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

通过对单个昆虫体外乙酰胆碱酯酶(AChE)敏感性的分析，建立了一种简便的监测稻纵卷叶蝉对杀虫剂抗性的方法。通过这种方法，我们发现杀虫剂(N-氨基甲酸甲酯杀虫剂和久效磷)在体外AChE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)没有发现这一现象。抗性绿叶蝉的高脂肪酶活性被认为是造成这一现象的原因之一。通过抗性品系与敏感品系回交试验，选育出一株脂肪酯酶活性较低的抗药性品系。通过生物测定，可以发现抗性品系中的脂肪酶活性是在田间品系中没有发现负相关的交叉抗性的原因。为了从分子水平上探讨W-甲基氨基甲酸酯与久效磷产生负相关交叉抗性的机理，我们分析了AChE基因的氨基酸序列，发现杀虫剂敏感品系和抗性品系的氨基酸序列没有差异。由此可见，绿叶蝉交叉抗性的分子机制可能来源于基因的翻译后修饰。我们想要找出在巨相关交叉耐药的机制中涉及到哪种类型的翻译修饰，并找出这种有趣的负相关交叉耐药现象的全部故事。

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.