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1.
BMC Genomics ; 22(1): 639, 2021 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-34479486

RESUMO

BACKGROUND: Resistance of pest insect species to insecticides, including B. thuringiensis (Bt) pesticidal proteins expressed by transgenic plants, is a threat to global food security. Despite the western corn rootworm, Diabrotica virgifera virgifera, being a major pest of maize and having populations showing increasing levels of resistance to hybrids expressing Bt pesticidal proteins, the cell mechanisms leading to mortality are not fully understood. RESULTS: Twenty unique RNA-seq libraries from the Bt susceptible D. v. virgifera inbred line Ped12, representing all growth stages and a range of different adult and larval exposures, were assembled into a reference transcriptome. Ten-day exposures of Ped12 larvae to transgenic Bt Cry3Bb1 and Gpp34/Tpp35Ab1 maize roots showed significant differential expression of 1055 and 1374 transcripts, respectively, compared to cohorts on non-Bt maize. Among these, 696 were differentially expressed in both Cry3Bb1 and Gpp34/Tpp35Ab1 maize exposures. Differentially-expressed transcripts encoded protein domains putatively involved in detoxification, metabolism, binding, and transport, were, in part, shared among transcripts that changed significantly following exposures to the entomopathogens Heterorhabditis bacteriophora and Metarhizium anisopliae. Differentially expressed transcripts in common between Bt and entomopathogen treatments encode proteins in general stress response pathways, including putative Bt binding receptors from the ATP binding cassette transporter superfamily. Putative caspases, pro- and anti-apoptotic factors, as well as endoplasmic reticulum (ER) stress-response factors were identified among transcripts uniquely up-regulated following exposure to either Bt protein. CONCLUSIONS: Our study suggests that the up-regulation of genes involved in ER stress management and apoptotic progression may be important in determining cell fate following exposure of susceptible D. v. virgifera larvae to Bt maize roots. This study provides novel insights into insect response to Bt intoxication, and a possible framework for future investigations of resistance mechanisms.


Assuntos
Bacillus thuringiensis , Besouros , Praguicidas , Animais , Bacillus thuringiensis/genética , Sobrevivência Celular , Besouros/genética , Endotoxinas/toxicidade , Resistência a Inseticidas , Larva/genética , Controle Biológico de Vetores , Plantas Geneticamente Modificadas/genética , Regulação para Cima , Zea mays/genética
2.
Insects ; 12(7)2021 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-34357286

RESUMO

The phylum Arthropoda includes species crucial for ecosystem stability, soil health, crop production, and others that present obstacles to crop and animal agriculture. The United States Department of Agriculture's Agricultural Research Service initiated the Ag100Pest Initiative to generate reference genome assemblies of arthropods that are (or may become) pests to agricultural production and global food security. We describe the project goals, process, status, and future. The first three years of the project were focused on species selection, specimen collection, and the construction of lab and bioinformatics pipelines for the efficient production of assemblies at scale. Contig-level assemblies of 47 species are presented, all of which were generated from single specimens. Lessons learned and optimizations leading to the current pipeline are discussed. The project name implies a target of 100 species, but the efficiencies gained during the project have supported an expansion of the original goal and a total of 158 species are currently in the pipeline. We anticipate that the processes described in the paper will help other arthropod research groups or other consortia considering genome assembly at scale.

3.
Nat Commun ; 12(1): 2818, 2021 05 14.
Artigo em Inglês | MEDLINE | ID: mdl-33990556

RESUMO

The sex pheromone system of ~160,000 moth species acts as a powerful form of assortative mating whereby females attract conspecific males with a species-specific blend of volatile compounds. Understanding how female pheromone production and male preference coevolve to produce this diversity requires knowledge of the genes underlying change in both traits. In the European corn borer moth, pheromone blend variation is controlled by two alleles of an autosomal fatty-acyl reductase gene expressed in the female pheromone gland (pgFAR). Here we show that asymmetric male preference is controlled by cis-acting variation in a sex-linked transcription factor expressed in the developing male antenna, bric à brac (bab). A genome-wide association study of preference using pheromone-trapped males implicates variation in the 293 kb bab intron 1, rather than the coding sequence. Linkage disequilibrium between bab intron 1 and pgFAR further validates bab as the preference locus, and demonstrates that the two genes interact to contribute to assortative mating. Thus, lack of physical linkage is not a constraint for coevolutionary divergence of female pheromone production and male behavioral response genes, in contrast to what is often predicted by evolutionary theory.


