ORCID Profile
0000-0002-5762-5146
Current Organisation
Macquarie University
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Publisher: The Science Breaker
Date: 2021
Publisher: Wiley
Date: 12-11-2019
Abstract: Research into causative agents underlying coral disease have focused primarily on bacteria, whereas potential roles of viruses have been largely unaddressed. Bacteriophages may contribute to diseases through the lysogenic introduction of virulence genes into bacteria, or prevent diseases through lysis of bacterial pathogens. To identify candidate phages that may influence the pathogenicity of black band disease (BBD), communities of bacteria (16S rRNA) and T4-bacteriophages (gp23) were simultaneously profiled with licon sequencing among BBD-lesions and healthy-coral-tissue of Montipora hispida, as well as seawater (study site: the central Great Barrier Reef). Bacterial community compositions were distinct among BBD-lesions, healthy coral tissue and seawater s les, as observed in previous studies. Surprisingly, however, viral beta ersities based on both operational taxonomic unit (OTU)-compositions and overall viral community compositions of assigned taxa did not differ statistically between the BBD-lesions and healthy coral tissue. Nonetheless, relative abundances of three bacteriophage OTUs, affiliated to Cyanophage PRSM6 and Prochlorococcus phages P-SSM2, were significantly higher in BBD-lesions than in healthy tissue. These OTUs associated with BBD s les suggest the presence of bacteriophages that infect members of the cyanobacteria-dominated BBD community, and thus have potential roles in BBD pathogenicity.
Publisher: PeerJ
Date: 09-06-2016
DOI: 10.7717/PEERJ.2110
Abstract: Black band disease (BBD) is a common disease of reef-building corals with a worldwide distribution that causes tissue loss at a rate of up to 3 cm/day. Critical for a mechanistic understanding of the disease’s aetiology is the cultivation of its proposed pathogen, filamentous cyanobacteria (genus Roseofilum ). Here, we optimise existing protocols for the isolation and cultivation of Roseofilum cyanobacteria using a new strain from the central Great Barrier Reef. We demonstrate that the isolation of this bacterium via inoculation onto agar plates was highly effective with a low percentage agar of 0.6% and that growth monitoring was most sensitive with fluorescence measurements of chlorophyll-a (440/685 nm). Cell growth curves in liquid and solid media were generated for the first time for this cyanobacterium and showed best growth rates for the previously untested L1-medium (growth rate k = 0.214 biomass/day doubling time t gen = 4.67 days). Our results suggest that the trace metals contained in L1-medium maximise biomass increase over time for this cyanobacterium. Since the newly isolated Roseofilum strain is genetically closest to Pseudoscillatoria coralii , but in terms of pigmentation and cell size closer to Roseofilum reptotaenium , we formally merge the two species into a single taxon by providing an emended species description, Roseofilum reptotaenium (Rasoulouniriana) Casamatta emend. Following this optimized protocol is recommended for fast isolation and cultivation of Roseofilum cyanobacteria, for growth curve generation in strain comparisons and for maximisation of biomass in genetic studies.
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/MA18004
Abstract: Marine viruses are the largest, but most poorly explored genetic reservoir on the planet. They occur ubiquitously in the ocean at an average density of 5–15 × 106 viruses per mL of seawater, which represents abundances an order of magnitude higher than those of bacteria. While viruses are known agents of a number of diseases in the marine environment, little is known about their beneficial function to corals. Herein, we briefly introduce the topic of viruses as potential drivers of coral bleaching and disease.
Publisher: Frontiers Media SA
Date: 22-12-2016
Publisher: American Association for the Advancement of Science (AAAS)
Date: 15-05-2020
Abstract: Coral bleaching tolerance can be enhanced through directed evolution of their microalgal symbionts.
