Trypsin-catalyzed deltamethrin degradation

Characteristics of Trypsin genes and their roles in insecticide resistance based on omics and functional analyses in the malaria vector Anopheles sinensis

Trypsin is one of the most diverse and widely studied protease hydrolases. However, the diversity and characteristics of the Trypsin superfamily of genes have not been well understood, and their role in insecticide resistance is yet to be investigated. In this study, a total of 342 Trypsin genes were identified and classified into seven families based on homology, characteristic domains and phylogenetics in Anopheles sinensis, and the LY-Domain and CLECT-Domain families are specific to the species. Four Trypsin genes, (Astry2b, Astry43a, Astry90, Astry113c) were identified to be associated with pyrethroid resistance based on transcriptome analyses of three field resistant populations and qRT-PCR validation, and the knock-down of these genes significantly decrease the pyrethroid resistance of Anopheles sinensis based on RNAi. The activity of Astry43a can be reduced by five selected insecticides (indoxacarb, DDT, temephos, imidacloprid and deltamethrin); and however, the Astry43a could not directly metabolize these five insecticides, like the trypsin NYD-Tr did in earlier reports. This study provides the overall information frame of Trypsin genes, and proposes the role of Trypsin genes to insecticide resistance. Further researches are necessary to investigate the metabolism function of these trypsins to insecticides.

Analytical assessment of modulated electric flux triggered degradation of chlorfenapyr and deltamethrin pesticides in guava fruits

The purpose of this study was to explore the new effective method and investigate the dissipation of chlorfenapyr and deltamethrin (DM) pesticides used in the treatment of guava fruit from tropical and sub-tropical areas of Pakistan. Five different solutions of varying concentrations of pesticides were prepared. This study involved the in-vitro and in-vivo analysis of modulated electric flux-triggered degradation as an efficient method for the safer degradation of selected pesticides. The Taser gun was used as a tool for providing different numbers of electrical shocks of million voltages to the pesticides present in guava fruit at different temperatures. The degraded pesticides were extracted and analyzed by High-performance liquid chromatography (HPLC). The HPLC chromatograms verified that significant dissipation of pesticides took place when these were exposed to 9 shocks at 37 °C, which proved the efficiency of this degradation method. More than 50% of the total spray of both pesticides was dissipated. Thus, modulated electrical flux-triggered degradation is one of the effective methods for pesticide degradation.

Expansive and Diverse Phenotypic Landscape of Field Aedes aegypti (Diptera: Culicidae) Larvae with Differential Susceptibility to Temephos: Beyond Metabolic Detoxification

Arboviruses including dengue, Zika, and chikungunya are amongst the most significant public health concerns worldwide. Arbovirus control relies on the use of insecticides to control the vector mosquito Aedes aegypti (Linnaeus), the success of which is threatened by widespread insecticide resistance. The work presented here profiled the gene expression of Ae. aegypti larvae from field populations of Ae. aegypti with differential susceptibility to temephos originating from two Colombian urban locations, Bello and Cúcuta, previously reported to have distinctive disease incidence, socioeconomics, and climate. We demonstrated that an exclusive field-to-lab (Ae. aegypti strain New Orleans) comparison generates an over estimation of differential gene expression (DGE) and that the inclusion of a geographically relevant field control yields a more discrete, and likely, more specific set of genes. The composition of the obtained DGE profiles is varied, with commonly reported resistance associated genes including detoxifying enzymes having only a small representation. We identify cuticle biosynthesis, ion exchange homeostasis, an extensive number of long noncoding RNAs, and chromatin modelling among the differentially expressed genes in field resistant Ae. aegypti larvae. It was also shown that temephos resistant larvae undertake further gene expression responses when temporarily exposed to temephos. The results from the sampling triangulation approach here contribute a discrete DGE profiling with reduced noise that permitted the observation of a greater gene diversity, increasing the number of potential targets for the control of insecticide resistant mosquitoes and widening our knowledge base on the complex phenotypic network of the Ae. aegypti response to insecticides.

