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1.
Pestic Biochem Physiol ; 159: 27-33, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31400781

RESUMO

Imidacloprid has been used to control one of most serious pests, Bemisia tabaci. However, B. tabaci has developed imidacloprid resistance mainly by over-expressing CYP6CM1. It was reported that imidacloprid-resistant B. tabaci showed no or low level of cross-resistance against dinotefuran. Here, we expressed CYP6CM1 variants using Sf9/baculovirus and/or Drosophila S2 cells and showed that CYP6CM1 variants metabolized imidacloprid but not dinotefuran. In addition, we demonstrated that imidacloprid and pymetrozine competed for a CYP6CM1 variant more efficiently than dinotefuran, using a luminescent substrate competition assay. These results suggest that lack of metabolic activity of CYP6CM1 variants against dinotefuran caused no or low level of cross-resistance.


Assuntos
Guanidinas/metabolismo , Guanidinas/farmacologia , Hemípteros/efeitos dos fármacos , Hemípteros/metabolismo , Inseticidas/metabolismo , Inseticidas/farmacologia , Neonicotinoides/metabolismo , Neonicotinoides/farmacologia , Nitrocompostos/metabolismo , Nitrocompostos/farmacologia , Animais , Hemípteros/genética , Proteínas de Insetos/genética , Proteínas de Insetos/metabolismo , Resistência a Inseticidas/genética , Triazinas/metabolismo , Triazinas/farmacologia
2.
World J Microbiol Biotechnol ; 35(7): 106, 2019 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-31267229

RESUMO

Xenorhabdus nematophila HB310 secreted the insecticidal protein toxin complex. Two chitinase genes, chi60 and chi70, were found in X. nematophila toxin complex locus. In order to clarify the function of two chitinases, chi60 and chi70 genes were cloned and expressed in Escherichia coli Transetta (DE3). As a result, we found that the Chi60 and Chi70 belonged to glycoside hydrolases (GH) family 18 with a molecular mass of 65 kDa and 78 kDa, respectively. When colloidal chitin was treated as the substrate, Chi60 and Chi70 were proved to have the highest enzymatic activity at pH 6.0 and 50 °C. Chi60 and Chi70 had obvious growth inhibition effect against the second larvae of Helicoverpa armigera with growth inhibiting rate of 81.99% and 90.51%. Chi70 had synergistic effect with the insecticidal toxicity of Bt Cry 1Ac, but the Chi60 had no synergistic effect with Bt Cry 1Ac. Chi60 and Chi70 showed antifungal activity against Alternaria brassicicola, Verticillium dahliae and Coniothyrium diplodiella. The results increased our understanding of the chitinases produced by X. nematophila and laid a foundation for further studies on the mechanism of the chitinases.


Assuntos
Antifúngicos/farmacologia , Quitinases/antagonistas & inibidores , Quitinases/genética , Quitinases/metabolismo , Xenorhabdus/metabolismo , Alternaria/efeitos dos fármacos , Animais , Ascomicetos/efeitos dos fármacos , Quitina/metabolismo , Quitinases/classificação , Clonagem Molecular , Sinergismo Farmacológico , Ensaios Enzimáticos , Estabilidade Enzimática , Escherichia coli/genética , Expressão Gênica , Glicosídeo Hidrolases/genética , Concentração de Íons de Hidrogênio , Inseticidas/metabolismo , Inseticidas/farmacologia , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Peso Molecular , Mariposas/efeitos dos fármacos , Mariposas/crescimento & desenvolvimento , Micotoxinas/genética , Micotoxinas/metabolismo , Filogenia , Domínios Proteicos , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Temperatura Ambiente , Verticillium/efeitos dos fármacos , Xenorhabdus/genética
3.
Microbiol Res ; 226: 41-47, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31284943

RESUMO

Myzus persicae Sulzer (Hemiptera: Aphididae), is a generalist cosmopolitan insect that infests more than 400 plant species of 40 different families and is one of the major pests infesting potato crops. It causes direct damage and also spread plant viruses. The intensive use of synthetic insecticide to control aphids has led to resistant populations. Therefore, there is a need to develop biopesticides for effective control that minimizes environmental hazards. The bacteria Bacillus amyloliquefaciens is recognized as a producer of a variety of bioactive compounds. The aim here was to evaluate the aphicidal effect of B. amyloliquefaciens strains, CBMDDrag3, PGPBacCA2, and CBMDLO3, and their metabolites on the mortality and fecundity of M. persicae. Cells suspensions, heat-killed cell suspensions, cell-free supernatants, or isolated lipopeptide fractions from B. amyloliquefaciens strains were offered to aphids through artificial diets. The isolated lipopeptide fractions composed mainly of kurstakins, surfactins, iturins, and fengycins, when were administrated through diets, had no aphicidal effect against M. persicae. However, aphids fed on diets with whole cell suspensions and its cell-free supernatant of all three bacteria strains resulted in 100% mortality of adult aphids and nymphs. Specially, B. amyloliquefaciens CBMDLO3, has an effective aphicidal effect on M. persicae, used both bacterial cells and their metabolites. Moreover, heat-killed cells of B. amyloliquefaciens CBMDLO3 also had aphicidal action, although the aphid mortality was lower than on diet with living bacteria. Therefore, these results propose that B. amyloliquefaciens, could function as a novel eco-friendly biopesticide for the control of M. persicae.


