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1.
Ecotoxicol Environ Saf ; 220: 112384, 2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-34091185

RESUMO

Flonicamid (N-cyanomethyl-4-trifluoromethylnicotinamide, FLO) is a new type of pyridinecarboxamide insecticide that exhibits particularly good efficacy in pest control. However, the extensive use of FLO in agricultural production poses environmental risks. Hence, its environmental behavior and degradation mechanism have received increasing attention. Microvirga flocculans CGMCC 1.16731 rapidly degrades FLO to produce the intermediate N-(4-trifluoromethylnicotinoyl) glycinamide (TFNG-AM) and the end acid metabolite 4-(trifluoromethyl) nicotinol glycine (TFNG). This bioconversion is mediated by the nitrile hydratase/amidase system; however, the amidase that is responsible for the conversion of TFNG-AM to TFNG has not yet been reported. Here, gene cloning, overexpression in Escherichia coli and characterization of pure enzymes showed that two amidases-AmiA and AmiB-hydrolyzed TFNG-AM to TFNG. AmiA and AmiB showed only 20-30% identity to experimentally characterized amidase signature family members, and represent novel amidases. Compared with AmiA, AmiB was more sensitive to silver and copper ions but more resistant to organic solvents. Both enzymes demonstrated good pH tolerance and exhibited broad amide substrate specificity. Homology modeling suggested that residues Asp191 and Ser195 may strongly affect the catalytic activity of AmiA and AmiB, respectively. The present study furthers our understanding of the enzymatic mechanisms of biodegradation of nitrile-containing insecticides and may aid in the development of a bioremediation agent for FLO.


Assuntos
Amidoidrolases/metabolismo , Inseticidas/metabolismo , Methylobacteriaceae/metabolismo , Niacinamida/análogos & derivados , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Biodegradação Ambiental , Regulação Bacteriana da Expressão Gênica/fisiologia , Regulação Enzimológica da Expressão Gênica , Inseticidas/química , Niacinamida/metabolismo
2.
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
3.
Ecotoxicol Environ Saf ; 217: 112247, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-33901780

RESUMO

Flupyradifurone, a novel butenolide insecticide, selectively targets insect nicotinic acetylcholine receptors (nAChRs), comparable to structurally different insecticidal chemotypes such as neonicotinoids and sulfoximines. However, flupyradifurone was shown in acute toxicity tests to be several orders of magnitude less toxic to western honey bee (Apis mellifera L.) than many other insecticides targeting insect nAChRs. The underlying reasons for this difference in toxicity remains unknown and were investigated here. Pharmacokinetic studies after contact application of [14C]flupyradifurone to honey bees revealed slow uptake, with internalized compound degraded into a few metabolites that are all practically non-toxic to honey bees in both oral and contact bioassays. Furthermore, receptor binding studies revealed a lack of high-affinity binding of these metabolites to honey bee nAChRs. Screening of a library of 27 heterologously expressed honey bee cytochrome P450 enzymes (P450s) identified three P450s involved in the detoxification of flupyradifurone: CYP6AQ1, CYP9Q2 and CYP9Q3. Transgenic Drosophila lines ectopically expressing CYP9Q2 and CYP9Q3 were significantly less susceptible to flupyradifurone when compared to control flies, confirming the importance of these P450s for flupyradifurone metabolism in honey bees. Biochemical assays using the fluorescent probe substrate 7-benzyloxymethoxy-4-(trifluoromethyl)-coumarin (BOMFC) indicated a weak, non-competitive inhibition of BOMFC metabolism by flupyradifurone. In contrast, the azole fungicides prochloraz and propiconazole were strong nanomolar inhibitors of these flupyradifurone metabolizing P450s, explaining their highly synergistic effects in combination with flupyradifurone as demonstrated in acute laboratory contact toxicity tests of adult bees. Interestingly, the azole fungicide prothioconazole is only slightly synergistic in combination with flupyradifurone - an observation supported by molecular P450 inhibition assays. Such molecular assays have value in the prediction of potential risks posed to bees by flupyradifurone mixture partners under applied conditions. Quantitative PCR confirmed the expression of the identified P450 genes in all honey bee life-stages, with highest expression levels observed in late larvae and adults, suggesting honey bees have the capacity to metabolize flupyradifurone across all life-stages. These findings provide a biochemical explanation for the low intrinsic toxicity of flupyradifurone to honey bees and offer a new, more holistic approach to support bee pollinator risk assessment by molecular means.