Publisher: Wiley
Date: 20-02-2021
DOI: 10.1111/GCB.15546
Abstract: Marine microalgae are a erse group of microscopic eukaryotic and prokaryotic organisms capable of photosynthesis. They are important primary producers and carbon sinks but their physiology and persistence are severely affected by global climate change. Powerful experimental evolution technologies are being used to examine the potential of microalgae to respond adaptively to current and predicted future conditions, as well as to develop resources to facilitate species conservation and restoration of ecosystem functions. This review synthesizes findings and insights from experimental evolution studies of marine microalgae in response to elevated temperature and/or p CO 2 . Adaptation to these environmental conditions has been observed in many studies of marine dinoflagellates, diatoms and coccolithophores. An enhancement in traits such as growth and photo‐physiological performance and an increase in upper thermal limit have been shown to be possible, although the extent and rate of change differ between microalgal taxa. Studies employing multiple monoclonal replicates showed variation in responses among replicates and revealed the stochasticity of mutations. The work to date is already providing valuable information on species’ climate sensitivity or resilience to managers and policymakers but extrapolating these insights to ecosystem‐ and community‐level impacts continues to be a challenge. We recommend future work should include in situ experiments, diurnal and seasonal fluctuations, multiple drivers and multiple starting genotypes. Fitness trade‐offs, stable versus plastic responses and the genetic bases of the changes also need investigating, and the incorporation of genome resequencing into experimental designs will be invaluable.
Publisher: Springer Science and Business Media LLC
Date: 08-12-2015
DOI: 10.1038/SREP17889
Abstract: Disease is an increasing threat to reef-building corals. One of the few identified pathogens of coral disease is the bacterium Vibrio coralliilyticus . In Vibrio cholerae , infection by a bacterial virus (bacteriophage) results in the conversion of non-pathogenic strains to pathogenic strains and this can lead to cholera pandemics. Pathogenicity islands encoded in the V. cholerae genome play an important role in pathogenesis. Here we analyse five whole genome sequences of V. coralliilyticus to examine whether virulence is similarly driven by horizontally acquired elements. We demonstrate that bacteriophage genomes encoding toxin genes with homology to those found in pathogenic V. cholerae are integrated in V. coralliilyticus genomes. Virulence factors located on chromosomal pathogenicity islands also exist in some strains of V. coralliilyticus . The presence of these genetic signatures indicates virulence in V. coralliilyticus is driven by prophages and other horizontally acquired elements. Screening for pathogens of coral disease should target conserved regions in these elements.
Publisher: Wiley
Date: 05-2020
DOI: 10.1111/MEC.15432
Publisher: American Association for the Advancement of Science (AAAS)
Date: 15-05-2020
Abstract: EccDNAs are hiding in plain sight in conventional ATAC-seq data.
Publisher: Springer Science and Business Media LLC
Date: 07-02-2022
DOI: 10.1038/S41396-022-01203-0
Abstract: Early life stages of most coral species acquire microalgal endosymbionts (Symbiodiniaceae) from the environment, but whether exogenous symbiont uptake is possible in the adult life stage is unclear. Deep sequencing of the Symbiodiniaceae ITS2 genetic marker has revealed novel symbionts in adult corals following bleaching however these strains may have already been present at densities below detection limits. To test whether acquisition of symbionts from the environment occurs, we subjected adult fragments of corals (six species in four families) to a chemical bleaching treatment (menthol and DCMU). The treatment reduced the native microalgal symbiont abundance to below 2% of their starting densities. The bleached corals were then inoculated with a cultured Cladocopium C1 acro strain. Genotyping of the Symbiodiniaceae communities before bleaching and after reinoculation showed that fragments of all six coral species acquired the Cladocopium C1 acro strain used for inoculation. Our results provide strong evidence for the uptake of Symbiodiniaceae from the environment by adult corals. We also demonstrate the feasibility of chemical bleaching followed by reinoculation to manipulate the Symbiodiniaceae communities of adult corals, providing an innovative approach to establish new symbioses between adult corals and heat-evolved microalgal symbionts, which could prove highly relevant to coral reef restoration efforts.