Trypsin Genes Are Regulated through the miRNA Bantam and Associated with Drug Sensitivity in the Sea Louse Caligus rogercresseyi

The role of trypsin genes in pharmacological sensitivity has been described in numerous arthropod species, including the sea louse Caligus rogercresseyi. This ectoparasite species is mainly controlled by xenobiotic drugs in Atlantic salmon farming. However, the post-transcriptional regulation of trypsin genes and the molecular components involved in drug response remain unclear. In particular, the miRNA bantam family has previously been associated with drug response in arthropods and is also found in C. rogercresseyi, showing a high diversity of isomiRs. This study aimed to uncover molecular interactions among trypsin genes and bantam miRNAs in the sea louse C. rogercresseyi in response to delousing drugs. Herein, putative mRNA/miRNA sequences were identified and localized in the C. rogercresseyi genome through genome mapping and blast analyses. Expression analyses were obtained from the mRNA transcriptome and small-RNA libraries from groups with differential sensitivity to three drugs used as anti-sea lice agents: azamethiphos, deltamethrin, and cypermethrin. The validation was conducted by qPCR analyses and luciferase assay of selected bantam and trypsin genes identified from in silico transcript prediction. A total of 60 trypsin genes were identified in the C. rogercresseyi genome, and 39 bantam miRNAs were differentially expressed in response to drug exposure. Notably, expression analyses and correlation among values obtained from trypsin and bantam revealed an opposite trend and potential binding sites with significant ΔG values. The luciferase assay showed a reduction of around 50% in the expression levels of the trypsin 2-like gene, which could imply that this gene is a potential target for bantam. The role of trypsin genes and bantam miRNAs in the pharmacological sensitivity of sea lice and the use of miRNAs as potential markers in these parasites are discussed in this study.

Green photosensitisers for the degradation of selected pesticides of high risk in most susceptible food: A safer approach

Pesticides are the leading defence against pests, but their unsafe use reciprocates the pesticide residues in highly susceptible food and is becoming a serious risk for human health. In this study, mint extract and riboflavin were tested as photosensitisers in combination with light irradiation of different frequencies, employed for various time intervals to improve the photo-degradation of deltamethrin (DM) and lambda cyhalothrin (λ-CHT) in cauliflower. Different source of light was studied, either in ultraviolet range (UV-C, 254 nm or UV-A, 320-380 nm) or sunlight simulator (> 380-800 nm). The degradation of the pesticides varied depending on the type of photosensitiser and light source. Photo-degradation of the DM and λ-CHT was enhanced by applying the mint extracts and riboflavin and a more significant degradation was achieved with UV-C than with either UV-A or sunlight, reaching a maximum decrement of the concentration by 67-76%. The light treatments did not significantly affect the in-vitro antioxidant activity of the natural antioxidants in cauliflower. A calculated dietary risk assessment revealed that obvious dietary health hazards of DM and λ-CHT pesticides when sprayed on cauliflower for pest control. The use of green chemical photosensitisers (mint extract and riboflavin) in combination with UV light irradiation represents a novel, sustainable, and safe approach to pesticide reduction in produce.

Deltamethrin transformation by Bacillus thuringiensis and the associated metabolic pathways

The biological toxicity of deltamethrin at molecular level has been investigated, whereas, the proteome responsive mechanisms of cells under deltamethrin stress at the phylogenetic level are not clear. The proteome expression, transformation-related pathway and regulatory network of Bacillus thuringiensis during the process of deltamethrin transformation were explored using proteomics and metabolomics approaches in the present study. The results showed that deltamethrin was effectively removed by B. thuringiensis within 48 h. The stress responses of B. thuringiensis were activated to resist deltamethrin stress, with significant differential expression of proteins that were primarily involved in the synthesis of DNA and shock proteins, endospore formation, carbon metabolism. The expression patterns of ribosomal proteins confirmed that the transcription and translation of DNA, and biosynthesis of heat shock proteins were inhibited as deltamethrin transformation. The synthesis of oxaloacetate and acetyl-CoA were also hindered, resulting in downregulated expression of carbohydrate metabolism, TCA cycle and energy metabolism. Meanwhile, endospore formation and germination were promoted to resist oxidative stress induced by deltamethrin. These findings imparted novel insight to elucidate underlying stress response mechanisms of the organism under target contaminants stress, and the interaction between deltamethrin transformation and cellular metabolism at the pathway and network levels.