Assuntos
4-Butirolactona/análogos & derivados , Abelhas/fisiologia , Fungicidas Industriais/toxicidade , Inseticidas/toxicidade , Piridinas/toxicidade , 4-Butirolactona/toxicidade , Animais , Sistema Enzimático do Citocromo P-450/metabolismo , Imidazóis , Inseticidas/metabolismo , Neonicotinoides , Toxicogenética , Triazóis
4.
Ecotoxicol Environ Saf ; 212: 112001, 2021 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-33545407

RESUMO

Neonicotinoid insecticides (NEOs) are widely used around the world. The distribution of NEOs in paired saliva and periodontal blood samples was not previously documented in China. In this study, the concentrations of six NEOs and three corresponding metabolites were measured in 188 paired saliva and periodontal blood samples collected from South China. NEOs and their metabolites were frequently detected (68-94%) in paired saliva and periodontal blood, with median levels of 0.01-0.99 ng/mL. 1-Methyl-3-(tetrahydro-3-furylmethyl) urea was the most predominant NEO in paired saliva (39%) and periodontal blood (42%). Gender-related differences in NEOs and their metabolite concentrations were found: males showed lower levels than females. We calculated the concentration ratios between saliva and periodontal blood (S/PB ratios), and found that the median S/PB ratios of NEO and their metabolites were higher than 1, indicating that NEOs and their metabolites were easily excreted via saliva. 8-Hydroxy-2'-deoxyguanosine (8-OHdG) was measured in paired saliva and periodontal blood as a marker of oxidative stress. 8-OHdG concentrations in saliva and periodontal blood were significantly and positively correlated (p < 0.05) with the concentrations of most NEOs and their metabolites in saliva and periodontal blood samples. These findings indicated that exposure to NEOs and their metabolites is associated with oxidative stress. This study is the first to report NEOs and their metabolites in paired saliva and periodontal blood samples collected from South China.


Assuntos
Inseticidas/sangue , Neonicotinoides/sangue , Estresse Oxidativo/efeitos dos fármacos , Periodonto/irrigação sanguínea , Saliva/química , 8-Hidroxi-2'-Desoxiguanosina/análise , Adolescente , Adulto , Biomarcadores/análise , Criança , China , Feminino , Humanos , Inseticidas/análise , Inseticidas/metabolismo , Masculino , Pessoa de Meia-Idade , Neonicotinoides/análise , Neonicotinoides/metabolismo , Adulto Jovem
5.
Proc Natl Acad Sci U S A ; 118(1)2021 01 05.
Artigo em Inglês | MEDLINE | ID: mdl-33443170

RESUMO

Invasive organisms pose a global threat and are exceptionally difficult to eradicate after they become abundant in their new habitats. We report a successful multitactic strategy for combating the pink bollworm (Pectinophora gossypiella), one of the world's most invasive pests. A coordinated program in the southwestern United States and northern Mexico included releases of billions of sterile pink bollworm moths from airplanes and planting of cotton engineered to produce insecticidal proteins from the bacterium Bacillus thuringiensis (Bt). An analysis of computer simulations and 21 y of field data from Arizona demonstrate that the transgenic Bt cotton and sterile insect releases interacted synergistically to reduce the pest's population size. In Arizona, the program started in 2006 and decreased the pest's estimated statewide population size from over 2 billion in 2005 to zero in 2013. Complementary regional efforts eradicated this pest throughout the cotton-growing areas of the continental United States and northern Mexico a century after it had invaded both countries. The removal of this pest saved farmers in the United States $192 million from 2014 to 2019. It also eliminated the environmental and safety hazards associated with insecticide sprays that had previously targeted the pink bollworm and facilitated an 82% reduction in insecticides used against all cotton pests in Arizona. The economic and social benefits achieved demonstrate the advantages of using agricultural biotechnology in concert with classical pest control tactics.


Assuntos
Toxinas de Bacillus thuringiensis/genética , Bacillus thuringiensis/genética , Erradicação de Doenças/métodos , Gossypium/genética , Mariposas/genética , Controle Biológico de Vetores/métodos , Animais , Animais Geneticamente Modificados , Arizona , Toxinas de Bacillus thuringiensis/metabolismo , Simulação por Computador , Erradicação de Doenças/economia , Infertilidade/genética , Inseticidas/metabolismo , México , Mariposas/crescimento & desenvolvimento , Mariposas/patogenicidade , Plantas Geneticamente Modificadas , Sudoeste dos Estados Unidos
6.
Int J Biol Macromol ; 172: 263-269, 2021 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-33453254

