Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 592
Filtrar
1.
Int J Mol Sci ; 22(17)2021 Aug 26.
Artigo em Inglês | MEDLINE | ID: mdl-34502147

RESUMO

Tetramethrin is a pyrethroid insecticide that is commonly used worldwide. The toxicity of this insecticide into the living system is an important concern. In this study, a novel tetramethrin-degrading bacterial strain named A16 was isolated from the activated sludge and identified as Gordonia cholesterolivorans. Strain A16 exhibited superior tetramethrin degradation activity, and utilized tetramethrin as the sole carbon source for growth in a mineral salt medium (MSM). High-performance liquid chromatography (HPLC) analysis revealed that the A16 strain was able to completely degrade 25 mg·L-1 of tetramethrin after 9 days of incubation. Strain A16 effectively degraded tetramethrin at temperature 20-40 °C, pH 5-9, and initial tetramethrin 25-800 mg·L-1. The maximum specific degradation rate (qmax), half-saturation constant (Ks), and inhibition constant (Ki) were determined to be 0.4561 day-1, 7.3 mg·L-1, and 75.2 mg·L-1, respectively. The Box-Behnken design was used to optimize degradation conditions, and maximum degradation was observed at pH 8.5 and a temperature of 38 °C. Five intermediate metabolites were identified after analyzing the degradation products through gas chromatography-mass spectrometry (GC-MS), which suggested that tetramethrin could be degraded first by cleavage of its carboxylester bond, followed by degradation of the five-carbon ring and its subsequent metabolism. This is the first report of a metabolic pathway of tetramethrin in a microorganism. Furthermore, bioaugmentation of tetramethrin-contaminated soils (50 mg·kg-1) with strain A16 (1.0 × 107 cells g-1 of soil) significantly accelerated the degradation rate of tetramethrin, and 74.1% and 82.9% of tetramethrin was removed from sterile and non-sterile soils within 11 days, respectively. The strain A16 was also capable of efficiently degrading a broad spectrum of synthetic pyrethroids including D-cyphenothrin, chlorempenthrin, prallethrin, and allethrin, with a degradation efficiency of 68.3%, 60.7%, 91.6%, and 94.7%, respectively, after being cultured under the same conditions for 11 days. The results of the present study confirmed the bioremediation potential of strain A16 from a contaminated environment.


Assuntos
Actinobacteria/metabolismo , Inseticidas/metabolismo , Piretrinas/metabolismo , Poluentes do Solo/metabolismo , Actinobacteria/crescimento & desenvolvimento , Biotransformação , Microbiologia Industrial/métodos
2.
Arch Insect Biochem Physiol ; 108(3): e21842, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34499777

RESUMO

Glyphodes pyloalis Walker has become one of the most significant mulberry pests, and it has caused serious economic losses in major mulberry growing regions in China. Peptidoglycan recognition proteins (PGRPs) are responsible for initiating and regulating immune signalling pathways in insects. However, their roles responding to chemical pesticides is still less known. This study aimed to investigate the possible detoxication function of GpPGRP-S2 and GpPGRP-S3 in G. pyloalis in response to chlorfenapyr and phoxim. The chlorfenapyr and phoxim treatment significantly induced the expression level of GpPGRP-S3 at 48 h. In addition, the expression levels of GpPGRP-S2 and GpPGRP-S3 in the chlorfenapyr/phoxim treatment group were significantly higher in midgut than those in the control group at 48 h. The results of the survival experiment showed that silencing either GpPGRP-S2 or GpPGRP-S3 would not influence the survival rate of G. pyloalis which treated with phoxim, however, silencing GpPGRP-S2 or GpPGRP-S3 would cause G. pyloalis to be more easily killed by chlorfenapyr. The expression of carboxylesterase GpCXE1 was significantly induced by chlorfenapyr/phoxim treatment, while it was suppressed once silenced GpPGRP-S2 followed with chlorfenapyr treatment or silenced GpPGRP-S3 followed with phoxim treatment. These results might suggest that under the chlorfenapyr/phoxim treatment condition, the connection between GpPGRPs and detoxification genes in insect was induced to maintain physiological homeostasis; and these results may further enrich the mechanisms of insects challenged by insecticides.


Assuntos
Proteínas de Transporte , Inseticidas , Mariposas , Animais , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Inseticidas/metabolismo , Inseticidas/farmacologia , Mariposas/efeitos dos fármacos , Mariposas/genética , Mariposas/metabolismo , Compostos Organotiofosforados/metabolismo , Compostos Organotiofosforados/farmacologia , Controle de Pragas/métodos , Piretrinas/metabolismo , Piretrinas/farmacologia
3.
Molecules ; 26(15)2021 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-34361721

RESUMO

To improve the proinsecticidal activity and phloem mobility of amino acid-tralopyril conjugates further, nine conjugates were designed and synthesized by introducing glutamic acid to tralopyril, and the length of the linker between glutamic acid and tralopyril ranged from 2 atoms to 10 atoms. The results of insecticidal activity against the third-instar larvae of P. xylostella showed that conjugates 42, 43, 44,and 45 (straight-chain containing 2-5 atoms) exhibited good insecticidal activity, and their LC50 values were 0.2397 ± 0.0366, 0.4413 ± 0.0647, 0.4400 ± 0.0624, and 0.4602 ± 0.0655 mM, respectively. The concentrations of conjugates 43-45 were higher than that of conjugate 42 in the phloem sap at 2 h, and conjugate 43 showed the highest concentration. The introduction of glutamic acid can improve phloem mobility. The in vivo metabolism of conjugates 42 and 43 was investigated in P. xylostella, and the parent compound tralopyril was detected at concentrations of 0.5950 and 0.3172 nmol/kg, respectively. According to the above results, conjugates 42 and 43 were potential phloem mobile pro-insecticide candidates.


