Paul Ebert

Determining changes in the distribution and abundance of a Rhyzopertha dominica phosphine resistance allele in farm grain storages using a DNA marker

Publisher: Wiley

Date: 03-04-2013

DOI: 10.1002/PS.3514

Abstract: The lesser grain borer, Rhyzopertha dominica (F.), is a highly destructive pest of stored grain that is strongly resistant to the fumigant phosphine (PH3 ). Phosphine resistance is due to genetic variants at the rph2 locus that alter the function of the dihydrolipoamide dehydrogenase (DLD) gene. This discovery now enables direct detection of resistance variants at the rph2 locus in field populations. A genotype assay was developed for direct detection of changes in distribution and frequency of a phosphine resistance allele in field populations of R. dominica. Beetles were collected from ten farms in south-east Queensland in 2006 and res led in 2011. Resistance allele frequency increased in the period from 2006 to 2011 on organic farms with no history of phosphine use, implying that migration of phosphine-resistant R. dominica had occurred from nearby storages. Increasing resistance allele frequencies on organic farms suggest local movement of beetles and dispersal of insects from areas where phosphine has been used. This research also highlighted for the first time the utility of a genetic DNA marker in accurate and rapid determination of the distribution of phosphine-resistant insects in the grain value chain. Extending this research over larger landscapes would help in identifying resistance problems and enable timely pest management decisions.

Synergism Between Phosphine (PH3) and Carbon Dioxide (CO2): Implications for Managing PH3 Resistance in Rusty Grain Beetle (Laemophloeidae: Coleoptera)

Publisher: Oxford University Press (OUP)

Date: 24-04-2020

DOI: 10.1093/JEE/TOAA081

Abstract: Strong resistance to phosphine (PH3) in the rusty grain beetle, Cryptolestes ferrugineus (Stephens) (Laemophloeidae: Coleoptera) poses a serious risk to stored-grain biosecurity. Resistant populations hold risk of surviving in PH3 fumigation, particularly in storage structure that limits achieving very high concentrations of PH3, demanding the need for alternative fumigation strategies. Cofumigation with PH3 and carbon dioxide (CO2) is one alternative approach that has the potential to be used widely. CO2 fumigation of adults of strongly PH3-resistant reference strain of C. ferrugineus, for 48 h, showed that the effective concentration (LC50) of CO2 was 30.99%. This 30% level of CO2 in combination with PH3 decreased the LC50 of PH3 from 6.7 mg/liter to 0.84 mg/liter, an eightfold increase in PH3 efficacy relative to PH3 fumigation in normal air. The LC99.9 decreased from 16.2 mg/liter to 5.8 mg/liter, a 2.8-fold increase in PH3 efficacy. Comparison of mortality response data of PH3 alone and the PH3 + CO2 mixture confirmed that CO2 enhances the toxicity of PH3 synergistically in addition to exerting its own toxicity. These results were validated against three independently field-derived strains of strongly resistant C. ferrugineus that confirmed that observed enhancement in toxicity with the PH3 + CO2 mixture was consistent, irrespective of differences in resistance phenotypes and inherent tolerance levels. Results of the current study provide further opportunities to develop new commercially viable strategy to control strongly PH3-resistant C. ferrugineus.

Isolation of seven unique biogenic amine receptor clones from the honey bee by library scanning

Publisher: Wiley

Date: 05-1998

DOI: 10.1046/J.1365-2583.1998.72059.X

Abstract: The biogenic amine receptor genes constitute an ancient and highly ergent family within the larger superfamily of G-protein-coupled receptors. These receptors play a central role in modulating nerve cell activity and thus behaviour. Because the honey bee offers numerous advantages for behavioural studies we endeavoured to isolate as many members of this gene family as possible from the bee. We compared numerous approaches to gene isolation and found that PCR lification from small subfractions of cDNA or genomic DNA libraries enabled us to isolate clones that are otherwise undetectable. In total we isolated seven biogenic amine receptor clones and identified five additional related sequences by low-stringency Southern hybridization. Two clones, AmBAR4 and AmBAR6, are 84% and 72% identical to the Drosophila 5-HT2 and D1b receptors, respectively, and probably represent orthologous genes. Phylogenetic analysis indicates that AmBAR5 clusters loosely with a variety of tyramine and octopamine receptors with which it shares <66% identity. The other four clones, AmBAR1, AmBAR2, AmBAR3 and AmBAR7, are weakly to moderately related (28-45% identical) to Drosophila dopaminergic or mammalian adrenergic receptors and probably represent receptors of these classes whose orthologues have not previously been isolated from any insect. The honey bee clones expand the size of the known insect biogenic amine receptor gene family to sixteen members. Therefore the size of the biogenic amine receptor gene family of insects approaches that of vertebrates. This is true despite the reduced behavioural and genetic complexity of the insects relative to vertebrate animals.