RESUMO

In insects, the cytochrome P450 CYP6B family plays key roles in the detoxification of toxic plant substances. However, the function of CYP6 family genes in degrading plant toxicants in Tribolium castaneum, an extremely destructive global storage pest, have yet to be elucidated. In this study, a T. castaneum CYP gene, TcCYP6BQ7, was characterized. TcCYP6BQ7 expression was significantly induced after exposure to essential oil of the plant Artemisia vulgaris (EOAV). Spatiotemporal expression profiling revealed that TcCYP6BQ7 expression was higher in larval and adult stages of T. castaneum than in other developmental stages, and that TcCYP6BQ7 was predominantly expressed in the brain and hemolymph from the late larval stage. TcCYP6BQ7 silencing by RNA interference increased larvae mortality in response to EOAV from 49.67% to 71.67%, suggesting that this gene is associated with plant toxicant detoxification. Combined results from this study indicate that the CYP6 family gene TcCYP6BQ7 likely plays a pivotal role in influencing the susceptibility of T. castaneum to plant toxicants. These findings may have implications for the development of novel therapeutics to control this agriculturally important pest.


Assuntos
Sistema Enzimático do Citocromo P-450/genética , Inseticidas/farmacologia , Larva/efeitos dos fármacos , Óleos Voláteis/farmacologia , Proteínas de Plantas/genética , Pupa/efeitos dos fármacos , Tribolium/efeitos dos fármacos , Animais , Artemisia/química , Artemisia/metabolismo , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Sistema Enzimático do Citocromo P-450/metabolismo , Feminino , Regulação da Expressão Gênica , Hemolinfa/efeitos dos fármacos , Hemolinfa/metabolismo , Inseticidas/isolamento & purificação , Inseticidas/metabolismo , Larva/genética , Larva/crescimento & desenvolvimento , Larva/metabolismo , Longevidade/efeitos dos fármacos , Longevidade/genética , Masculino , Óleos Voláteis/isolamento & purificação , Óleos Voláteis/metabolismo , Proteínas de Plantas/antagonistas & inibidores , Proteínas de Plantas/metabolismo , Pupa/genética , Pupa/crescimento & desenvolvimento , Pupa/metabolismo , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Tribolium/genética , Tribolium/crescimento & desenvolvimento , Tribolium/metabolismo
7.
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
8.
PLoS Pathog ; 17(1): e1009199, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33465145

RESUMO

The insecticidal Cry11Aa and Cyt1Aa proteins are produced by Bacillus thuringiensis as crystal inclusions. They work synergistically inducing high toxicity against mosquito larvae. It was proposed that these crystal inclusions are rapidly solubilized and activated in the gut lumen, followed by pore formation in midgut cells killing the larvae. In addition, Cyt1Aa functions as a Cry11Aa binding receptor, inducing Cry11Aa oligomerization and membrane insertion. Here, we used fluorescent labeled crystals, protoxins or activated toxins for in vivo localization at nano-scale resolution. We show that after larvae were fed solubilized proteins, these proteins were not accumulated inside the gut and larvae were not killed. In contrast, if larvae were fed soluble non-toxic mutant proteins, these proteins were found inside the gut bound to gut-microvilli. Only feeding with crystal inclusions resulted in high larval mortality, suggesting that they have a role for an optimal intoxication process. At the macroscopic level, Cry11Aa completely degraded the gastric caeca structure and, in the presence of Cyt1Aa, this effect was observed at lower toxin-concentrations and at shorter periods. The labeled Cry11Aa crystal protein, after midgut processing, binds to the gastric caeca and posterior midgut regions, and also to anterior and medium regions where it is internalized in ordered "net like" structures, leading finally to cell break down. During synergism both Cry11Aa and Cyt1Aa toxins showed a dynamic layered array at the surface of apical microvilli, where Cry11Aa is localized in the lower layer closer to the cell cytoplasm, and Cyt1Aa is layered over Cry11Aa. This array depends on the pore formation activity of Cry11Aa, since the non-toxic mutant Cry11Aa-E97A, which is unable to oligomerize, inverted this array. Internalization of Cry11Aa was also observed during synergism. These data indicate that the mechanism of action of Cry11Aa is more complex than previously anticipated, and may involve additional steps besides pore-formation activity.