Assuntos
Ácido Glutâmico/química , Inseticidas/farmacologia , Larva/efeitos dos fármacos , Mariposas/efeitos dos fármacos , Pró-Fármacos/farmacologia , Pirróis/farmacologia , Animais , Transporte Biológico , Biotransformação , Concentração Inibidora 50 , Inseticidas/síntese química , Inseticidas/metabolismo , Larva/crescimento & desenvolvimento , Larva/metabolismo , Longevidade/efeitos dos fármacos , Mariposas/crescimento & desenvolvimento , Mariposas/metabolismo , Floema/metabolismo , Floema/parasitologia , Plantas/metabolismo , Plantas/parasitologia , Pró-Fármacos/síntese química , Pró-Fármacos/metabolismo , Piretrinas/metabolismo , Piretrinas/farmacologia , Pirróis/síntese química , Pirróis/metabolismo , Relação Estrutura-Atividade
4.
PLoS Genet ; 17(7): e1009677, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-34237075

RESUMO

Pyrethrum extract from dry flowers of Tanacetum cinerariifolium (formally Chrysanthemum cinerariifolium) has been used globally as a popular insect repellent against arthropod pests for thousands of years. However, the mechanistic basis of pyrethrum repellency remains unknown. In this study, we found that pyrethrum spatially repels and activates olfactory responses in Drosophila melanogaster, a genetically tractable model insect, and the closely-related D. suzukii which is a serious invasive fruit crop pest. The discovery of spatial pyrethrum repellency and olfactory response to pyrethrum in D. melanogaster facilitated our identification of four odorant receptors, Or7a, Or42b, Or59b and Or98a that are responsive to pyrethrum. Further analysis showed that the first three Ors are activated by pyrethrins, the major insecticidal components in pyrethrum, whereas Or98a is activated by (E)-ß-farnesene (EBF), a sesquiterpene and a minor component in pyrethrum. Importantly, knockout of Or7a, Or59b or Or98a individually abolished fly avoidance to pyrethrum, while knockout of Or42b had no effect, demonstrating that simultaneous activation of Or7a, Or59b and Or98a is required for pyrethrum repellency in D. melanogaster. Our study provides insights into the molecular basis of repellency of one of the most ancient and globally used insect repellents. Identification of pyrethrum-responsive Ors opens the door to develop new synthetic insect repellent mixtures that are highly effective and broad-spectrum.


Assuntos
Chrysanthemum cinerariifolium/metabolismo , Repelentes de Insetos/química , Receptores Odorantes/metabolismo , Animais , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/genética , Flores , Repelentes de Insetos/metabolismo , Inseticidas/química , Odorantes/análise , Piretrinas/química , Piretrinas/metabolismo , Receptores Odorantes/genética , Receptores Odorantes/fisiologia , Sesquiterpenos/química
5.
Insect Biochem Mol Biol ; 135: 103597, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34089822

RESUMO

Lepidopteran P450s of the CYP6B and CYP9A subfamilies are thought to play important roles in host plant adaptation and insecticide resistance. An increasing number of paralogs and orthologs with high levels of sequence identity have been found in these subfamilies by mining recent genome projects. However, the biochemical function of most of them remains unknown. A better understanding of the evolution of P450 genes and of the catalytic competence of the enzymes they encode is needed to facilitate studies of host plant use and insecticide resistance. Here, we focused on the full complement of CYP6B (4 genes) and CYP9A (7 genes) in the generalist herbivore, Helicoverpa armigera. These P450s were heterologously expressed in Sf9 cells and compared functionally. In vitro assays showed that all CYP6B and CYP9A P450s can metabolize esfenvalerate efficiently, except for the evolutionarily divergent CYP6B43. A new 2'-hydroxy-metabolite of esfenvalerate was identified and found to be the main metabolite produced by CYP9A12. All tested P450s showed only low induction responses to esfenvalerate. To put these results from H. armigera P450s in perspective, 158 complete CYP6B and 100 complete CYP9A genes from 34 ditrysian species were manually curated. The CYP9A subfamily was more widespread than the CYP6B subfamily and the latter showed dramatic gains and losses, with ten species lacking CYP6B genes. Two adjacent CYP6B loci were found on chromosome 21, with different fates during the evolution of Lepidoptera. The diversity and functional redundancy of CYP6B and CYP9A genes challenge resistance management and pest control strategies as many P450s are available to insects to cope with chemical stresses they encounter.