Publisher: Frontiers Media SA
Date: 05-2023
DOI: 10.3389/FMARS.2023.1094792
Abstract: Corals’ tolerance to high temperature stress largely depends on their symbiotic microalgae (Symbiodiniaceae). However, the contributing microalgal traits and their relationships to one another are largely unclear. Here we compare the in vitro cellular profiles of seven Cladocopium C1 acro microalgal strains (derived from the same ancestral strain) during a four-week exposure to 27°C or 31°C. One was an unselected wild-type strain (WT), three were selected at 31°C for nine years and shown to confer thermal tolerance on the coral host (SS+) and three others were similarly selected but did not confer tolerance (SS-). Flow cytometry was used to measure the staining intensities of cells treated with dyes representing the intracellular stress indicators reactive oxygen species (ROS), reduced glutathione (rGSH) and mitochondrial activity, as well as cell size/shape and photosynthetic pigments. Cell densities and photosynthetic efficiency (ϕPSII, F v /F m ) were also measured. WT showed the highest levels of intracellular ROS and mitochondrial activity, lowest rGSH and largest cell sizes at both temperatures. SS+ strains had the lowest ROS and highest rGSH values and a unique pattern of correlations among parameters at 31°C. Our results support previous reports implicating the role of microalgal ROS, mitochondria and rGSH in holobiont thermal tolerance and suggest flow cytometry is a useful screening tool for identifying microalgal strains with enhanced thermal tolerance.
Publisher: Wiley
Date: 08-09-2011
Publisher: MDPI AG
Date: 28-04-2022
DOI: 10.3390/IJMS23094913
Abstract: Heat-tolerant strains of the coral endosymbiont, Cladocopium C1acro (Symbiodiniaceae), have previously been developed via experimental evolution. Here, we examine physiological responses and bacterial community composition (using 16S rRNA gene metabarcoding) in cultures of 10 heat-evolved (SS) and 9 wild-type (WT) strains, which had been exposed for 6 years to 31 °C and 27 °C, respectively. We also examine whether the associated bacterial communities were affected by a three-week reciprocal transplantation to both temperatures. The SS strains had bacterial communities with lower ersities that showed more stability and lower variability when exposed to elevated temperatures compared with the WT strains. Amplicon sequence variants (ASVs) of the bacterial genera Labrenzia, Algiphilus, Hyphobacterium and Roseitalea were significantly more associated with the SS strains compared with the WT strains. WT strains showed higher abundance of ASVs assigned to the genera Fabibacter and Tropicimonas. We hypothesize that these compositional differences in associated bacterial communities between SS and WT strains also contribute to the thermal tolerance of the microalgae. Future research should explore functional potential between bacterial communities using metagenomics to unravel specific genomic adaptations.
Publisher: MDPI AG
Date: 03-03-2021
Abstract: Coral cover worldwide has been declining due to heat stress caused by climate change. Here we report the impacts of the 2015–2016 El Niño mass coral bleaching event on the coral cover of reefs located on central and northern atolls of the Mal es. We surveyed six reef sites in the Alifu Alifu (Ari) and Baa (South Maalhosmadulu) Atolls using replicate 20 m benthic photo transects at two depths per reef site. Live and recently dead coral cover identified from images differed between reef sites and depth. Recently dead corals on average made up 33% of the coral assemblage at shallow sites and 24% at deep sites. This mortality was significantly lower in massive corals than in branching corals, reaching an average of only 6% compared to 41%, respectively. The best predictors of live coral cover were depth and morphology, with a greater percentage of live coral at deep sites and in massive corals. The same predictors best described the prevalence of recently dead coral, but showed inverse trends to live coral. However, there was high variability among reef sites, which could be attributed to additional local stressors. Coral bleaching and resulting coral mortalities, such as the ones reported here, are of particular concern for small island nations like the Mal es, which are reliant on coral reefs.