Assuntos
Aedes/efeitos dos fármacos , Toxinas de Bacillus thuringiensis/metabolismo , Sinergismo Farmacológico , Endotoxinas/metabolismo , Trato Gastrointestinal/efeitos dos fármacos , Proteínas Hemolisinas/metabolismo , Inseticidas/metabolismo , Larva/efeitos dos fármacos , Aedes/metabolismo , Animais , Toxinas de Bacillus thuringiensis/genética , Toxinas de Bacillus thuringiensis/toxicidade , Proteínas de Bactérias , Endotoxinas/genética , Endotoxinas/toxicidade , Trato Gastrointestinal/metabolismo , Proteínas Hemolisinas/genética , Proteínas Hemolisinas/toxicidade , Inseticidas/toxicidade , Larva/metabolismo , Ligação Proteica
9.
Protein Pept Lett ; 28(2): 131-139, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-32586243

RESUMO

BACKGROUND: Vip3Aa is a vegetative insecticidal protein produced by Bacillus thuringiensis. The protein is produced as an 88-kDa protoxin that could be processed by insect gut proteases into a 22-kDa N-terminal and a 66-kDa C-terminal fragments. The C-terminal part could bind to a specific receptor while the N-terminal part is required for toxicity and structural stability. OBJECTIVE: To demonstrate the antagonistic effect of truncated fragments on the insecticidal activity of the full-length Vip3Aa. METHODS: The full-length protein (Vip3Aa), a 66-kDa C-terminal fragment (Vip3Aa-D199) and a predicted carbohydrate binding module (CBM) were produced in Escherichia coli. Purified proteins were mixed at different ratios and fed to Spodoptera litura and Spodoptera exigua larvae. Mortality was recorded and compared between larvae fed with individual toxin and mixtures of the full-length and truncated toxins. RESULTS: Production level of the Vip3Aa-D199 was significantly decreased comparing to that of the full-length protein. Vip3Aa-D199 and CBM fragment were not toxic to insect larvae whereas Vip3Aa showed high toxicity with LC50 about 200 ng/cm2. Feeding the larvae with mixtures of the Vip3Aa and Vip3Aa-D199 at different ratios revealed antagonistic effect of the Vip3Aa-D199 on the toxicity of Vip3Aa. Results showed that the lethal time (LT 50 and LT 95) of larvae fed the mixture toxins was longer than those fed the Vip3Aa alone. In addition, a CBM fragment could inhibit toxicity of the full-length Vip3Aa. CONCLUSION: Our results demonstrated that the Vip3Aa-D199 and a CBM fragment could complete for the membrane binding thus rendering activity of the full-length Vip3Aa.


Assuntos
Bacillus thuringiensis/metabolismo , Proteínas de Bactérias/toxicidade , Interações Hospedeiro-Patógeno/efeitos dos fármacos , Inseticidas/toxicidade , Larva/efeitos dos fármacos , Spodoptera/efeitos dos fármacos , Animais , Proteínas de Bactérias/metabolismo , Inseticidas/metabolismo , Larva/crescimento & desenvolvimento , Larva/metabolismo , Controle Biológico de Vetores , Spodoptera/crescimento & desenvolvimento , Spodoptera/metabolismo
10.
J Appl Microbiol ; 130(5): 1571-1581, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33030814

RESUMO

AIMS: This study evaluates flonicamid biotransformation ability of Aminobacter sp. CGMCC 1.17253 and the enzyme catalytic mechanism involved. METHODS AND RESULTS: Flonicamid transformed by resting cells of Aminobacter sp. CGMCC 1.17253 was carried out. Aminobacter sp. CGMCC 1.17253 converts flonicamid into N-(4-trifluoromethylnicotinoyl) glycinamide (TFNG-AM). Aminobacter sp. CGMCC 1.17253 transforms 31·1% of the flonicamid in a 200 mg l-1 conversion solution in 96 h. Aminobacter sp. CGMCC 1.17253 was inoculated in soil, and 72·1% of flonicamid with a concentration of 0·21 µmol g-1 was transformed in 9 days. The recombinant Escherichia coli expressing Aminobacter sp. CGMCC 1.17253 nitrile hydratase (NHase) and purified NHase were tested for the flonicamid transformation ability, both of them acquired the ability to transform flonicamid into TFNG-AM. CONCLUSIONS: Aminobacter sp. CGMCC 1.17253 transforms flonicamid into TFNG-AM via hydration pathway mediated by cobalt-containing NHase. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report that bacteria of genus Aminobacter has flonicamid-transforming ability. This study enhances our understanding of flonicamid-degrading mechanism. Aminobacter sp. CGMCC 1.17253 has the potential for bioremediation of flonicamid pollution.


