Molecular mechanism of esterase in insecticide resistance of the smaller brown planthopper

较小的褐飞虱体内的酯酶E7被认为与对有机磷杀虫剂的抗性密切相关。本研究进一步将酯酶E7分离纯化为多个酯酶同工酶。酯酶同工酶表现出相似的生化特性。同一株褐飞虱同工酶的分子量没有差异。不同菌株褐飞虱同工酶的分子量不同。不同酯酶同工酶的n端氨基酸含量存在差异。通过对酯酶基因氨基酸序列的分析，发现酯酶具有丝氨酸残基，属于酯酶超家族。从酯酶基因的基因组分析来看，耐药菌株的高酯酶活性是由酯酶同工酶基因扩增引起的，而不是由酯酶蛋白的质变引起的。在对较小褐飞虱的研究结果的基础上，对褐飞虱酯酶基因的克隆进行了研究。对绿稻叶蝉的乙酰胆碱酯酶进行了分离和鉴定。此时，我们已经从绿叶蝉体内分离出三种不同的乙酰胆碱酯酶。该酯酶的分子机制有待进一步研究。

Esterase called E7 in the smaller brown planthopper was considered to be strongly associated with resistance to organophosphorus insecticides. In this research, esterase E7 was further separated and purified into several esterase isozymes. Esterase isozymes were found to show similar biochemical characteristics. Molecular weight of isozymes from the same strain of the smaller brown planthopper was not different. However, molecular weigh of isozymes from the different strains of the smaller brown planthopper was different. There were any differences in N-terminus amino acids among different esterase isozymes. From the analysis of amino acids sequence of esterase gene, esterase was found to possess serine residue and to be classified to be a esterase super family. From genom analysis of esterase gene, high esterase activity in the insecticide resistant strains was caused by gene amplification of esterase isozymes, not by qualitative change of esterase protein.Based on the result of the study on the smaller brown planthopper, cloning of esterase gene of the brown planthopper is being studied. Acetylcholinesterases of green rice leafhopper are separated and characterized. At this moment, we have separated three different acetylcholinesterase from the greenrice leafhopper. This esterase is a further subject for the molecular mechanism of this enzyme.