Philip Batterham

Exon-primed intron-crossing (EPIC) PCR markers of Helicoverpa armigera (Lepidoptera

Publisher: Cambridge University Press (CUP)

Date: 16-06-2008

DOI: 10.1017/S000748530800583X

Abstract: Applying microsatellite DNA markers in population genetic studies of the pest moth Helicoverpa armigera is subject to numerous technical problems, such as the high frequency of null alleles, occurrence of size homoplasy, presence of multiple copies of flanking sequence in the genome and the lack of PCR lification robustness between populations. To overcome these difficulties, we developed exon-primed intron-crossing (EPIC) nuclear DNA markers for H. armigera based on ribosomal protein (Rp) and the Dopa Decarboxylase (DDC) genes and sequenced alleles showing length polymorphisms. Allele length polymorphisms were usually from random indels (insertions or deletions) within introns, although variation of short dinucleotide DNA repeat units was also detected. Mapping crosses demonstrated Mendelian inheritance patterns for these EPIC markers and the absence of both null alleles and allele ‘dropouts’. Three ex les of allele size homoplasies due to indels were detected in EPIC markers RpL3, RpS6 and DDC, while sequencing of multiple in iduals across 11 randomly selected alleles did not detect indel size homoplasies. The robustness of the EPIC-PCR markers was demonstrated by PCR lification in the related species, H. zea , H. assulta and H. punctigera .

Gene content evolution in the arthropods

Publisher: Springer Science and Business Media LLC

Date: 23-01-2020

DOI: 10.1186/S13059-019-1925-7

Abstract: Arthropods comprise the largest and most erse phylum on Earth and play vital roles in nearly every ecosystem. Their ersity stems in part from variations on a conserved body plan, resulting from and recorded in adaptive changes in the genome. Dissection of the genomic record of sequence change enables broad questions regarding genome evolution to be addressed, even across hyper- erse taxa within arthropods. Using 76 whole genome sequences representing 21 orders spanning more than 500 million years of arthropod evolution, we document changes in gene and protein domain content and provide temporal and phylogenetic context for interpreting these innovations. We identify many novel gene families that arose early in the evolution of arthropods and during the ersification of insects into modern orders. We reveal unexpected variation in patterns of DNA methylation across arthropods and ex les of gene family and protein domain evolution coincident with the appearance of notable phenotypic and physiological adaptations such as flight, metamorphosis, sociality, and chemoperception. These analyses demonstrate how large-scale comparative genomics can provide broad new insights into the genotype to phenotype map and generate testable hypotheses about the evolution of animal ersity.

Using Drosophila melanogaster to validate metabolism-based insecticide resistance from insect pests

Publisher: Elsevier BV

Date: 12-2012

DOI: 10.1016/J.IBMB.2012.09.003

Abstract: Identifying molecular mechanisms of insecticide resistance is important for preserving insecticide efficacy, developing new insecticides and implementing insect control. The metabolic detoxification of insecticides is a widespread resistance mechanism. Enzymes with the potential to detoxify insecticides are commonly encoded by members of the large cytochrome P450, glutathione S-transferase and carboxylesterase gene families, all rapidly evolving in insects. Here, we demonstrate that the model insect Drosophila melanogaster is useful for functionally validating the role of metabolic enzymes in conferring metabolism-based insecticide resistance. Alleles of three well-characterized genes from different pest insects were expressed in transgenic D. melanogaster : a carboxylesterase gene (αE7) from the Australian sheep blowfly Lucilia cuprina, a glutathione S-transferase gene (GstE2) from the mosquito Anopheles gambiae and a cytochrome P450 gene (Cyp6cm1) from the whitefly Bemisia tabaci. For all genes, expression in D. melanogaster resulted in insecticide resistance phenotypes mirroring those observed in resistant populations of the pest species. Using D. melanogaster to assess the potential for novel metabolic resistance mechanisms to evolve in pest species is discussed.

Identification, analysis, and linkage mapping of expressed sequence tags from the Australian sheep blowfly

Publisher: Springer Science and Business Media LLC

Date: 10-08-2011

DOI: 10.1186/1471-2164-12-406

Nucleotide diversity in the Hsp90 gene in natural populations of Drosophila melanogaster from Australia

Publisher: Wiley

Date: 06-11-2008

DOI: 10.1111/J.1365-2583.2008.00843.X

Abstract: Hsp90 is regarded as one of the best candidates for an evolved mechanism that regulates the expression of genetic and phenotypic variability. We examined nucleotide ersity in both the promoter and coding regions of Hsp90, the gene which encodes Hsp90 in Drosophila, in natural populations of Drosophila melanogaster from eastern Australia. We found that Hsp90 is polymorphic for only two nonsynonymous changes in the coding region, both of which are deletions of a lysine residue. One of these lysine deletions was in complete linkage disequilibrium with the inversion In(3L)P, and showed a significant association with latitude. The other lysine deletion reported here for the first time varied from 0 to 15% in natural populations, but did not show a clinal pattern. The regulatory and coding regions of Hsp90 showed very low nucleotide ersity compared to other nuclear genes, and chromosomes containing In(3L)P had lower levels of nucleotide ersity than the standard arrangements. Non-neutral evolution of Hsp90 was not supported by analyses of either the regulatory or coding regions of the gene. These results are discussed within the context of Hsp90 variation being involved in thermotolerance as well as the expression of genetic and phenotypic variability.

The role of Rdl in resistance to phenylpyrazoles in Drosophila melanogaster

Publisher: Elsevier BV

Date: 11-2014

DOI: 10.1016/J.IBMB.2014.08.008

Abstract: Extensive use of older generation insecticides may result in pre-existing cross-resistance to new chemical classes acting at the same target site. Phenylpyrazole insecticides block inhibitory neurotransmission in insects via their action on ligand-gated chloride channels (LGCCs). Phenylpyrazoles are broad-spectrum insecticides widely used in agriculture and domestic pest control. So far, all identified cases of target site resistance to phenylpyrazoles are based on mutations in the Rdl (Resistance to dieldrin) LGCC subunit, the major target site for cyclodiene insecticides. We examined the role that mutations in Rdl have on phenylpyrazole resistance in Drosophila melanogaster, exploring naturally occurring variation, and generating predicted resistance mutations by mutagenesis. Natural variation at the Rdl locus in inbred strains of D. melanogaster included gene duplication, and a line containing two Rdl mutations found in a highly resistant line of Drosophila simulans. These mutations had a moderate impact on survival following exposure to two phenylpyrazoles, fipronil and pyriprole. Homology modelling suggested that the Rdl chloride channel pore contains key residues for binding fipronil and pyriprole. Mutagenesis of these sites and assessment of resistance in vivo in transgenic lines showed that amino acid identity at the Ala(301) site influenced resistance levels, with glycine showing greater survival than serine replacement. We confirm that point mutations at the Rdl 301 site provide moderate resistance to phenylpyrazoles in D. melanogaster. We also emphasize the beneficial aspects of testing predicted mutations in a whole organism to validate a candidate gene approach.

The insect growth regulator insecticide cyromazine causes earlier emergence inDrosophila melanogaster

Publisher: Wiley

Date: 2006

DOI: 10.1002/ARCH.20146

Abstract: The insecticide cyromazine, classified as an insect growth regulator, inhibits the growth and development of Diptera. The precise mode of cyromazine action remains unknown. We investigated mortality and developmental time effects after exposing first instar Drosophila melanogaster larvae to cyromazine for 8-h intervals. Significant increases in mortality were only observed for cyromazine exposure within the first 16 h of the first instar stage, suggesting that cyromazine accumulates in the larvae over time and that there is a delay between cyromazine exposure and effect. We observed that exposure to cyromazine during the early first instar stage resulted in earlier eclosion of adults when compared to cyromazine exposure at later first instar stages. The presence of 20-hydroxyecdysone during cyromazine exposure significantly reduced the lethal effect of cyromazine. We raise the possibility that the mode of cyromazine action is related to the development hormone, 20-hydroxyecdysone.

