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1.
Pestic Biochem Physiol ; 158: 166-174, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31378353

RESUMO

Pesticidal properties of Bacillus thuringiensis and its associated toxic proteins is an ever-growing science with potential implications in biological pest management. In the present study 80 Bacillus thuringiensis isolates native to Uttarakhand Himalayas were evaluated for chitinolytic activity and potent ones (11 isolates) were further subjected to multiphasic characterization for their antifungal, insecticidal and synergistic properties with selected chemical insecticides. Although all the 11 potent isolates were biologically active, only three isolates (VLBt27, VLBt109 and VLBt238) showed >90% inhibition in radial growth of 3 out of 4 tested plant pathogenic fungi (Rhizoctonia solani, Fusarium oxysporum, Alternaria pori and Pyricularia oryzae). The key antagonism was manifested in the form of disruptions in growing tips and uneven mycelial thickenings. In insect bioassays (against Helicoverpa armigera, Mythimna separata and Thysanoplusia orichalcea), no considerable direct mortality was observed. However, the larval weight reduction was prominent in four isolates (VLBt27, VLBt38, VLBt109 and VLBt135) which accounts to >75% in first instar larvae of H. armigera. Joint action of these four isolates with chemical insecticides showed an overall additive interaction against Brevicoryne brassicae and synergism against H. armigera. All the isolates were compatible with tested insecticides at their field recommended doses except for chlorpyriphos with around 130 kDa protein as chitinase. The study identified VLBt27 and VLBt109, two native isolates of B. thuringiensis with potential antagonistic activity and synergism as well. These isolates have possible implications as single strategy against two diverse pest problems (pathogenic fungi and phytophagous insect) of agriculture with a view of reduced pesticide application.


Assuntos
Bacillus thuringiensis/fisiologia , Inseticidas/farmacologia , Mariposas/efeitos dos fármacos , Animais , Quitinases/metabolismo , Controle Biológico de Vetores
2.
Pestic Biochem Physiol ; 158: 32-39, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31378358

RESUMO

Mutations in the GABA-gated chloride channel are associated with resistance to cyclodiene organochlorine and phenyl pyrazole insecticides. The best characterised of these is A301S, which was initially identified in a Dieldrin resistant strain of Drosophila melanogaster. The orthologous mutation has been found in a variety of different crop pests including the diamond back moth Plutella xylostella. However, the contribution of this mutation to resistance in this species remains unclear. We have used the CRISPR/Cas9 system in order to edit Plutella xylostella PxGABARalpha1 to Serine at the 301 orthologous position (282 in PxGABARalpha1) in an insecticide sensitive strain isolated from Vero Beach (VB) USA. In this edited line, no high level of resistance is conferred to Dieldrin, Endosulfan or Fipronil, rather only a subtle shift in sensitivity which could not confer commercially important resistance. We conclude that the high level of commercial resistance to cyclodiene organochlorine and phenyl pyrazole insecticides observed in some field isolates of Plutella xylostella cannot arise from A282S in PxGABARalpha1 alone.


Assuntos
Inseticidas/farmacologia , Mariposas/efeitos dos fármacos , Animais , Sistemas CRISPR-Cas/genética , Dieldrin/farmacologia , Endossulfano/farmacologia , Resistência a Inseticidas/genética , Mariposas/genética , Mutação/genética , Pirazóis/farmacologia , Receptores de GABA-A/genética
3.
Pestic Biochem Physiol ; 158: 54-60, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31378361

