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通过解毒酶活性测定与钠离子通道基因片段的克隆、测序,研究了南京小菜蛾对拟除虫菊酯产生高水平抗性的生化和分子机制。结果表明,南京抗性种群的酯酶和多功能氧化酶O-脱甲基活性分别是敏感种群的1.06和1.16倍,无显著差异;以2,4二硝基氯苯(CDNB)和1,2-二氯-4-硝基苯(DCNB)为底物,南京抗性种群的谷胱甘肽S-转移酶活性分别是敏感种群的0.68倍和1.03倍;进一步利用聚合酶链式反应(PCR)分别从敏感和抗性小菜蛾基因组DNA中扩增出了位于钠离子通道结构域IIS6的232bp和248bp的DNA片段;与敏感种群相比,南京抗性种群钠离子通道基因存在一个保守性点突变,即C突变为T,并导致亮氨酸突变为苯丙氨酸,表明神经不敏感性是南京小菜蛾对拟除虫菊酯产生高水平抗性的主要机制。
Through the detoxification enzyme activity assay and the cloning and sequencing of the sodium ion channel gene fragments, the biochemical and molecular mechanisms of high level resistance to pyrethroid in diamondback moth (Plutella xylostella) in Nanjing were studied. The results showed that the O-demethylation activities of esterase and multi-functional oxidase in Nanjing resistant population were 1.06 and 1.16 times of those of the susceptible population, respectively. There was no significant difference between the two populations. 2,4 dinitrochlorobenzene (CDNB) and 1, 2-dichloro-4-nitrobenzene (DCNB) as substrates, the glutathione S-transferase activities of Nanjing resistant population were 0.68 times and 1.03 times of that of the sensitive population, respectively. Polymerase chain reaction PCR) were used to amplify the 232 bp and 248 bp DNA fragments of IIS6 from the sensitive and resistant diamondback moth (Plutella xylostella) genomes, respectively. Compared with the susceptible populations, there was a conservative gene in the Nanjing population The point mutation, that is, the mutation of C to T, led to the mutation of leucine to phenylalanine, indicating that neurotoxicity is the major mechanism of high level resistance to pyrethroid in Plutella xylostella Linn.