Genetic characterization of field-evolved resistance to phosphine in the rusty grain beetle, Cryptolestes ferrugineus (Laemophloeidae: Coleoptera)

Publisher: Elsevier BV

Date: 02-2016

DOI: 10.1016/J.PESTBP.2015.09.008

Abstract: Inheritance of resistance to phosphine fumigant was investigated in three field-collected strains of rusty grain beetle, Cryptolestes ferrugineus, Susceptible (S-strain), Weakly Resistant (Weak-R) and Strongly Resistant (Strong-R). The strains were purified for susceptibility, weak resistance and strong resistance to phosphine, respectively, to ensure homozygosity of resistance genotype. Crosses were established between S-strain×Weak-R, S-strain×Strong-R and Weak-R×Strong-R, and the dose mortality responses to phosphine of these strains and their F1, F2 and F1-backcross progeny were obtained. The fumigations were undertaken at 25°C and 55% RH for 72h. Weak-R and Strong-R showed resistance factors of 6.3× and 505× compared with S-strain at the LC50. Both weak and strong resistances were expressed as incompletely recessive with degrees of dominance of -0.48 and -0.43 at the LC50, respectively. Responses of F2 and F1-backcross progeny indicated the existence of one major gene in Weak-R, and at least two major genes in Strong-R, one of which was allelic with the major factor in Weak-R. Phenotypic variance analyses also estimated that the number of independently segregating genes conferring weak resistance was 1 (nE=0.89) whereas there were two genes controlling strong resistance (nE=1.2). The second gene, unique to Strong-R, interacted synergistically with the first gene to confer a very high level of resistance (~80×). Neither of the two major resistance genes was sex linked. Despite the similarity of the genetics of resistance to that previously observed in other pest species, a significant proportion (~15 to 30%) of F1 in iduals survived at phosphine concentrations higher than predicted. Thus it is likely that additional dominant heritable factors, present in some in iduals in the population, also influenced the resistance phenotype. Our results will help in understanding the process of selection for phosphine resistance in the field which will inform resistance management strategies. In addition, this information will provide a basis for the identification of the resistance genes.

Phosphine resistance in India is characterised by a dihydrolipoamide dehydrogenase variant that is otherwise unobserved in eukaryotes

Publisher: Springer Science and Business Media LLC

Date: 08-04-2015

DOI: 10.1038/HDY.2015.24

Variant Linkage Analysis Using de Novo Transcriptome Sequencing Identifies a Conserved Phosphine Resistance Gene in Insects

Publisher: Oxford University Press (OUP)

Date: 28-02-2018

DOI: 10.1534/GENETICS.118.300688

Abstract: Next-generation sequencing methods enable identification of the genetic basis of traits in species that have no prior genomic information available. The combination of next-generation sequencing, variant analysis, and linkage is a powerful way of identifying candidate genes for a trait of interest. Here, we used a comparative transcriptomics [RNA sequencing (RNAseq)] and genetic linkage analysis approach to identify the rph1 gene. rph1 variants are responsible for resistance to the fumigant phosphine (PH3) that is used to control insect pests of stored grain. In each of the four major species of pest insect of grain we have investigated, there are two major resistance genes, rph1 and rph2, which interact synergistically to produce strongly phosphine-resistant insects. Using RNAseq and genetic linkage analyses, we identified candidate resistance (rph1) genes in phosphine-resistant strains of three species: Rhyzopertha dominica (129 candidates), Sitophilus oryzae (206 candidates), and Cryptolestes ferrugineus (645 candidates). We then compared these candidate genes to 17 candidate resistance genes previously mapped in Tribolium castaneum and found only one orthologous gene, a cytochrome b5 fatty acid desaturase (Cyt-b5-r), to be associated with the rph1 locus in all four species. This gene had either missense amino acid substitutions and/or insertion/deletions/frameshift variants in each of 18 phosphine-resistant strains that were not observed in the susceptible strains of the four species. We propose a model of phosphine action and resistance in which phosphine induces lipid peroxidation through reactive oxygen species generated by dihydrolipoamide dehydrogenase, whereas disruption of Cyt-b5-r in resistant insects decreases the polyunsaturated fatty acid content of membranes, thereby limiting the potential for lipid peroxidation.