Assuntos
Hidroliases/metabolismo , Inseticidas/metabolismo , Niacinamida/análogos & derivados , Phyllobacteriaceae/metabolismo , Poluentes do Solo/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/isolamento & purificação , Proteínas de Bactérias/metabolismo , Biodegradação Ambiental , Biotransformação , Hidroliases/genética , Hidroliases/isolamento & purificação , Niacinamida/metabolismo , Phyllobacteriaceae/enzimologia , Phyllobacteriaceae/genética , Proteínas Recombinantes/genética , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo
11.
Food Chem ; 344: 128579, 2021 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-33199115

RESUMO

The absorption, distribution, metabolism and primary risk evaluation data of four neonicotinoids and two organophosphate insecticides in tea plant (Camellia sinensis L.) were compared. 22 neonicotinoid metabolites and 2 organophosphate metabolites were identified. The amount ratio of each neonicotinoid metabolite to its corresponding parent (M/P) was lower than 0.076 in the treated time. The organophosphates (omethoate and methamidophos) increased sharply, with M/Ps as high as 1.111 and 0.612. The risks evaluation of insecticides and their metabolites in treated leaves on day seven showed that the chronic risk was from the lowest 0.0759 (clothianidin) to highest 43.6409% (dimethoate), and the acute risk was highest 0.0370 for all targets. The calculated combined toxicity of leaves treated with acephate reached 1.5 folds in mature, 1.5 folds in tender leaves than no metabolites, and which of dimethoate were 2.1 folds in mature and 3.7 folds in tender leaves.


Assuntos
Camellia sinensis/química , Inseticidas/análise , Neonicotinoides/análise , Organofosfatos/análise , Camellia sinensis/metabolismo , Cromatografia Líquida de Alta Pressão , Humanos , Inseticidas/metabolismo , Neonicotinoides/química , Neonicotinoides/metabolismo , Nitrocompostos/química , Nitrocompostos/metabolismo , Organofosfatos/metabolismo , Folhas de Planta/química , Folhas de Planta/metabolismo , Raízes de Plantas/química , Raízes de Plantas/metabolismo , Caules de Planta/química , Caules de Planta/metabolismo , Risco , Espectrometria de Massas em Tandem , Tiametoxam/análise , Tiametoxam/metabolismo
12.
J Environ Sci Health B ; 56(2): 122-131, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33283619

RESUMO

Flonicamid is a novel, selective, systemic pyridinecarboxamide insecticide that effectively controls hemipterous pests. Sulfoxaflor, a sulfoximine insecticide, effectively controls many sap-feeding insect pests. Ensifer meliloti CGMCC 7333 transforms flonicamid into N-(4-trifluoromethylnicotinoyl) glycinamide (TFNG-AM). Resting cells of E. meliloti CGMCC 7333 (optical density at 600 nm [OD600] = 5) transformed 67.20% of the flonicamid in a 200-mg/L solution within 96 h. E. meliloti CGMCC 7333 transforms sulfoxaflor into N-(methyl(oxido){1-[6-(trifluoromethyl) pyridin-3-yl] ethyl}-k4-sulfanylidene) urea (X11719474). E. meliloti CGMCC 7333 resting cells (OD600 = 5) transformed 89.36% of the sulfoxaflor in a 200 mg/L solution within 96 h. On inoculating 2 mL of E. meliloti CGMCC 7333 (OD600 = 10) into soil containing 80 mg/kg flonicamid, 91.1% of the flonicamid was transformed within 9 d (half-life 2.6 d). On inoculating 2 mL of E. meliloti CGMCC 7333 (OD600 = 10) into soil containing 80 mg/kg sulfoxaflor, 83.9% of the sulfoxaflor was transformed within 9 d (half-life 3.4 d). Recombinant Escherichia coli harboring the E. meliloti CGMCC 7333 nitrile hydratase (NHase)-encoding gene and NHase both showed the ability to transform flonicamid or sulfoxaflor into their corresponding amides, TFNG-AM and X11719474, respectively. These findings may help develop a bioremediation agent for the elimination of flonicamid and sulfoxaflor contamination.


Assuntos
Inseticidas/metabolismo , Niacinamida/análogos & derivados , Piridinas/metabolismo , Sinorhizobium meliloti/metabolismo , Compostos de Enxofre/metabolismo , Biotransformação , Niacinamida/metabolismo
13.
Microbiol Res ; 242: 126642, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33191102