Positional cloning of a cyromazine resistance gene in Drosophila melanogaster

Publisher: Wiley

Date: 31-03-2006

DOI: 10.1111/J.1365-2583.2006.00622.X

Abstract: Cyromazine is an effective insecticide used to control dipteran insects. Its precise mode of action is yet to be determined, although it has been suggested that it interferes with the hormone system, sclerotization of the cuticle, or nucleic acid metabolism. To understand the way in which cyromazine acts, we have positionally cloned a cyromazine resistance gene from Drosophila melanogaster. Six cyromazine resistance alleles had previously been generated by ethyl methanasulphonate treatment. Two of these failed to complement each other and here we identify them as having independent non-sense mutations in CG32743, which is an ortholog of Smg1 of worms and mammals and encodes a phosphatidylinositol kinase-like kinase (PIKK). RNAi experiments confirm that cyromazine resistance can be achieved by knocking down CG32743. These are the first cyromazine resistant mutations identified at the nucleotide level. In mammals Smg1 phosphorylates P53 in response to DNA damage. This finding supports the hypothesis that cyromazine interferes with nucleic acid metabolism.

A cytochrome p450 conserved in insects is involved in cuticle formation

Publisher: Public Library of Science (PLoS)

Date: 04-05-2012

DOI: 10.1371/JOURNAL.PONE.0036544

Tissue‐specific transcriptome analyses in Drosophila provide novel insights into the mode of action of the insecticide spinosad and the function of its target, nAChRα6

Publisher: Wiley

Date: 11-06-2023

DOI: 10.1002/PS.7585

Abstract: The insecticides spinosad and imidacloprid are neurotoxins with distinct modes of action. Both target nicotinic acetylcholine receptors (nAChRs), albeit different subunits. Spinosad is an allosteric modulator, that upon binding initiates endocytosis of its target, nAChRα6. Imidacloprid binding triggers excessive neuronal ion influx. Despite these differences, low‐dose effects converge downstream in the precipitation of oxidative stress and neurodegeneration. Using RNA‐sequencing, we compared the transcriptional signatures of spinosad and imidacloprid, at low‐dose exposures. Both insecticides cause up‐regulation of glutathione S‐transferase and cytochrome P450 genes in the brain and down‐regulation in the fat body, whereas reduced expression of immune‐related genes is observed in both tissues. Spinosad shows unique impacts on genes involved in lysosomal function, protein folding, and reproduction. Co‐expression analyses revealed little to no correlation between genes affected by spinosad and nAChRα6 expressing neurons, but a positive correlation with glial cell markers. We also detected and experimentally confirmed nAChRα6 expression in fat body cells and male germline cells. This led us to uncover lysosomal dysfunction in the fat body following spinosad exposure, and a fitness cost in spinosad‐resistant ( nAChRα6 null) males – oxidative stress in testes, and reduced fertility. Spinosad and imidacloprid share transcriptional perturbations in immunity‐, energy homeostasis‐, and oxidative stress‐related genes. Low doses of other neurotoxic insecticides should be investigated for similar impacts. While target‐site spinosad resistance mutation has evolved in the field, this may have a fitness cost. Our findings demonstrate the power of tissue‐specific transcriptomics approach and the use of single‐cell transcriptome data. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Two independent duplications forming the Cyp307a genes in Drosophila

Publisher: Elsevier BV

Date: 10-2007

DOI: 10.1016/J.IBMB.2007.05.017

Abstract: The conserved relationship between orthologs of many cytochrome P450 genes involved in ecdysone synthesis is not reflected in the evolution of the Drosophila Cyp307a genes. In Drosophila melanogaster Cyp307a1 (spook) and Cyp307a2 (spookier) both play essential roles in ecdysone synthesis and may possess biochemically redundant functions. Using phylogenetic analyses we show that the Drosophila Cyp307a genes were formed from two independent duplication events depicting a complicated evolutionary scenario. An initial duplication, from a Cyp307a2 ancestral gene produced the Cyp307a1 gene that has been maintained only in the Sophophoran subgenus. A second duplication in the Drosophila subgenus formed an additional paralog, Cyp307a3. Microsynteny is conserved for Cyp307a2 throughout the Drosophila species, but is not conserved between Cyp307a1 and Cyp307a3. These are located in different genomic positions in the Sophophora and Drosophila subgenera, respectively. Cyp307a3 appears to encode a functional gene product and is expressed in a different spatial and temporal manner to Cyp307a1. This suggests some level of functional ergence between the Cyp307a paralogs in different Drosophila species.

Multiple P450s and Variation in Neuronal Genes Underpins the Response to the Insecticide Imidacloprid in a Population of Drosophila melanogaster

Publisher: Springer Science and Business Media LLC

Date: 12-09-2017

DOI: 10.1038/S41598-017-11092-5

Abstract: Insecticide resistance is an economically important ex le of evolution in response to intense selection pressure. Here, the genetics of resistance to the neonicotinoid insecticide imidacloprid is explored using the Drosophila Genetic Reference Panel, a collection of inbred Drosophila melanogaster genotypes derived from a single population in North Carolina. Imidacloprid resistance varied substantially among genotypes, and more resistant genotypes tended to show increased capacity to metabolize and excrete imidacloprid. Variation in resistance level was then associated with genomic and transcriptomic variation, implicating several candidate genes involved in central nervous system function and the cytochrome P450s Cyp6g1 and Cyp6g2 . CRISPR-Cas9 mediated removal of Cyp6g1 suggested that it contributed to imidacloprid resistance only in backgrounds where it was already highly expressed. Cyp6g2 , previously implicated in juvenile hormone synthesis via expression in the ring gland, was shown to be expressed in metabolically relevant tissues of resistant genotypes. Cyp6g2 overexpression was shown to both metabolize imidacloprid and confer resistance. These data collectively suggest that imidacloprid resistance is influenced by a variety of previously known and unknown genetic factors.

Cis-regulatory elements in the accord retrotransposon result in tissue-specific expression of the Drosophila melanogaster insecticide resistance gene Cyp6g1

Publisher: Oxford University Press (OUP)

Date: 03-2007

DOI: 10.1534/GENETICS.106.066597

Abstract: Transposable elements are a major mutation source and powerful agents of adaptive change. Some transposable element insertions in genomes increase to a high frequency because of the selective advantage the mutant phenotype provides. Cyp6g1-mediated insecticide resistance in Drosophila melanogaster is due to the upregulation of the cytochrome P450 gene Cyp6g1, leading to the resistance to a variety of insecticide classes. The upregulation of Cyp6g1 is correlated with the presence of the long terminal repeat (LTR) of an Accord retrotransposon inserted 291bp upstream of the Cyp6g1 transcription start site. This resistant allele (DDT-R) is currently at a high frequency in D. melanogaster populations around the world. Here, we characterize the spatial expression of Cyp6g1 in insecticide-resistant and -susceptible strains. We show that the Accord LTR insertion is indeed the resistance-associated mutation and demonstrate that the Accord LTR carries regulatory sequences that increase the expression of Cyp6g1 in tissues important for detoxification, the midgut, Malpighian tubules, and the fat body. This study provides a significant ex le of how changes in tissue-specific gene expression caused by transposable-element insertions can contribute to adaptation.

Gene duplication in the major insecticide target site, Rdl , in Drosophila melanogaster

Publisher: Proceedings of the National Academy of Sciences

Date: 19-08-2013

DOI: 10.1073/PNAS.1311341110

Abstract: The Resistance to Dieldrin gene, Rdl , encodes a GABA-gated chloride channel subunit that is targeted by cyclodiene and phenylpyrazole insecticides. The gene was first characterized in Drosophila melanogaster by genetic mapping of resistance to the cyclodiene dieldrin. The 4,000-fold resistance observed was due to a single amino acid replacement, Ala 301 to Ser. The equivalent change was subsequently identified in Rdl orthologs of a large range of resistant insect species. Here, we report identification of a duplication at the Rdl locus in D. melanogaster . The 113-kb duplication contains one WT copy of Rdl and a second copy with two point mutations: an Ala 301 to Ser resistance mutation and Met 360 to Ile replacement. In iduals with this duplication exhibit intermediate dieldrin resistance compared with single copy Ser 301 homozygotes, reduced temperature sensitivity, and altered RNA editing associated with the resistant allele. Ectopic recombination between Roo transposable elements is involved in generating this genomic rearrangement. The duplication phenotypes were confirmed by construction of a transgenic, artificial duplication integrating the 55.7-kb Rdl locus with a Ser 301 change into an Ala 301 background. Gene duplications can contribute significantly to the evolution of insecticide resistance, most commonly by increasing the amount of gene product produced. Here however, duplication of the Rdl target site creates permanent heterozygosity, providing unique potential for adaptive mutations to accrue in one copy, without abolishing the endogenous role of an essential gene.