Assuntos
Genes de Insetos , Mariposas/genética , Mariposas/fisiologia , Atrativos Sexuais/genética , Atrativos Sexuais/fisiologia , Aldeído Oxirredutases/genética , Aldeído Oxirredutases/metabolismo , Alelos , Animais , Evolução Molecular , Feminino , Regulação da Expressão Gênica , Estudo de Associação Genômica Ampla , Endogamia , Proteínas de Insetos/genética , Proteínas de Insetos/metabolismo , Desequilíbrio de Ligação , Masculino , Preferência de Acasalamento Animal/fisiologia , Polimorfismo Genético , Locos de Características Quantitativas , Recombinação Genética , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo
4.
Viruses ; 13(2)2021 02 09.
Artigo em Inglês | MEDLINE | ID: mdl-33572446

RESUMO

Analysis of pooled genomic short read sequence data revealed the presence of nudivirus-derived sequences from U.S. populations of both southern corn rootworm (SCR, Diabrotica undecimpunctata howardi Barber) and western corn rootworm (WCR, Diabrotica virgifera virgifera LeConte). A near complete nudivirus genome sequence was assembled from sequence data for an SCR population with relatively high viral titers. A total of 147,179 bp was assembled from five contigs that collectively encode 109 putative open reading frames (ORFs) including 20 nudivirus core genes. In contrast, genome sequence recovery was incomplete for a second nudivirus from WCR, although sequences derived from this virus were present in three geographically dispersed populations. Only 48,989 bp were assembled with 48 putative ORFs including 13 core genes, representing about 20% of a typical nudivirus genome. Phylogenetic analysis indicated that both corn rootworm nudiviruses grouped with the third known nudivirus of beetles, Oryctes rhinoceros nudivirus in the genus Alphanudivirus. On the basis of phylogenetic and additional analyses, we propose further taxonomic separation of nudiviruses within Alphanudivirus and Betanudivirus into two subfamilies and five genera. Identification of nudivirus-derived sequences from two species of corn rootworm highlights the diversity of viruses associated with these agricultural insect pests.


Assuntos
Besouros/virologia , Nudiviridae/genética , Animais , Besouros/classificação , DNA Viral/genética , Genes Virais , Genoma Viral/genética , Genômica , Nudiviridae/classificação , Fases de Leitura Aberta , Filogenia , Viroma/genética
5.
Sci Rep ; 10(1): 19123, 2020 11 05.
Artigo em Inglês | MEDLINE | ID: mdl-33154458

RESUMO

Although mitochondrial DNA (mtDNA) haplotype variation is often applied for estimating population dynamics and phylogenetic relationships, economical and generalized methods for entire mtDNA genome enrichment prior to high-throughput sequencing are not readily available. This study demonstrates the utility of differential centrifugation to enrich for mitochondrion within cell extracts prior to DNA extraction, short-read sequencing, and assembly using exemplars from eight maternal lineages of the insect species, Ostrinia nubilalis. Compared to controls, enriched extracts showed a significant mean increase of 48.2- and 86.1-fold in mtDNA based on quantitative PCR, and proportion of subsequent short sequence reads that aligned to the O. nubilalis reference mitochondrial genome, respectively. Compared to the reference genome, our de novo assembled O. nubilalis mitochondrial genomes contained 82 intraspecific substitution and insertion/deletion mutations, and provided evidence for correction of mis-annotated 28 C-terminal residues within the NADH dehydrogenase subunit 4. Comparison to a more recent O. nubilalis mtDNA assembly from unenriched short-read data analogously showed 77 variant sites. Twenty-eight variant positions, and a triplet ATT codon (Ile) insertion within ATP synthase subunit 8, were unique within our assemblies. This study provides a generalizable pipeline for whole mitochondrial genome sequence acquisition adaptable to applications across a range of taxa.