Assuntos
Afídeos/efeitos dos fármacos , Afídeos/microbiologia , Bacillus amyloliquefaciens/metabolismo , Controle Biológico de Vetores , Animais , Bacillus amyloliquefaciens/isolamento & purificação , Agentes de Controle Biológico/isolamento & purificação , Agentes de Controle Biológico/metabolismo , Agentes de Controle Biológico/farmacologia , Feminino , Controle de Insetos/métodos , Inseticidas/isolamento & purificação , Inseticidas/metabolismo , Inseticidas/farmacologia , Lipopeptídeos/isolamento & purificação , Lipopeptídeos/metabolismo , Lipopeptídeos/farmacologia , Doenças das Plantas/parasitologia , Doenças das Plantas/prevenção & controle
4.
Chem Biol Interact ; 310: 108756, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31325422

RESUMO

Human butyrylcholinesterase (BChE) is a widely distributed plasma enzyme. For decades, numerous research efforts have been directed at engineering BChE as a bioscavenger of organophosphorus insecticides and chemical warfare nerve agents. However, it has been a grand challenge to cost-efficiently produce BChE in large-scale. Recently reported studies have successfully designed a truncated BChE mutant (with amino-acid substitutions on 47 residues that are far away from the catalytic site), denoted as BChE-M47 for convenience, which can be expressed in E. coli without loss of its catalytic activity. In this study, we aimed to dimerize the truncated BChE mutant protein expressed in a prokaryotic system (E. coli) in order to further improve its thermal stability by introducing a pair of cross-subunit disulfide bonds to the BChE-M47 structure. Specifically, the E377C/A516C mutations were designed and introduced to BChE-M47, and the obtained new protein entity, denoted as BChE-M48, with a pair of cross-subunit disulfide bonds indeed exists as a dimer with significantly improved thermostability and unaltered catalytic activity and reactivity compared to BChE-M47. These results provide a new strategy for optimizing protein stability for production in a cost-efficient prokaryotic system. Our enzyme, BChE-M48, has a half-life of almost one week at a 37°C, suggesting that it could be utilized as a highly stable bioscavenger of OP insecticides and chemical warfare nerve agents.


Assuntos
Butirilcolinesterase/metabolismo , Engenharia de Proteínas/métodos , Butirilcolinesterase/genética , Substâncias para a Guerra Química/metabolismo , Dimerização , Estabilidade Enzimática , Escherichia coli/genética , Humanos , Inseticidas/metabolismo , Proteínas Mutantes/genética , Proteínas Mutantes/metabolismo , Compostos Organofosforados/metabolismo
5.
Pestic Biochem Physiol ; 157: 219-229, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31153472

RESUMO

Photorhabdus akhurstii can produce a variety of proteins that aid this bacterium and its mutualistic nematode vector, Heterorhabditis indica to kill the insect host. Herein, we characterized (by heterologously expressing in E. coli) an open reading frame (1713 bp) of the toxin complex protein, TcaB from P. akhurstii strains IARI-SGHR2 and IARI-SGMS1 and assessed its toxic effect on G. mellonella larvae. The intra-hemocoel injection of purified TcaB (molecular weight-63 kDa) caused fourth instar larval bodies to blacken and die with LD50 values of 67.25 (IARI-SGHR2) and 52.08 (IARI-SGMS1) ng per larva at 12 h. Additionally, oral administration of the toxin caused larval mortality with LD50 values of 709.55 (IARI-SGHR2) and 598.44 (IARI-SGMS1) ng per g diet per larva at 7 days post feeding. Injection of purified TcaB caused loss of viability of fourth instar G. mellonella hemocytes at 6 h post incubation; cells displayed morphological changes typical of apoptosis, including cell shrinkage, membrane blebbing, nuclear condensation and disintegration. Injection of TcaB also elevated the phenoloxidase activity in insect hemolymph which triggers an extensive immune response that potentially leads to larval death. Similar to other bacterial toxins TcaB possesses potent biological activity which may enable it to be used as an efficient agent for pest management.