RESUMO

The nematode-bacterium pair Heterorhabditis indica-Photorhabdus akhurstii is a malleable model system to investigate mutualistic relations. A number of toxins produced by P. akhurstii allow the bacterium to kill the insect host. However, a few of these heterologously expressed toxins are orally active against different insects which possibly caused neglected attention to Photorhabdus toxins compared to Bt (Bacillus thuringiensis). In the current study, a functional subunit of orally active toxin complex (Tc) protein, TcaB (63 kDa), isolated from two strains of P. akhurstii namely IARI-SGHR2 and IARI-SGMS1, was tested for biological activity against Galleria mellonella. A force feeding-based administration of the toxin translated into LD50 values of 45.63-58.90 ng/g which was even lower compared to injection LD50 values (51.48-64.30 ng/g) at 48 h after inoculation. An oral uptake of 500 ng toxin caused extensive gut damage in G. mellonella during 6-24 h incubation period coupled with a gradual disruption of gut integrity leading to escape of TcaB into the hemocoel. This finding was supported by the cytotoxic and immune-stimulatory effect of TcaB in the insect hemocoel at 6-24 h after force feeding. The circulatory hemocyte numbers and cell viability was markedly reduced to 0.66-0.68 × 106 ml-1 and 49-52 %, respectively, in TcaB force fed insect at 24 h, compared to control (2.55 × 106 ml-1; 100 %). The hemolymph phenoloxidase (PO) activity was elevated by 10.2-fold in force fed larvae than control at 24 h. An in silico docking study revealed that TcaB putatively interacts with a number of G. mellonella receptor proteins in order to become a gut-active toxin. Present research reinforces the potential of gut-active Photorhabdus toxins for their inclusion in sustainable insect management tactics and strengthens the existing Bt-dominated management repository.


Assuntos
Toxinas Bacterianas/metabolismo , Toxinas Bacterianas/farmacologia , Inseticidas/metabolismo , Inseticidas/farmacologia , Photorhabdus/metabolismo , Animais , Bacillus thuringiensis/metabolismo , Proteínas de Bactérias , Agentes de Controle Biológico/metabolismo , Agentes de Controle Biológico/farmacologia , Epitélio/efeitos dos fármacos , Epitélio/microbiologia , Controle de Insetos , Insetos , Larva , Mariposas
14.
Artigo em Inglês | MEDLINE | ID: mdl-32979584

RESUMO

Neonicotinoid insecticides are used for agricultural and non-agricultural purposes worldwide. Pets are directly exposed to neonicotinoids in veterinary products and through environmental contamination. Cytochrome P450 (CYP) is among the most significant xenobiotic metabolizing enzymes that oxidizes several chemicals, including neonicotinoids. However, CYP activities and metabolite compositions of neonicotinoid metabolites are unknown in most domesticated pet species. Our objectives were to reveal the differences in metabolites of neonicotinoids (imidacloprid, clothianidin, and acetamiprid) and CYP activities among common pet species (cats and dogs), humans, and rats. The results indicated that the CYP-mediated neonicotinoid metabolism was different depending on species and each neonicotinoid. Among these four species, the kinetics of imidacloprid metabolism indicated that rats have the highest rate of oxidation of imidacloprid to 4OH-imidacloprid, while the greatest enzyme kinetics of imidacloprid metabolism to 5OH-imidacloprid were found in rats and humans. Clothianidin was rapidly metabolized to 1-methyl-3-nitroguanidine and dm-clothianidin in rats, but cats and humans showed the lowest formation of dm-clothianidin. CYP activities in metabolism of acetamiprid to dm-acetamiprid and N-acetyl-acetamiprid were determined to be significantly higher in humans compared to other species. However, further studies should be targeted at identifying the differences in hepatic metabolism of neonicotinoids in these species using recombinant CYP enzymes.


Assuntos
Sistema Enzimático do Citocromo P-450/metabolismo , Inseticidas , Neonicotinoides , Animais , Gatos , Cães , Humanos , Inseticidas/metabolismo , Inseticidas/toxicidade , Microssomos Hepáticos/metabolismo , Neonicotinoides/metabolismo , Neonicotinoides/toxicidade , Oxirredução , Ratos , Ratos Sprague-Dawley , Especificidade da Espécie
15.
Aquat Toxicol ; 231: 105715, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33341507