RESUMO

Extensive planting of transgenic crops producing insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) has spurred increasingly rapid evolution of resistance in pests. In the pink bollworm, Pectinophora gossypiella, a devastating global pest, resistance to Bt toxin Cry1Ac produced by transgenic cotton is linked with mutations in a gene (PgCad1) encoding a cadherin protein that binds Cry1Ac in the larval midgut. We previously reported a long non-coding RNA (lncRNA) in intron 20 of cadherin alleles associated with both resistance and susceptibility to Cry1Ac. Here we tested the hypothesis that reducing expression of this lncRNA decreases transcription of PgCad1 and susceptibility to Cry1Ac. Quantitative RT-PCR showed that feeding susceptible neonates small interfering RNAs (siRNAs) targeting this lncRNA but not PgCad1 decreased the abundance of transcripts of both the lncRNA and PgCad1. Moreover, neonates fed the siRNAs had lower susceptibility to Cry1Ac. The results imply that the lncRNA increases transcription of PgCad1 and susceptibility of pink bollworm to Cry1Ac. The results suggest that disruption of lncRNA expression could be a novel mechanism of pest resistance to Bt toxins.


Assuntos
Bacillus thuringiensis/metabolismo , Proteínas de Bactérias/farmacologia , Caderinas/genética , Endotoxinas/farmacologia , Proteínas Hemolisinas/farmacologia , Mariposas/efeitos dos fármacos , RNA Longo não Codificante/genética , Transcrição Genética/genética , Animais , Bacillus thuringiensis/genética , Resistência a Inseticidas/genética , Inseticidas/farmacologia , Mariposas/genética , Mariposas/metabolismo , Controle Biológico de Vetores
4.
J Agric Food Chem ; 67(37): 10498-10504, 2019 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-31452369

RESUMO

Owing to the changing needs of agriculture, the exploration of new pest control agents remains as critical as ever. The analogues 3a-3v of the natural product cerbinal were synthesized from genipin by an efficient and practical method under additive-free conditions. The antiviral and insecticidal effects of cerbinal and these cyclopenta[c]pyridines (3a-3v) were evaluated systematically. Most of the synthesized compounds exhibited higher anti-TMV activities than the lead compound cerbinal. Compound 3s (2-(4-methoxyphenyl)) had the most promising inhibitory activities against TMV (inactivation effect 49.0 ± 0.8%, curative effect 41.2 ± 4.3%, and protection effect 51.5 ± 2.7% at 500 µg/mL). Among the synthesized compounds, only 3v (2-(2-chloro-4-(trifluoromethoxy)phenyl)) reached the activity level of cerbinal against Plutella xylostella. This suggested that the cyclopenta[c]pyridines obtained by modifications of cerbinal at position 2 are very significant for the anti-TMV activity, and yet were exceptionally less active for the insecticidal activities.


Assuntos
Antivirais/síntese química , Antivirais/farmacologia , Produtos Biológicos/síntese química , Produtos Biológicos/farmacologia , Indenos/química , Indenos/farmacologia , Inseticidas/química , Inseticidas/farmacologia , Animais , Antivirais/química , Produtos Biológicos/química , Descoberta de Drogas , Indenos/síntese química , Inseticidas/síntese química , Iridoides/química , Estrutura Molecular , Mariposas/efeitos dos fármacos , Mariposas/crescimento & desenvolvimento , Piridinas/síntese química , Piridinas/química , Piridinas/farmacologia , Relação Estrutura-Atividade , Vírus do Mosaico do Tabaco/efeitos dos fármacos , Vírus do Mosaico do Tabaco/crescimento & desenvolvimento
5.
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
6.
J Enzyme Inhib Med Chem ; 34(1): 1226-1232, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31307248

RESUMO

Allosamidins come from the secondary metabolites of Streptomyces species, and they have the pseudotrisaccharide structures. Allosamidins are chitinase inhibitors that can be used to study the physiological effects of chitinases in a variety of organisms. They have the novel antiasthmatic activity and insecticidal/antifungal activities. Herein, the synthesis and activities of allosamidins were summarized and analyzed.