Assuntos
Proteínas de Bactérias/farmacologia , Toxinas Bacterianas/farmacologia , Inseticidas/metabolismo , Inseticidas/farmacologia , Mariposas/efeitos dos fármacos , Photorhabdus/metabolismo , Animais , Proteínas de Bactérias/metabolismo , Toxinas Bacterianas/metabolismo , Hemócitos/efeitos dos fármacos , Photorhabdus/genética
6.
Pestic Biochem Physiol ; 157: 69-79, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31153479

RESUMO

Carboxylesterases (CarEs) are a major class of detoxification enzymes involved in insecticide resistance in various insect species. In this study, a novel CarE 001G was isolated from the cotton bollworm Helicoverpa armigera, one of the most destructive agricultural insect pests. The open reading frame of 001G has 2244 nucleotides and putatively encodes 747 amino acid residues. The deduced CarE possessed the highly conserved catalytic triads(Ser-Glu-His) and pentapeptide motifs (Gly-X-Ser-X-Gly), suggesting 001G is biologically active. The truncated 001G was successfully expressed in Escherichia coli, and the recombinant proteins were purified and tested. The enzyme kinetic assay showed the purified proteins could catalyze two model substrates, α-naphthyl acetate and ß-naphthyl acetate, with a kcat of 8.8 and 2.3 s-1, a Km of 9.6 and 16.2 µM, respectively. The inhibition study with pyrethroid, organophosphate and neonicotinoid insecticides showed different inhibition profile against the purified CarE. The HPLC assay demonstrated that the purified proteins were able to metabolize ß-cypermethrin, λ-cyhalothrin and fenvalerate insecticides, exhibiting respective specific activities of 1.7, 1.4 and 0.5 nM/min/mg protein. However, the purified proteins were not able to metabolize the chlorpyrifos, parathion-methyl, paraoxon-ethyl and imidacloprid. The modeling and docking analyses consistently demonstrated that the pyrethroid molecule fits snugly into the catalytic pocket of the CarE 001G. Collectively, our results suggest that 001G may play a role in pyrethroids detoxification in H. armigera.


Assuntos
Carboxilesterase/metabolismo , Inseticidas/metabolismo , Inseticidas/farmacologia , Mariposas/enzimologia , Mariposas/metabolismo , Animais , Carboxilesterase/genética , Mariposas/efeitos dos fármacos , Nitrilos/metabolismo , Nitrilos/farmacologia , Piretrinas/metabolismo , Piretrinas/farmacologia
7.
J Agric Food Chem ; 67(26): 7538-7546, 2019 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-31180663

RESUMO

Thiamethoxam (TMX) has already been proven to have a physiological effect in plant tissue or cell expect for the insecticidal activity. In our previous study, TMX was verified to be metabolized by tea cells in either a suspension culture or tea plant into several metabolites. Here, tea cell suspension cultures were treated for 45 days to investigate the metabolite effects in both the tea cells and the culture supernatants by nontargeted metabolomics. Using multivariate analysis (PCA and OPLS-DA), all treatment and control groups could be clearly separated. Inside the cells, 113 metabolites were found to be up-regulated while 122 were down-regulated, when compared with untreated cells. In the culture supernatant, there were 128 up-regulated and 35 down-regulated metabolites, compared to untreated cultures. KEGG searches revealed that the alanine, aspartate, and glutamate metabolic pathways were strongly affected by TMX metabolism within the tea cell. Molecular docking models showed that (i) 4-aminobutyrate aminotransferase may be related to the formation of 2-chloro-thiazole-5-carboxylic acid and (ii) 3'(2'),5'-bisphosphate nucleotidase may be able to interact with TMX. This study can help us to understand the interaction mechanism of pesticides with plant cells.


Assuntos
Camellia sinensis/química , Camellia sinensis/metabolismo , Inseticidas/metabolismo , Tiametoxam/metabolismo , Células Cultivadas , Inseticidas/química , Redes e Vias Metabólicas , Metabolômica , Simulação de Acoplamento Molecular , Tiametoxam/química
8.
Toxicol Lett ; 312: 173-180, 2019 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-31082524