Publisher: Oxford University Press (OUP)
Date: 12-12-2020
DOI: 10.1111/IJPP.12597
Abstract: Pharmacist personality traits may explain the incomplete uptake of extended scope pharmacy practice roles. The objective of this study was to explore the personality traits of Australian pharmacists using the Big Five Inventory (BFI). A cross-sectional survey of Australian pharmacists was undertaken. Pharmacists were asked to complete a short demographic survey and the BFI, a 44-item survey that measures the Big Five personality traits: extraversion, agreeableness, conscientiousness, neuroticism and openness. Each trait can be scored out of a maximum of 5. The BFI and multivariate linear regression were used to assess associations between personality traits and demographic variables. A total of 122 responses were available for analysis. The majority of study participants were female (79.5%), were aged between 30 and 39 years (32.0%) and worked in hospital pharmacy (46.7%). Pharmacists scored (mean (standard deviation)) 3.4 (0.7) for extraversion, 3.9 (0.5) for agreeableness, 4.2 (0.5) for conscientiousness, 2.5 (0.8) for neuroticism and 3.5 (0.6) for openness. Associations were found between agreeableness and qualifications and location of pharmacy practice, neuroticism and working in a practice location (rural versus metropolitan) and age, and openness and practice location (rural versus metropolitan) and principle role in pharmacy. Pharmacists displayed high scores on the traits of extraversion, agreeableness, conscientiousness and openness and scored moderately on the trait of openness. Confirmation with a larger s le size and evaluation in the context of pharmacy practice change may assist in overcoming barriers to change in the pharmacy profession.
Publisher: Elsevier BV
Date: 10-2015
Publisher: Springer Science and Business Media LLC
Date: 30-03-2022
DOI: 10.1038/S43705-022-00114-7
Abstract: The sea anemone, Exaiptasia diaphana , is a model of coral-dinoflagellate (Symbiodiniaceae) symbiosis. However, little is known of its potential to form symbiosis with Cladocopium —a key Indo-Pacific algal symbiont of scleractinian corals, nor the host nutritional consequences of such an association. Aposymbiotic anemones were inoculated with homologous algal symbionts, Breviolum minutum , and seven heterologous strains of Cladocopium C1 acro (wild-type and heat-evolved) under ambient conditions. Despite lower initial algal cell density, Cladocopium C1 acro -anemeones achieved similar cell densities as B. minutum -anemones by week 77. Wild-type and heat-evolved Cladocopium C1 acro showed similar colonization patterns. Targeted LC-MS-based metabolomics revealed that almost all significantly different metabolites in the host and Symbiodiniaceae fractions were due to differences between Cladocopium C1 acro and B. minutum , with little difference between heat-evolved and wild-type Cladocopium C1 acro at week 9. The algal fraction of Cladocopium C1 acro -anemones was enriched in metabolites related to nitrogen storage, while the host fraction of B. minutum -anemones was enriched in sugar-related metabolites. Compared to B. minutum , Cladocopium C1 acro is likely slightly less nutritionally beneficial to the host under ambient conditions, but more capable of maintaining its own growth when host nitrogen supply is limited. Our findings demonstrate the value of E. diaphana to study experimentally evolved Cladocopium .