Assuntos
Acetilglucosamina/análogos & derivados , Antiasmáticos/farmacologia , Antifúngicos/farmacologia , Inseticidas/farmacologia , Trissacarídeos/farmacologia , Acetilglucosamina/química , Acetilglucosamina/isolamento & purificação , Acetilglucosamina/farmacologia , Animais , Antiasmáticos/química , Antiasmáticos/isolamento & purificação , Antifúngicos/química , Antifúngicos/isolamento & purificação , Asma/tratamento farmacológico , Fungos/efeitos dos fármacos , Humanos , Inseticidas/química , Inseticidas/isolamento & purificação , Conformação Molecular , Mariposas/efeitos dos fármacos , Streptomyces/química , Trissacarídeos/química , Trissacarídeos/isolamento & purificação
7.
J Agric Food Chem ; 67(31): 8573-8580, 2019 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-31293156

RESUMO

Glycosylation endows both natural and synthetic small molecules with modulated physicochemical and biological properties. Plant and bacterial glycosyltransferases capable of decorating various privileged scaffolds have been extensively studied, but those from kingdom Fungi still remain underexploited. Here, we use a combination of genome mining and heterologous expression techniques to identify four novel glycosyltransferase-methyltransferase (GT-MT) functional modules from Hypocreales fungi. These GT-MT modules display decent substrate promiscuity and regiospecificity, methylglucosylating a panel of natural products such as flavonoids, stilbenoids, anthraquinones, and benzenediol lactones. Native GT-MT modules can be split up and regrouped into hybrid modules with similar or even improved efficacy as compared with native pairs. Methylglucosylation of kaempferol considerably improves its insecticidal activity against the larvae of oriental armyworm Mythimna separata (Walker). Our work provides a set of efficient biocatalysts for the combinatorial biosynthesis of small molecule glycosides that may have significant importance to the pharmaceutical, agricultural, and food industries.


Assuntos
Proteínas Fúngicas/química , Glicosiltransferases/química , Hypocreales/enzimologia , Metiltransferases/química , Fenóis/química , Animais , Biocatálise , Cristalografia por Raios X , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Glicosilação , Glicosiltransferases/genética , Glicosiltransferases/metabolismo , Hypocreales/genética , Inseticidas/química , Inseticidas/farmacologia , Metilação , Metiltransferases/genética , Metiltransferases/metabolismo , Mariposas/efeitos dos fármacos , Fenóis/farmacologia , Especificidade por Substrato
8.
Pestic Biochem Physiol ; 157: 211-218, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31153471

RESUMO

Herbivore attack leads to enhanced production of defensive compounds to mount anti-herbivore defense in plants via activation of the jasmonate signaling pathway. On the other hand, some herbivores can eavesdrop on plants defense signaling and up-regulate their cytochrome P450 genes to increase detoxification of defensive compounds. However, the ecological risk of eavesdropping on plant defense signaling is largely unknown. In this study, we examined the induction of cytochrome P450s by methyl jasmonate (MeJA) and its consequence on the toxicity of aflatoxin B1 (AFB1) to Helicoverpa armigra larvae. The results show that MeJA applications either in a diet or volatile exposure enhanced the toxicity of AFB1 to the larvae. RNA sequences analysis revealed that cytochrome P450 CYP6AE19 was highly induced when MeJA was applied with AFB1. In addition, HaGST encoding glutathione-S-transferase that mainly transforms aflatoxin B1 exo-8,9-epoxide to aflatoxin B1 exo-8,9-glutathione was also induced. RNA interference of CYP6AE19 via injecting a double-stranded RNA decreased mortality of larvae exposed to AFB1; while injecting a double-stranded RNA of HaGST increased larval mortality. Furthermore, a protein model was generated and a subsequent docking simulation for AFB1 suggests the bioactivation as a major mechanism of AFB1. This study provides evidence that MeJA increased larval mortality of H. armigera via induction of CYP6AE19 that can bioactivate AFB1.