RESUMO

Triflumuron (TFM) is a benzoylurea insecticide commonly used in Tunisian agriculture and around the world to control crop pests and flies as a promising alternative to conventional insecticides for its arthropod specificity and low toxicity. From the evidence available in animal models, it can be expected that the metabolism of TFM is catalyzed by cytochrome P450 (CYP) and esterases. However, no data are available on human metabolism of TFM with regards to phase I metabolism and CYP isoform specificity. Hence, this manuscript describes experimental investigations to underpin in vitro phase I TFM metabolism in human samples for the first time. TFM biotransformation by recombinant human CYPs was characterized, then human liver microsomes (HLM) and chemical specific inhibitors have been used to identify the relative contribution of CYPs and esterases. Our results showed that all CYP isoforms were able to metabolize TFM with different affinity and efficiency. The relative contribution based both on the kinetic parameters and the CYP hepatic content was 3A4 > >2C9 > 2C8 > 2A6 > 1A2 > 2B6 > 2D6 > 2C19 > 2C18 > 1A1 at low TFM concentration, whilst at high TFM concentration it was 1A2 > >2C9 = 3A4 = 2A6 > 2C19 > 2B6 = 2C8 > 2D6 > 1A1 > 2C18. Experiments with HLMs confirmed the involvement of the most relevant CYPs in the presence of specific chemical inhibitors with a catalytic efficiency (Cliapp) lower by an order of magnitude compared with recombinant enzymes. Esterases were also relevant to the overall TFM kinetics and metabolism, with catalytic efficiency higher than that of CYPs. It is foreseen that such isoform-specific information in humans will further support in silico models for the refinement of the human risk assessment of single pesticides or mixtures.


Assuntos
Benzamidas/metabolismo , Sistema Enzimático do Citocromo P-450/metabolismo , Inseticidas/metabolismo , Isoenzimas/metabolismo , Microssomos Hepáticos/metabolismo , Humanos
9.
J Agric Food Chem ; 67(21): 5922-5931, 2019 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-31067049

RESUMO

Neonicotinoid insecticide pollution in soil and water poses serious environmental risks. Microbial biodegradation is an important neonicotinoid insecticide degradation pathway in the environment. In this study, 70.0% of the acetamiprid in a 200 mg/L solution was degraded by actinomycetes Streptomyces canus CGMCC 13662 (isolated from soil) in 48 h, and the acetamiprid degradation half-life was 27.7 h. Acetamiprid was degraded to IM-1-2 (( E)-1-(1-(((6-chloropyridin-3-yl)methyl)(methyl) amino)ethylidene)urea) through hydrolysis of the cyanoimine moiety. Gene cloning and overexpression indicated that a novel nitrile hydratase with three unusual subunits (AnhD, AnhE, and AnhA) without accessory protein mediated IM-1-2 formation. The purified nitrile hydratase responsible for degrading acetamiprid had a Km of 5.85 mmol/L and a Vmax of 15.99 U/mg. A homology model suggested that AnhD-Glu56 and AnhE-His21 play important roles in the catalytic efficiency of the nitrile hydratase. S. canus CGMCC 13662 could be used to remediate environments contaminated with acetamiprid.


Assuntos
Actinobacteria/metabolismo , Proteínas de Bactérias/metabolismo , Hidroliases/metabolismo , Inseticidas/metabolismo , Neonicotinoides/metabolismo , Actinobacteria/enzimologia , Actinobacteria/genética , Actinobacteria/isolamento & purificação , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Biodegradação Ambiental , Estabilidade Enzimática , Hidroliases/química , Hidroliases/genética , Inseticidas/química , Cinética , Neonicotinoides/química , Filogenia , Microbiologia do Solo
10.
Chemosphere ; 231: 450-456, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31146137

RESUMO

The translation control tumor protein (TCTP) is a kind of conservative, common and important molecule, several functions (such as regulating cell cycle, apoptosis and calcium binding) have been reported. However, few academic researches for role of TCTP in insecticides stress were made so far. In this research, Drosophila kc cells treated with different doses of deltamethrin at different times, indicated that the expression of TCTP reached the highest level when the cells were treated with 20 ppm of deltamethrin at 24 h. The results showed that TCTP expression is associated with deltamethrin stress. To investigate the functional relationship between this gene and deltamethrin resistance, RNA interference (RNAi) and cell transfection were utilized. TCTP knockdown significantly reduced the level of resistance of RNAi-treated cells, and the overexpressions of TCTP in Drosophila kc cells conferred a degree of protection against deltamethrin. Flow cytometry data showed increased apoptosis rate of RNAi-treated cells and decreased apoptosis following cell transfection. These results represent the first evidence that TCTP plays an important role in the regulation of deltamethrin resistance. Therefore, this study could help us to elucidate the environmental toxicity of deltamethrin and new target genes associated with resistance.