The rph1 Gene Is a Common Contributor to the Evolution of Phosphine Resistance in Independent Field Isolates of Rhyzopertha Dominica

Publisher: Public Library of Science (PLoS)

Date: 20-02-2012

DOI: 10.1371/JOURNAL.PONE.0031541

Mitochondrial Modulation of Phosphine Toxicity and Resistance in Caenorhabditis elegans

Publisher: Oxford University Press (OUP)

Date: 12-11-2007

DOI: 10.1093/TOXSCI/KFM278

Abstract: Phosphine is a fumigant used to protect stored commodities from infestation by pest insects, though high-level phosphine resistance in many insect species threatens the continued use of the fumigant. The mechanisms of toxicity and resistance are not clearly understood. In this study, the model organism, Caenorhabditis elegans, was employed to investigate the effects of phosphine on its proposed in vivo target, the mitochondrion. We found that phosphine rapidly perturbs mitochondrial morphology, inhibits oxidative respiration by 70%, and causes a severe drop in mitochondrial membrane potential (DeltaPsim) within 5 h of exposure. We then examined the phosphine-resistant strain of nematode, pre-33, to determine whether resistance was associated with any changes to mitochondrial physiology. Oxygen consumption was reduced by 70% in these mutant animals, which also had more mitochondrial genome copies than wild-type animals, a common response to reduced metabolic capacity. The mutant also had an unexpected increase in the basal DeltaPsim, which protected in iduals from collapse of the membrane potential following phosphine treatment. We tested whether directly manipulating mitochondrial function could influence sensitivity toward phosphine and found that suppression of mitochondrial respiratory chain genes caused up to 10-fold increase in phosphine resistance. The current study confirms that phosphine targets the mitochondria and also indicates that direct alteration of mitochondrial function may be related to phosphine resistance.

Phosphine Resistance in the Rust Red Flour Beetle, Tribolium castaneum (Coleoptera: Tenebrionidae): Inheritance, Gene Interactions and Fitness Costs

Publisher: Public Library of Science (PLoS)

Date: 21-02-2012

DOI: 10.1371/JOURNAL.PONE.0031582

Mitochondrial dysfunction in Caenorhabditis elegans causes metabolic restructuring, but this is not linked to longevity

Publisher: Elsevier BV

Date: 09-2010

DOI: 10.1016/J.MAD.2010.07.004

Abstract: Lifespan in Caenorhabditis elegans, Drosophila, and mice can be extended by a decrease in mitochondrial electron transport chain (ETC) function, but the mechanism behind this extension is unknown. In the present study, we combine detailed metabolic analysis with lifespan determination following suppression of in idual genes encoding respiratory complexes I-IV. We report that reduced complexes I, III, and IV activity extend lifespan but that complex II disruption does not. However, disruption to all four complexes affected metabolism in a similar manner suggesting that metabolic effects induced by ETC disruption are separable from lifespan extension. We found that suppression of ETC components induces a starvation-like metabolic response via the nuclear hormone receptor NHR-49. This includes induction of genes for mitochondrial fatty-acid β-oxidation (acs-2), the glyoxylate cycle (gei-7), gluconeogensis (PEPCK), and glycolysis (gpd-3). Interestingly, a null mutation of nhr-49 attenuated induction of these metabolic pathways, but did not affect the lifespan extension associated with decreases in complexes I, III, and IV function. Together, our results suggest that restructuring of metabolism via NHR-49 in C. elegans with mitochondrial dysfunction does not cause lifespan extension.

Automated Wormscan

Publisher: F1000 Research Ltd

Date: 27-02-2017

DOI: 10.12688/F1000RESEARCH.10767.1

Abstract: There has been a recent surge of interest in computer-aided rapid data acquisition to increase the potential throughput and reduce the labour costs of large scale Caenorhabditis elegans studies. We present Automated WormScan, a low-cost, high-throughput automated system using commercial photo scanners, which is extremely easy to implement and use, capable of scoring tens of thousands of organisms per hour with minimal operator input, and is scalable. The method does not rely on software training for image recognition, but uses the generation of difference images from sequential scans to identify moving objects. This approach results in robust identification of worms with little computational demand. We demonstrate the utility of the system by conducting toxicity, growth and fecundity assays, which demonstrate the consistency of our automated system, the quality of the data relative to manual scoring methods and congruity with previously published results.