Assuntos
Sistema Enzimático do Citocromo P-450 , Resistência a Inseticidas/genética , Mariposas , Piretrinas , Animais , Sistema Enzimático do Citocromo P-450/efeitos dos fármacos , Sistema Enzimático do Citocromo P-450/genética , Sistema Enzimático do Citocromo P-450/metabolismo , Genes de Insetos , Genoma de Inseto , Controle de Insetos/métodos , Proteínas de Insetos/efeitos dos fármacos , Proteínas de Insetos/genética , Proteínas de Insetos/metabolismo , Inseticidas/metabolismo , Inseticidas/farmacologia , Mariposas/efeitos dos fármacos , Mariposas/genética , Mariposas/metabolismo , Filogenia , Piretrinas/metabolismo , Piretrinas/farmacologia
6.
Aquat Toxicol ; 236: 105860, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34015756

RESUMO

Resistance to chemical insecticides including pyrethroids, the main insecticide class used against mosquitoes, has re-kindled interest in the use of neonicotinoids. In this context, the present study aimed to characterize the molecular basis of neonicotinoid resistance in the mosquito Aedes aegypti. Resistance mechanisms were studied by combining transcriptomic and genomic data obtained from a laboratory strain selected at the larval stage after 30 generations of exposure to imidacloprid (Imida-R line). After thirty generations of selection, larvae of the Imida-R line showed an 8-fold increased resistance to imidacloprid and a significant cross-tolerance to the pyrethroids permethrin and deltamethrin. Cross-resistance to pyrethroids was only observed in adults when larvae were previously exposed to imidacloprid suggesting a low but inducible expression of resistance alleles at the adult stage. Resistance of the Imida-R line was associated with a slower larval development time in females. Multiple detoxification enzymes were over-transcribed in larvae in association with resistance including the P450s CYP6BB2, CYP9M9 and CYP6M11 previously associated with pyrethroid resistance. Some of them together with their redox partner NADPH P450 reductase were also affected by non-synonymous mutations associated with resistance. Combining genomic and transcriptomic data allowed identifying promoter variations associated with the up-regulation of CYP6BB2 in the resistant line. Overall, these data confirm the key role of P450s in neonicotinoid resistance in Ae. aegypti and their potential to confer cross-resistance to pyrethroids, raising concerns about the use of neonicotinoids for resistance management in this mosquito species.


Assuntos
Resistência a Inseticidas/fisiologia , Neonicotinoides/toxicidade , Nitrocompostos/toxicidade , Aedes , Animais , Feminino , Resistência a Inseticidas/efeitos dos fármacos , Resistência a Inseticidas/genética , Inseticidas/metabolismo , Larva/metabolismo , Permetrina , Piretrinas/metabolismo , Transcriptoma/efeitos dos fármacos
7.
Parasit Vectors ; 14(1): 141, 2021 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-33676552

RESUMO

BACKGROUND: Since their detection in 2013, Aedes aegypti has become a widespread urban pest in California. The availability of cryptic larval breeding sites in residential areas and resistance to insecticides pose significant challenges to control efforts. Resistance to pyrethroids is largely attributed to mutations in the voltage gated sodium channels (VGSC), the pyrethroid site of action. However, past studies have indicated that VGSC mutations may not be entirely predictive of the observed resistance phenotype. METHODS: To investigate the frequencies of VGSC mutations and the relationship with pyrethroid insecticide resistance in California, we sampled Ae. aegypti from four locations in the Central Valley, and the Greater Los Angeles area. Mosquitoes from each location were subjected to an individual pyrethrum bottle bioassay to determine knockdown times. A subset of assayed mosquitoes from each location was then analyzed to determine the composition of 5 single nucleotide polymorphism (SNP) loci within the VGSC gene. RESULTS: The distribution of knockdown times for each of the five Californian populations sampled was non-parametric with potentially bimodal distributions. One group succumbs to insecticidal effects around 35-45 min and the second group lasts up to and beyond the termination of the assay (120+ min). We detected 5 polymorphic VGSC SNPs within the sampled California populations. One is potentially new and alternatively spliced (I915K), and four are documented and associated with resistance: F1534C, V1016I, V410L and S723T. The Central Valley populations (Clovis, Dinuba, Sanger and Kingsburg) are fairly homogenous with only 5% of the mosquitoes showing heterozygosity at any given position. In the Greater LA mosquitoes, 55% had at least one susceptible allele at any of the five SNP loci. The known resistance allele F1534C was detected in almost all sampled mosquitoes (99.4%). We also observe significant heterogeneity in the knockdown phenotypes of individuals with the identical VGSC haplotypes suggesting the presence of additional undefined resistance mechanisms. CONCLUSIONS: Resistance associated VGSC SNPs are prevalent, particularly in the Central Valley. Interestingly, among mosquitoes carrying all 4 resistance associated SNPs, we observe significant heterogeneity in bottle bioassay profiles suggesting that other mechanisms are important to the individual resistance of Ae. aegypti in California.