Assuntos
Inseticidas/toxicidade , Nitrilos/toxicidade , Piretrinas/toxicidade , Testes de Toxicidade , Animais , Apoptose/efeitos dos fármacos , Ciclo Celular/efeitos dos fármacos , Drosophila , Proteínas de Drosophila/genética , Resistência a Inseticidas/efeitos dos fármacos , Inseticidas/metabolismo , Neoplasias/genética , Interferência de RNA
11.
J Agric Food Chem ; 67(20): 5891-5898, 2019 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-31059246

RESUMO

A study was carried out to evaluate the dissipation kinetics of field-applied omethoate during wheat storage. Both the identification and metabolic dynamics of omethoate metabolites were analyzed using UPLC-QTOF/MS. The presence of the metabolite dimethyl phosphate (DMP) was confirmed in wheat samples with applied omethoate. This might be because the group attached to the P atom of omethoate is replaced by a hydroxyl group through hydrolysis, thus leading to the formation of the specific metabolite DMP during wheat storage. Although the initial concentrations of DMP in different doses were considerably lower than those of omethoate, the half-life values of DMP were 11.87-31.50 days, which were close to the half-life of the parent omethoate (11.85-30.94 days). This indicates that potential health risks might be caused by dietary exposure to DMP and omethoate. Therefore, more importance should be given to the risk assessment for omethoate and its metabolite DMP in wheat.


Assuntos
Dimetoato/análogos & derivados , Inseticidas/química , Compostos Organofosforados/química , Triticum/química , Cromatografia Líquida de Alta Pressão , Dimetoato/química , Dimetoato/metabolismo , Contaminação de Alimentos/análise , Armazenamento de Alimentos , Inseticidas/metabolismo , Cinética , Compostos Organofosforados/metabolismo , Espectrometria de Massas em Tandem , Triticum/metabolismo
12.
Curr Microbiol ; 76(7): 888-895, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31093691

RESUMO

Lindane is an organochlorine pesticide that is highly persistent in the environment. The amassing of lindane has been identified worldwide and has been found to be very toxic to the environment, human, and animal health. Therefore, urgent consideration and management of the problem is necessary. The current study intends to isolate and identify lindane degrading rhizospheric bacteria from Phragmites karka and to study its degradation kinetics. Also, plant growth promoting potential of the bacterium was evaluated in the presence and absence of studied pesticide. Rhizospheric bacteria were isolated by standard enrichment technique in Mineral Salt Medium. Microbacterium sp. P27 showed the highest degradation percentage, 82.7 ± 1.79% for 50 mg l-1 lindane, after 15 days. Degradation was also studied at different concentrations of lindane. Maximum degradation was achieved at 10 mg l-1 followed by 50 mg l-1 and 100 mg l-1 lindane. Microbacterium sp. P27 showed positive result for Indole-3-acetic acid production, ammonia production, and 1-aminocyclopropane-1-carboxylate deaminase activity. Presence of lindane revealed a concentration-dependent decrease in plant growth promoting activity. Since the isolated bacterial strain possesses lindane degrading capacity and also other characters that help in plant growth promotion, the isolate can be an important candidate for the progress of bioremediation strategy.


Assuntos
Actinomycetales/fisiologia , Hexaclorocicloexano/metabolismo , Reguladores de Crescimento de Planta/fisiologia , Plantas/microbiologia , Rizosfera , Microbiologia do Solo , Poluentes do Solo/metabolismo , Actinomycetales/metabolismo , Biodegradação Ambiental , Hexaclorocicloexano/toxicidade , Inseticidas/metabolismo , Inseticidas/toxicidade , Desenvolvimento Vegetal/efeitos dos fármacos , Reguladores de Crescimento de Planta/metabolismo , Poaceae/microbiologia , Poluentes do Solo/toxicidade
13.
Chem Biol Interact ; 308: 252-257, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31145888

RESUMO

Trichloronate is a racemic organophosphonothioate insecticide that induced delayed neuropathic in hens and human. The avian are species with great susceptibility to organophosphorus poisoning due to their low levels of A-esterases. However, a significant copper-dependent A-esterase activity has been identified in chicken and turkey serum. This study aims at characterizing the trichloronate enantiomers hydrolysis by serum and albumin from chicken (CSA) and turkey (TSA) in the presence of copper by chiral chromatography. A significant Cu2+-dependent hydrolysis for both trichloronate enantiomers (38%) was observed in turkey serum and TSA (p < 0.05). The hydrolysis is stereoselective for (-)-trichloronate (p < 0.05). TSA incubation (200 µg) showed residual values of 56 µM and 20 µM of (+)-trichloronate and (-)-trichloronate, respectively; while the chicken serum and CSA presented a slight hydrolysis (1-7%) of both enantiomers. This copper-dependent hydrolysis and stereoselectivity of trichloronate by TSA was proportional to the incubation time. The increase of TSA in the assay (200-3000 µg) in the presence of 100 µM copper did not significantly increase the levels of hydrolysis and stereoselectivity, an opposite effect was observed for turkey serum (100-200 mL), which totally inhibited this copper-dependent activity of both isomers. The present study evidences an A-esterase activity of TSA on a thio form OP compound, which is stereoselective and activated by copper.