Copper homeostasis gene discovery in Drosophila melanogaster

Publisher: Springer Science and Business Media LLC

Date: 10-01-2007

DOI: 10.1007/S10534-006-9075-2

Abstract: Recent studies have shown a high level of conservation between Drosophila melanogaster and mammalian copper homeostasis mechanisms. These studies have also demonstrated the efficiency with which this species can be used to characterize novel genes, at both the cellular and whole organism level. As a versatile and inexpensive model organism, Drosophila is also particularly useful for gene discovery applications and thus has the potential to be extremely useful in identifying novel copper homeostasis genes and putative disease genes. In order to assess the suitability of Drosophila for this purpose, three screening approaches have been investigated. These include an analysis of the global transcriptional response to copper in both adult flies and an embryonic cell line using DNA microarray analysis. Two mutagenesis-based screens were also utilized. Several candidate copper homeostasis genes have been identified through this work. In addition, the results of each screen were carefully analyzed to identify any factors influencing efficiency and sensitivity. These are discussed here with the aim of maximizing the efficiency of future screens and the most suitable approaches are outlined. Building on this information, there is great potential for the further use of Drosophila for copper homeostasis gene discovery.

Selective Sweeps at the Organophosphorus Insecticide Resistance Locus, Rop-1, Have Affected Variation across and beyond the  -Esterase Gene Cluster in the Australian Sheep Blowfly, Lucilia cuprina

Publisher: Oxford University Press (OUP)

Date: 12-01-2011

DOI: 10.1093/MOLBEV/MSR006

Abstract: A major theoretical consequence of selection at a locus is the genetic hitchhiking of linked sites (selective sweep). The extent of hitchhiking around a gene is related to the strength of selection and the rate of recombination, with its impact diminishing with distance from the selected site. At the Rop-1 locus of the sheep blowfly, Lucilia cuprina, polymorphisms at two different sites within the LcαE7 gene encode forms of the protein that confer organophosphorus insecticide resistance. To assess the impact of selection at these two sites on variation around LcαE7, we sequenced regions within six other genes along chromosome IV across isogenic (IV) strains of L. cuprina. High levels of linkage disequilibrium, characterized by low haplotype number (K) and ersity (H), and significant R(2) values were observed for two genes, LcαE1 and LcαE10, both members of the same α-esterase gene cluster as LcαE7. A significant R(2) value was also observed for a gene predicted to be the next closest to LcαE7, AL03, but not for any of the other genes, LcRpL13a, Lcdsx, or LcAce. Skews in the site frequency spectra toward high-frequency variants were significant for LcαE1 (Fay and Wu's H = -2.91), LcαE10 (H = -1.85), and Lcdsx (H = -2.00). Since the selective sweeps, two forms of likely returning variation were observed, including variation in microsatellites in an intron of LcαE10 and a recombination event between LcαE7 and LcαE10. These data suggest that two incomplete soft sweeps have occurred at LcαE7 that have significantly affected variation across, and beyond, the α-esterase gene cluster of L. cuprina. The speed and impact of these selective sweeps on surrounding genomic variation and the ability of L. cuprina to respond to future environmental challenges are discussed.

Translational asymmetry as a sensitive indicator of cadmium stress in plants: a laboratory test with wild-type and mutant Arabidopsis thaliana

Publisher: Wiley

Date: 20-06-2003

DOI: 10.1046/J.1469-8137.2003.00815.X

Describing the role of Drosophila melanogaster ABC transporters in insecticide biology using CRISPR-Cas9 knockouts

Publisher: Elsevier BV

Date: 12-2017

DOI: 10.1016/J.IBMB.2017.09.017

Abstract: ABC transporters have a well-established role in drug resistance, effluxing xenobiotics from cells and tissues within the organism. More recently, research has been dedicated to understanding the role insect ABC transporters play in insecticide toxicity, but progress in understanding the contribution of specific transporters has been h ered by the lack of functional genetic tools. Here, we report knockouts of three Drosophila melanogaster ABC transporter genes, Mdr49, Mdr50, and Mdr65, that are homologous to the well-studied mammalian ABCB1 (P-glycoprotein). Each knockout mutant was created in the same wild type background and tested against a panel of insecticides representing different chemical classes. Mdr65 knockouts were more susceptible to all neuroactive insecticides tested, but Mdr49 and Mdr50 knockouts showed increased susceptibility or resistance depending on the insecticide used. Mdr65 was chosen for further analysis. Calculation of LC

Author response: Low doses of the organic insecticide spinosad trigger lysosomal defects, elevated ROS, lipid dysregulation, and neurodegeneration in flies

Publisher: eLife Sciences Publications, Ltd

Date: 12-01-2022

DOI: 10.7554/ELIFE.73812.SA2

Low doses of the neonicotinoid insecticide imidacloprid induce ROS triggering neurological and metabolic impairments in Drosophila

Publisher: Proceedings of the National Academy of Sciences

Date: 28-09-2020

DOI: 10.1073/PNAS.2011828117

Abstract: Intense insecticide usage is suggested to be a significant contributor to the observed decline of insect populations around the world. Beneficial insects play essential roles in food production and ecosystem health. It is therefore vital to understand the mechanisms by which low doses of insecticide impact insect biology in order to understand and assess the threat posed. We investigated the impacts of the neonicotinoid insecticide imidacloprid on Drosophila . The binding of the insecticide to receptors in the brain triggers oxidative stress, reduces energy levels, and induces neurodegeneration as well as vision loss. As the receptors targeted by imidacloprid are conserved among insects, and other insecticides have also been shown to cause oxidative stress, these findings have wider significance.

The acetylcholinesterase gene and organophosphorus resistance in the Australian sheep blowfly, Lucilia cuprina

Publisher: Elsevier BV

Date: 06-2001

DOI: 10.1016/S0965-1748(00)00186-7

Abstract: Acetylcholinesterase (AChE), encoded by the Ace gene, is the primary target of organophosphorous (OP) and carbamate insecticides. Ace mutations have been identified in OP resistants strains of Drosophila melanogaster. However, in the Australian sheep blowfly, Lucilia cuprina, resistance in field and laboratory generated strains is determined by point mutations in the Rop-1 gene, which encodes a carboxylesterase, E3. To investigate the apparent bias for the Rop-1/E3 mechanism in the evolution of OP resistance in L. cuprina, we have cloned the Ace gene from this species and characterized its product. Southern hybridization indicates the existence of a single Ace gene in L. cuprina. The amino acid sequence of L. cuprina AChE shares 85.3% identity with D. melanogaster and 92.4% with Musca domestica AChE. Five point mutations in Ace associated with reduced sensitivity to OP insecticides have been previously detected in resistant strains of D. melanogaster. These residues are identical in susceptible strains of D. melanogaster and L. cuprina, although different codons are used. Each of the amino acid substitutions that confer OP resistance in D. melanogaster could also occur in L. cuprina by a single non-synonymous substitution. These data suggest that the resistance mechanism used in L. cuprina is determined by factors other than codon bias. The same point mutations, singly and in combination, were introduced into the Ace gene of L. cuprina by site-directed mutagenesis and the resulting AChE enzymes expressed using a baculovirus system to characterise their kinetic properties and interactions with OP insecticides. The K(m) of wild type AChE for acetylthiocholine (ASCh) is 23.13 microM and the point mutations change the affinity to the substrate. The turnover number of Lucilia AChE for ASCh was estimated to be 1.27x10(3) min(-1), similar to Drosophila or housefly AChE. The single amino acid replacements reduce the affinities of the AChE for OPs and give up to 8.7-fold OP insensitivity, while combined mutations give up to 35-fold insensitivity. However, other published studies indicate these same mutations yield higher levels of OP insensitivity in D. melanogaster and A. aegypti. The inhibition data indicate that the wild type form of AChE of L. cuprina is 12.4-fold less sensitive to OP inhibition than the susceptible form of E3, suggesting that the carboxylesterases may have a role in the protection of AChE via a sequestration mechanism. This provides a possible explanation for the bias towards the evolution of resistance via the Rop-1/E3 mechanism in L. cuprina.