RESUMO

This study was conceptualized in order to assess the 96-h LC50 of bifenthrin (BF) in O. niloticus and also to measure the biochemical, behavioral, and molecular responses of the fish suchronically exposed to a sub-lethal concentration of the insecticide. The role of Petroselinum crispum essential oil (PEO) supplementation in mitigating the resulted neurotoxic insult was also investigated. The acute toxicity study revealed that the 96-h LC50 of BF is 6.81 µg/L, and varying degrees of behavioral changes were recorded in a dose-dependent manner. The subchronic study revealed reduction of dissolved oxygen and increased ammonia in aquaria of BF-exposed fish. Clinical signs revealed high degree of discomfort and aggressiveness together with reductions in survival rate and body weight gain. The levels of monoamines in brain, and GABA and amino acids in serum were reduced, together with decreased activities of Na+/K+-ATPase and acetylcholine esterases (AchE). The activities of antioxidant enzymes were also diminshed in the brain while oxdative damage and DNA breaks were elevated. Myeloperoxidase (MPO) activity in serum increased with overexpression of the pro-inflammatory cytokines in the brain tissue. BF also upregulated the expression of brain-stress related genes HSP70, Caspase-3 and P53. Supplemention of PEO to BF markedly abrogated the toxic impacts of the insecticide, specially at the high level. These findings demonstrate neuroprotective, antioxidant, genoprotective, anti-inflammatory and antiapoptic effects of PEO in BF-intoxicated fish. Based on these mechanistic insights of PEO, we recommend its use as an invaluable supplement in the fish feed.


Assuntos
Encéfalo/patologia , Ciclídeos/fisiologia , Suplementos Nutricionais , Inflamação/patologia , Óleos Voláteis/farmacologia , Petroselinum/química , Piretrinas/toxicidade , Acetilcolinesterase/metabolismo , Aminoácidos/metabolismo , Animais , Antioxidantes/metabolismo , Comportamento Animal , Biomarcadores/metabolismo , Encéfalo/efeitos dos fármacos , Ciclídeos/crescimento & desenvolvimento , Citocinas/metabolismo , Dano ao DNA , Regulação da Expressão Gênica/efeitos dos fármacos , Inseticidas/metabolismo , Dose Letal Mediana , Neurotoxinas/toxicidade , Neurotransmissores/metabolismo , Estresse Oxidativo/efeitos dos fármacos , ATPase Trocadora de Sódio-Potássio/metabolismo , Análise de Sobrevida , Poluentes Químicos da Água/toxicidade , Qualidade da Água , Ácido gama-Aminobutírico/metabolismo
16.
Chemosphere ; 262: 128388, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33182095

RESUMO

Arbitrary use of insecticides in agricultural practices cause severe environmental hazard that adversely affects the growth and productivity of edible crops. Considering theses, the aim of the present study was to evaluate the toxicological potential of two neonicotinoid insecticides, imidacloprid (IMID) and thiamethoxam (THIA) using chickpea as a test crop. Application of insecticides at three varying doses revealed a gradual decrease in biological performance of chickpea plants which however, varied noticeably among insecticides and their doses. Significant (P ≤ 0.05) decline in germination efficiency, length of plant organs under in vitro condition was observed in a dose related manner. Among insecticides, 300 µgIMIDkg-1 (3X dose) maximally and significantly (P ≤ 0.05) inhibited germination efficiency, vigor index, length, dry matter accumulation, photosynthetic pigment formation, nodule volume and mass, nutrient uptake, grain yield and protein over untreated control. In contrast, 75 µgTHIAkg-1 (3X dose) considerably declined the leghaemoglobin content, shoot phosphorus and root nitrogen. Enhanced expression of stress biomarkers including proline, malondialdehyde (MDA), and antioxidant defence enzymes was noticed in the presence of insecticides. For instance, at 3X IMID, shoot proline, MDA, ascorbate peroxidase (APX), guaiacol peroxidase (GPX) and peroxidase (POD) were increased significantly (P ≤ 0.05) by 66%, 81%, 36% and 35%, respectively. Additionally, electrolyte leakage was maximally (77%) increased at 3X dose of IMID, whereas, H2O2 in foliage was maximally accumulated (0.0156 µ moles min-1 g-1 fw) at 3X dose of THIA which was 58% greater than untreated foliage. A clear distortion/damage in tip and surface of roots and ultrastructural deformation in xylem and phloem of plant tissues as indication of insecticidal phytotoxicity was observed under scanning electron microscope (SEM). For oxidative stress and cytotoxicity assessment, root tips were stained with a combination of acridine orange and propidium iodide, and Evan blue dyes and examined. Confocal laser scanning microscopic (CLSM) images of roots revealed a 10-fold and 13.5-fold increase in red and blue fluorescence when 3X IMID treated roots were assessed quantitatively. Conclusively, the present investigation recommends that a careful and protected approach should be adopted before the application of insecticides in agricultural ecosystems.


