Studies of molecular mechanisms on negatively correlated cross resistance in the green rice leafhopper, Nephotettix cincticeps Uhler

摘要通过对青稻叶蝉（nephotetix cincticeps Uhler）体内乙酰胆碱酯酶（AChE）敏感性的分析，建立了一种简便的农药抗性监测方法。通过这种方法，我们发现n -氨基甲酸甲酯类杀虫剂和单效磷组合杀虫剂在体外乙酰胆碱酯酶抑制水平上表现出负相关的交叉抗性。然而，生物测定（毒性试验）没有发现这种现象。抗杀虫剂绿稻叶蝉的高脂酯酶活性被认为是造成这一现象的原因。通过抗虫菌株与感虫菌株的回交试验，选育了一株低酯酶活性的抗虫菌株。通过生物测定，我们发现抗性品系的酯酶活性是导致绿稻叶跳虫田间品系没有出现负相关交叉抗性的原因。为了在分子水平上验证w -氨基甲酸甲酯与单效磷负相关交叉抗性的机制，我们分析了AChE基因的氨基酸序列，发现绿稻叶蝉的敏感品系和抗性品系之间的氨基酸序列没有差异。因此，绿稻叶蝉产生交叉抗性的分子机制可能来源于翻译后修饰。我们想要找出哪种类型的翻译修饰参与了负相关交叉抗性的机制，并找出这个有趣现象的整个故事，负相关交叉抗性。

By analyzing the sensitivity of acetylcholinesterase (AChE) of individual insects in vitro, we developed a simple monitoring method for insecticide resistance in the green rice leafhopper, Nephotettix cincticeps Uhler. By using this mehtod, we found that a combination of insecticides (N-methyl carbamate insecticides and monocrotophos) showed a negatively corelated cross resistance at the AChE inhibition level in vitro. However, this phenomenon was not found by the bioassay (toxicity test). High aliesterase actrivity in the insecticide resistant green rice leafhopper was thought to be a cause of this phenomenon. We bred an insecticide resistant strain which shows a low aliesterase activityby by back cross experiment between insecticide resistant and susceptible strains. By the bioassay, we could find that the aliesterase activity in the resistant strain was a cause that we could not find negatively correlated cross resistance in the field strains of green rice leafhopper. To calrify the mechanisms of negatively correlated cross resistance between W-methyl carbamates and monocrotophos at the molecular level, we analyzed the aminoacid sequence of AChE gene and found that there was no difference in the aminoacid sequence between insecticide susceptible and resistant strains of the green rice leafhopper. Thus, the molecular mechanism of cross resistance in the green rice leafhopper was thought to be derived from the post translational modification. We would like to find out what type of translational modification is involved in the mechanisms of megatively correlated cross resistance and find out the whole story of this interesting phenomeno, negatively correlated cross resistance.