Assuntos
Cobre/química , Compostos Organotiofosforados/metabolismo , Albumina Sérica/metabolismo , Perus/metabolismo , Animais , Catálise , Galinhas/metabolismo , Hidrólise , Inseticidas/química , Inseticidas/metabolismo , Compostos Organotiofosforados/química , Estereoisomerismo
14.
Chemosphere ; 226: 645-650, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30959449

RESUMO

Encapsulating fungicides and/or insecticides in film-coatings applied to agronomic seeds has become a widely accepted method for enhancing seed germination and overall seedling health by protecting against many diseases and early-season insect pests. Despite advancements in seed film-coating technologies, abrasion of the seed coating can occur during handling and mechanical planting operations, resulting in variable amounts of detached fragments entering the soil. The present study investigated the degradation in soil of these plastic-like, small-sized fragments, referred to here as microplastic coating fragments. Degradation of microplastic coating fragments in soil was found to be highly variable. The lowest degradation rate (≤48 days) was observed in fragments detached from seeds coated with a commercial polymer mixture, while fragments from a biodegradable plastic formulation degraded completely within 32 days. When spores of the plant growth-promoting bacterium, Bacillus subtilis, were incorporated into the bioplastic, degradation was even more rapid (≤24 days). The fragment degradation rate was unaffected by incorporating two commonly used neonicotinoid insecticides, imidacloprid or thiacloprid, into either coating formulations, but insecticide dissipation rates in soil were more rapid when added associated with seed coating fragments than when spiked in directly. Half-lives of these two insecticides were reduced by up to 27% in fragments from bioplastic-coated seeds. These results are consistent with variable and not easily predicted soil degradation rates for seed coating fragments, with enhanced dissipation of coating-entrapped pesticides and with a higher degradation rate for biodegradable seed coating incorporating selected microbial strains.


Assuntos
Fungicidas Industriais/metabolismo , Inseticidas/metabolismo , Praguicidas/metabolismo , Plásticos/metabolismo , Sementes/química , Poluentes do Solo/metabolismo , Solo/química , Bacillus subtilis/metabolismo , Inseticidas/análise , Neonicotinoides/metabolismo , Nitrocompostos/metabolismo , Plântula/metabolismo , Poluentes do Solo/análise , Tiazinas/metabolismo
15.
J Environ Sci Health B ; 54(6): 449-458, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30939985

RESUMO

Fipronil is a broad-spectrum insecticide that has a good control effect on pests of commercial poultry. Although many studies have reported the environmental fate of fipronil, the influence of residual fipronil in poultry waste on biogas production has not been further explored yet. In this article, an experimental comparative study on anaerobic digestion (AD) of chicken manure (CM) and corn straw (CS) with different fipronil concentrations (FCs) was carried at 8% of total solid (TS) and mid-temperature (35 ± 1)°C. The results showed that fipronil had a significant effect on biogas production during AD of CM and CS. When the FC is at a low level (≤10 mg·kg-1), the biogas production rate is increased and the digestion period was shortened, while higher FC (≥ 20 mg·kg-1) showed an inhibitory effect. During the monitoring of enzyme activity, low FC showed no significant effect on cellulase and saccharase, but the urease activity increased in the early stage. High FC showed inhibition of activity of cellulase and urease, but the saccharase activity was significantly inhibited until FC reached 40 mg·kg-1. This study also confirms that the environment in anaerobic digester is favorable for the degradation of fipronil, and its half-life is about 15.83 days.


Assuntos
Biocombustíveis , Esterco , Pirazóis , Eliminação de Resíduos Líquidos/métodos , Zea mays , Anaerobiose/efeitos dos fármacos , Animais , Celulase/antagonistas & inibidores , Celulase/metabolismo , Galinhas , Meia-Vida , Inseticidas/metabolismo , Inseticidas/farmacologia , Metano , Caules de Planta/metabolismo , Pirazóis/metabolismo , Pirazóis/farmacologia , Temperatura Ambiente , Eliminação de Resíduos Líquidos/instrumentação , beta-Frutofuranosidase/antagonistas & inibidores , beta-Frutofuranosidase/metabolismo
16.
J Microbiol Biotechnol ; 29(5): 809-812, 2019 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-30955256

RESUMO

Bacterial strains that improve mycelial morphology and growth of white-rot fungi in liquid medium could enhance the impact of white-rot fungi towards lesser recovery of neonicotinoids when cocultured. This was demonstrated by the recovery of clothianidin and acetamiprid from cocultures of the white-rot fungus Phlebia brevispora strains with two mycelial-growth-promoting bacteria, Enterobacter sp. TN3W-14 and Pseudomonas sp. TN3W-8. Clothianidin recovery from cocultures of white-rot fungi and bacteria was over 40% lower than that from axenic microbial cultures and mixed-bacterial cultures. About 20% less acetamiprid was equally recovered from both TMIC33929+TN3W-14 cocultures and mixedbacterial cultures than from axenic fungal and bacterial cultures.