Lipase is associated with deltamethrin resistance in Culex pipiens pallens

The wide application of pyrethroids has led to the rapid development of insecticide resistance in mosquitoes, leading to a rise in mosquito-borne diseases. We previously identified five differentially expressed lipase family genes upon evaluating the transcriptomes of deltamethrin-resistant and deltamethrin-susceptible strains of Culex pipiens pallens. Herein, the gene expression levels were verified by quantitative real-time PCR, and two lipase family genes, lipase A and pancreatic triacylglycerol lipase A, were chosen for further investigations. Using cell viability assays and Centers for Disease Control and Prevention bottle bioassays, lipase A was found to increase the resistance of mosquitoes against deltamethrin both in vitro and in vivo. Our findings indicate that lipase A is involved in conferring deltamethrin resistance in Cx. pipiens pallens.

The implication of p66shc in oxidative stress induced by deltamethrin

Deltamethrin (DLT) is effective against a broad spectrum of insects. Exposure to DLT has been demonstrated to cause oxidative stress. However, the mechanism of oxidative stress induced by DLT is little known. Groups of rats were gavaged with DLT once daily for 7 days at six dosages: 0, 2, 5, 10, 20, 40 mg/kg. The intensity of neurotoxicity and liver dysfunction caused by DLT were significantly increased in a dose-dependent manner. We found that DLT caused the increase of cytosolic superoxide in tissues. Western blot analysis showed that both the expression of p66shc and Ser36 phosphorylated p66shc, which were involved in ROS generation, were increased in tissues treated with DLT. Further investigation showed that DLT treatment resulted in the increase of intracellular ROS accompanied with elevated p66shc expression in different cell lines. And treatment of cells with DLT induced p66shc phosphorylation at Ser36 and the translocation of p66shc from cytoplasm to mitochondria. Moreover, the overexpression of wildtype p66shc caused the increase of DLT-mediated ROS level in SH-SY5Y cells, but cells overexpressing p66shcSer36Ala mutant plasmid had the opposite effect. And p66shc suppression by siRNA blunted DLT-mediated ROS generation. Taken together, our findings indicated p66shc mediated DLT-induced oxidative stress, which may be partly responsible for toxic effects.

Cypermethrin exposure induces metabolic and stress-related gene expression in copepodid salmon lice (Lepeophtheirus salmonis)

Cypermethrin has been administered for decades to control salmon lice (Lepeophtheirus salmonis) infestations in Atlantic salmon farming regions globally. However, resistance to cypermethrin and other available therapeutants has threatened the sustainability of this growing industry. To better understand the effects of cypermethrin on L. salmonis, a 38K oligonucleotide microarray and RT-qPCR analyses were applied to pools of copepodid larvae exposed to 1.0ppb cypermethrin or seawater controls for 24h. Phenotypic assessments and global gene expression profiles showed a significant disruption of homeostasis in copepodid L. salmonis exposed to cypermethrin. Multiple degradative enzymes were overexpressed in cypermethrin-treated lice including five trypsin-like serine proteases and three cytochrome p450s CYP3a24 (p=0.03, fold change (FC)=3.8; GenBank accession no. JP326960.1), CYP6w1 (p=0.008, FC=5.3; GenBank accession no. JP317875.1), and CYP6d4 (p=0.01; FC=7.9; GenBank accession no. JP334550.1). These enzymes represent preliminary markers for understanding the physiological response of L. salmonis to cypermethrin exposure. A general stress response was also observed in cypermethrin-treated lice which included differential expression of cell signaling genes involved in the induction of cell growth, solute transport, and metabolism. Lastly, a consensus-based analysis was completed with two previously published L. salmonis transcriptome studies revealing genes that respond to cypermethrin, emamectin benzoate (another delousing agent) and hyposalinity. This included concordant differential expression of heat shock beta-1, ammonium transporter Rh types B, and 72kDa type IV collagenase across different L. salmonis studies. This is currently the most comprehensive transcriptome assessment of chemical exposure on the first infectious stage of L. salmonis, providing novel markers for studying drug resistance and general stress in this important parasite.