Assuntos
Aedes/efeitos dos fármacos , Aedes/genética , Genótipo , Inseticidas/farmacologia , Polimorfismo de Nucleotídeo Único/genética , Piretrinas/farmacologia , Canais de Sódio Disparados por Voltagem/genética , Aedes/metabolismo , Animais , Bioensaio , Feminino , Resistência a Inseticidas/genética , Inseticidas/metabolismo , Mosquitos Vetores/genética , Fenótipo , Piretrinas/metabolismo , Canais de Sódio Disparados por Voltagem/classificação
8.
J Food Sci ; 86(4): 1475-1487, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33655547

RESUMO

Cypermethrin (CY) is a synthetic pyrethroid widely used to control insect pests and it elicits a toxic effect on the human body. In this study, Bacillus licheniformis B-1 isolated from tea garden soil was used to degrade CY effectively. A specific enzyme was mainly localized in the extracellular compartments of B-1. This enzyme was identified as an esterase that could be produced without CY. The enzyme was purified 23.03-fold to apparent homogeneity with 8.38% overall recovery by ammonium sulfate precipitation, anion exchange chromatography, and gel filtration chromatography. The molecular mass of the CY-degrading enzyme was 66.4 kDa, and its optimal pH and temperature were 8.5 and 40 °C, respectively. Appropriate Zn2+ , Mn2+ , Mg2+ , Tween 80, SDS, Triton X-100, and BSA concentrations could greatly increase the activity of this enzyme. By contrast, EDTA, 1,10-phenanthroline, NaF, and PMSF strongly inhibited its activity. The purified enzyme showed Km and Vmax values were 5.532 nmol/mL and 33.445 nmol/min. The CY residue in lettuce and cherry tomatoes could be removed more than 50% under the conditions of the treatment concentration for 500 mg/L and the enzyme preparation dilution of 100 times. These results suggested that the CY-degrading enzyme, a constitutive enzyme that mainly exists in the extracellular space, was a novel esterase that might be used to detoxify CY, and could remove CY in vegetables effectively. PRACTICAL APPLICATION: Our research found a novel cypermethrin-hydrolyzing esterase from Bacillus licheniformis B-1 and proved that the enzyme could remove cypermethrin in vegetables effectively.


Assuntos
Bacillus licheniformis/enzimologia , Esterases/isolamento & purificação , Esterases/metabolismo , Piretrinas/metabolismo , Cromatografia em Gel , Estabilidade Enzimática , Esterases/química , Humanos , Concentração de Íons de Hidrogênio , Hidrólise , Peso Molecular , Temperatura
9.
Food Chem ; 347: 129000, 2021 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-33465690

RESUMO

In this study, the cypermethrin binding characteristics of lactic acid bacteria were investigated for the first time. Two strains, Lactobacillus plantarum RS60 and Pediococcus acidilactici D15, possessed the highest cypermethrin removal capacity and good tolerance to simulated digestive juices. They were employed for further studies on cypermethrin binding characteristics. 55.06% and 56.46% of cypermethrin were removed within 0.25 h by strains RS60 and D15, respectively. The effect of pH on binding capacity was negligible. Heat treatment enhanced cypermethrin binding rate. Moreover, inactive cells were capable of removing cypermethrin from fruit and vegetable juices, with over 60% cypermethrin reduction within 2 h. No adverse effect was found on the quality of juice during the biosorption process. Besides, these two strains also could bind other several pyrethroids and 3-phenoxybenzoic acid. These findings indicated that L. plantarum RS60 and P. acidilactici D15 may be useful to reduce cypermethrin in contaminated foods.


Assuntos
Lactobacillus plantarum/metabolismo , Pediococcus acidilactici/metabolismo , Piretrinas/metabolismo , Adsorção , Cromatografia Líquida de Alta Pressão , Digestão , Contaminação de Alimentos/análise , Sucos de Frutas e Vegetais/análise , Concentração de Íons de Hidrogênio , Inseticidas/análise , Inseticidas/isolamento & purificação , Inseticidas/metabolismo , Lactobacillus plantarum/química , Pediococcus acidilactici/química , Piretrinas/análise , Piretrinas/isolamento & purificação , Temperatura
10.
PLoS One ; 16(1): e0245803, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33481873

RESUMO

Pyrethroid resistance was first reported in 2013 for the navel orangeworm, Amyelois transitella, but the genetic underpinnings of pyrethroid resistance are unknown. We investigated the role of cytochrome P450 monooxygenases (P450s) belonging to the CYP3 and CYP4 clans using colonies derived from individuals collected in 2016 from almond orchards in two counties. One colony (ALM) originated from an almond orchard in Madera County with no reported pyrethroid resistance and the second colony (R347) originated from the same Kern County orchard where pyrethroid resistance was first reported. We used high-throughput quantitative real-time PCR (qRT-PCR) analyses of 65 P450s in the CYP3 and CYP4 clans of A. transitella to identify P450s induced by bifenthrin and associated with pyrethroid resistance. Nine P450s were constitutively overexpressed in R347 compared to ALM, including CYP6AE54 (11.7-fold), belonging to a subfamily associated with metabolic pesticide detoxification in Lepidoptera and CYP4G89 (33-fold) belonging to a subfamily associated with cuticular hydrocarbon (CHC) synthesis and resistance via reduced pesticide penetrance. Cuticular hydrocarbons analysis revealed that R347 produced twice as many total CHCs in the egg and adult stages as ALM. Topical toxicity bioassays for R347 determined that egg mortality was reduced at low bifenthrin concentrations and larval mortality was reduced at high concentrations of bifenthrin compared to ALM. Our discovery of both changes in metabolism and production of CHCs for R347 have implications for the possible decreased efficacy of other classes of insecticide used to control this insect. The threat of widespread pyrethroid resistance combined with the potential for cross-resistance to develop through the mechanism of reduced penetrance warrants developing management strategies that facilitate insecticide passage across the cuticle.