Assuntos
Cicer/fisiologia , Inseticidas/toxicidade , Neonicotinoides/toxicidade , Antioxidantes/metabolismo , Ascorbato Peroxidases/metabolismo , Cicer/enzimologia , Ecossistema , Germinação , Peróxido de Hidrogênio/metabolismo , Inseticidas/metabolismo , Malondialdeído/metabolismo , Nitrocompostos , Estresse Oxidativo , Peroxidase , Fotossíntese
17.
Chemosphere ; 263: 127928, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32835975

RESUMO

Imidacloprid (IMI) is a widely used neonicotinoid insecticide effective against sucking and some chewing insects. Translocation and metabolism of IMI in plants are related to food safety. In this study, 14C-labeled IMI was used to investigate its translocation, transformation, radioactive IMI metabolites and possible metabolic pathways in cabbage. The amount of IMI accumulated in the edible part of cabbage accounted for 80.3-95.4% of the applied amounts by foliar application. There was a tendency to transport from edible parts to inedible parts. The proportions of extractable IMI decreased gradually from 92.4% to 83.0% in edible parts, greater than that in inedible parts over the experiment (0-19 days), while the bound residues showed an opposite trend. The half-life of IMI was determined as 33.0 and 63.0 days in the edible parts and whole plant, respectively. Five radioactive components including the parent IMI were detected by HPLC-LSC. The relative content of M1 was less than 0.01 mg kg-1, which was not required to identify according to the metabolic scheme proposed by the US Environmental Protection Agency. The metabolites N-nitro(1-6-chloro-3-pyridylmethyl)-4,5-dihydroxyimidazol-2-imine (M2), N-nitro(1-6-chloro-3-pyridylmethyl)-4/5-hydroxyimidazole-2-imine (M3) and 1/3-(1-6-chloro-3-pyridylmethyl)-2,4-imidazodione (M4) were identified by LC-QTOF-MS. The primary metabolism of IMI in cabbage included hydrolysis and oxidation. The residue level and daily intake values of IMI in cabbage were estimated to be 0.033-0.078 mg kg-1 and 9.56-20.01 ng d-1 kg-1, respectively, which were far below the maximum residue level and allowable daily intake values.


Assuntos
Brassica/metabolismo , Inseticidas/metabolismo , Neonicotinoides/metabolismo , Nitrocompostos/metabolismo , Animais , Cromatografia Líquida de Alta Pressão , Imidazóis/metabolismo
18.
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
19.
Ecotoxicol Environ Saf ; 209: 111814, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33360286

RESUMO

Thiamethoxam (THM) and imidacloprid (IMI), are environmentally persistent neonicotinoid insecticides which have become increasingly favored in the past decade due to their specificity as insect neurotoxicants. However, neonicotinoids have been implicated as a potential contributing factor in Colony Collapse Disorder (CCD) which affects produce production on a global scale. The present study characterizes the bioremediation potential of six bacterial species: Pseudomonas fluorescens, Pseudomonas putida, Pseudomonas aeruginosa, Alcaligenes faecalis, Escherichia coli, and Streptococcus lactis. In Phase I, we evaluated the utilization of IMI or THM as the sole carbon or nitrogen source by P. fluorescens, P. putida, and P. aeruginosa. All three species were better able to utilize THM over IMI as their sole carbon or nitrogen source. Thus, further studies proceeded with THM only. In Phase II, we assessed the kinetics of THM removal from aqueous media by the six species. Significant (p < 0.0001) reductions in 70 mg/L THM concentration were observed for P. fluorescens (67%), P. putida (65%), P. aeruginosa (52%), and A. faecalis (39%) over the 24-day study period, and for E. coli (60%) and S. lactis (12%) over the 14-day study period. The THM removal by all species followed a first-order kinetic reaction. HPLC chromatograms of P. fluorescens, P. putida, and E. coli cultures revealed that as the area of the THM peak decreased over time, the area of an unidentified metabolite peak increased. In Phase III, we examined the effect of temperature on the transformation capacity of the bacterial species which was observed at 2 â„ƒ, 22 â„ƒ, and 30 â„ƒ. Maximal THM removal occurred at 30 °C for all bacterial species assessed. Identification of the metabolite is currently underway. If the metabolite is found to be less hazardous than THM, further testing will follow to evaluate the use of this bioremediation technique in the field.


Assuntos
Biodegradação Ambiental , Inseticidas/metabolismo , Neonicotinoides/metabolismo , Nitrocompostos/metabolismo , Tiametoxam/metabolismo , Animais , Escherichia coli/metabolismo , Inseticidas/análise , Inseticidas/toxicidade , Cinética , Neonicotinoides/toxicidade , Nitrocompostos/toxicidade , Oxazinas , Pseudomonas putida/metabolismo , Tiametoxam/toxicidade
20.
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
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