Assuntos
DNA Mitocondrial/genética , Variação Genética , Genoma Mitocondrial , Mitocôndrias/genética , Animais , Mariposas/genética , Sequenciamento Completo do Genoma
6.
Sci Rep ; 10(1): 14394, 2020 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-32873850

RESUMO

The role of miRNAs in mediating insecticide resistance remains largely unknown, even for the model species Drosophila melanogaster. Building on prior research, this study used microinjection of synthetic miR-310s mimics into DDT-resistant 91-R flies and observed both a significant transcriptional repression of computationally-predicted endogenous target P450 detoxification genes, Cyp6g1 and Cyp6g2, and also a concomitant increase in DDT susceptibility. Additionally, co-transfection of D. melanogaster S2 cells with dual luciferase reporter constructs validated predictions that miR-310s bind to target binding sites in the 3' untranslated regions (3'-UTR) of both Cyp6g1 and Cyp6g2 in vitro. Findings in the current study provide empirical evidence for a link between reduced miRNA expression and an insecticidal resistance phenotype through reduced targeted post-transcriptional suppression of transcripts encoding proteins involved in xenobiotic detoxification. These insights are important for understanding the breadth of adaptive molecular changes that have contributed to the evolution of DDT resistance in D. melanogaster.


Assuntos
Sistema Enzimático do Citocromo P-450/genética , DDT/farmacologia , Proteínas de Drosophila/genética , Drosophila melanogaster/efeitos dos fármacos , Inseticidas/farmacologia , MicroRNAs/farmacologia , Processamento de Proteína Pós-Traducional/efeitos dos fármacos , Regiões 3' não Traduzidas , Animais , Sítios de Ligação , Sistema Enzimático do Citocromo P-450/metabolismo , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/genética , Evolução Molecular , Regulação da Expressão Gênica/efeitos dos fármacos , Resistência a Inseticidas , MicroRNAs/metabolismo , Fenótipo
7.
J Econ Entomol ; 113(5): 2465-2472, 2020 10 16.
Artigo em Inglês | MEDLINE | ID: mdl-32740653

RESUMO

The western bean cutworm (WBC), Striacosta albicosta (Lepidoptera: Noctuidae), can be a severe pest of transgenic corn in the western Plains and Great Lakes regions of North America, including on hybrids expressing the Bacillus thuringiensis (Bt) Cry1F toxin. The level and geographic distribution of Cry1F resistance are not completely known. Neonate S. albicosta from 10 locations between Nebraska and New York state were subjected to dose-response trypsin-activated native Cry1F toxin overlay bioassays. In 2017, the mean estimated lethal concentration causing 50% larval mortality (LC50) ranged from 15.1 to 18.4 µg Cry1F cm-2, and were not significantly different among locations. In 2018, LC50 estimates at Scottsbluff, NE (22.0 µg Cry1F cm-2) and Watertown, NY (21.7 µg Cry1F cm-2) were significantly higher when compared to locations in Michigan (15.8 µg Cry1F cm-2). Significantly lower 14-day larval weight among survivors was correlated with higher Cry1F dose. Results from this study indicate that S. albicosta survivorship on purified Bt Cry1F toxin shows a relatively even distribution across the native and range expansion areas where seasonal field infestations typically occur.


Assuntos
Bacillus thuringiensis , Mariposas , Animais , Bacillus thuringiensis/genética , Proteínas de Bactérias/genética , Endotoxinas , Great Lakes Region , Proteínas Hemolisinas/genética , Larva , Michigan , Nebraska , New York , América do Norte , Plantas Geneticamente Modificadas , Estados Unidos , Zea mays/genética
8.
Insect Biochem Mol Biol ; 123: 103405, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32534986

RESUMO

Sequence analysis of the genomic DNA isolated from four biotypes of the soybean aphid, Aphis glycines (AG), revealed that in addition to the commonly observed retrovirus-related retrotransposons, viral sequences derived from multiple RNA and DNA viruses have integrated into the genome. Notably, sequences of more than 60 nudiviral genes were identified from de novo assembled DNA contigs, and mapped to assembled genomic scaffolds of AG, indicating that an ancient nudivirus, named Aphis glycines endogenous nudivirus (AgENV), had integrated into the AG genome. Furthermore, sequences derived from a similar endogenous nudivirus, Melanaphis sacchari endogenous nudivirus (MsENV), were identified from the genomic scaffolds of the sugarcane aphid, Melanaphis sacchari. Analysis of transcriptome and small RNA sequence data derived from AG did not provide evidence for transcription of the integrated AgENV genes. Hence, the genes of AgENV may be present as pseudogenes. Phylogenetic analysis based on nudivirus core genes indicated that these aphid ENVs belong to the genus Alphanudivirus.


