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Three cDNA clones for cytochrome P450s, CYP6B2, CYP6B6 and CYP6B7 which have 84–87% protein sequence identity have been isolated previously from Helicoverpa armigera, and the CYP6B7 mRNA was found to be over-expressed in a pyrethroid-resistant field population. Subsequent analysis has shown that over-expression is observed in a majority of individuals in all populations tested. Single-pair crosses between resistant and sensitive individuals indicated that the pyrethroid resistance co-segregated with the over-expression of this mRNA. Southern analysis indicated that the over-expression, which was confined to midgut only in many insects, was not related to gene amplification. These observations add weight to the conclusion that CYP6B7 is the cytochrome P450 form involved in pyrethroid resistance, and that over-expression of cytochrome P450 CYP6B7 is a common cause of pyrethroid resistance in H. armigera. The results suggest that specific probes for CYP6B7 protein or mRNA could provide the basis for the development of tools for monitoring pyrethroid resistance due to mixed function oxidase activity in field populations of this insect. © 1998 Society of Chemical Industry 相似文献
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Genetic linkage of hscp (heliothis sodium channel protein) and CYP6B10 was discovered in Heliothis virescens. The hscp gene encodes the sodium channel target of pyrethroid insecticides and cytochrome P450 genes encode important enzymes involved in detoxication of various pesticides. Previously, two mechanisms, nerve insensitivity due to sodium channel and synergism by propynyl aryl ethers, were observed in pyrethroid-resistant H virescens and were not separated by repeated back-crossing. We hypothesized genetic linkage of target site insensitivity and monooxygenase-mediated detoxication. Single nucleotide polymorphisms were discovered in IIS6 of hscp; Hpy of hscp and CYP6B10. Segregation of these and other markers was tested in backcrosses. We observed cosegregation of hscp to CYP6B10, but both genes assorted independently of y, ye and sex. Genes y and ye assorted independently of each other. This was the first observation of linkage between genes controlling detoxication and sodium ion channel insensitivity in a species known to express high levels of pyrethroid resistance. Linkage was not likely because this species has 31 chromosomes; therefore, we will investigate the possibility of a resistance cassette. We expect similar linkage in other noctuid pests. 相似文献
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The massive use of DDT as an insecticide between 1940 and 1970 has resulted in the emergence of a resistant population of insects. One of the main metabolic mechanisms developed by resistant insects involves detoxification enzymes such as cytochrome P450s. These enzymes can metabolise the insecticide to render it less toxic and facilitate its elimination from the organism. The P450 Cyp6g1 was identified as the major factor responsible for DDT resistance in Drosophila melanogaster field populations. In this article, we review the data available for this gene since it was associated with resistance in 2002. The knowledge gained on Cyp6g1 allows a better understanding of the evolution of insecticide resistance mechanisms and highlights the major role of transposable elements in evolutionary processes. © 2016 Society of Chemical Industry 相似文献
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Ding Dai Yan Cao Greg Falls Patricia E. Levi Ernest Hodgson Randy L. Rose 《Pesticide biochemistry and physiology》2001,70(3):127