5-Methoxyindole-2-carboxylic acid (MICA) suppresses Aβ-mediated pathology in C. elegans

Publisher: Elsevier BV

Date: 07-2018

DOI: 10.1016/J.EXGER.2018.04.021

Abstract: Alzheimer's disease (AD) is an age-related disease characterized by loss of memory and disrupted thinking that is associated with altered energy metabolism. Variants of an important enzyme of energy metabolism, dihydrolipoamide dehydrogenase (dld), have been genetically linked to late-onset AD. Moreover, reduced activity of DLD-containing enzyme complexes is associated with AD progression. To understand how energy metabolism influences AD progression, we exposed C. elegans expressing human Aβ peptide to the chemical inhibitor of DLD, 2-methoxyindole-5-carboxylic acid (MICA). Expression of human Aβ in C. elegans causes a variety of pathologies that can be used to monitor the efficacy of treatments against proteotixicity. We found that MICA alleviated the Aβ-induced paralysis and improved cholinergic neurotransmission in C. elegans that express Aβ in muscle cells. MICA also reduced both hypersensitivity to serotonin and perturbation of chemotaxis associated with neuronal expression of human Aβ. Furthermore, low doses of MICA helped to alleviate an Aβ-mediated decrease in fecundity. Protection against AD pathogenesis by MICA in the C. elegans model was associated with a decrease in Aβ oligomerization that could be reversed by the calcium ionophore, A23187. MICA also caused a decrease in oxidative stress, which could also contribute to the protective effect of MICA against Aβ toxicity.

Automated Wormscan

Publisher: F1000 Research Ltd

Date: 06-09-2017

DOI: 10.12688/F1000RESEARCH.10767.2

Abstract: There has been a recent surge of interest in computer-aided rapid data acquisition to increase the potential throughput and reduce the labour costs of large scale Caenorhabditis elegans studies. We present Automated WormScan, a low-cost, high-throughput automated system using commercial photo scanners, which is extremely easy to implement and use, capable of scoring tens of thousands of organisms per hour with minimal operator input, and is scalable. The method does not rely on software training for image recognition, but uses the generation of difference images from sequential scans to identify moving objects. This approach results in robust identification of worms with little computational demand. We demonstrate the utility of the system by conducting toxicity, growth and fecundity assays, which demonstrate the consistency of our automated system, the quality of the data relative to manual scoring methods and congruity with previously published results.

Molecular Genetics and Biology of Self-Incompatibility in Nicotiana alata, an Ornamental Tobacco

Publisher: CSIRO Publishing

Date: 1990

DOI: 10.1071/PP9900345

Abstract: Glycoproteins are present in the styles of several self-incompatible species within the Solanaceae which segregate with particular alleles of the S-(self-incompatibility) gene. The amino acid sequences of style glycoproteins corresponding to different S-alleles of N. alata are homologous in some regions and variable in others. Homologous regions include N-terminal sequences as well as most of the glycosylation sites and cysteine residues. The isolated style S-glycoproteins inhibit in vitro growth of pollen tubes of several S-genotypes, with some specificity in the interaction. The isolated S-glycoproteins have ribonuclease activity which may be involved in their action in arrest of growth of incompatible (self) pollen.

The failure to extend lifespan via disruption of complex II is linked to preservation of dynamic control of energy metabolism

Publisher: Elsevier BV

Date: 03-2012

DOI: 10.1016/J.MITO.2011.10.003

Abstract: A decrease in mitochondrial electron transport chain (ETC) activity results in an extended lifespan in Caenorhabditis elegans. This longevity has only been reported when complexes I, III and IV genes are silenced, but not genes of complex II. We now have suppressed each complex II subunit in turn and have confirmed that in no case is lifespan extended. Animals with impaired complex II function exhibit similar metabolic changes to those observed following suppression of complexes I, III and IV genes, but the magnitude of the changes is smaller. Furthermore, an inverse correlation exists between mitochondrial membrane potential and ATP levels (r(2)=0.82), which strongly suggests that dynamic allocation of energy resources is maintained. In contrast, suppression of genes from complexes I, III and IV, results in a metabolic crisis with an associated stress response and loss of metabolic flexibility. Thus, the maintenance of a normal metabolism at a moderately decreased level does not alter normal lifespan, whereas metabolic crisis and induction of a stress response is linked to lifespan extension.