Assuntos
Afídeos/genética , Elementos de DNA Transponíveis/genética , Nudiviridae/genética , Animais , Genes Virais , Genoma de Inseto , Filogenia , Pseudogenes , Soja
9.
Insect Biochem Mol Biol ; 124: 103364, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32360957

RESUMO

Multiple biotypes of soybean aphid, Aphis glycines, occur in North America adapted for survival (virulence) on soybean, Glycine max, with one or more different resistance to A. glycines (Rag) traits. The degree of genome-wide variance between biotypes and the basis of virulence remains unknown, but the latter is hypothesized to involve secreted effector proteins. Between 167,249 and 217,750 single nucleotide polymorphisms (SNPs) were predicted from whole genome re-sequencing of A. glycines avirulent biotype 1 (B1) and virulent B2, B3 and B4 colony-derived iso-female lines when compared to the draft B1 genome assembly, Ag_bt1_v6.0. Differences in nucleotide diversity indices (π) estimated within 1000 bp sliding windows demonstrated that 226 of 353 (64.0%) regions most differentiated between B1 and ≥ 2 virulent biotypes, representing < 0.1% of the 308 Mb assembled genome size, are located on 15 unordered scaffolds. Furthermore, these 226 intervals were coincident and show a significant association with 326 of 508 SNPs with significant locus-by-locus FST estimates between biotype populations (r = 0.6271; F1,70 = 45.36, P < 0.001) and genes showing evidence of directions selection (πN/πS > 2.0; r = 0.6233; F1,70 = 50.20, P < 0.001). A putative secreted effector glycoprotein is encoded in proximity to genome intervals of low estimated π (putative selective sweep) within avirulent B1 compared to all three virulent biotypes. Additionally, SNPs are clustered in or in proximity to genes putatively involved in intracellular protein cargo transport and the regulation of secretion. Results of this study indicate that factors on a small number of scaffolds of the A. glycines genome may contribute to variance in virulence towards Rag traits in G. max.


Assuntos
Afídeos/genética , Defesa das Plantas contra Herbivoria/genética , Soja/genética , Virulência/genética , Animais , Afídeos/patogenicidade , Evolução Biológica , Genes de Plantas , Genoma de Inseto , Genômica/métodos , Herbivoria , Controle de Pragas , Plantas , Sequenciamento Completo do Genoma
10.
Insect Biochem Mol Biol ; 123: 102917, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-28119199

RESUMO

Aphids are emerging as model organisms for both basic and applied research. Of the 5,000 estimated species, only three aphids have published whole genome sequences: the pea aphid Acyrthosiphon pisum, the Russian wheat aphid, Diuraphis noxia, and the green peach aphid, Myzus persicae. We present the whole genome sequence of a fourth aphid, the soybean aphid (Aphis glycines), which is an extreme specialist and an important invasive pest of soybean (Glycine max). The availability of genomic resources is important to establish effective and sustainable pest control, as well as to expand our understanding of aphid evolution. We generated a 302.9 Mbp draft genome assembly for Ap. glycines using a hybrid sequencing approach. This assembly shows high completeness with 19,182 predicted genes, 92% of known Ap. glycines transcripts mapping to contigs, and substantial continuity with a scaffold N50 of 174,505 bp. The assembly represents 95.5% of the predicted genome size of 317.1 Mbp based on flow cytometry. Ap. glycines contains the smallest known aphid genome to date, based on updated genome sizes for 19 aphid species. The repetitive DNA content of the Ap. glycines genome assembly (81.6 Mbp or 26.94% of the 302.9 Mbp assembly) shows a reduction in the number of classified transposable elements compared to Ac. pisum, and likely contributes to the small estimated genome size. We include comparative analyses of gene families related to host-specificity (cytochrome P450's and effectors), which may be important in Ap. glycines evolution. This Ap. glycines draft genome sequence will provide a resource for the study of aphid genome evolution, their interaction with host plants, and candidate genes for novel insect control methods.