Characterization of Drosophila melanogaster cytochrome P450 genes

Publisher: Proceedings of the National Academy of Sciences

Date: 07-04-2009

DOI: 10.1073/PNAS.0812141106

Abstract: Cytochrome P450s form a large and erse family of heme-containing proteins capable of carrying out many different enzymatic reactions. In both mammals and plants, some P450s are known to carry out reactions essential for processes such as hormone synthesis, while other P450s are involved in the detoxification of environmental compounds. In general, functions of insect P450s are less well understood. We characterized Drosophila melanogaster P450 expression patterns in embryos and 2 stages of third instar larvae. We identified numerous P450s expressed in the fat body, Malpighian (renal) tubules, and in distinct regions of the midgut, consistent with hypothesized roles in detoxification processes, and other P450s expressed in organs such as the gonads, corpora allata, oenocytes, hindgut, and brain. Combining expression pattern data with an RNA interference lethality screen of in idual P450s, we identify candidate P450s essential for developmental processes and distinguish them from P450s with potential functions in detoxification.

The spread of resistance to imidacloprid is restricted by thermotolerance in natural populations of Drosophila melanogaster

Publisher: Springer Science and Business Media LLC

Date: 18-03-2019

DOI: 10.1038/S41559-019-0837-Y

Abstract: Imidacloprid, the world's most used insecticide, has caused considerable controversy due to harmful effects on non-pest species and increasing evidence showing that insecticides have become the primary selective force in many insect species. The genetic response to insecticides is heterogeneous across populations and environments, leading to more complex patterns of genetic variation than previously thought. This motivated the investigation of imidacloprid resistance at different temperatures in natural populations of Drosophila melanogaster originating from four climate extremes replicated across two continents. Population and quantitative genomic analysis, supported by functional tests, have revealed a mixed genetic architecture to resistance involving major genes (Paramyosin and Nicotinic-Acetylcholine Receptor Alpha 3) and polygenes with a major trade-off with thermotolerance. Reduced genetic differentiation at resistance-associated loci indicated enhanced gene flow at these loci. Resistance alleles showed stronger evidence of positive selection in temperate populations compared to tropical populations in which chromosomal inversions In(2 L)t, In(3 R)Mo and In(3 R)Payne harbour susceptibility alleles. Polygenic architecture and ecological factors should be considered when developing sustainable management strategies for both pest and beneficial insects.

Genomic knockout of hsp23 both decreases and increases fitness under opposing thermal extremes in Drosophila melanogaster

Publisher: Elsevier BV

Date: 12-2021

DOI: 10.1016/J.IBMB.2021.103652

Abstract: Under exposure to harmful environmental stresses, organisms exhibit a general stress response involving upregulation of the expression of heat shock proteins (HSPs) which is thought to be adaptive. Small heat shock proteins (sHSPs) are key components of this response, although shsp genes may have other essential roles in development. However, the upregulation of expression of a suite of genes under stress may not necessarily be evidence of an adaptive response to stress that involves those genes. To explore this issue, we used the CRISPR/Cas9 system to investigate pleiotropic effects of the hsp23 gene in Drosophila melanogaster. Transgenic flies carrying a pCFD5 plasmid containing sgRNAs were created to generate a complete knockout of the hsp23 gene. The transgenic line lacking hsp23 showed an increased hatch rate and no major fitness costs under an intermediate temperature used for culturing the flies. In addition, hsp23 knockout affected tolerance to hot and cold temperature extremes but in opposing directions knockout flies had reduced tolerance to cold, but increased tolerance to heat. Despite this, hsp23 expression (in wild type flies) was increased under both hot and cold conditions. The hsp23 gene was required for heat hardening at the pupal stage, but not at the 1st-instar larval stage, even though the gene was upregulated in wild type controls at that life stage. The phenotypic effects of hsp23 were not compensated for by expression changes in other shsps. Our study shows that the fitness consequences of an hsp gene knockout depends on environmental conditions, with potential fitness benefits of gene loss even under conditions when the gene is normally upregulated.

Inhibiting the proteasome reduces molecular and biological impacts of the natural product insecticide, spinosad

Publisher: Wiley

Date: 05-02-2021

DOI: 10.1002/PS.6290

Abstract: Insecticide targets are often identified by mutations that confer resistance, but the intricacies of insecticide binding and downstream processes leading to insect death often remain obscure. Mutations in α6‐like nicotinic acetylcholine receptor subunit genes have been associated with high levels of resistance to spinosad in many insect species, including Drosophila melanogaster . Here, we aimed to expand our understanding of the effects of the natural product insecticide spinosad on its protein target, the α6 subunit, using genetic tools available in D. melanogaster . Functional, fluorescently tagged Dα6 subunits (Dα6 YFP ) were developed to allow observation of the protein in vivo . Larvae expressing Dα6 YFP were exposed to a sub‐lethal concentration of spinosyn A (0.025 ppm) for 6 days, leading to a 64% reduction in fluorescence relative to unexposed larvae. Direct application of high doses of spinosyn A to dissected larval brains resulted in a visible 38.25% decrease in Dα6 YFP within 20 min, indicating that degradation of the Dα6 protein occurred in response to spinosyn A exposure. Chemical inhibition of the proteasome system using the multiple myeloma treatment drug, PS‐341 reduced loss of Dα6 YFP in response to spinosyn A at the 20‐min time point to 6.35%. In addition, in vivo administration of PS‐341 prior to spinosad exposure reduced the effect of spinosad on larval activity. Based on these data, we propose that exposure to spinosad leads to degradation of the α6‐like target protein, a potentially novel element in the mode of action of spinosyns that may contribute to their toxicity towards insects. © 2021 Society of Chemical Industry

Syntaxin 5 Is Required for Copper Homeostasis in Drosophila and Mammals

Publisher: Public Library of Science (PLoS)

Date: 20-12-2010

DOI: 10.1371/JOURNAL.PONE.0014303

Ttk69-dependent repression of lozenge prevents the ectopic development of R7 cells in the Drosophila larval eye disc

Publisher: Springer Science and Business Media LLC

Date: 12-2009

DOI: 10.1186/1471-213X-9-64

Beyond barcoding: A mitochondrial genomics approach to molecular phylogenetics and diagnostics of blowflies (Diptera: Calliphoridae)

Publisher: Elsevier BV

Date: 12-2012

DOI: 10.1016/J.GENE.2012.09.103

Abstract: Members of the Calliphoridae (blowflies) are significant for medical and veterinary management, due to the ability of some species to consume living flesh as larvae, and for forensic investigations due to the ability of others to develop in corpses. Due to the difficulty of accurately identifying larval blowflies to species there is a need for DNA-based diagnostics for this family, however the widely used DNA-barcoding marker, cox1, has been shown to fail for several groups within this family. Additionally, many phylogenetic relationships within the Calliphoridae are still unresolved, particularly deeper level relationships. Sequencing whole mt genomes has been demonstrated both as an effective method for identifying the most informative diagnostic markers and for resolving phylogenetic relationships. Twenty-seven complete, or nearly so, mt genomes were sequenced representing 13 species, seven genera and four calliphorid subfamilies and a member of the related family Tachinidae. PCR and sequencing primers developed for sequencing one calliphorid species could be reused to sequence related species within the same superfamily with success rates ranging from 61% to 100%, demonstrating the speed and efficiency with which an mt genome dataset can be assembled. Comparison of molecular ergences for each of the 13 protein-coding genes and 2 ribosomal RNA genes, at a range of taxonomic scales identified novel targets for developing as diagnostic markers which were 117-200% more variable than the markers which have been used previously in calliphorids. Phylogenetic analysis of whole mt genome sequences resulted in much stronger support for family and subfamily-level relationships. The Calliphoridae are polyphyletic, with the Polleninae more closely related to the Tachinidae, and the Sarcophagidae are the sister group of the remaining calliphorids. Within the Calliphoridae, there was strong support for the monophyly of the Chrysomyinae and Luciliinae and for the sister-grouping of Luciliinae with Calliphorinae. Relationships within Chrysomya were not well resolved. Whole mt genome data, supported the previously demonstrated paraphyly of Lucilia cuprina with respect to L. sericata and allowed us to conclude that it is due to hybrid introgression prior to the last common ancestor of modern sericata populations, rather than due to recent hybridisation, nuclear pseudogenes or incomplete lineage sorting.