Assuntos
Acetatos/farmacologia , Aflatoxina B1/metabolismo , Ciclopentanos/farmacologia , Sistema Enzimático do Citocromo P-450/metabolismo , Mariposas/efeitos dos fármacos , Mariposas/metabolismo , Oxilipinas/farmacologia , Animais , Larva/efeitos dos fármacos , Larva/metabolismo , Oxirredução/efeitos dos fármacos
9.
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
10.
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
11.
J Sci Food Agric ; 99(13): 5962-5968, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31215022

RESUMO

BACKGROUND: Cadra (=Ephestia) cautella (Walker) is a serious cosmopolitan pest that can feed on a wide variety of stored foods. It is controlled mainly by fumigation with phosphine, to which strong resistance has been documented in major stored-product insects in many countries. The need for reliable, user- and environmentally friendly alternatives is therefore high on the agenda to avoid the development of potential resistance and to reduce human exposure to toxic insecticides. Two modified atmospheres (MAs) composed of high carbon dioxide (CO2 ) and low oxygen (O2 ) (90% and 96% CO2 in air) were studied at the laboratory at 20 °C and 65 ± 3% relative humidity (RH) against C. cautella. RESULTS: Eggs (1, 2, and 3 days old), young and mature larvae (10 and 20 days old), pupae (1, 2 and 3 days old) and adults (1 day old) were exposed to two MAs consisting of high CO2 and low O2 for the range of 2 to 104 h. Eggs, old larvae, and pupae were found to be the most tolerant. Adults were rather easily killed and young larvae were the most susceptible. Lethal exposure time (LT99 ) values were between 11.74 h and 128.97 h. CONCLUSION: Modified atmospheres consisting of high CO2 and low O2 offer an affordable combination to control C. cautella effectively. From the perspective of economics and efficacy, 90% CO2 might be the concentration of choice. © 2019 Society of Chemical Industry.


Assuntos
Dióxido de Carbono/farmacologia , Controle de Insetos/métodos , Mariposas/efeitos dos fármacos , Animais , Atmosfera/análise , Dióxido de Carbono/análise , Controle de Insetos/instrumentação , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Mariposas/crescimento & desenvolvimento , Oxigênio/análise , Pupa/efeitos dos fármacos , Pupa/crescimento & desenvolvimento
12.
Arch Insect Biochem Physiol ; 101(4): e21588, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31180585

RESUMO

Boric acid (BA) is widely used in various industrial process and can be accessed to nontarget organisms. This study aimed to investigate the insecticidal effects of BA and its toxic activities with respect to immunologic and genotoxic effects using Galleria mellonella larvae as a model. BA concentrations (78.125-10,000 ppm) were administrated to the larvae using the feeding method. Concentration-dependent mortality was observed in all larval groups. Probit analysis revealed LC30 , LC50 , and LC70 values to be 112.4, 320.1, and 911.4 ppm, respectively. These concentrations were used in all bioassays. Drastic reductions in total hemocyte counts along with changes in differential hemocyte counts were observed following BA treatment. Cell viability assays showed dose-dependent reductions in viable cells and an increase in the necrotic and apoptotic ratios after BA treatment. However, mitotic indices of larval hemocytes did not change at all BA concentrations. The cytotoxic effect of BA led to a significant reduction in cellular immune responses such as encapsulation, melanization, and nodulation activities of treated larvae. While BA increased micronucleus ratios at the highest concentration, comet parameters indicating DNA damage increased in G. mellonella larval hemocytes at all concentrations. These report that BA suppresses the immune system of G. mellonella and also poses risks of genotoxicity at high concentrations.


