Wan Hua, Liu Yan, Li Mei, Zhu Shunyi, Li Xianchun, Pittendrigh Barry R, Qiu Xinghui
State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China.
Pest Manag Sci. 2014 Jul;70(7):1048-58. doi: 10.1002/ps.3645. Epub 2013 Oct 8.
Increased insecticide detoxification mediated by cytochrome P450s is a common mechanism of insecticide resistance. Although Cyp6a2 has been observed to be overexpressed in many 4,4'-dichlorodiphenyltrichloroethane (DDT)-resistant strains of Drosophila melanogaster, how Cyp6a2 is regulated and whether its overproduction confers DDT resistance remain elusive.
Molecular analysis identified five Cyp6a2 alleles (Cyp6a2(Canton) (-S-1) , Cyp6a2(Canton) (-S-2) , Cyp6a2(91-C) , Cyp6a2(91-R) and Cyp6a2(Wisconsin) (-) (WD) ) from four D. melanogaster strains, notably differing in the presence or absence of an intact Nrf2/Maf (a transcription factor) binding site in the 5'-promoter core region, a 'G1410' frameshift deletion mutation in the heme-binding region and a long terminal repeat (LTR) of transposable element 17.6 in the 3'-untranslated region (UTR). Linkage analysis confirmed that DDT resistance was genetically linked to a Nrf2/Maf-binding-site-containing, LTR-lacking functional allele of Cyp6a2 (Cyp6a2(91-R) ). The qRT-PCR results showed that overexpression of functional Cyp6a2 was consistently associated with DDT resistance. Luciferase reporter gene assays revealed that an intact Nrf2/Maf binding site in the 5'-promoter core region enhanced the constitutive transcription of Cyp6a2.
The results suggest that the Nrf2/Maf binding-site-containing functional Cyp6a2 allele is associated with DDT resistance in the D. melanogaster strains under study.
细胞色素P450介导的杀虫剂解毒作用增强是杀虫剂抗性的常见机制。尽管已观察到Cyp6a2在许多对4,4'-二氯二苯三氯乙烷（DDT）具有抗性的黑腹果蝇品系中过表达，但Cyp6a2如何被调控以及其过量产生是否赋予DDT抗性仍不清楚。
分子分析从四个黑腹果蝇品系中鉴定出五个Cyp6a2等位基因（Cyp6a2（广州）（-S-1）、Cyp6a2（广州）（-S-2）、Cyp6a2（91-C）、Cyp6a2（91-R）和Cyp6a2（威斯康星）（-）（WD）），它们在5'-启动子核心区域是否存在完整的Nrf2/Maf（一种转录因子）结合位点、血红素结合区域的“G1410”移码缺失突变以及3'-非翻译区（UTR）中的转座因子17.6的长末端重复序列（LTR）方面存在显著差异。连锁分析证实，DDT抗性与含有Nrf2/Maf结合位点、缺乏LTR的Cyp6a2功能等位基因（Cyp6a2（91-R））存在遗传连锁。qRT-PCR结果表明，功能性Cyp6a2的过表达始终与DDT抗性相关。荧光素酶报告基因检测显示，5'-启动子核心区域完整的Nrf2/Maf结合位点增强了Cyp6a2的组成型转录。
结果表明，在所研究的黑腹果蝇品系中，含有Nrf2/Maf结合位点的功能性Cyp6a2等位基因与DDT抗性相关。