Assuntos
Afídeos/genética , Genoma de Inseto , Animais , Evolução Biológica , Sistema Enzimático do Citocromo P-450/genética , Elementos de DNA Transponíveis/genética , Tamanho do Genoma , Genômica , Controle de Pragas , Filogenia , Soja
11.
Curr Biol ; 29(20): 3501-3509.e5, 2019 10 21.
Artigo em Inglês | MEDLINE | ID: mdl-31607536

RESUMO

Synchronizing the annual timing of physiological, morphological, and behavioral transitions with seasons enables survival in temperate environments [1]. The capacity to adjust life history timing and track local seasonal cycles can facilitate geographic expansion [2], adaptation [3], and tolerance [4-6] during rapid environmental change. Understanding the proximate causes of variation in seasonal timing improves prediction of future response and persistence [7, 8]. However, relatively little is known about the molecular basis generating this diversity [9], particularly in Lepidoptera, a group with many species in decline [10, 11]. In insects, the stress-tolerant physiological state of diapause enables coping with seasonal challenges [1, 12-15]. Seasonal changes in photoperiod and temperature are used to synchronize diapause with winter, and timing of diapause transitions varies widely within and among species [9, 16]. Changes in spring diapause termination in the European corn borer moth (Ostrinia nubilalis) have allowed populations to respond to shorter winters and emerge ∼3 weeks earlier in the year [17]. Multiple whole-genome approaches suggest two circadian clock genes, period (per) and pigment-dispersing factor receptor (Pdfr), underlie this polymorphism. Per and Pdfr are within interacting quantitative trait loci (QTL) and differ in allele frequency among individuals that end diapause early or late, with alleles maintained in high linkage disequilibrium. Our results provide testable hypotheses about the physiological role of circadian clock genes in the circannual timer. We predict these gene candidates will be targets of selection for future adaptation under continued global climate change [18].


Assuntos
Genoma de Inseto/fisiologia , Mariposas/genética , Animais , Genômica , Ritmo Infradiano/genética , Fatores de Tempo
12.
Mol Ecol ; 28(19): 4439-4452, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31495004

RESUMO

Patterns of mating for the European corn borer (Ostrinia nubilalis) moth depend in part on variation in sex-pheromone blend. The ratio of (E)-11- and (Z)-11-tetradecenyl acetate (E11- and Z11-14:OAc) in the pheromone blend that females produce and males respond to differs between strains of O. nubilalis. Populations also vary in female oviposition preference for and larval performance on maize (C4) and nonmaize (C3) host plants. The relative contributions of sexual and ecological trait variation to the genetic structure of O. nubilalis remains unknown. Host-plant use (13 C/14 C ratios) and genetic differentiation were estimated among sympatric E and Z pheromone strain O. nubilalis males collected in sex-pheromone baited traps at 12 locations in Pennsylvania and New York between 2007 and 2010. Among genotypes at 65 single nucleotide polymorphism marker loci, variance at a position in the pheromone gland fatty acyl-reductase (pgfar) gene at the locus responsible for determining female pheromone ratio (Pher) explained 64% of the total genetic differentiation between males attracted to different pheromones (male response, Resp), providing evidence of sexual inter-selection at these unlinked loci. Principal coordinate, Bayesian clustering, and distance-based redundancy analysis (dbRDA) demonstrate that host plant history or geography does not significantly contribute to population variation or differentiation among males. In contrast, these analyses indicate that pheromone response and pgfar-defined strain contribute significantly to population genetic differentiation. This study suggests that behavioural divergence probably plays a larger role in driving genetic variation compared to host plant-defined ecological adaptation.


Assuntos
Genética Populacional , Genômica , Mariposas/genética , Atrativos Sexuais , Zea mays/parasitologia , Animais , Ecologia , Feminino , Geografia , Interações Hospedeiro-Parasita , Masculino , Mariposas/fisiologia , New York , Oviposição , Pennsylvania , Reprodução , Simpatria
13.
Pestic Biochem Physiol ; 159: 136-143, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31400775