Assuntos
Ácidos Bóricos/toxicidade , Mariposas/efeitos dos fármacos , Animais , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Ensaio Cometa , Relação Dose-Resposta a Droga , Hemócitos/efeitos dos fármacos , Hemolinfa , Inseticidas/toxicidade , Larva/efeitos dos fármacos , Larva/genética , Larva/imunologia , Testes para Micronúcleos , Mariposas/genética , Mariposas/imunologia
13.
J Insect Sci ; 19(3)2019 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-31225881

RESUMO

Prothoracicotropic hormone (PTTH) is a neuropeptide that triggers a cascade of events within the prothoracic gland (PG) cells, leading to the activation of all the crucial enzymes involved in ecdysone biosynthesis, the main insect steroid hormone. Studies concerning ecdysteroidogenesis predicted PTTH action using brain extract (BE), consisting in a complex mixture in which some components positively or negatively interfere with PTTH-stimulated ecdysteroidogenesis. Consequently, the integration of these opposing factors in steroidogenic tissues leads to a complex secretory pattern. A recombinant form of prothoracicotropic hormone (rPTTH) from the tobacco budworm Heliothis virescens (F.) (Lepidoptera: Noctuidae) was expressed and purified to perform in vitro tests in a standard and repeatable manner. A characterization of rPTTH primary and secondary structures was performed. The ability of rPTTH and H. virescens BE to stimulate ecdysteroidogenesis was investigated on the third day of fifth larval stage. rPTTH activity was compared with the BE mixture by enzyme immunoassay and western blot, revealing that they equally stimulate the production of significant amount of ecdysone, through a transduction cascade that includes the TOR pathway, by the phosphorylation of 4E binding protein (4E-BP) and S6 kinase (S6K), the main targets of TOR protein. The results of these experiments suggest the importance of obtaining a functional pure hormone to perform further studies, not depending on the crude brain extract, composed by different elements and susceptible to different uncontrollable variables.


Assuntos
Ecdisteroides/biossíntese , Hormônios de Inseto/farmacologia , Mariposas/metabolismo , Extratos de Tecidos/farmacologia , Animais , Encéfalo , Hormônios de Inseto/isolamento & purificação , Mariposas/efeitos dos fármacos
14.
J Agric Food Chem ; 67(22): 6387-6396, 2019 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-31090403

RESUMO

Insect chitinolytic ß- N-acetylhexosaminidase OfHex1, from the agricultural pest Ostrinia furnacalis (Guenée), is considered as a potential target for green pesticide design. In this study, rational molecular design and optimization led to the synthesis of compounds 15r ( Ki = 5.3 µM) and 15y ( Ki = 2.7 µM) that had superior activity against OfHex1 than previously reported lead compounds. Both compounds 15r and 15y had high selectivity toward OfHex1 over human ß- N-acetylhexosaminidase B (HsHexB) and human O-GlcNAcase (hOGA). In addition, to investigate the basis for the potency of glycosylated naphthalimides against OfHex1, molecular docking and molecular dynamics simulations were performed to study possible binding modes. Furthermore, the in vivo biological activity of target compounds with efficient OfHex1 inhibitory potency was assayed against Myzus persicae, Plutella xylostella, and O. furnacalis. This present work indicates that glycosylated naphthalimides can be further developed as potential pest control and management agents targeting OfHex1.


Assuntos
Inibidores Enzimáticos/síntese química , Proteínas de Insetos/antagonistas & inibidores , Inseticidas/síntese química , Mariposas/enzimologia , Naftalimidas/síntese química , beta-N-Acetil-Hexosaminidases/antagonistas & inibidores , Animais , Avaliação de Medicamentos , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Glicosilação , Humanos , Proteínas de Insetos/química , Inseticidas/química , Inseticidas/farmacologia , Cinética , Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Mariposas/efeitos dos fármacos , Naftalimidas/química , Naftalimidas/farmacologia , beta-N-Acetil-Hexosaminidases/química
15.
Gene ; 710: 387-398, 2019 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-31136783

