Department of Nanobiology, Graduate School of Advanced Integration Science, Chiba University, 1-33 Yayoi, Inage-ku, Chiba 263-8522, Japan.
Insect Biochem Mol Biol. 2010 Sep;40(9):631-40. doi: 10.1016/j.ibmb.2010.06.001. Epub 2010 Jun 18.
Development of insecticide resistance reduces the efficacy of controlling measures against the medical and agricultural insect pests. Cytochrome P450s are one of the major detoxification enzymes involved in insecticide metabolisms. Previously, we have reported that the P450 gene Cyp9m10 is about 260-fold overexpressed in a pyrethroid-resistant strain of Culex quinquefasciatus compared to a susceptible strain. In this study, we obtained direct evidence that the Cyp9m10 overexpression is caused by a cis-acting mutation. Additionally, a region of approximately 100 kb 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 1.1 kb upstream of the transcriptional start site. A Miniature Inverted-repeat Transposable Element (MITE)-like element was specifically inserted 0.2 kb upstream of both Cyp9m10 copies in the resistant strain. In backcross experiment, a haplotype containing the two duplicated Cyp9m10 copies was strongly associated with the pyrethroid resistance.
昆虫抗药性的发展降低了控制医学和农业害虫的措施的效果。细胞色素 P450s 是参与杀虫剂代谢的主要解毒酶之一。以前，我们已经报道过，与敏感株相比，在拟除虫菊酯抗性的库蚊（Culex quinquefasciatus）品系中，P450 基因 Cyp9m10 的表达水平高出约 260 倍。在本研究中，我们获得了直接证据表明 Cyp9m10 的过表达是由顺式作用突变引起的。此外，在抗性株中，大约 100kb 长度的包含 Cyp9m10 基因座的区域被特异性地重复。两个重复的 Cyp9m10 拷贝在转录区域和侧翼区域内具有完全相同的序列，直到转录起始位点上游 1.1kb 的断点。在抗性株中，一个类似于微型反向重复转座元件（MITE）的元件被特异性地插入到两个 Cyp9m10 拷贝的上游 0.2kb 处。在回交实验中，含有两个重复 Cyp9m10 拷贝的单倍型与拟除虫菊酯抗性强烈相关。