Next-Generation Transcriptome Profiling of the Salmon Louse Caligus rogercresseyi Exposed to Deltamethrin (AlphaMax™): Discovery of Relevant Genes and Sex-Related Differences

Sea lice are one of the main parasites affecting the salmon aquaculture industry, causing significant economic losses worldwide. Increased resistance to traditional chemical treatments has created the need to find alternative control methods. Therefore, the objective of this study was to identify the transcriptome response of the salmon louse Caligus rogercresseyi to the delousing drug deltamethrin (AlphaMax™). Through bioassays with different concentrations of deltamethrin, adult salmon lice transcriptomes were sequenced from cDNA libraries in the MiSeq Illumina platform. A total of 78 million reads for females and males were assembled in 30,212 and 38,536 contigs, respectively. De novo assembly yielded 86,878 high-quality contigs and, based on published data, it was possible to annotate and identify relevant genes involved in several biological processes. RNA-seq analysis in conjunction with heatmap hierarchical clustering evidenced that pyrethroids modify the ectoparasitic transcriptome in adults, affecting molecular processes associated with the nervous system, cuticle formation, oxidative stress, reproduction, and metabolism, among others. Furthermore, sex-related transcriptome differences were evidenced. Specifically, 534 and 1033 exclusive transcripts were identified for males and females, respectively, and 154 were shared between sexes. For males, estradiol 17-beta-dehydrogenase, sphingolipid delta4-desaturase DES1, ketosamine-3-kinase, and arylsulfatase A, among others, were discovered, while for females, vitellogenin 1, glycoprotein G, transaldolase, and nitric oxide synthase were among those identified. The shared transcripts included annotations for tropomyosin, γ-crystallin A, glutamate receptor-metabotropic, glutathione S-transferase, and carboxipeptidase B. The present study reveals that deltamethrin generates a complex transcriptome response in C. rogercresseyi, thus providing valuable genomic information for developing new delousing drugs.

Venom allergen 5 is Associated With Deltamethrin Resistance in Culex pipiens pallens (Diptera: Culicidae)

The mosquito, Culex pipiens pallens (L.), is an important vector of encephalitis and filariasis in northern China. The control of these mosquitoes occurs primarily via the use of pyrethroid insecticides, such as deltamethrin. The widespread and improper application of pyrethroid has resulted in the evolution of pyrethroid resistance amongst many mosquito populations, including Cx. pipiens pallens. Previous studies using high-throughput transcriptome sequencing have identified that the venom allergen 5 gene is differentially expressed between deltamethrin-susceptible and deltamethrin-resistant Cx. pipiens pallens. In this study, quantitative real-time polymerase chain reaction analyses revealed that venom allergen 5 was significantly overexpressed in adult females of both deltamethrin-resistant laboratory populations and two field populations. The transcriptional level of venom allergen 5 in the laboratory populations was elevated as the levels of deltamethrin resistance increased. Full-length cDNAs of the venom allergen 5 gene were cloned from Cx. pipiens pallens, and contained an open reading frame of 765 bp, encoding a protein with 254 amino acids. The deduced amino acid sequence shared 100% identity with the ortholog in Culex quinquefasciatus Say. The overexpression of venom allergen 5 decreased the susceptibility of mosquito cells to deltamethrin, while knockdown of this gene by RNAi increased the susceptibility of mosquitoes to deltamethrin. This study provides the first evidence of the association between the venom allergen 5 gene and deltamethrin resistance in mosquitoes.