Stress pre-conditioning with temperature, UV and gamma radiation induces tolerance against phosphine toxicity

Publisher: Public Library of Science (PLoS)

Date: 19-04-2018

DOI: 10.1371/JOURNAL.PONE.0195349

Functional promoter analysis using an approach based on an in vitro evolution strategy

Publisher: Future Science Ltd

Date: 02-2005

DOI: 10.2144/05382ST01

Abstract: In vitro evolution imitates the natural evolution of genes and has been very successfully applied to the modification of coding sequences, but it has not yet been applied to promoter sequences. We propose an alternative method for functional promoter analysis by applying an in vitro evolution scheme consisting of rounds of error-prone PCR, followed by DNA shuffling and selection of mutant promoter activities. We modified the activity in embryogenic sugarcane cells of the promoter region of the “Goldfinger” isolate of banana streak virus and obtained mutant promoter sequences that showed an average mutation rate of 2.5% after applying one round of error-prone PCR and DNA shuffling. Selection and sequencing of promoter sequences with decreased or unaltered activity allowed us to rapidly map the position of one cis-acting element that influenced promoter activity in embryogenic sugarcane cells and to discover neutral mutations that did not affect promoter function. The “selective-shotgun” approach of this promoter analysis method immediately after the promoter boundaries have been defined by 5′ deletion analysis dramatically reduces the labor associated with traditional “linker-scanning” deletion analysis to reveal the position of functional promoter domains. Furthermore, this method allows the entire promoter to be investigated at once, rather than selected domains or nucleotides, increasing the prospect of identifying interacting promoter regions.

Identification of functional sequences in the pregenomic RNA promoter of the Banana streak virus Cavendish strain (BSV-Cav)

Publisher: Elsevier BV

Date: 03-2005

DOI: 10.1016/J.VIRUSRES.2004.09.005

Abstract: The promoter regions of plant pararetroviruses direct transcription of the full-length viral genome into a pregenomic RNA that is an intermediate in the replication of the virus. It serves as template for reverse transcription and as polycistronic mRNA for translation to viral proteins. We have identified functional promoter elements in the intergenic region of the Cavendish isolate of Banana streak virus (BSV-Cav), a member of the genus Badnavirus. Potential binding sites for plant transcription factors were found both upstream and downstream of the transcription start site by homology search in the PLACE database of plant cis-acting elements. The functionality of these putative cis-acting elements was tested by constructing loss-of-function and "regain"-of-function mutant promoters whose activity was quantified in embryogenic sugarcane suspension cells. Four regions that are important for activity of the BSV-Cav promoter were identified: the region containing an as-1-like element, the region around -141 and down to -77, containing several putative transcription factor binding sites, the region including the CAAT-box, and the leader region. The results could help explain the high BSV-Cav promoter activity that was observed previously in transgenic sugarcane plants and give more insight into the plant cell-mediated replication of the viral genome in banana streak disease.

A Core Metabolic Enzyme Mediates Resistance to Phosphine Gas

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

Date: 09-11-2012

DOI: 10.1126/SCIENCE.1224951

Abstract: Worldwide populations of pest insects—such as the lesser grain borer, Rhyzopertha dominica , and the rust-red flour beetle, Tribolium castaneum —have become highly resistant to the fumigant phosphine, providing a potential threat to global food security. The nematode, Caenorhabditis elegans is vulnerable to phosphine, but phosphine-resistant strains are known. Schlipalius et al. (p. 807 ) show that mutations in the delta-1-pyrroline-5-carboxylate dehydrogenase and dihydrolipoamide dehydrogenase ( dld-1 ) genes both give rise to phosphine resistance in C. elegans . Phosphine resistance mutants in R. dominica , and T. castaneum also map to the dld-1 gene, which codes for a core metabolic enzyme. These mutants are, however, hypersensitive to arsenic, mimics of which might thus synergize with phosphine.