RESUMO

Cytochrome P450s are part of a super-gene family that has undergone gene duplication, divergence, over-expression and, in some cases, loss of function. One such case is the 91-R and 91-C strains of common origin, in Drosophila melanogaster, whereby 91-R (DDT resistant strain) overexpresses Cyp4p1 and Cyp4p2 and both genes are lost in 91-C (DDT susceptible strain). In this study, we used a comparative approach to demonstrate that transcription of Cyp4p1 and Cyp4p2 were constitutively up-regulated in the Drosophila melanogaster strain 91-R as compared to another DDT susceptible strain Canton-S which does not have a loss of function of these genes. Furthermore, significantly increased expression of Cyp4p1 and Cyp4p2 was induced in 91-R in response to sublethal DDT exposure, however, such induction did not occur in the DDT treated Canton-S. Additionally, fixed nucleotide variation within putative transcription factor binding sites of Cyp4p1 and Cyp4p2 promoters were observed between 91-R and Canton-S, however, their impact on transcription remains to be determined. Two GAL4/UAS transgenic strains with integrated heat shock-inducible Cyp4p1- or Cyp4p2-RNAi constructs within wild-type genetic backgrounds were developed. Following heat shock induction of Cyp4p1 and Cyp4p2 knockdown, these transgenic lines showed increased DDT mortality as compared to their corresponding non-heat shock controls. These results provide a functional link of Cyp4p1 and Cyp4p2 in conferring tolerance to DDT exposure.


Assuntos
DDT/farmacologia , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/efeitos dos fármacos , Drosophila melanogaster/metabolismo , Inseticidas/farmacologia , Animais , Sistema Enzimático do Citocromo P-450/genética , Sistema Enzimático do Citocromo P-450/metabolismo , Proteínas de Drosophila/genética , Resistência a Inseticidas/genética
14.
J Econ Entomol ; 112(4): 2007-2011, 2019 08 03.
Artigo em Inglês | MEDLINE | ID: mdl-31321434

RESUMO

The European corn borer, Ostrinia nubilalis (Lepidoptera: Crambidae), is a perennial insect pest of cultivated maize that was inadvertently introduced into North America in the early 1900s, but population densities have decreased since the widespread adoption of transgenic hybrids that express Bacillus thuringiensis (Bt) toxins. The native American lotus borer, Ostrinia penitalis (Lepidoptera: Crambidae), is among the most ancestral species described in the genus Ostrinia, and has a geographic range that coincides with that of O. nubilalis across major maize growing regions of North America. Due to the recent decrease in O. nubilalis populations, O. penitalis has become more pronounced in light trap samples intended to monitor O. nubilalis. A molecular tool based on variation in restriction endonuclease digestion pattern of a polymerase chain reaction amplified fragment of the mitochondrial cytochrome c oxidase subunit I (coxI) gene was developed and validated to differentiate these two species. This method was applied to light trap samples over a 2-yr period and achieved accurate quantification of species, and shows that O. penitalis can be prevalent in O. nubilalis first flight sampling. These methods are useful for contemporary O. nubilalis field research in North America.


Assuntos
Bacillus thuringiensis , Lepidópteros , Mariposas , Nelumbo , Animais , Proteínas de Bactérias , Endotoxinas , América do Norte , Zea mays
15.
Front Genet ; 10: 45, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30804985

RESUMO

Ten constitutively differentially expressed miRNAs were previously described between DDT-resistant 91-R and -susceptible control Drosophila melanogaster strains, and among their predicted target genes were those associated with metabolic DDT resistance mechanisms. The present study evaluated the inducibility of miRNA expression and putative downstream regulation of cytochrome P450s in response to DDT exposure in a time-dependent manner in 91-R and the susceptible Canton-S strain. Specifically, RT-qPCR analysis showed that DDT exposures led to the significant down-regulation (repression) of miR-310-3p, miR-311-3p, miR-312-3p, miR-313-3p, and miR-92a-3p levels in Canton-S. This is contrasted with the lack of significant changes in 91-R at most time-points following DDT exposure. The levels of expression among miRNAs exhibited opposite expression patterns compared to their corresponding putative target cytochrome P450s at the same time points after DDT exposure. Collectively, results from this study suggest that miR-310-3p, miR-311-3p, miR-312-3p, miR-313-3p, and miR-92a-3p might have a potential role in the control of DDT detoxification through the post-transcriptional regulation of target cytochrome P450s in Canton-S. Conversely, the lack of significant changes of these same miRNAs in 91-R following DDT-exposure suggests a possible adaptive mutation that removes repressive control mechanisms. These data are important for the understanding impact of adaptive changes in miRNA expression on post-transcriptional regulatory mechanism involved in the evolution of DDT resistance in 91-R.