RESUMO

Busseola fusca (Fuller) (Lepidoptera: Noctuidae), a major insect pest of maize in sub-Saharan Africa, has developed high levels of non-recessive resistance to Cry1Ab toxin expressed in genetically modified Bt maize. Multiple resistance mechanisms to various Cry toxins have been identified in Lepidoptera, but no study has yet been done to determine the mechanism of Cry1Ab resistance in B. fusca. Therefore, the larval transcriptome of B. fusca was sequenced, de novo assembled and characterized. Differential expression analysis was performed to compare gene expression profiles of Cry toxin challenged and unchallenged neonate larvae to assess the molecular basis of the defence mechanism employed by this insect. Several genes associated with Cry toxin resistance in other lepidopteran pests were detected in B. fusca. Results suggest that differential expression of metabolic and immune-related genes might explain Cry1Ab toxin defence in this pest (supplemental file). Transcript expression profiles of neonates demonstrated that 33.59% and 60.31% of the 131 differentially expressed genes were upregulated and downregulated in the toxin-challenged neonate larvae, respectively. Transcripts were grouped into two subclusters according to the similarity of their expression patterns. Transcripts in subcluster 1 were moderately upregulated in the toxin-challenged neonate larvae, and, conversely, downregulated in the unchallenged neonate larvae. The solute carrier organic anion transporter, which is involved in insecticide detoxification, was upregulated in the toxin-challenged neonate larvae. Conversely, most of the transcripts in subcluster 2 were moderately downregulated in the toxin-challenged neonate larvae, and upregulated for neonates feeding on non-challenged maize. Four unidentified transcripts were extremely down-regulated in the toxin-challenged neonate larvae, and upregulated in the unchallenged neonate larvae. Further studies are recommended to establish if there is a direct correlation between these differentially expressed genes and the observed resistance. Elucidation of such defence mechanisms is crucial for developing insect resistance management strategies to ensure sustainable use of genetically modified maize in Africa. Nevertheless, this is the first study on gene expression profiles of B. fusca strains challenged with Cry toxin. The transcriptome characterized in this study provides a significant resource base for future studies on B. fusca and contributes to understanding some of the gene regulation and signalling networks involved in the defence of B. fusca against Cry1Ab toxin.


Assuntos
Proteínas de Bactérias/farmacologia , Endotoxinas/farmacologia , Perfilação da Expressão Gênica/métodos , Proteínas Hemolisinas/farmacologia , Proteínas de Insetos/genética , Resistência a Inseticidas , Mariposas/genética , Animais , Bacillus thuringiensis/genética , Bacillus thuringiensis/metabolismo , Proteínas de Bactérias/genética , Endotoxinas/genética , Regulação da Expressão Gênica/efeitos dos fármacos , Proteínas Hemolisinas/genética , Larva/efeitos dos fármacos , Larva/genética , Redes e Vias Metabólicas , Mariposas/efeitos dos fármacos , Plantas Geneticamente Modificadas/parasitologia , Análise de Sequência de RNA , Zea mays/genética , Zea mays/metabolismo , Zea mays/parasitologia
16.
Chemosphere ; 229: 525-528, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31100623

RESUMO

Anticarsia gemmatalis Hübner (Lepidoptera: Noctuidae) is mainly controlled with synthetic insecticides such as chlorantraniliprole. However, these compounds may affect non-target organs of insect metabolism. The objective of this study was to evaluate the toxic effect in the midgut goblet cells of A. gemmatalis caterpillars exposed to chlorantraniliprole. The midgut of these caterpillars, which ingested the insecticide in medium-lethal dose (LD50), was dissected and evaluated by transmission electron microscopy. The goblet cells microvilli, after exposure to the insecticide, were disorganized and degenerated. This can compromise ionic homeostasis and nutrient absorption, impair physiological mechanisms of detoxification, and reduce the movement of food boluses throughout the insect midgut.