Evolution, Expression, and Function of Nonneuronal Ligand-Gated Chloride Channels inDrosophila melanogaster

Publisher: Oxford University Press (OUP)

Date: 07-2016

DOI: 10.1534/G3.116.029546

Abstract: Ligand-gated chloride channels have established roles in inhibitory neurotransmission in the nervous systems of vertebrates and invertebrates. Paradoxically, expression databases in Drosophila melanogaster have revealed that three uncharacterized ligand-gated chloride channel subunits, CG7589, CG6927, and CG11340, are highly expressed in nonneuronal tissues. Furthermore, subunit copy number varies between insects, with some orders containing one ortholog, whereas other lineages exhibit copy number increases. Here, we show that the Dipteran lineage has undergone two gene duplications followed by expression-based functional differentiation. We used promoter-GFP expression analysis, RNA-sequencing, and in situ hybridization to examine cell type and tissue-specific localization of the three D. melanogaster subunits. CG6927 is expressed in the nurse cells of the ovaries. CG7589 is expressed in multiple tissues including the salivary gland, ejaculatory duct, malpighian tubules, and early midgut. CG11340 is found in malpighian tubules and the copper cell region of the midgut. Overexpression of CG11340 increased sensitivity to dietary copper, and RNAi and ends-out knockout of CG11340 resulted in copper tolerance, providing evidence for a specific nonneuronal role for this subunit in D. melanogaster. Ligand-gated chloride channels are important insecticide targets and here we highlight copy number and functional ergence in insect lineages, raising the potential that order-specific receptors could be isolated within an effective class of insecticide targets.

Dissecting chill coma recovery as a measure of cold resistance:evidence for a biphasic response in Drosophila melanogaster

Publisher: Elsevier BV

Date: 08-2004

DOI: 10.1016/J.JINSPHYS.2004.05.004

Genomic innovations, transcriptional plasticity and gene loss underlying the evolution and divergence of two highly polyphagous and invasive Helicoverpa pest species

Publisher: Springer Science and Business Media LLC

Date: 31-07-2017

DOI: 10.1186/S12915-017-0402-6

Recombinant expression and characterization of Lucilia cuprina CYP6G3: Activity and binding properties toward multiple pesticides

Publisher: Elsevier BV

Date: 11-2017

DOI: 10.1016/J.IBMB.2017.09.004

Abstract: The Australian sheep blowfly, Lucilia cuprina, is a primary cause of sheep flystrike and a major agricultural pest. Cytochrome P450 enzymes have been implicated in the resistance of L. cuprina to several classes of insecticides. In particular, CYP6G3 is a L. cuprina homologue of Drosophila melanogaster CYP6G1, a P450 known to confer multi-pesticide resistance. To investigate the basis of resistance, a bicistronic Escherichia coli expression system was developed to co-express active L. cuprina CYP6G3 and house fly (Musca domestica) P450 reductase. Recombinant CYP6G3 showed activity towards the high-throughput screening substrates, 7-ethoxycoumarin and p-nitroanisole, but not towards p-nitrophenol, coumarin, 7-benzyloxyresorufin, or seven different luciferin derivatives (P450-Glo™ substrates). The addition of house fly cytochrome b

Quantitative trait symmetry independent of Hsp90 buffering:Distinct modes of genetic canalization and developmental stability

Publisher: Proceedings of the National Academy of Sciences

Date: 31-10-2003

DOI: 10.1073/PNAS.1835613100

Abstract: The Hsp90 chaperone buffers development against a wide range of morphological changes in many organisms and in Drosophila masks the effects of hidden genetic variation. Theory predicts that genetic and nongenetic buffering will share common mechanisms. For ex le, it is argued that Hsp90 genetic buffering evolved solely as a by-product of environmental buffering, and that Hsp90 should mask morphological deviations from any source. To test this idea, we examined the effect of Hsp90 on purely nongenetic variation in phenotype, measured as differences between the left and right sides of several bilaterally symmetrical bristle and wing traits in in idual flies. Consistent with previous reports, Hsp90 buffered the expression of rare morphogenic variants specific to particular genetic backgrounds. However, neither trait-by-trait nor global asymmetry was affected in outbred flies treated with an Hsp90 inhibitor or across a series of inbred genetic backgrounds from a wild population tested in isogenic F 1 heterozygotes carrying either ( i ) a dominant negative Hsp90 allele on a mutant 3rd chromosome or ( ii ) a null P -insertion mutation, which was introgressed into the control genetic background on all chromosomes. By contrast, Hsp90-regulated trait means and significant effects of sex, temperature, and genetic background on trait symmetry were clearly detected. We conclude that, by maintaining the function of signaling proteins, Hsp90 masks variation affecting target pathways and traits in populations independent of purely nongenetic sources of variation, refuting the idea that a single Hsp90-dependent process generally controls genetic canalization and developmental stability.

A comparison of Drosophila melanogaster detoxification gene induction responses for six insecticides, caffeine and phenobarbital

Publisher: Elsevier BV

Date: 12-2006

DOI: 10.1016/J.IBMB.2006.09.004

Abstract: Modifications of metabolic pathways are important in insecticide resistance evolution. Mutations leading to changes in expression levels or substrate specificities of cytochrome P450 (P450), glutathione-S-transferase (GST) and esterase genes have been linked to many cases of resistance with the responsible enzyme shown to utilize the insecticide as a substrate. Many studies show that the substrates of enzymes are capable of inducing the expression of those enzymes. We investigated if this was the case for insecticides and the enzymes responsible for their metabolism. The induction responses for P450s, GSTs and esterases to six different insecticides were investigated using a custom designed microarray in Drosophila melanogaster. Even though these gene families can all contribute to insecticide resistance, their induction responses when exposed to insecticides are minimal. The insecticides spinosad, diazinon, nitenpyram, lufenuron and dicyclanil did not induce any P450, GST or esterase gene expression after a short exposure to high lethal concentrations of insecticide. DDT elicited the low-level induction of one GST and one P450. These results are in contrast to induction responses we observed for the natural plant compound caffeine and the barbituate drug phenobarbital, both of which highly induced a number of P450 and GST genes under the same short exposure regime. Our results indicate that, under the insecticide exposure conditions we used, constitutive over-expression of metabolic genes play more of a role in insect survival than induction of members of these gene families.

Evolutionary Changes in Gene Expression, Coding Sequence and Copy-Number at the Cyp6g1 Locus Contribute to Resistance to Multiple Insecticides in Drosophila

Publisher: Public Library of Science (PLoS)

Date: 08-01-2014

DOI: 10.1371/JOURNAL.PONE.0084879

Transcriptome analysis of Drosophila melanogaster third instar larval ring glands points to novel functions and uncovers a cytochrome p450 required for development

Publisher: Oxford University Press (OUP)

Date: 02-2017

DOI: 10.1534/G3.116.037333

Abstract: In Drosophila melanogaster larvae, the ring gland (RG) is a control center that orchestrates major developmental transitions. It is a composite organ, consisting of the prothoracic gland, the corpus allatum, and the corpora cardiaca, each of which synthesizes and secretes a different hormone. Until now, the RG’s broader developmental roles beyond endocrine secretion have not been explored. RNA sequencing and analysis of a new transcriptome resource from D. melanogaster wandering third instar larval RGs has provided a fascinating insight into the ersity of developmental signaling in this organ. We have found strong enrichment of expression of two gene pathways not previously associated with the RG: immune response and fatty acid metabolism. We have also uncovered strong expression for many uncharacterized genes. Additionally, RNA interference against RG-enriched cytochrome p450s Cyp6u1 and Cyp6g2 produced a lethal ecdysone deficiency and a juvenile hormone deficiency, respectively, flagging a critical role for these genes in hormone synthesis. This transcriptome provides a valuable new resource for investigation of roles played by the RG in governing insect development.