16.
J Insect Sci ; 18(6)2018 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-30383265

RESUMO

The organochloride insecticide dichlorodiphenyltrichloroethane (DDT) and its metabolites can increase cellular levels of reactive oxygen species (ROS), cause mitochondrial dysfunction, and induce apoptosis. The highly DDT-resistant Drosophila melanogaster Meigen 1830 (Drosophila) strain, 91-R, and its susceptible control, 91-C, were used to investigate functional and structural changes among mitochondrial-derived pathways. Resequencing of mitochondrial genomes (mitogenomes) detected no structural differences between 91-R and 91-C, whereas RNA-seq suggested the differential expression of 221 mitochondrial-associated genes. Reverse transcriptase-quantitative PCR validation of 33 candidates confirmed that transcripts for six genes (Cyp12d1-p, Cyp12a4, cyt-c-d, COX5BL, COX7AL, CG17140) were significantly upregulated and two genes (Dif, Rel) were significantly downregulated in 91-R. Among the upregulated genes, four genes are duplicated within the reference genome (cyt-c-d, CG17140, COX5BL, and COX7AL). The predicted functions of the differentially expressed genes, or known functions of closely related genes, suggest that 91-R utilizes existing ROS regulation pathways of the mitochondria to combat increased ROS levels from exposure to DDT. This study represents, to our knowledge, the initial investigation of mitochondrial genome sequence variants and functional adaptations in responses to intense DDT selection and provides insights into potential adaptations of ROS management associated with DDT selection in Drosophila.


Assuntos
DDT , Drosophila melanogaster/genética , Regulação da Expressão Gênica , Genes de Insetos/genética , Genes Mitocondriais/genética , Resistência a Inseticidas/genética , Animais
17.
Genome Biol Evol ; 10(11): 2997-3011, 2018 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-30335145

RESUMO

The wheat stem sawfly, Cephus cinctus, is a major pest of wheat and key ecological player in the grasslands of western North America. It also represents the distinctive Cephoidea superfamily of sawflies (Symphyta) that appeared early during the hymenopteran radiation, but after three early-branching eusymphytan superfamilies that form the base of the order Hymenoptera. We present a high-quality draft genome assembly of 162 Mb in 1,976 scaffolds with a scaffold N50 of 622 kb. Automated gene annotation identified 11,210 protein-coding gene models and 1,307 noncoding RNA models. Thirteen percent of the assembly consists of ∼58,000 transposable elements partitioned equally between Class-I and Class-II elements. Orthology analysis reveals that 86% of Cephus proteins have identifiable orthologs in other insects. Phylogenomic analysis of conserved subsets of these proteins supports the placement of the Cephoidea between the Eusymphyta and the parasitic woodwasp superfamily Orussoidea. Manual annotation and phylogenetic analysis of families of odorant, gustatory, and ionotropic receptors, plus odorant-binding proteins, shows that Cephus has representatives for most conserved and expanded gene lineages in the Apocrita (wasps, ants, and bees). Cephus has also maintained several insect gene lineages that have been lost from the Apocrita, most prominently the carbon dioxide receptor subfamily. Furthermore, Cephus encodes a few small lineage-specific chemoreceptor gene family expansions that might be involved in adaptations to new grasses including wheat. These comparative analyses identify gene family members likely to have been present in the hymenopteran ancestor and provide a new perspective on the evolution of the chemosensory gene repertoire.


Assuntos
Evolução Molecular , Genoma de Inseto , Himenópteros/genética , Proteínas de Insetos/genética , Receptores Odorantes/genética , Animais , Elementos de DNA Transponíveis , Feminino , Masculino , MicroRNAs/genética , Filogenia
18.
Curr Opin Insect Sci ; 26: 50-56, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29764660

RESUMO

The European corn borer, Ostrinia nubilalis, is a model species for elucidating mechanisms underlying adaptively differentiated subpopulations in the face of reciprocal gene flow, and is a major pest of cultivated maize in North America and Eurasia. Strains are characterized by different pheromone communication systems in combination with voltinism strains that are adapted to distinct local climate and photoperiod through adjustments in diapause traits. However, only partial barriers to inter-strain hybridization exist in areas of sympatry. Recent research shows that genes governing important strain-specific isolating traits are disproportionately located on the Z-chromosome. Furthermore, co-adapted combinations of some of these genes are non-recombining due to location within a large chromosomal inversion, and assist in maintaining strain integrity despite hybridization.