Assuntos
Sistema Digestório/citologia , Células Caliciformes/efeitos dos fármacos , Inseticidas/toxicidade , Mariposas/efeitos dos fármacos , ortoaminobenzoatos/toxicidade , Animais , Sistema Digestório/efeitos dos fármacos , Células Caliciformes/patologia , Células Caliciformes/ultraestrutura , Inativação Metabólica/efeitos dos fármacos , Microscopia Eletrônica de Transmissão , Microvilosidades/efeitos dos fármacos , Microvilosidades/patologia , Mariposas/metabolismo
17.
Pestic Biochem Physiol ; 156: 56-62, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31027581

RESUMO

Glutamate-gated chloride channels (GluCls) mediate inhibitory synaptic transmission in invertebrate nervous systems, and only one GluCl gene has been found in insects. Therefore, insect GluCls are one of the major targets of insecticides including avermectins. In the present study, a 1347 bp full-length cDNA encoding a 449-amino acid protein (named MsGluCl, GenBank ID: MK336885) was cloned from the oriental armyworm, Mythimna separata, and characterized two alternative splicing variants of MsGluCl. The protein shares 76.9-98.6% identity with other insect GluCl isoforms. Spatial and temporal expression analysis revealed that MsGluCl was highly expressed in the 3rd instar and adult head. Dietary ingestion of dsMsGluCl significantly reduced the mRNA level of MsGluCl and decreased abamectin mortality. Thus, our results reveal that MsGluCl could be the molecular target of abamectin and provide the basis for further understanding the resistance mechanism to abamectin in arthropods.


Assuntos
Processamento Alternativo/genética , Canais de Cloreto/metabolismo , Clonagem Molecular/métodos , Mariposas/genética , Animais , Canais de Cloreto/genética , DNA Complementar/genética , DNA Complementar/metabolismo , Inseticidas/farmacologia , Ivermectina/análogos & derivados , Ivermectina/farmacologia , Mariposas/efeitos dos fármacos , RNA Mensageiro/genética , RNA Mensageiro/metabolismo
18.
Pestic Biochem Physiol ; 156: 72-79, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31027583

RESUMO

Metalloenzyme SODs play important roles in insects dealing with environmental stress. Here, we cloned the Cu/ZnSOD (LdCZS) and MnSOD (LdMS) mRNA of Lymantria dispar by rapid amplification of cDNA ends (RACE). Afterwards their expression patterns were detected by quantitative real-time polymerase chain reaction (qPCR) after bioinformatic analysis. We found that both LdCZS and LdMS were widely detected in all gypsy moth larvae and all five tissues that we analyzed, and both of them were up-regulated after larvae were fed with avermectin of sublethal concentration and LC10. The LdCZS expression value are always higher than LdMS after treating with avermectin of sublethal concentrations. In addition, temporal expression profile in avermectin treated larvae showed that LdCZS expressed highest at 2nd hour, and LdMS expressed highest at 6th hour. The cuticulas transcribed LdCZS and LdMS significantly higher than heads, fat bodies, Malpighian tubes, and midguts after spraying avermectin of sublethal concentration. These results suggested that both Cu/ZnSOD and MnSOD are important antioxidant enzymes in L. dispar defensing against pesticide stress, and LdCZS always responded rapider and stronger than LdMS.


Assuntos
Ivermectina/análogos & derivados , Larva/metabolismo , Mariposas/metabolismo , Superóxido Dismutase/metabolismo , Sequência de Aminoácidos , Animais , Biologia Computacional , DNA Complementar/genética , Ivermectina/farmacologia , Larva/efeitos dos fármacos , Larva/genética , Dados de Sequência Molecular , Mariposas/efeitos dos fármacos , Mariposas/genética , Praguicidas/farmacologia , Reação em Cadeia da Polimerase , Superóxido Dismutase/química , Superóxido Dismutase/genética
19.
Biofouling ; 35(2): 129-142, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30950296