Assuntos
Sistema Enzimático do Citocromo P-450/genética , Sistema Enzimático do Citocromo P-450/metabolismo , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Inativação Metabólica , Resistência a Inseticidas/genética , Mariposas/genética , Piretrinas/metabolismo , Animais , Larva/genética , Piretrinas/toxicidade
11.
Ecotoxicol Environ Saf ; 209: 111861, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33383338

RESUMO

Soybean pod borer (Leguminivora glycinivorella) is an important pest in soybean production, and chemical pesticides was major way for prevention. However, it is difficult to balance the efficiency and safety of pesticide application. In this paper, we evaluated safety and effectiveness of common insecticides (chlorpyrifos and lambda-cyhalothrin) on soybean from three aspects, including distribution, dissipation and control effect, around three major soybean production area (Anhui, Jilin and Shandong) in China. For chlorpyrifos, the initial deposition of each position (upper leaf, lower leaf, upper stem, lower stem, soybean and root) was determinated for 0.23 mg/kg to 70.7 mg/kg, and the half-lifes ranged from 1.96 days to 5.36 days. For lambda-cyhalothrin, the initial deposition of the position was determinated for 0.10 mg/kg to 2.54 mg/kg, and the half-lifes ranged from 2.45 days to 7.26 days. We found that the target insecticides were major deposition and faster degradation in upper stem and leaf. Through comparing the relationship between field control effect and residue, it can be suggested that 40% chlorpyrifos EC and 2.5% lambda-cyhalothrin WE should be sprayed at 600 g a.i./ha and 5.63 g a.i./ha for SPB prevention. This study enhanced our understanding of distribution, dissipation and relationship between residue and control effect. The results provided data support for guiding the precise and scientific application of chemical insecticides on soybean.


Assuntos
Clorpirifos/metabolismo , Inseticidas/metabolismo , Mariposas , Nitrilas/metabolismo , Piretrinas/metabolismo , Soja/metabolismo , Animais , China , Inseticidas/análise , Praguicidas/metabolismo , Folhas de Planta/química
12.
Xenobiotica ; 51(1): 40-50, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32757971

RESUMO

The kinetics of metabolism of deltamethrin (DLM) and cis- and trans-permethrin (CPM and TPM) was studied in male Sprague-Dawley rat and human liver microsomes. DLM metabolism kinetics was also studied in isolated rat hepatocytes, liver microsomes and cytosol. Apparent intrinsic clearance (CLint) values for the metabolism of DLM, CPM and TPM by cytochrome P450 (CYP) and carboxylesterase (CES) enzymes in rat and human liver microsomes decreased with increasing microsomal protein concentration. However, when apparent CLint values were corrected for nonspecific binding to allow calculation of unbound (i.e., corrected) CLint values, the unbound values did not vary greatly with microsomal protein concentration. Unbound CLint values for metabolism of 0.05-1 µM DLM in rat liver microsomes (CYP and CES enzymes) and cytosol (CES enzymes) were not significantly different from rates of DLM metabolism in isolated rat hepatocytes. This study demonstrates that the nonspecific binding of these highly lipophilic compounds needs to be taken into account in order to obtain accurate estimates of rates of in vitro metabolism of these pyrethroids. While DLM is rapidly metabolised in vitro, the hepatocyte membrane does not appear to represent a barrier to the absorption and hence subsequent hepatic metabolism of this pyrethroid.


Assuntos
Citosol/metabolismo , Fígado/metabolismo , Permetrina/metabolismo , Animais , Carboxilesterase/metabolismo , Sistema Enzimático do Citocromo P-450/metabolismo , Hepatócitos/metabolismo , Humanos , Cinética , Masculino , Microssomos Hepáticos/metabolismo , Nitrilas/metabolismo , Piretrinas/metabolismo , Ratos , Ratos Sprague-Dawley
13.
J Agric Food Chem ; 68(50): 14988-14995, 2020 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-33287534

RESUMO

The aim of this study was to monitor the degradation of three insecticides licensed for the control of cabbage moths during the 14-day fermentation period of sauerkraut samples. The hypothesis of this study is that the different sauerkraut fermentation processes could affect the degradation of applied insecticides. For this purpose, the fresh cabbage leaves contaminated with (λ-cyhalothrin, malathion, and chlorpyrifos-methyl) were left for fermentation with and without (natural) starter addition (Lactobacillus plantarum 112), and vacuum-packed as a control under laboratory conditions. The pH values and microbial growth were periodically monitored in sauerkraut samples during the fermentation period. During this time, the insecticide residues were determined in control and treatment samples using LC-MS-MS. In control samples, the degradation of chlorpyrifos-methyl and malathion was higher with rates of 69 and 98%, respectively, compared with the sauerkraut samples (12 and 59%; 31 and 34%, respectively) 14 days after the insecticide application. At the end of fermentation (14 d), no significant reduction in λ-cyhalothrin was detected in both treatments and control (13-19% reduction). The current study demonstrated that the presence of the lactic acid bacteria in the sauerkraut fermentation accelerated pH decline (below 4.0), and these fermentation conditions probably decelerated the degradation of malathion and chlorpyrifos-methyl. The results showed that the stability of different insecticides varied during the same fermentation process.