Rapid genome wide mapping of phosphine resistance loci by a simple regional averaging analysis in the red flour beetle, Tribolium castaneum

Publisher: Springer Science and Business Media LLC

Date: 24-09-2013

DOI: 10.1186/1471-2164-14-650

Abstract: Next-generation sequencing technology is an important tool for the rapid, genome-wide identification of genetic variations. However, it is difficult to resolve the ‘signal’ of variations of interest and the ‘noise’ of stochastic sequencing and bioinformatic errors in the large datasets that are generated. We report a simple approach to identify regional linkage to a trait that requires only two pools of DNA to be sequenced from progeny of a defined genetic cross (i.e. bulk segregant analysis) at low coverage ( ×) and without parentage assignment of in idual SNPs. The analysis relies on regional averaging of pooled SNP frequencies to rapidly scan polymorphisms across the genome for differential regional homozygosity, which is then displayed graphically. Progeny from defined genetic crosses of Tribolium castaneum (F 4 and F 19 ) segregating for the phosphine resistance trait were exposed to phosphine to select for the resistance trait while the remainders were left unexposed. Next generation sequencing was then carried out on the genomic DNA from each pool of selected and unselected insects from each generation. The reads were mapped against the annotated T. castaneum genome from NCBI (v3.0) and analysed for SNP variations. Since it is difficult to accurately call in idual SNP frequencies when the depth of sequence coverage is low, variant frequencies were averaged across larger regions. Results from regional SNP frequency averaging identified two loci, tc_ rph1 on chromosome 8 and tc_ rph2 on chromosome 9, which together are responsible for high level resistance. Identification of the two loci was possible with only 5-7× average coverage of the genome per dataset. These loci were subsequently confirmed by direct SNP marker analysis and fine-scale mapping. In idually, homozygosity of tc_ rph1 or tc_ rph2 results in only weak resistance to phosphine (estimated at up to 1.5-2.5× and 3-5× respectively), whereas in combination they interact synergistically to provide a high-level resistance ×. The tc_ rph2 resistance allele resulted in a significant fitness cost relative to the wild type allele in unselected beetles over eighteen generations. We have validated the technique of linkage mapping by low-coverage sequencing of progeny from a simple genetic cross. The approach relied on regional averaging of SNP frequencies and was used to successfully identify candidate gene loci for phosphine resistance in T. castaneum . This is a relatively simple and rapid approach to identifying genomic regions associated with traits in defined genetic crosses that does not require any specialised statistical analysis.

The rph2 Gene Is Responsible for High Level Resistance to Phosphine in Independent Field Strains of Rhyzopertha dominica

Publisher: Public Library of Science (PLoS)

Date: 26-03-2012

DOI: 10.1371/JOURNAL.PONE.0034027

Mitochondrial uncouplers act synergistically with the fumigant phosphine to disrupt mitochondrial membrane potential and cause cell death

Publisher: Elsevier BV

Date: 10-2008

DOI: 10.1016/J.TOX.2008.07.060

Abstract: Phosphine is the most widely used fumigant for the protection of stored commodities against insect pests, especially food products such as grain. However, pest insects are developing resistance to phosphine and thereby threatening its future use. As phosphine inhibits cytochrome c oxidase (complex IV) of the mitochondrial respiratory chain and reduces the strength of the mitochondrial membrane potential (DeltaPsi(m)), we reasoned that mitochondrial uncouplers should act synergistically with phosphine. The mitochondrial uncouplers FCCP and PCP caused complete mortality in populations of both wild-type and phosphine-resistant lines of Caenorhabditis elegans simultaneously exposed to uncoupler and phosphine at concentrations that were in idually nonlethal. Strong synergism was also observed with a third uncoupler DNP. We have also tested an alternative complex IV inhibitor, azide, with FCCP and found that this also caused a synergistic enhancement of toxicity in C. elegans. To investigate potential causes of the synergism, we measured DeltaPsi(m), ATP content, and oxidative damage (lipid hydroperoxides) in nematodes subjected to phosphine-FCCP treatment and found that neither an observed 50% depletion in ATP nor oxidative stress accounted for the synergistic effect. Instead, a synergistic reduction in DeltaPsi(m) was observed upon phosphine-FCCP co-treatment suggesting that this is directly responsible for the subsequent mortality. These results support the hypothesis that phosphine-induced mortality results from the in vivo disruption of normal mitochondrial activity. Furthermore, we have identified a novel pathway that can be targeted to overcome genetic resistance to phosphine.