Several environmental chemicals are disruptive to the reproductive and endocrine systems of many species, including humans. Mechanisms for endocrine disruption are presently under scrutiny. Xenobiotic inducible mammalian cytochrome P450 (CYP) enzymes metabolize a variety of substrates including environmental chemicals, pesticides, and drugs. The metabolism, and thus the effect, of endogenous chemicals including steroid hormones, vitamins, etc. that are transformed by CYP enzymes can be influenced by environmental exposure to CYP-inducing chemicals. This study demonstrated that structurally diverse environmental chemicals including mirex, 2,2-Bis(p-chlorophenyl)-1,1-dichloroethylene (DDE), vinclozolin, and flutamide are capable of inducing several mouse liver CYP isozymes. As demonstrated by Western blotting, mirex induced CYP1A2, 2B10, 2E1, and 3A and vinclozolin induced 1A2 and 2B10. The only isoforms significantly induced by DDE and flutamide were 3A and 1A2, respectively. Since some of these isoforms are known to be involved in metabolism of endogenous hormones, we also studied the effects of these CYP inducers on testosterone metabolism and seminal vesicle weights. Mirex and DDE treatments had profound effects on the metabolism of testosterone, resulting in 2.5- to 3-fold more hydroxylated products than controls. Lesser, but significant, increases in specific metabolites of testosterone were also observed following treatment with vinclozolin and flutamide. Seminal vesicle weights were lower for all treatment groups except DDE. Results of this study demonstrate that, due to their CYP-inducing potential, these chemicals may significantly impact testosterone metabolism and this may be a contributing factor in their antiandrogenic effects. 相似文献
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Thomas C. Sparks Gerrit J. DeBoerNick X. Wang James M. HaslerMichael R. Loso Gerald B. Watson 《Pesticide biochemistry and physiology》2012,103(3):159-165
Sulfoxaflor [N-[methyloxido[1-[6-(trifluoromethyl)-3-pyridinyl]ethyl]-λ4-sulfanylidene] cyanamide] is in development as the first product from the new sulfoximine class of insect control agents. Highly effective against a variety of sap-feeding pest insects, available data indicate no cross-resistance to sulfoxaflor in pest insect strains that exhibit high levels of resistance to neonicotinoids and other insecticides. In vitro studies of the cytochrome P450 monooxygenase CYP6G1 from Drosophila melanogaster, expressed in a Drosophila cell line, show very high levels of metabolism for a variety of neonicotinoids, but not for sulfoxaflor and its chloropyridine-analog. A sulfoxaflor analog with nitrogen in place of the carbon in the bridge between the pyridine and sulfoximine moiety shows a modest degree of metabolism. In silico homology modeling of the CYP6G1 with the sulfoximines and neonicotinoids suggests that steric effects may limit interactions of the sulfoximines with the reactive heme-oxo complex. A distinct relationship was identified for the summed Hückel charges and the degree of metabolism observed. These observations help explain the lack of sulfoxaflor metabolism by CYP6G1, and in turn provide a basis for the lack of cross-resistance to sulfoxaflor in insecticide resistant strains of pest insects. 相似文献
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以抗氰戊菊酯棉铃虫六龄幼虫中肠组织总RNA为模板,采用特异性引物,通过对反转录-聚合酶链式反应(RT-PCR)的条件进行不断探索和优化,成功克隆出全长为1 557 bp的基因片段(GenBank登录号DQ497428)。该片段包括一个完整的开放阅读框架(1 515 bp)及5'端的42个碱基,编码504个氨基酸残基。与国外报道的细胞色素P450 CYP6B7基因(GenBank登录号AF031468)的核苷酸、氨基酸同源性分别为97.75%和98.81%,为CYP6B7的等位基因。Northern杂交分析表明,抗性品系棉铃虫中肠组织中CYP6B7 mRNA的表达量明显高于敏感品系的,初步表明CYP6B7在棉铃虫对氰戊菊酯的抗药性中起着重要作用。 相似文献