Assuntos
Brassica/microbiologia , Inseticidas/metabolismo , Lactobacillus plantarum/metabolismo , Biodegradação Ambiental , Brassica/química , Brassica/metabolismo , Contagem de Colônia Microbiana , Fermentação , Contaminação de Alimentos/análise , Microbiologia de Alimentos , Inseticidas/química , Lactobacillus plantarum/crescimento & desenvolvimento , Malation/química , Malation/metabolismo , Nitrilas/química , Nitrilas/metabolismo , Piretrinas/química , Piretrinas/metabolismo
14.
Genes (Basel) ; 11(11)2020 11 05.
Artigo em Inglês | MEDLINE | ID: mdl-33167550

RESUMO

Pyrethroid resistance in major malaria vectors such as Anopheles funestus threatens malaria control efforts in Africa. Cytochrome P450-mediated metabolic resistance is best understood for CYP6P9 genes in southern Africa in An. funestus. However, we do not know if this resistance mechanism is spreading across Africa and how it relates to broader patterns of gene flow across the continent. Nucleotide diversity of the CYP6P9a gene and the diversity pattern of five gene fragments spanning a region of 120 kb around the CYP6P9a gene were surveyed in mosquitoes from southern, eastern and central Africa. These analyses revealed that a Cyp6P9a resistance-associated allele has swept through southern and eastern Africa and is now fixed in these regions. A similar diversity profile was observed when analysing genomic regions located 34 kb upstream to 86 kb downstream of the CYP6P9a locus, concordant with a selective sweep throughout the rp1 locus. We identify reduced gene flow between southern/eastern Africa and central Africa, which we hypothesise is due to the Great Rift Valley. These potential barriers to gene flow are likely to prevent or slow the spread of CYP6P9-based resistance mechanism to other parts of Africa and would to be considered in future vector control interventions such as gene drive.


Assuntos
Anopheles/genética , Família 6 do Citocromo P450/genética , Resistência a Inseticidas/genética , África/epidemiologia , África Oriental/epidemiologia , Alelos , Animais , Sistema Enzimático do Citocromo P-450/genética , Família 6 do Citocromo P450/metabolismo , Fluxo Gênico/genética , Genômica , Proteínas de Insetos/genética , Insetos Vetores , Inseticidas/farmacologia , Malária/transmissão , Mosquitos Vetores/genética , Polimorfismo Genético/genética , Piretrinas/metabolismo , Piretrinas/farmacologia
15.
Insect Biochem Mol Biol ; 127: 103486, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33069773

RESUMO

The cotton bollworm P450s of the clustered CYP6AE subfamily share high sequence identities but differ dramatically in their capacity to metabolize xenobiotics, especially esfenvalerate. Among them, CYP6AE17 has the highest sequence identity with CYP6AE18 but shows ~7-fold higher metabolic efficiency. CYP6AE11 is most active towards esfenvalerate but CYP6AE20 is inactive even though the enzymes share 54.8% sequence identity. Sequence analysis revealed the SRS1 (Substrate Recognition Site) and SRS6 between CYP6AE17 and CYP6AE18, and SRS1 between CYP6AE11 and CYP6AE20 are the most variable among all six SRSs. In order to identify the key factors that underlie the observed catalytic difference, we exchanged these SRS sequences between two pairs of P450s and studied the activity of the resulting hybrid mutants or chimeras. In vitro metabolism showed that the CYP6AE17/18 chimeras had 2- and 14-fold decreased activities and the CYP6AE18/17 chimeras had 6- and 10-fold increased activities to esfenvalerate. Meanwhile, after exchanging SRS1 with each other, the CYP6AE11/20 chimera folded incorrectly but the CYP6AE20/11 chimera gained moderate activity to esfenvalerate. Molecular modelling showed that amino acids variants within SRS1 or SRS6 change the shape and chemical environment of the active sites, which may affect the ligand-binding interactions. These results indicate that the protein structure variation resulting from the sequence diversity of SRSs promotes the evolution of insect chemical defense and contributes to the development of insect resistance to pesticides.