Publisher: Frontiers Media SA
Date: 09-2017
Publisher: Wiley
Date: 19-08-2023
DOI: 10.1111/EVA.13586
Abstract: Despite the relevance of heat‐evolved microalgal endosymbionts to coral reef restoration, to date, few Symbiodiniaceae strains have been thermally enhanced via experimental evolution. Here, we investigated whether the thermal tolerance of Symbiodiniaceae can be increased through chemical mutagenesis followed by thermal selection. Strains of Durusdinium trenchii , Fugacium kawagutii and Symbiodinium pilosum were exposed to ethyl methanesulfonate to induce random mutagenesis, and then underwent thermal selection at high temperature (31/33°C). After 4.6–5 years of experimental evolution, the in vitro thermal tolerance of these strains was assessed via reciprocal transplant experiments to ambient (27°C) and elevated (31/35°C) temperatures. Growth, photosynthetic efficiency, oxidative stress and nutrient use were measured to compare thermal tolerance between strains. Heat‐evolved D. trenchii , F. kawagutii and S. pilosum strains all exhibited increased photosynthetic efficiency under thermal stress. However, trade‐offs in growth rates were observed for the heat‐evolved D. trenchii lineage at both ambient and elevated temperatures. Reduced phosphate and nitrate uptake rates in F. kawagutii and S. pilosum heat‐evolved lineages, respectively, suggest alterations in nutrition resource usage and allocation processes may have occurred. Increased phosphate uptake rates of the heat‐evolved D. trenchii strain indicate that experimental evolution resulted in further trade‐offs in this species. These findings deepen our understanding of the physiological responses of Symbiodiniaceae cultures to thermal selection and their capacity to adapt to elevated temperatures. The new heat‐evolved Symbiodiniaceae developed here may be beneficial for coral reef restoration efforts if their enhanced thermal tolerance can be conferred in hospite .
Publisher: Cold Spring Harbor Laboratory
Date: 21-11-2022
DOI: 10.1101/2022.11.21.517290
Abstract: Corals’ tolerance to high temperature stress largely depends on their symbiotic microalgae (Symbiodiniaceae). However, the contributing microalgal traits are largely unclear. Here we compare the in vitro cellular profiles of seven Cladocopium C1 acro microalgal strains (derived from the same ancestral strain) during a four-week exposure to 27°C or 31°C. One was an unselected wild-type strain (WT), three were selected at 31°C for nine years and shown to confer thermal tolerance on the coral host (SS+) and three others were similarly selected but did not confer tolerance (SS-). Flow cytometry was used to measure the intracellular stress indicators reactive oxygen species (ROS), reduced glutathione (rGSH) and mitochondrial-membrane potential (ΔΨm), as well as cell size/shape and photosynthetic pigments. Cell densities and photosynthetic efficiency (ΦPSII, Fv/Fm) were also measured. WT showed the highest levels of intracellular ROS and ΔΨm, lowest rGSH and largest cell sizes at both temperatures. SS+ strains had the lowest ROS and highest rGSH values and a unique pattern of correlations among parameters at 31°C. Our results support previous reports implicating the role of microalgal ROS, ΔΨm and rGSH in holobiont thermal tolerance and suggest flow cytometry is a useful pre-screening tool for identifying microalgal strains with enhanced thermal tolerance.
Publisher: PeerJ
Date: 06-09-2017
DOI: 10.7717/PEERJ.3732
Abstract: Here we describe an efficient and effective technique for rearing sexually-derived coral propagules from spawning through larval settlement and symbiont uptake with minimal impact on natural coral populations. We sought to maximize larval survival while minimizing expense and daily husbandry maintenance by experimentally determining optimized conditions and protocols for gamete fertilization, larval cultivation, induction of larval settlement by crustose coralline algae, and inoculation of newly settled juveniles with their dinoflagellate symbiont Symbiodinium . Larval rearing densities at or below 0.2 larvae mL −1 were found to maximize larval survival and settlement success in culture tanks while minimizing maintenance effort. Induction of larval settlement via the addition of a ground mixture of erse crustose coralline algae (CCA) is recommended, given the challenging nature of in situ CCA identification and our finding that non settlement-inducing CCA assemblages do not inhibit larval settlement if suitable assemblages are present. Although order of magnitude differences in infectivity were found between common Great Barrier Reef Symbiodinium clades C and D, no significant differences in Symbiodinium uptake were observed between laboratory-cultured and wild-harvested symbionts in each case. The technique presented here for Acropora millepora can be adapted for research and restoration efforts in a wide range of broadcast spawning coral species.
No related grants have been discovered for Patrick Buerger.