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小菜蛾Plutella xylostella是为害十字花科作物的世界性重要害虫,对氯虫苯甲酰胺产生了严重抗性。已经明确小菜蛾CYP6BG1的过量表达与其对氯虫苯甲酰胺的抗性相关。本文进一步通过昆虫杆状病毒表达系统在Sf9细胞中表达了小菜蛾CYP6BG1和NADPH-细胞色素P450还原酶(CPR)蛋白,并检测Sf9细胞表达CYP6BG1蛋白后对氯虫苯甲酰胺的敏感变化及氯虫苯甲酰胺经CYP6BG1蛋白代谢后对小菜蛾幼虫毒力的变化。结果显示:Sf9细胞中与CPR共表达的CYP6BG1具有7-乙氧基香豆素O-脱乙基酶活性,且细胞对氯虫苯甲酰胺的敏感性显著下降。将表达的蛋白与不同浓度的氯虫苯甲酰胺孵育24 h后,对3龄小菜蛾幼虫致死率显著低于对照组。本研究结果间接表明CYP6BG1能够降解氯虫苯甲酰胺,从而增强小菜蛾对氯虫苯甲酰胺的抗性。 相似文献
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于2011年采集北京、山东和湖南三地的烟粉虱,进行B、Q隐种鉴定,并测定4种杀虫剂的抗药性,同时通过荧光定量PCR分析CYP4v2和CYP6CX1两个基因的mRNA水平的表达量。结果表明,北京、湖南和长沙烟粉虱均为Q隐种。抗药性监测表明,北京和湖南种群对阿维菌素敏感,山东种群抗性水平较低,而对烟碱类药剂噻虫嗪出现不同程度的抗药性,其中湖南地区烟粉虱对噻虫嗪的抗药性达到49.08倍的高抗水平,北京和山东地区也达到中抗水平。另外,这3个地区的种群对毒死蜱和联苯菊酯抗性水平都较低。通过qRT-PCR分析三地的CYP4v2和CYP6CX1基因表达量,发现相对于敏感种群CYP4v2基因在北京、山东和湖南3个地理种群中分别过量表达3.85倍、19.57倍和10.78倍,而CYP6CX1基因在北京种群中过量表达20.55倍。结果提示田间烟粉虱的细胞色素P450基因CYP4v2和CYP6CX1过量表达可能会是烟粉虱抗药性的形成机制之一。 相似文献
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烟粉虱是一种世界性农业害虫,其防治手段以化学防治为主,新烟碱类杀虫剂吡虫啉常年用于防治烟粉虱,田间烟粉虱已经形成严重的抗药性。本研究通过分析烟粉虱吡虫啉抗性和敏感种群,发现细胞色素CYP6EM1基因在吡虫啉抗性品系中上调了4.7倍,进而克隆了其全长基因,进行了荧光定量PCR分析,发现该基因在吡虫啉抗性烟粉虱3龄若虫期和雄虫成虫期过量表达,并且在抗性成虫胸部和腹部过量表达。最后通过RNA干扰的方法使成虫的CYP6EM1基因表达量下降了54.8%,之后发现当烟粉虱暴露于吡虫啉时死亡率显著升高了39.65%,这表明CYP6EM1与烟粉虱对吡虫啉抗性的形成相关。研究结果对于揭示烟粉虱对吡虫啉产生抗性的机制有帮助,也为烟粉虱抗性水平田间监测及烟粉虱综合治理提供理论依据。 相似文献
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ABSTRACT Resistance to scab originating from Malus floribunda clone 821 is the most widely form of resistance used in apple breeding programs. A dominant gene, named Vf, was introgressed from this clone into recent cultivars, although the genetic determinants of the resistance of M. floribunda 821 are apparently more complex than a single gene. The appearance of new races overcoming the resistance of cultivars with the Vf gene, the parental clone, or both made it possible to undertake a genetic analysis of host-pathogen interactions. The segregation of resistance in progenies of crosses from 'Golden Delicious' x M. floribunda 821 and 'Golden Delicious' x 'Idared' into five strains of Venturia inaequalis-races 1 (strains 104, 1093, and 301), 6 (strain 302), and 7 (strain 1066)-demonstrated the existence of a second dominant gene in M. floribunda 821. This gene, independent of Vf, was named Vfh because it seemed to induce a hypersensitive reaction. The results obtained with strain 1066, virulent to M. floribunda 821, allowed identification of another dominant gene, Vg, responsible for the resistance of 'Golden Delicious' to this strain. Vg is also carried by 'Florina', which was selected for its Vf resistance. The pathogenicity of a progeny originating from a cross between V. inaequalis strains 1066 and 301, characterized in vitro on leaf disks of differential genotypes, revealed two independent avirulence genes involved in the pathogenicity toward the Vg and Vf genes, respectively. These avirulence genes were named Avr Vg and Avr Vf. The host-pathogen interactions detected are consistent with a gene-for-gene relationship. 相似文献
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Andrew Plant Achim Harder Norbert Mencke Heinz-Jürgen Bertram 《Pest management science》1996,48(4):351-358
7-Hydroxy-5-oxo-5H-thieno[3,2-b]pyran-6-carboxanilides and -6-thio-carboxanilides represent a novel series of anthelmintic compounds, with broad-spectrum activity against important parasitic nematodes in sheep and dogs. In particular, an improved efficacy against Trichostrongylus colubriformis in sheep over the related 3-carbamoyl-4-hydroxycoumarins has been noted. New synthetic routes to the key intermediate, 7-hydroxythieno[3,2-b]pyran-5-one, have been developed. 相似文献
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