Evolution of genes and genomes on the Drosophila phylogeny

Publisher: Springer Science and Business Media LLC

Date: 11-2007

DOI: 10.1038/NATURE06341

Copy Number Variation and Transposable Elements Feature in Recent, Ongoing Adaptation at the Cyp6g1 Locus

Publisher: Public Library of Science (PLoS)

Date: 24-06-2010

DOI: 10.1371/JOURNAL.PGEN.1000998

Erratum to: Genomic innovations, transcriptional plasticity and gene loss underlying the evolution and divergence of two highly polyphagous and invasive Helicoverpa pest species

Publisher: Springer Science and Business Media LLC

Date: 15-08-2017

DOI: 10.1186/S12915-017-0413-3

Deletion of the nicotinic acetylcholine receptor subunit gene Dα1 confers insecticide resistance, but at what cost?

Publisher: Informa UK Limited

Date: 22-11-2018

DOI: 10.1080/19336934.2017.1396399

Essential Roles in Development and Pigmentation for theDrosophilaCopper Transporter DmATP7

Publisher: American Society for Cell Biology (ASCB)

Date: 2006

DOI: 10.1091/MBC.E05-06-0492

Abstract: Defects in the mammalian Menkes and Wilson copper transporting P-type ATPases cause severe copper homeostasis disease phenotypes in humans. Here, we find that DmATP7, the sole Drosophila orthologue of the Menkes and Wilson genes, is vital for uptake of copper in vivo. Analysis of a DmATP7 loss-of-function allele shows that DmATP7 is essential in embryogenesis, early larval development, and adult pigmentation and is probably required for copper uptake from the diet. These phenotypes are analogous to those caused by mutation in the mouse and human Menkes genes, suggesting that like Menkes, DmATP7 plays at least two roles at the cellular level: delivering copper to cuproenzymes required for pigmentation and neuronal function and removing excess cellular copper via facilitated efflux. DmATP7 displays a dynamic and unexpected expression pattern in the developing embryo, implying novel functions for this copper pump and the lethality observed in DmATP7 mutant flies is the earliest seen for any copper homeostasis gene.

Smg1 Nonsense Mutations Do Not Abolish Nonsense-Mediated mRNA Decay in Drosophila melanogaster

Publisher: Oxford University Press (OUP)

Date: 09-2005

DOI: 10.1534/GENETICS.105.045674

Abstract: Smg1 is a key component of nonsense-mediated decay (NMD) in Caenorhabditis elegans and mammals. Here we report that two nonsense alleles of the ortholog of Smg1 do not affect NMD in Drosophila melanogaster.

Evidence for activation of nitenpyram by a mitochondrial cytochrome P450 in Drosophila melanogaster

Publisher: Wiley

Date: 26-02-2018

DOI: 10.1002/PS.4852

Abstract: Nitenpyram is a member of the economically important neonicotinoid class of insecticides. The in vivo metabolism of nitenpyram is not well characterised, but cytochrome P450 activity is the major mechanism of resistance to neonicotinoids identified in insect pests, and P450s metabolise other neonicotinoids including imidacloprid. Here, we used the GAL4-UAS targeted expression system to direct RNA interference (RNAi) against the cytochrome P450 redox partners to interrupt P450 functions in specific tissues in Drosophila melanogaster. RNAi of the mitochondrial redox partner defective in the avoidance of repellents (dare) in the digestive tissues reduced nitenpyram mortality, suggesting an activation step in the metabolism of nitenpyram carried out by a mitochondrial P450. RNAi of the mitochondrial cytochrome P450 Cyp12a5, which is expressed in the digestive tissues, resulted in the same phenotype, and transgenic overexpression of Cyp12a5 increased nitenpyram sensitivity. These results suggest that in vivo metabolism of nitenpyram by the mitochondrial P450 CYP12A5 results in the formation of a product with higher toxicity than the parent compound. © 2018 Society of Chemical Industry.

The Ovicidal, Larvacidal and Adulticidal Properties of 5,5′-Dimethyl-2,2′-Bipyridyl against Drosophila melanogaster

Publisher: Public Library of Science (PLoS)

Date: 20-11-2012

DOI: 10.1371/JOURNAL.PONE.0049961

Copper homoeostasis in Drosophila melanogaster S2 cells

Publisher: Portland Press Ltd.

Date: 08-10-2004

DOI: 10.1042/BJ20040745

Abstract: Copper homoeostasis was investigated in the Drosophila melanogaster S2 cell line to develop an insect model for the study of copper regulation. Real-time PCR studies have demonstrated expression in S2 cells of putative orthologues of human Cu regulatory genes involved in the uptake, transport, sequestration and efflux of Cu. Drosophila orthologues of the mammalian Cu chaperones, ATOX1 (a human orthologue of yeast ATX1), CCS (copper chaperone for superoxide dismutase), COX17 (a human orthologue of yeast COX17), and SCO1 and SCO2, did not significantly respond transcriptionally to increased Cu levels, whereas MtnA, MtnB and MtnD (Drosophila orthologues of human metallothioneins) were up-regulated by Cu in a time- and dose-dependent manner. To examine the effect on Cu homoeostasis, expression of several key copper homoeostasis genes was suppressed using double-stranded RNA interference. Suppression of the MTF-1 (metal-regulatory transcription factor 1), reduced both basal and Cu-induced gene expressions of MtnA, MtnB and MtnD, significantly reducing the tolerance of these cells to increased Cu. Suppression of either Ctr1A (a Drosophila orthologue of yeast CTR1) or Ctr1B significantly reduced Cu uptake from media, demonstrating that both these proteins function to transport Cu into S2 cells. Significantly, Cu induced Ctr1B gene expression, and this could be prevented by suppressing MTF-1, suggesting that Ctr1B might be involved in Cu detoxification. Suppression of DmATP7, the putative homologue of human Cu transporter genes ATP7A and ATP7B, significantly increased Cu accumulation, demonstrating that DmATP7 is essential for efflux of excess Cu. This work is consistent with previous studies in mammalian cells, validating S2 cells as a model system for studying Cu transport and identifying novel Cu regulatory mechanisms.

Low doses of the organic insecticide spinosad trigger lysosomal defects, ROS driven lipid dysregulation and neurodegeneration in flies

Publisher: Cold Spring Harbor Laboratory

Date: 04-02-2021

DOI: 10.1101/2021.02.03.429672

Abstract: The plight of insect populations around the world and the threats it poses to agriculture and ecosystems has thrown insecticide use into the spotlight. Spinosad is an organic insecticide, considered less harmful to beneficial insects than synthetic insecticides, but its mode of action remains unclear. Using Drosophila, we show that low doses of spinosad reduce cholinergic response in neurons by antagonizing Dα6 nAChRs. Dα6 nAChRs are transported to lysosomes that become enlarged and accumulate upon spinosad treatment. Oxidative stress is initiated in the central nervous system, and spreads to midgut and disturbs lipid storage in metabolic tissues in a Dα6-dependent manner. Spinosad toxicity was ameliorated with the antioxidant N-Acetylcysteine amide (NACA). Chronic exposures lead to mitochondrial defects, severe neurodegeneration and blindness in adult animals. The many deleterious effects of low doses of this insecticide reported here point to an urgent need for rigorous investigation of its impacts on beneficial insects.

Induction of a detoxification gene in Drosophila melanogaster requires an interaction between tissue specific enhancers and a novel cis-regulatory element

Publisher: Elsevier BV

Date: 11-2011

DOI: 10.1016/J.IBMB.2011.07.002

Abstract: Organisms induce the expression of detoxification enzymes such as cytochrome P450s to deal with xenobiotics encountered in the environment. Research using cell culture systems has identified some of the cis-regulatory elements (CREs) and transcription factors involved in the induction of P450 genes in response to xenobiotic challenges. It was recently found that the CREs required for the basal expression of some P450s are distinct from the CREs involved in their induction. How these CREs mediate induction to xenobiotics in a tissue specific manner is not known. In this paper we show that, in Drosophila melanogaster, the induction response of the P450 gene Cyp6g1 to the xenobiotic Phenobarbital (PB) requires the presence of both tissue specific enhancers and a distinct CRE. The CRE does not drive gene expression but is required for the induction response. Site-directed mutagenesis of sequences within the CRE, sequences similar to mouse PB induction sequences, reduces the level of induction by PB, suggesting some degree of mechanistic conservation between flies and mice. This CRE may represent a unique class of CREs that has no inherent role in the basal transcriptional activity of genes, but is required for induction responses. Variations within this class of CREs may explain the variability of gene induction responses.