Potential of Co-Fumigation with Phosphine (PH3) and Sulfuryl Fluoride (SO2F2) for the Management of Strongly Phosphine-Resistant Insect Pests of Stored Grain

Publisher: Oxford University Press (OUP)

Date: 17-09-2018

DOI: 10.1093/JEE/TOY269

Abstract: Resistance to phosphine (PH3) in key insect pests of stored grain is increasing, with a requirement for maintaining a dose as high as 1 mg l-1 for 14 d for effective fumigation, which is difficult to achieve under most commercial storage conditions. There is no suitable replacement for PH3, as most of the available alternatives suffer from specific weaknesses, creating an urgent need to increase the efficacy of this fumigant. One such possibility is co-fumigation of PH3 with another fumigant, sulfuryl fluoride (SO2F2-SF), with the goal of decreasing the time required for a successful fumigation. In this study, adult of two PH3-resistant strains in each of four key grain insect pests, Rhyzopertha dominica, (F.) (Coleoptera: Bostrichidae) Tribolium castaneum Herbst (Coleoptera: Tenebrionidae), Sitophilus oryzae (L.) (Coleoptera: Curculionidae), and Cryptolestes ferrugineus (Stephens) (Coleoptera: Laemophloeidae) were fumigated with PH3 and SF in idually as well as in combinations at 25°C over 48 h. Mortality responses in each species were subjected to probit analysis to determine the LC50 and LC99.9 of PH3, SF, and PH3 + SF. Co-fumigation of PH3 with SF resulted in a 50% reduction of the PH3 concentration required to achieve 99.9% mortality in two pest species. For ex le, the PH3 + SF mixture, reduced the amount of PH3 required from 14.2-14.5 to 5.6-6.36 mg l-1 and from 2.71-5.03 to 0.93-1.2 mg l-1, respectively, for C. ferrugineus and S. oryzae. The overall mortality response to the PH3 + SF mixture followed an "additive model" suggesting that mutual enhancement in toxicity can be achieved with this mixture specifically to control PH3-resistant insects.

Frogs and estivation: transcriptional insights into metabolism and cell survival in a natural model of extended muscle disuse

Publisher: American Physiological Society

Date: 15-05-2013

DOI: 10.1152/PHYSIOLGENOMICS.00163.2012

Abstract: Green-striped burrowing frogs ( Cyclorana alboguttata ) survive in arid environments by burrowing underground and entering into a deep, prolonged metabolic depression known as estivation. Throughout estivation, C. alboguttata is immobilized within a cast-like cocoon of shed skin and ceases feeding and moving. Remarkably, these frogs exhibit very little muscle atrophy despite extended disuse and fasting. Little is known about the transcriptional regulation of estivation or associated mechanisms that may minimize degradative pathways of atrophy. To investigate transcriptional pathways associated with metabolic depression and maintenance of muscle function in estivating burrowing frogs, we assembled a skeletal muscle transcriptome using next-generation short read sequencing and compared gene expression patterns between active and 4 mo estivating C. alboguttata . This identified a complex suite of gene expression changes that occur in muscle during estivation and provides evidence that estivation in burrowing frogs involves transcriptional regulation of genes associated with cytoskeletal remodeling, avoidance of oxidative stress, energy metabolism, the cell stress response, and apoptotic signaling. In particular, the expression levels of genes encoding cell cycle and prosurvival proteins, such as serine/threonine-protein kinase Chk1, cell ision protein kinase 2, survivin, and vesicular overexpressed in cancer prosurvival protein 1, were upregulated during estivation. These data suggest that estivating C. alboguttata are able to regulate the expression of genes in several major cellular pathways critical to the survival and viability of cells, thus preserving muscle function while avoiding the deleterious consequences often seen in laboratory models of muscle disuse.

Discovery Projects - Grant ID: DP140103513

Start Date: 2014

End Date: 05-2017

Amount: $355,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0209518

Start Date: 2002

End Date: 12-2005

Amount: $155,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0668507

Start Date: 2006

End Date: 12-2006

Amount: $260,000.00

Funder: Australian Research Council

Special Research Initiatives - Grant ID: SR0354908

Start Date: 2004

End Date: 12-2004

Amount: $10,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0558507

Start Date: 2005

End Date: 12-2007

Amount: $230,000.00

Funder: Australian Research Council