Assuntos
Bactérias/metabolismo , Neonicotinoides/metabolismo , Polyporales/metabolismo , Biodegradação Ambiental , Técnicas de Cocultura , Guanidinas/metabolismo , Inseticidas/metabolismo , Tiazóis/metabolismo
17.
Chemosphere ; 225: 166-173, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30875499

RESUMO

The fungicide imazalil is a chiral compound with one R- and one S-enantiomer. Enantiomers, while having the same chemical properties, can differ in their biological activity expressed as efficacy/toxicity as well as in their degradation kinetics and pathways. Azoles such as imazalil have been shown to synergize the effect of pyrethroid insecticides like α-cypermethrin through inhibition of cytochrome P450 monooxygenase responsible for pyrethroid detoxification. The aim of this study was to investigate, if the enantiomers of imazalil are selective in their synergistic potential in a mixture with a pyrethroid insecticide tested in Chironomus riparius. Potential enantioselectivity was studied on the level of uptake and elimination, inhibition of cytochrome P450 activity measured in vitro and in vivo and on synergistic potential of α-cypermethrin induced immobilization. Synergy was measured as an increase in α-cypermethrin toxicity after 144h applying a constant non-lethal imazalil concentration of 0.65 µmol/L. The R- and S-imazalil enantiomers increased α-cypermethrin toxicity from an EC50 of 1580 ±â€¯980 pmol/L to an EC50 of 83 ±â€¯10 pmol/L and 53 ±â€¯8 pmol/L, respectively. The relatively small potency difference between imazalil enantiomers could not be explained by the in vitro cytochrome P450 inhibition, as the IC50 values were similar (0.11 ±â€¯0.01 and 0.09 ±â€¯0.01 µmol/L for R- and S-imazalil). Measuring in vivo P450 inhibition and the toxicokinetic of imazalil did not show a clear trend of selectivity towards one or the other enantiomer. The study therefore suggests that cytochrome P450 enzymes involved in detoxification in C. riparius are not enantioselective for imazalil.


Assuntos
Chironomidae/efeitos dos fármacos , Chironomidae/metabolismo , Sistema Enzimático do Citocromo P-450/metabolismo , Imidazóis/química , Imidazóis/toxicidade , Piretrinas/química , Piretrinas/toxicidade , Animais , Inibidores das Enzimas do Citocromo P-450/química , Inibidores das Enzimas do Citocromo P-450/metabolismo , Inibidores das Enzimas do Citocromo P-450/toxicidade , Interações de Medicamentos , Fungicidas Industriais/química , Fungicidas Industriais/metabolismo , Fungicidas Industriais/toxicidade , Imidazóis/metabolismo , Inativação Metabólica/efeitos dos fármacos , Inseticidas/química , Inseticidas/metabolismo , Inseticidas/toxicidade , Piretrinas/metabolismo , Estereoisomerismo , Toxicocinética
18.
Phytochemistry ; 161: 107-116, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30825705

RESUMO

Styrene analogs are known to be naturally synthesized in the leaves of pears and in other plant species, including several trees in the Styracaceae family. Styrene analogs are potential contributors to the aroma of wine, perfumes, pharmaceuticals, and other fermented foods and beverages. In addition, styrene analogs perform important ecological functions such as insecticidal and antifeedant activities against insects. We showed here that exogenous applications of styrene and p-hydroxystyrene caused a dramatic reduction the number of eggs laid by psylla and of subsequent nymph survival. Despite their importance specific reactions that lead to the biosynthesis of the styrene analogs in pear are unknown. To identify genes involved in the synthesis of these metabolites, existing genome databases of the Rosaceae were screened for pear genes with significant sequence similarity to bacterial phenolic acid decarboxylase. Herein described are the isolation and characterization of a pear phenolic acid decarboxylase, designated PyPAD1, which catalyzed the decarboxylation of p-coumaric acid and ferulic acid to p-hydroxystyrene and 3-methoxy-4-hydroxystyrene respectively. Its apparent Km values for p-coumaric acid and ferulic acid were 34.42 and 84.64 µM, respectively. The PyPAD1 preferred p-coumaric acid to ferulic acid as a substrate by a factor of 2.4 when comparing catalytic efficiencies in vitro. Expression analysis of PyPAD1 showed that the gene was transcribed in all five pear genotypes examined. However, transcript abundance was increased in correlation with the presence of p-hydroxystyrene in resistant cultivars Py-701 and Py-760 and in the sensitive cultivar Spadona when grafted on these resistant cultivars. Thus, PyPAD1 appears to be responsible for the decarboxylation of the p-coumaric acid, and for the production of metabolites that are active against pear psylla.


