不同地域有机磷杀虫药剂抗性库蚊复合组酯酶B1扩增的研究

A STUDY ON ESTERASE BI AMPLIFICATION IN INSECTICIDE RESISTANT CULEX PIPIENS COMPLEX FROM DIFFERENT GEOGRAPHICAL REGIONS

在库蚊Ｃｕｌｅｘｐｉｐｉｅｎｓ品系中，非专一性酯酶的过量产牛是对有机磷杀虫药剂抗性的普遍机理。酯酶基因位于紧密连锁的Ａ和Ｂ座位上。现已知所有酯酶Ｂ的过量产牛都是基因扩增的结果。为了确定不同国家库蚊品系的酯酶Ｂ１的过量产生是否都是相同ＤＮＡ单基因型扩增的结果，我们构建了酯酶Ｂ１结构基因扩增区的限制性内切酶酶切图谱，分析了限制性酶切片段长度多态性（ＲＦＬＰ）。研究发现不同地理位置的酯酶Ｂ１库蚊，如法属圭亚那、委内瑞拉、波多黎各岛、美国加利福尼亚和中国北京，都有着相同的单基因扩增，但在扩增水平上有较大的差异。我们认为无论在美洲或亚洲，凡是酯酶Ｂ１扩增的库蚊都为同一个起源，之后经迁移而传播到各地；同时发现酯酶Ｂ１扩增的库蚊与酯酶Ａ２－Ｂ２扩增的库蚊相比，其迁移有一定的局限性；并巨酯酶Ｂ１扩增的库蚊仅仅限于美国、加勒比和中国的一些地区，而酯酶Ａ２－Ｂ２扩增的库蚊则广泛地分布于美国、加勒比、亚洲、非洲、太平洋各岛及欧洲等地。

in Culex pipiens, overproduction of nonspecific esterases is a commonmechanism of resistance to organol,hosphate insecticides. The esterases are attributed to closely linked loci named A and B, and overproduction of all esterases B is due to gene amplification. In order to determine whether the esterase Bl identified by electrophoretic studies in Culex pip lens mosquitoes from different countries is over-produced due to the amplification of the same DNA haplotype, the amplified region encompassing the structural esterase Bl gene was characterized by restriction mapping and RFLP. Thesame amplified haplotype was found in mosquitoes with an esterase Bl protein,independently of their geographical origin: French Guyana, Venezuela, Puerto Rico,California and Chuna. Large variations in amplification levels were observed. In addition to the highLly amplified 2.Ikb fragment, EcoRI digestion led to two other restriction fragments of low amplification in mosqintoes from the Americas but not from China. It is concluded that BI amplification has a unique origin, either in America or in Asia, and has subsequently spread on a large scale by migration. Thismigration is more limited than that of A2-B2 esterases, since Bl is confined to the Americas, Carribean and part of China, whereas the A2-B2 distribution now includes the Americas, Carribean, Asia, Africa, Pacific islands and Europe.