Molecular Evolution of Glutathione S-Transferases in the Genus Drosophila

Publisher: Oxford University Press (OUP)

Date: 11-2007

DOI: 10.1534/GENETICS.107.075838

Abstract: As classical phase II detoxification enzymes, glutathione S-transferases (GSTs) have been implicated in insecticide resistance and may have evolved in response to toxins in the niche-defining feeding substrates of Drosophila species. We have annotated the GST genes of the 12 Drosophila species with recently sequenced genomes and analyzed their molecular evolution. Gene copy number variation is attributable mainly to unequal crossing-over events in the large δ and ε clusters. Within these gene clusters there are also GST genes with slowly erging orthologs. This implies that they have their own unique functions or have spatial/temporal expression patterns that impose significant selective constraints. Searches for positively selected sites within the GSTs identified G171K in GSTD1, a protein that has previously been shown to be capable of metabolizing the insecticide DDT. We find that the same radical substitution (G171K) in the substrate-binding domain has occurred at least three times in the Drosophila radiation. Homology-modeling places site 171 distant from the active site but adjacent to an alternative DDT-binding site. We propose that the parallel evolution observed at this site is an adaptive response to an environmental toxin and that sequencing of historical alleles suggests that this toxin was not a synthetic insecticide.

Characterization of a novel pesticide transporter and P-glycoprotein orthologues in Drosophila melanogaster

Publisher: The Royal Society

Date: 18-05-2022

DOI: 10.1098/RSPB.2022.0625

Abstract: Pesticides remain one of the most effective ways of controlling agricultural and public health insects, but much is still unknown regarding how these compounds reach their targets. Specifically, the role of ABC transporters in pesticide absorption and excretion is poorly understood, especially compared to the detailed knowledge about mammalian systems. Here, we present a comprehensive characterization of pesticide transporters in the model insect Drosophila melanogaster . An RNAi screen was performed, which knocked down in idual ABCs in specific epithelial tissues and examined the subsequent changes in sensitivity to the pesticides spinosad and fipronil. This implicated a novel ABC drug transporter, CG4562, in spinosad transport, but also highlighted the P-glycoprotein orthologue Mdr65 as the most impactful ABC in terms of chemoprotection. Further characterization of the P-glycoprotein family was performed via transgenic overexpression and immunolocalization, finding that Mdr49 and Mdr50 play enigmatic roles in pesticide toxicology perhaps determined by their different subcellular localizations within the midgut. Lastly, transgenic Drosophila lines expressing P-glycoprotein from the major malaria vector Anopheles gambiae were used to establish a system for in vivo characterization of this transporter in non-model insects. This study provides the basis for establishing Drosophila as a model for toxicology research on drug transporters.

Recognition and Detoxification of the Insecticide DDT by Drosophila melanogaster Glutathione S-Transferase D1

Publisher: Elsevier BV

Date: 06-2010

DOI: 10.1016/J.JMB.2010.04.020

Abstract: GSTD1 is one of several insect glutathione S-transferases capable of metabolizing the insecticide DDT. Here we use crystallography and NMR to elucidate the binding of DDT and glutathione to GSTD1. The crystal structure of Drosophila melanogaster GSTD1 has been determined to 1.1 A resolution, which reveals that the enzyme adopts the canonical GST fold but with a partially occluded active site caused by the packing of a C-terminal helix against one wall of the binding site for substrates. This helix would need to unwind or be displaced to enable catalysis. When the C-terminal helix is removed from the model of the crystal structure, DDT can be computationally docked into the active site in an orientation favoring catalysis. Two-dimensional (1)H,(15)N heteronuclear single-quantum coherence NMR experiments of GSTD1 indicate that conformational changes occur upon glutathione and DDT binding and the residues that broaden upon DDT binding support the predicted binding site. We also show that the ancestral GSTD1 is likely to have possessed DDT dehydrochlorinase activity because both GSTD1 from D. melanogaster and its sibling species, Drosophila simulans, have this activity.

The Molecular Evolution of Cytochrome P450 Genes within and between Drosophila Species

Publisher: Oxford University Press (OUP)

Date: 20-04-2014

DOI: 10.1093/GBE/EVU083

Evaluating the insecticide resistance potential of eight Drosophila melanogaster cytochrome P450 genes by transgenic over-expression

Publisher: Elsevier BV

Date: 05-2007

DOI: 10.1016/J.IBMB.2007.02.008

Abstract: In Drosophila melanogaster, the increased expression of Cyp6g1 results in resistance to chemically unrelated insecticides including DDT, neonicotinoids and insect growth regulator insecticides. To determine the insecticide resistance capacity of other D. melanogaster cytochrome P450s, we used the GAL4/UAS system to express in idual P450s in the midgut, Malpighian tubules and fat body of transgenic flies. Drosophila over-expressing Cyp6g1, Cyp6g2, Cyp6t3, Cyp6a2, Cyp6a8, Cyp6a19, Cyp6a23 and Cyp12d1 were screened for resistance to four insecticides--DDT, nitenpyram, dicyclanil and diazinon. Increased survival on insecticides is detected for Cyp6g1 (DDT, nitenpyram and dicyclanil), Cyp6g2 (nitenpyram and diazinon) and Cyp12d1 (DDT and dicyclanil) over-expression lines. No increased survival on any insecticide was detected for flies over-expressing either Cyp6a2, Cyp6a8, Cyp6t3, Cyp6a19 or Cyp6a23.

The Wiggle Index: An Open Source Bioassay to Assess Sub-Lethal Insecticide Response in Drosophila melanogaster

Publisher: Public Library of Science (PLoS)

Date: 18-12-2015

DOI: 10.1371/JOURNAL.PONE.0145051

Effect of E (sev) andSu (Raf) Hsp83 mutants and trans-heterozygotes on bristle trait means and variation in Drosophila melanogaster

Publisher: Oxford University Press (OUP)

Date: 09-2005

DOI: 10.1534/GENETICS.104.038463

Abstract: The Hsp90 protein encoded by the Hsp83 gene is required for the development of many traits in Drosophila. Hsp83 is also thought to play a role in the expression of phenotypic and genetic variability for subsequent selection and evolutionary change. Here we examine the impact of different E(sev) and Su(Raf) Hsp83 mutants on means and phenotypic variances of invariant and variable bristle traits. One of the mutants influenced the normally invariant thoracic bristle number, while none affected invariant scutellar bristle number. E(sev) alleles consistently influenced variable bristle traits while there were fewer effects of the Su(Raf) alleles. For the variable traits, none of the Hsp83 alleles had any effect on phenotypic variance, environmental variance, or developmental stability of the bristle traits. When alleles were combined in trans-heterozygotes, there were both cumulative and complementary effects on thoracic and variable bristle trait numbers, depending on the allelic combination. Overall, the results suggest that Hsp83 mutants do not have detectable effects on the phenotypic or environmental variance of bristle traits and that complementation of E(sev) and Su(Raf) Hsp83 mutants can extend to thoracic bristles as well as previously reported effects on viability. Some allelic combinations lead to more severe effects on variable bristle trait means than do single Hsp83 mutations.

Low doses of the organic insecticide spinosad trigger lysosomal defects, elevated ROS, lipid dysregulation, and neurodegeneration in flies

Publisher: eLife Sciences Publications, Ltd

Date: 22-02-2022

DOI: 10.7554/ELIFE.73812

Abstract: Large-scale insecticide application is a primary weapon in the control of insect pests in agriculture. However, a growing body of evidence indicates that it is contributing to the global decline in population sizes of many beneficial insect species. Spinosad emerged as an organic alternative to synthetic insecticides and is considered less harmful to beneficial insects, yet its mode of action remains unclear. Using Drosophila , we show that low doses of spinosad antagonize its neuronal target, the nicotinic acetylcholine receptor subunit alpha 6 (nAChRα6), reducing the cholinergic response. We show that the nAChRα6 receptors are transported to lysosomes that become enlarged and increase in number upon low doses of spinosad treatment. Lysosomal dysfunction is associated with mitochondrial stress and elevated levels of reactive oxygen species (ROS) in the central nervous system where nAChRα6 is broadly expressed. ROS disturb lipid storage in metabolic tissues in an nAChRα6-dependent manner. Spinosad toxicity is ameliorated with the antioxidant N-acetylcysteine amide. Chronic exposure of adult virgin females to low doses of spinosad leads to mitochondrial defects, severe neurodegeneration, and blindness. These deleterious effects of low-dose exposures warrant rigorous investigation of its impacts on beneficial insects.