Assuntos
Sistema Enzimático do Citocromo P-450/genética , Proteínas de Insetos/genética , Resistência a Inseticidas/genética , Inseticidas/metabolismo , Mariposas/genética , Nitrilas/metabolismo , Piretrinas/metabolismo , Sequência de Aminoácidos , Animais , Sistema Enzimático do Citocromo P-450/química , Sistema Enzimático do Citocromo P-450/metabolismo , Proteínas de Insetos/química , Proteínas de Insetos/metabolismo , Inseticidas/farmacologia , Mariposas/efeitos dos fármacos , Mariposas/metabolismo , Nitrilas/farmacologia , Piretrinas/farmacologia , Alinhamento de Sequência
16.
J Agric Food Chem ; 68(45): 12585-12594, 2020 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-33107730

RESUMO

The codling moth, Cydia pomonella (L.), is a quarantine pest of global significance impacting pome fruits and walnuts. It has evolved resistance to many commonly used insecticides including λ-cyhalothrin. Glutathione S-transferases (GSTs) are multifunctional enzymes playing a crucial role in the detoxification of insecticides in insects. However, the role of specific GST gene in λ-cyhalothrin resistance in C. pomonella is unclear. In this study, we identified three sigma-class genes (CpGSTs1, CpGSTs2, and CpGSTs3). These genes were ubiquitously expressed at all developmental stages, and of these, the expression level of CpGSTs2 in the larval stage was significantly higher than in the egg, pupal, and adult stages. Moreover, CpGSTs2 was predominantly expressed in the fat body while lower levels in the cuticle. In addition to exposure of larvae to LD10 of λ-cyhalothrin elevating the expression level of CpGSTs2, mRNA levels of CpGSTs2 in a field population (ZW_R) from northeast China, which has developed moderate level resistance to λ-cyhalothrin, was significantly higher than that of susceptible strains. In vitro inhibition assays demonstrated that λ-cyhalothrin inhibited the conjugating activities of recombinant CpGSTs2, and metabolic assays indicated that λ-cyhalothrin could be depleted by recombinant CpGSTs2. These results bring evidence for the involvement of CpGSTs2 in C. pomonella in resistance to λ-cyhalothrin.


Assuntos
Glutationa Transferase/metabolismo , Proteínas de Insetos/metabolismo , Resistência a Inseticidas , Inseticidas/metabolismo , Mariposas/efeitos dos fármacos , Mariposas/enzimologia , Nitrilas/metabolismo , Piretrinas/metabolismo , Animais , Glutationa Transferase/química , Glutationa Transferase/genética , Proteínas de Insetos/química , Proteínas de Insetos/genética , Inseticidas/química , Inseticidas/farmacologia , Larva/efeitos dos fármacos , Larva/genética , Larva/crescimento & desenvolvimento , Larva/metabolismo , Mariposas/genética , Mariposas/crescimento & desenvolvimento , Nitrilas/farmacologia , Piretrinas/farmacologia
17.
Sci Rep ; 10(1): 16232, 2020 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-33004954

RESUMO

Fenazaquin, pyridaben, tolfenpyrad and fenpyroximate are Complex I inhibitors offering a new mode of action for insecticidal malaria vector control. However, extended exposure to pyrethroid based products such as long-lasting insecticidal nets (LLINs) has created mosquito populations that are largely pyrethroid-resistant, often with elevated levels of P450s that can metabolise and neutralise diverse substrates. To assess cross-resistance liabilities of the Complex I inhibitors, we profiled their susceptibility to metabolism by P450s associated with pyrethroid resistance in Anopheles gambiae (CYPs 6M2, 6P3, 6P4, 6P5, 9J5, 9K1, 6Z2) and An. funestus (CYP6P9a). All compounds were highly susceptible. Transgenic An. gambiae overexpressing CYP6M2 or CYP6P3 showed reduced mortality when exposed to fenpyroximate and tolfenpyrad. Mortality from fenpyroximate was also reduced in pyrethroid-resistant strains of An. gambiae (VK7 2014 and Tiassalé 13) and An. funestus (FUMOZ-R). P450 inhibitor piperonyl butoxide (PBO) significantly enhanced the efficacy of fenpyroximate and tolfenpyrad, fully restoring mortality in fenpyroximate-exposed FUMOZ-R. Overall, results suggest that in vivo and in vitro assays are a useful guide in the development of new vector control products, and that the Complex I inhibitors tested are susceptible to metabolic cross-resistance and may lack efficacy in controlling pyrethroid resistant mosquitoes.


Assuntos
Anopheles/enzimologia , Sistema Enzimático do Citocromo P-450/metabolismo , Complexo I de Transporte de Elétrons/antagonistas & inibidores , Resistência a Inseticidas , Inseticidas/metabolismo , Piretrinas/metabolismo , Animais , Animais Geneticamente Modificados , Anopheles/efeitos dos fármacos , Anopheles/genética , Anopheles/metabolismo , Cromatografia Líquida de Alta Pressão , Sistema Enzimático do Citocromo P-450/genética , Feminino
18.
Chemosphere ; 254: 126779, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32957265