Assuntos
Bidens/efeitos dos fármacos , Hemípteros/efeitos dos fármacos , Inseticidas/farmacologia , Pyrus/metabolismo , Estirenos/farmacologia , Animais , Bidens/metabolismo , Hemípteros/metabolismo , Inseticidas/química , Inseticidas/metabolismo , Pyrus/genética , Estirenos/química , Estirenos/metabolismo
19.
Environ Pollut ; 249: 390-397, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30909131

RESUMO

Alpha-cypermethrin (Alpha-CP), an important pyrethroid pesticide, has been widely used for pest control in agriculture and parasite control in livestock farms. Thus, alpha-CP is easily exposed to wild birds and poultry, which may pose a potential risk to birds. Alpha-CP and its metabolites have been detected in many environmental samples, including poultry and wild birds. We studied the distribution and metabolism of alpha-CP and its metabolites in embryo development and newborn chick. The results showed that metabolites were the main residual forms of alpha-CP in different stages of life and might increase the exposure risk of bird and its offspring. Metabolomics investigation of newborn chick exhibited that the metabolic profiles of chicks were disturbed, especially lipid metabolism. The concentrations of cis-DCCA and trans-DCCA were high in the first and second weeks of chick growth, indicating that chicks have limited ability to further metabolize and excrete cis-DCCA and trans-DCCA during the early stages of chicks. Toxicokinetics of alpha-CP in adult hens showed that alpha-CP was rapidly metabolized to acid metabolites, which could be further metabolized and excreted. The results about metabolism of alpha-CP in different stages of chicken indicate that the ability of the embryo and early chick to metabolize alpha-CP and its metabolites was the weakest. Therefore, it is of important significance to focus on evaluating the ecological risk of cypermethrin on birds at different stages of life cycle.


Assuntos
Inseticidas/análise , Inseticidas/metabolismo , Piretrinas/análise , Piretrinas/metabolismo , Agricultura , Animais , Embrião de Galinha , Galinhas/crescimento & desenvolvimento , Galinhas/metabolismo , Desenvolvimento Embrionário/efeitos dos fármacos , Feminino , Toxicocinética
20.
Sci Total Environ ; 668: 161-170, 2019 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-30852194

RESUMO

Ingested soil is a major vector of organic contaminants from environment to free-ranged animals, particularly for grazing herbivores. Therefore, a better understanding of processes driving soil intake may provide new insights to limit animal exposure to contaminants and ensure safety of animal products. To maintain the supply service of livestock farming activities in contaminated areas, it is necessary to design adapted farming practices aiming at controlling the risk for human health. This study was conducted in the French West Indies, where chlordecone, an organochlorine insecticide previously used to protect banana plantation against the black weevil and banned since 1993, has polluted nearly 20% of agricultural surfaces since the 1970s. A crossover study design was performed to estimate soil intake by twelve tethered Creole young bulls according to different grazing practices. The objectives were to characterize the influence of (i) daily herbage allowance (LOW, HIGH, ADLIB: 100, 150, 300 g DM/kg BW0.75 respectively); (ii) and soil surface moisture (SSM) testing grazing on a water-saturated (HUM) vs dried (DRY) ground. The herbage offer was managed via the allocated surfaces varying the chain length as animal holders commonly do in informal Caribbean systems. The results evidenced an increase in soil intake with DHA reduction (2.1 to 3.8% of DM intake; P < 0.05) and with SSM increase (2.4 to 3.6% of DM intake; P < 0.05). Herbage offer reduction involved a closer-to-the-ground grazing with shorter post-grazing sward surface height (82.2 to 63.3 mm; P < 0.001), and both herbage offer reduction and SSM increase amplified sward soiling (measured from titanium content in unwashed herbage and image analysis). This work showed that soil intake is unavoidable even when herbage offer is very generous. The animals will significantly increase soil intake when herbage offer would be at 150 g DM/kg BW0.75 or less, especially when the grazed surface is humid.


Assuntos
Criação de Animais Domésticos , Clordecona/análise , Inseticidas/análise , Poluentes do Solo/análise , Animais , Bovinos , Clordecona/metabolismo , Herbivoria , Inseticidas/metabolismo , Solo , Poluentes do Solo/metabolismo , Índias Ocidentais
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