: Microbialites are sedimentary rocks created in association with benthic microorganisms. While they harbour complex microbial communities, Cyanobacteria perform critical roles in sediment stabilisation and accretion. Microbialites have been described from permanent and ephemeral saline lakes in South Australia however, the microbial communities that generate and inhabit these biogeological structures have not been studied in detail. To address this knowledge gap, we investigated the composition, ersity and metabolic potential of bacterial communities from different microbialite‐forming mats and surrounding sediments in five South Australian saline coastal lakes using 16S rRNA gene sequencing and predictive metagenome analyses. While Proteobacteria and Bacteroidetes were the dominant phyla recovered from the mats and sediments, Cyanobacteria were significantly more abundant in the mat s les. Interestingly, at lower taxonomic levels, the mat communities were vastly different across the five lakes. Comparative analysis of putative mat and sediment metagenomes via PICRUSt2 revealed important metabolic pathways driving the process of carbonate precipitation, including cyanobacterial oxygenic photosynthesis, ureolysis and nitrogen fixation. These pathways were highly conserved across the five examined lakes, although they appeared to be performed by distinct groups of bacterial taxa found in each lake. Stress response, quorum sensing and circadian clock were other important pathways predicted by the in silico metagenome analysis. The enrichment of CRISPR/Cas and phage shock associated genes in these cyanobacteria‐rich communities suggests that they may be under selective pressure from viral infection. Together, these results highlight that a very stable ecosystem function is maintained by distinctly different communities in microbialite‐forming mats in the five South Australian lakes and reinforce the concept that ‘who’ is in the community is not as critical as their net metabolic capacity.

The expansion of mechanistic and organismic diversity associated with non-ribosomal peptides

Publisher: Oxford University Press (OUP)

Date: 10-2000

DOI: 10.1111/J.1574-6968.2000.TB09334.X

Abstract: Non-ribosomal peptides are a group of secondary metabolites with a wide range of bioactivities, produced by prokaryotes and lower eukaryotes. Recently, non-ribosomal synthesis has been detected in erse microorganisms, including the myxobacteria and cyanobacteria. Peptides biosynthesized non-ribosomally may often play a primary or secondary role in the producing organism. Non-ribosomal peptides are often small in size and contain unusual or modified amino acids. Biosynthesis occurs via large modular enzyme complexes, with each module responsible for the activation and thiolation of each amino acid, followed by peptide bond formation between activated amino acids. Modules may also be responsible for the enzymatic modification of the substrate amino acid. Recent analysis of biosynthetic gene clusters has identified novel integrated, mixed and hybrid enzyme systems. These erse mechanisms of biosynthesis result in the wide variety of non-ribosomal peptide structures and bioactivities seen today. Knowledge of these biosynthetic systems is rapidly increasing and methods of genetically engineering these systems are being developed. In the future, this may lead to rational drug design through combinatorial biosynthesis of these enzyme systems.

Identification of pilus-like structures and genes in Microcystis aeruginosa PCC7806

Publisher: American Society for Microbiology

Date: 11-2005

DOI: 10.1128/AEM.71.11.7621-7625.2005

Abstract: Four putative type IV pilus genes from the toxic, naturally transformable Microcystis aeruginosa PCC7806 were identified. Three of these genes were clustered in an arrangement which is identical to that from other cyanobacterial genomes. Type IV pilus-like appendages were also observed by electron microscopy.

Endolithic phototrophs from an active geothermal region in New Zealand

Publisher: Informa UK Limited

Date: 10-2006

DOI: 10.1080/01490450600897401

The University Of Newcastle

Location: Australia

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University Of Würzburg

Location: Germany

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RWTH Aachen University

Location: No location found

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RWTH Aachen University

Location: Germany

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University Of Technology

Location: Australia

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University Of New South Wales

Location: Australia

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Discovery Projects - Grant ID: DP0211703

Start Date: 02-2002

End Date: 06-2005

Amount: $175,000.00

Funder: Australian Research Council

Linkage - International - Grant ID: LX0668702

Start Date: 2006

End Date: 12-2007

Amount: $22,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP140100642

Start Date: 2015

End Date: 06-2020

Amount: $401,219.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP0562383

Start Date: 07-2005

End Date: 06-2008

Amount: $110,287.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP110201096

Start Date: 12-2011

End Date: 08-2015

Amount: $285,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0558710

Start Date: 2005

End Date: 06-2008

Amount: $402,000.00

Funder: Australian Research Council

Discovery Indigenous Researchers Development - Grant ID: DI0668388

Start Date: 07-2006

End Date: 03-2011

Amount: $87,458.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0880264

Start Date: 06-2008

End Date: 05-2012

Amount: $315,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP0776399

Start Date: 10-2007

End Date: 07-2011

Amount: $387,565.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0556484

Start Date: 05-2005

End Date: 06-2008

Amount: $960,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP0668313

Start Date: 05-2006

End Date: 12-2009

Amount: $221,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP100200792

Start Date: 12-2010

End Date: 01-2015

Amount: $300,000.00

Funder: Australian Research Council

Federation Fellowships - Grant ID: FF0883440

Start Date: 07-2008

End Date: 06-2013

Amount: $1,638,730.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP200100537

Start Date: 04-2021

End Date: 12-2024

Amount: $419,059.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP130102254

Start Date: 2013

End Date: 06-2016

Amount: $349,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP150100630

Start Date: 06-2016

End Date: 06-2021

Amount: $275,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP190103314

Start Date: 08-2019

End Date: 12-2022

Amount: $395,000.00

Funder: Australian Research Council

Linkage - International - Grant ID: LX0666993

Start Date: 2006

End Date: 12-2007

Amount: $80,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP0776759

Start Date: 02-2009

End Date: 04-2013

Amount: $244,609.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP0989830

Start Date: 07-2009

End Date: 06-2012

Amount: $78,420.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE140100032

Start Date: 2014

End Date: 12-2015

Amount: $1,000,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE130100007

Start Date: 2013

End Date: 12-2014

Amount: $650,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE120100027

Start Date: 04-2012

End Date: 12-2013

Amount: $320,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE230100090

Start Date: 2023

End Date: 12-2023

Amount: $682,792.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP230100495

Start Date: 2023

End Date: 12-2025

Amount: $630,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP0989475

Start Date: 09-2009

End Date: 02-2015

Amount: $378,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP0882630

Start Date: 04-2009

End Date: 03-2012

Amount: $196,462.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE140100111

Start Date: 2014

End Date: 06-2016

Amount: $475,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE100100096

Start Date: 2010

End Date: 06-2011

Amount: $450,000.00

Funder: Australian Research Council

ARC Centres Of Excellence - Grant ID: CE200100029

Start Date: 11-2020

End Date: 11-2027

Amount: $35,000,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0883080

Start Date: 2008

End Date: 12-2008

Amount: $490,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP130100311

Start Date: 2014

End Date: 12-2018

Amount: $612,756.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE100100229

Start Date: 2010

End Date: 12-2010

Amount: $160,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0668039

Start Date: 2006

End Date: 12-2006

Amount: $160,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0989147

Start Date: 2009

End Date: 12-2009

Amount: $950,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP180100835

Start Date: 02-2020

End Date: 02-2024

Amount: $456,527.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE200100016

Start Date: 06-2020

End Date: 06-2021

Amount: $400,000.00

Funder: Australian Research Council