RESUMO

Pyrethroids are a class of highly effective, broad-spectrum, less toxic, biodegradable synthetic pesticides. However, despite the extremely wide application of pyrethroids, there are many problems, such as insecticide resistance, lethal/sub-lethal toxicity to mammals, aquatic organisms or other beneficial organisms. The objectives of this review were to cover the main structures, synthesis, steroisomers, mechanisms of action, anti-mosquito activities, resistance, photodegradation and toxicities of pyrethroids. That was to provide a reference for synthesizing or screening novel pyrethroids with low insecticide resistance and low toxicity to beneficial organisms, evaluating the environmental pollution of pyrethroids and its metabolites. Besides, pyrethroids are mainly used for the control of vectors such as insects, and the non-target organisms are mammals, aquatic organisms etc. While maintaining the insecticidal activity is important, its toxic effects on non-target organisms should be also considered. Pyrethroid resistance is present not only in insect mosquitoes but also in environmental microorganisms, which results in anti-pyrethroids resistance (APR) strains. Besides, photodegradation product dibenzofurans is harmful to mammals and environment. Additionally, pyrethroid metabolites may have higher hormonal interference than the parents. Particularly, delivery of pyrethroids in nanoform can reduce the discharge of more toxic substances (such as organic solvents, etc.) to the environment.


Assuntos
Inseticidas/toxicidade , Piretrinas/toxicidade , Animais , Culicidae/efeitos dos fármacos , Resistência a Inseticidas/fisiologia , Inseticidas/química , Inseticidas/metabolismo , Mosquitos Vetores , Fotólise , Piretrinas/química , Piretrinas/metabolismo
19.
Xenobiotica ; 50(12): 1434-1442, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32672501

RESUMO

The metabolism of bifenthrin (BIF), ß-cyfluthrin (CYFL), λ-cyhalothrin (CYHA), cyphenothrin (CYPH) and esfenvalerate (ESF) was studied in liver microsomes, liver cytosol and plasma from male Sprague-Dawley rats aged 90, 21 and 15 days and from adult humans. Pyrethroid metabolism was also studied with some human expressed cytochrome P450 (CYP) and carboxylesterase (CES) enzymes. All five pyrethroids were metabolised by adult (90 day old) rat hepatic microsomal CYP and CES enzymes and by cytosolic CES enzymes. The pyrethroids were also metabolised by human liver microsomes and cytosol. Some species differences were observed. Pyrethroid metabolism by cytosolic CES enzymes contributes to the overall hepatic clearance of these compounds. CYFL, CYHA, CYPH and ESF were metabolised by rat plasma CES enzymes, whereas none of the pyrethroids were metabolised by human plasma. This study demonstrates that the ability of male rats to metabolise these pyrethroids by hepatic CYP and CES enzymes and plasma CES enzymes increases with age. In all instances, apparent intrinsic clearance values were lower in 15 than in 90 day old rats. All pyrethroids were metabolised by some of the human expressed CYP enzymes studied and apart from BIF were also metabolised by CES enzymes.


Assuntos
Carboxilesterase/metabolismo , Sistema Enzimático do Citocromo P-450/metabolismo , Piretrinas/metabolismo , Animais , Humanos , Masculino , Microssomos Hepáticos/metabolismo , Nitrilas/metabolismo , Ratos
20.
Chemosphere ; 257: 127162, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32485514

RESUMO

Deltamethrin is used widely in Eriocheir sinensis aquaculture to remove wild fish and parasites. The residual deltamethrin greatly affects the growth and quality of E. sinensis. In this study, the LC50 of deltamethrin against E. sinensis at 24, 48 and 96 h was determined to be 6.5, 5.0 and 2.8 µg/L, respectively. The enzyme activity and gene transcription of SOD, CAT, and PO in the hepatopancreas of E. sinensis after deltamethrin stimulation showed an increasing tendency, and these enzymes reached their maximum activities at 6-10 d. The MDA content accumulated with increased time of deltamethrin stress. After 15 d of deltamethrin stress, the hepatopancreas of E. sinensis was found to be damaged based on HE staining. These results showed that deltamethrin is highly toxic to E. sinensis. But the half-life of deltamethrin is long and mainly relies on biodegradation. To resolve the pollution of residual deltamethrin, a strain of deltamethrin-degrading bacteria, P-2, was isolated from the sediment of an E. sinensis culture pond. Through morphological observation, physiological and biochemical identification and 16S rDNA sequence analysis, we found that this strain belonged to Paracoccus sp. When the pH was 7, the substrate concentration was low, the inoculation amount was high, and the deltamethrin degradation effect of Paracoccus sp. P-2 was good. The deltamethrin residue in the hepatopancreas and muscle of E. sinensis decreased significantly when Paracoccus sp. P-2 was added at 6.0 × 108 CFU/L. The degradation efficiency of Paracoccus sp. P-2 in the hepatopancreas and muscle was more than 70%. These results showed that Paracoccus sp. P-2, the first deltamethrin-degrading bacterium in aquaculture, could be used to remove residual deltamethrin and improve the food safety of E. sinensis.


Assuntos
Braquiúros/fisiologia , Inseticidas/toxicidade , Nitrilas/toxicidade , Piretrinas/toxicidade , Animais , Aquicultura , Bactérias , Biodegradação Ambiental , Braquiúros/metabolismo , Hepatopâncreas/metabolismo , Inseticidas/metabolismo , Dose Letal Mediana , Nitrilas/metabolismo , Paracoccus/genética , Paracoccus/isolamento & purificação , Paracoccus/metabolismo , Polímeros , Piretrinas/metabolismo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...