Assuntos
Mariposas/genética , Simpatria/genética , Adaptação Fisiológica , Animais , Feminino , Fluxo Gênico , Genoma de Inseto , Hibridização Genética , Masculino , Feromônios/genética , Isolamento Reprodutivo , Zea mays
19.
Pest Manag Sci ; 74(11): 2530-2543, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-29656515

RESUMO

BACKGROUND: Cytochrome P450 monooxygenases (P450s) are involved in the biosynthesis of endogenous intracellular compounds and the metabolism of xenobiotics, including chemical insecticides. We investigated the structural and expression level variance across all P450 genes with respect to the evolution of insecticide resistance under multigenerational dichlorodiphenyltrichloroethane (DDT) selection. RESULTS: RNA-sequencing (RNA-seq) and reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR) indicated that the transcript levels of seven P450 genes were significantly up-regulated and three P450 genes were down-regulated in the DDT-resistant strain 91-R, as compared to the control strain 91-C. The overexpression of Cyp6g1 was associated with the presence of an Accord and an HMS-Beagle element insertion in the 5' upstream region in conjunction with copy number variation in the 91-R strain, but not in the 91-C strain. A total of 122 (50.2%) fixed nonsynonymous (amino acid-changing) mutations were found between 91-C and 91-R, and 20 (8.2%) resulted in amino acid changes within functional domains. Three P450 proteins were truncated as a result of premature stop codons and fixed between strains. CONCLUSION: Our results demonstrate that a combination of changes in P450 protein-coding regions and transcript levels are possibly associated with DDT resistance, and thereby suggest that selection for variant function may occur within this gene family in response to chronic DDT exposure. © 2018 Society of Chemical Industry.


Assuntos
Sistema Enzimático do Citocromo P-450/genética , DDT/farmacologia , Drosophila melanogaster/efeitos dos fármacos , Drosophila melanogaster/genética , Resistência a Inseticidas/genética , Inseticidas/farmacologia , Animais , Sistema Enzimático do Citocromo P-450/metabolismo , Drosophila melanogaster/enzimologia , Proteínas de Insetos/genética , Proteínas de Insetos/metabolismo , Proteômica
20.
PLoS One ; 13(4): e0196518, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29698530

RESUMO

Dichloro-diphenyl-trichloroethane (DDT) resistance among arthropod species is a model for understanding the molecular adaptations in response to insecticide exposures. Previous studies reported that DDT resistance may involve one or multiple detoxification genes, such as cytochrome P450 monooxygenases (P450s), glutathione S-transferases (GSTs), esterases, and ATP binding cassette (ABC) transporters, or changes in the voltage-sensitive sodium channel. However, the possible involvement of microRNAs (miRNAs) in the post-transcriptional regulation of genes associated with DDT resistance in the Drosophila melanogaster strain 91-R remains poorly understood. In this study, the majority of the resulting miRNAs discovered in small RNA libraries from 91-R and the susceptible control strain, 91-C, ranged from 16-25 nt, and contained 163 precursors and 256 mature forms of previously-known miRNAs along with 17 putative novel miRNAs. Quantitative analyses predicted the differential expression of ten miRNAs between 91-R and 91-C, and, based on Gene Ontology and pathway analysis, these ten miRNAs putatively target transcripts encoding proteins involved in detoxification mechanisms. RT-qPCR validated an inverse correlation between levels of differentially-expressed miRNAs and their putatively targeted transcripts, which implies a role of these miRNAs in the differential regulation of detoxification pathways in 91-R compared to 91-C. This study provides evidence associating the differential expression of miRNAs in response to multigenerational DDT selection in Drosophila melanogaster and provides important clues for understanding the possible roles of miRNAs in mediating insecticide resistance traits.


Assuntos
Drosophila melanogaster/genética , Resistência a Inseticidas/genética , MicroRNAs/metabolismo , Animais , Sistema Enzimático do Citocromo P-450/genética , Sistema Enzimático do Citocromo P-450/metabolismo , DDT/toxicidade , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/efeitos dos fármacos , Drosophila melanogaster/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Redes Reguladoras de Genes/efeitos dos fármacos , Inseticidas/química , MicroRNAs/química , MicroRNAs/genética , RNA/química , RNA/isolamento & purificação , RNA/metabolismo , Análise de Sequência de RNA
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