Loss of the Dβ1 nicotinic acetylcholine receptor subunit disrupts bursicon-driven wing expansion and diminishes adult viability in Drosophila melanogaster

Publisher: Oxford University Press (OUP)

Date: 13-07-2021

DOI: 10.1093/GENETICS/IYAB112

Abstract: Cholinergic signaling dominates the insect central nervous system, contributing to numerous fundamental pathways and behavioral circuits. However, we are only just beginning to uncover the erse roles different cholinergic receptors may play. Historically, insect nicotinic acetylcholine receptors have received attention due to several subunits being key insecticide targets. More recently, there has been a focus on teasing apart the roles of these receptors, and their constituent subunits, in native signaling pathways. In this study, we use CRISPR-Cas9 genome editing to generate germline and somatic deletions of the Dβ1 nicotinic acetylcholine receptor subunit and investigate the consequences of loss of function in Drosophila melanogaster. Severe impacts on movement, male courtship, longevity, and wing expansion were found. Loss of Dβ1 was also associated with a reduction in transcript levels for the wing expansion hormone bursicon. Neuron-specific somatic deletion of Dβ1 in bursicon-producing neurons (CCAP-GAL4) was sufficient to disrupt wing expansion. Furthermore, CCAP-GAL4-specific expression of Dβ1 in a germline deletion background was sufficient to rescue the wing phenotype, pinpointing CCAP neurons as the neuronal subset requiring Dβ1 for the wing expansion pathway. Dβ1 is a known target of multiple commercially important insecticides, and the fitness costs exposed here explain why field-isolated target-site resistance has only been reported for amino acid replacements and not loss of function. This work reveals the importance of Dβ1-containing nicotinic acetylcholine receptors in CCAP neurons for robust bursicon-driven wing expansion.

Partitioning the roles of CYP6G1 and gut microbes in the metabolism of the insecticide imidacloprid in Drosophila melanogaster

Publisher: Springer Science and Business Media LLC

Date: 12-09-2017

DOI: 10.1038/S41598-017-09800-2

Abstract: Resistance to insecticides through enhanced metabolism is a worldwide problem. The Cyp6g1 gene of the vinegar fly, Drosophila melanogaster , is a paradigm for the study of metabolic resistance. Constitutive overexpression of this gene confers resistance to several classes of insecticides, including the neonicotinoid imidacloprid (IMI). The metabolism of IMI in this species has been previously shown to yield oxidative and nitro-reduced metabolites. While levels of the oxidative metabolites are correlated with CYP6G1 expression, nitro-reduced metabolites are not, raising the question of how these metabolites are produced. Some IMI metabolites are known to be toxic, making their fate within the insect a second question of interest. These questions have been addressed by coupling the genetic tools of gene overexpression and CRISPR gene knock-out with the mass spectrometric technique, the Twin-Ion Method (TIM). Analysing axenic larvae indicated that microbes living within D . melanogaster are largely responsible for the production of the nitro-reduced metabolites. Knock-out of Cyp6g1 revealed functional redundancy, with some metabolites produced by CYP6G1 still detected. IMI metabolism was shown to produce toxic products that are not further metabolized but readily excreted, even when produced in the Central Nervous System (CNS), highlighting the significance of transport and excretion in metabolic resistance.

Dissecting the Insect Metabolic Machinery Using Twin Ion Mass Spectrometry: A Single P450 Enzyme Metabolizing the Insecticide Imidacloprid in Vivo

Publisher: American Chemical Society (ACS)

Date: 11-03-2014

DOI: 10.1021/AC404188G

Abstract: Insecticide resistance is one of the most prevalent ex les of anthropogenic genetic change, yet our understanding of metabolic-based resistance remains limited by the analytical challenges associated with rapidly tracking the in vivo metabolites of insecticides at nonlethal doses. Here, using twin ion mass spectrometry analysis of the extracts of whole Drosophila larvae and excreta, we show that (i) eight metabolites of the neonicotinoid insecticide, imidacloprid, can be detected when formed by susceptible larval genotypes and (ii) the specific overtranscription of a single gene product, Cyp6g1, associated with the metabolic resistance to neonicotinoids, results in a significant increase in the formation of three imidacloprid metabolites that are formed in C-H bond activation reactions that is, Cyp6g1 is directly linked to the enhanced metabolism of imidacloprid in vivo. These results establish a rapid and sensitive method for dissecting the metabolic machinery of insects by directly linking single gene products to insecticide metabolism.

Pleiotropic Effects of Loss of the Dα1 Subunit in Drosophila melanogaster: Implications for Insecticide Resistance

Publisher: Oxford University Press (OUP)

Date: 2017

DOI: 10.1534/GENETICS.116.195750

Abstract: Nicotinic acetylcholine receptors (nAChRs) are a highly conserved gene family that form pentameric receptors involved in fast excitatory synaptic neurotransmission. The specific roles in idual nAChR subunits perform in Drosophila melanogaster and other insects are relatively uncharacterized. Of the 10 D. melanogaster nAChR subunits, only three have described roles in behavioral pathways Dα3 and Dα4 in sleep, and Dα7 in the escape response. Other subunits have been associated with resistance to several classes of insecticides. In particular, our previous work has demonstrated that an allele of the Dα1 subunit is associated with resistance to neonicotinoid insecticides. We used ends-out gene targeting to create a knockout of the Dα1 gene to facilitate phenotypic analysis in a controlled genetic background. To our knowledge, this is the first report of a native function for any nAChR subunits known to be targeted by insecticides. Loss of Dα1 function was associated with changes in courtship, sleep, longevity, and insecticide resistance. While acetylcholine signaling had previously been linked with mating behavior and reproduction in D. melanogaster, no specific nAChR subunit had been directly implicated. The role of Dα1 in a number of behavioral phenotypes highlights the importance of understanding the biological roles of nAChRs and points to the fitness cost that may be associated with neonicotinoid resistance.

Cyp12a4 confers lufenuron resistance in a natural population of Drosophila melanogaster

Publisher: Proceedings of the National Academy of Sciences

Date: 24-08-2005

DOI: 10.1073/PNAS.0503709102

Abstract: Lufenuron is an insect growth regulator insecticide mainly used for the control of the cat flea. To understand mechanisms of resistance to lufenuron, we have characterized lufenuron resistance in a natural population of Drosophila melanogaster . In this study we have used precise genetic mapping to identify a mechanism of lufenuron resistance: the overexpression of the cytochrome P450 gene Cyp12a4. Cyp12a4 is predicted to encode a mitochondrial cytochrome P450 enzyme. Expression of Cyp12a4 in D. melanogaster third-instar larvae was detected in the midgut and Malpighian tubules of both lufenuron-resistant and wild-type strains. The level of Cyp12a4 expression in the midgut is higher in the lufenuron-resistant strain than in wild-type strains. Driving the expression of Cyp12a4 in the midgut and Malpighian tubules by using the GAL4/UAS gene expression system results in lufenuron resistance, but it does not result in resistance to three other insecticide classes. Transgenic expression of Cyp12a4 in a ubiquitous expression pattern results in late embryonic lethality, suggesting that high-level ectopic expression of Cyp12a4 is detrimental to development.

Discovery Projects - Grant ID: DP130102415

Start Date: 2013

End Date: 12-2016

Amount: $420,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP1095295

Start Date: 2010

End Date: 12-2013

Amount: $315,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP100100825

Start Date: 09-2010

End Date: 09-2013

Amount: $520,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0986107

Start Date: 2009

End Date: 12-2011

Amount: $380,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP0884047

Start Date: 04-2009

End Date: 07-2012

Amount: $280,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP200101635

Start Date: 02-2020

End Date: 12-2023

Amount: $578,043.00

Funder: Australian Research Council

Linkage - CSIRO - Grant ID: LC0348524

Start Date: 10-2003

End Date: 10-2006

Amount: $193,035.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP160100333

Start Date: 2016

End Date: 12-2018

Amount: $369,600.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0557497

Start Date: 2005

End Date: 12-2008

Amount: $280,000.00

Funder: Australian Research Council