RESUMO

The present study investigated the antimicrobial, anti-adhesion and anti-biofilm activity of the modified synthetic molecules nitrochalcone (NC-E05) and pentyl caffeate (C5) against microorganisms which have a high incidence in hospital-acquired infections. The compounds were further tested for their preliminary systemic toxicity in vivo. NC-E05 and C5 showed antimicrobial activity, with minimum inhibitory concentrations (MICs) ranging between 15.62 and 31.25 µg ml-1. Treatment with NC-E05 and C5 at 1 × MIC and/or 10 × MIC significantly reduced mono or mixed-species biofilm formation and viability. At MIC/2, the compounds decreased microbial adhesion to HaCaT keratinocytes from 1 to 3 h (p < 0.0001). In addition, NC-E05 and C5 demonstrated low toxicity in vivo in the Galleria mellonella model at anti-biofilm concentrations. Thus, the chemical modification of these molecules proved to be effective in the proposed anti-biofilm activity, opening opportunities for the development of new antimicrobials.


Assuntos
Anti-Infecciosos/farmacologia , Aderência Bacteriana/efeitos dos fármacos , Biofilmes/efeitos dos fármacos , Ácidos Cafeicos/farmacologia , Chalconas/farmacologia , Animais , Antibacterianos/farmacologia , Antibacterianos/toxicidade , Anti-Infecciosos/toxicidade , Antifúngicos/farmacologia , Antifúngicos/toxicidade , Biofilmes/crescimento & desenvolvimento , Ácidos Cafeicos/toxicidade , Candida albicans/efeitos dos fármacos , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Chalconas/toxicidade , Infecção Hospitalar/prevenção & controle , Humanos , Queratinócitos/citologia , Queratinócitos/efeitos dos fármacos , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Mariposas/efeitos dos fármacos , Staphylococcus aureus/efeitos dos fármacos
20.
Environ Sci Pollut Res Int ; 26(14): 14300-14312, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30864030

RESUMO

Spotted bollworm, Earias vittella, is one of the most serious and devastating insect pests of vegetables and cotton. Currently, insecticides are necessary for its control in nearly all crop systems. In this paper, we evaluate the sub-lethal effects of lufenuron on biological traits and activity of detoxification enzymes: cytochrome P450 monooxygenases, esterase, and glutathione S-transeferase (GST) in second instar larvae of E. vittella. Results showed that sub-lethal concentrations (LC15 and LC40 of lufenuron), prolonged larval period (at LC40 = 13.86 ± 1.22 day, LC15 = 13.14 ± 1.15 day, control = 12.28 ± 0.7), pupal duration (LC40 = 11.1 ± day, LC15 = 11.8 ± 0.28 day, control = 9.40 ± 0.52), and extended mean generation time (LC40 = 27.3 ± 0.43 LC15 = 29.0 ± 1.19 day, control = 26.0 ± 0.65). Sub-lethal exposure significantly prolonged the pre-adult stage, decreased pupal weight, and reduced adult longevity in the parent (F0) and F1 generation. Moreover, the fecundity and egg viability were significantly lowered in parental and F1 generations at both sub-lethal concentrations compared to the control. While no significant effects were noted on reproductive parameters such as the intrinsic rate of increase (r), finite rate of increase (λ), and net reproduction rate (R0) of F1 generation when compared to the control. Only mean generation time (T) in F1 at LC15 was significantly longer compared to the LC40 and control (LC40 = 3.79 ± 0.37, LC15 = 32.28 ± 1.55 day, control = 29.79 ± 0.55). Comparatively, the activities of cytochrome P450 monooxygenases and esterase were higher than GST in treated populations. The increase in resistance development against insecticides may possibly because of elevated activity of detoxification enzymes. These results provide useful information for monitoring resistance in integrated pest management (IPM) programs for E. vittella.


Assuntos
Benzamidas/farmacologia , Inseticidas/farmacologia , Mariposas/efeitos dos fármacos , Mariposas/enzimologia , Animais , Relação Dose-Resposta a Droga , Tolerância a Medicamentos , Inativação Metabólica/efeitos dos fármacos , Larva/efeitos dos fármacos , Larva/enzimologia , Pupa/efeitos dos fármacos , Pupa/enzimologia , Reprodução/efeitos dos fármacos
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