Genetic study on overexpression mechanisms of cytochrome P450 in insecticide resistant insect

P450基因Cyp9m10在致倦库蚊拟除虫菊酯抗性品系中的过度表达是敏感品系的260倍。在抗性品系中，包括Cyp9m10基因在内的一个约100kb的区域被特异性复制。两个重复的Cyp9m10拷贝在转录区域和侧翼区域内共享完全相同的序列，直到位于转录起始点上游1.1kb的断裂点。在抗性品系中，在两个Cyp9m10拷贝的上游特异性地插入了一个微型反向重复转座元件(MITE)样元件。我们获得了Cyp9m10过度表达的直接证据，这是由顺式作用突变引起的。在回交实验中，含有两个重复的Cyp9m10拷贝的单倍型与拟除虫菊酯抗性密切相关。

A P450 gene Cyp9m10 is about 260-fold overexpressing in a pyrethroid-resistant strain of Culex quinquefasciatus compared to a susceptible strain. a region of approximately 100kb in length including the Cyp9m10 locus was specifically duplicated in the resistant strain. The two duplicated Cyp9m10 copies shared a completely identical sequence within the transcribed region and the flanking region up to the breakpoint located 1.1kb upstream of the transcriptional start site. A Miniature Inverted-repeat Transposable Element (MITE)-like element was specifically inserted 0.2kb upstream of both Cyp9m10 copies in the resistant strain. We obtained direct evidence that the Cyp9m10 overexpression is caused by a cis-acting mutation. In backcross experiment, a haplotype containing the two duplicated Cyp9m10 copies was strongly associated with the pyrethroid resistance.