Liu N, Scott J G
Department of Entomology, Cornell University, Ithaca, New York 14853-0901, USA.
Insect Biochem Mol Biol. 1998 Aug;28(8):531-5. doi: 10.1016/s0965-1748(98)00039-3.
Insecticide resistance is a major problem that continues to plague efforts to control pests of animals and crops. An important mechanism by which insects become resistant to insecticides is via increased detoxification mediated by the cytochrome P450 microsomal monooxygenases (monooxygenases). One of the fundamental gaps in our knowledge about this resistance mechanism is an understanding of how insects express high levels of the specific cytochrome P450(s) responsible for resistance. One such P450, CYP6D1, causes resistance to pyrethroid in the house fly and is expressed at 9-fold higher levels (mRNA and protein) in the Learn Pyrethroid Resistant (LPR) strain (compared to susceptible strains). The relative stability of CYP6D1 mRNA in resistant and susceptible strains was measured following inhibition of transcription with actinomycin D. The same time course of decrease in CYP6D1 mRNA abundance was detected in both strains indicating that the high level of expression of CYP6D1 in LPR is not due to increased stability of the mRNA. The comparative rates of transcription of CYP6D1 were measured using an in vitro run-on transcription assay. The relative amount of CYP6D1 transcript produced in this assay was 10-fold greater in the LPR strain compared to the susceptible strain. This demonstrates that increased transcription of CYP6D1 is an underlying cause of monooxygenase-mediated insecticide resistance. The increased rate of transcription of CYP6D1 in the resistant strain (LPR) is controlled by two factors: one on autosome 1 and another on autosome 2.
杀虫剂抗性是一个持续困扰动物和农作物害虫防治工作的主要问题。昆虫对杀虫剂产生抗性的一个重要机制是通过细胞色素P450微粒体单加氧酶（单加氧酶）介导的解毒作用增强。我们对这种抗性机制认识的一个基本空白是了解昆虫如何高水平表达负责抗性的特定细胞色素P450。一种这样的P450，即CYP6D1，使家蝇对拟除虫菊酯产生抗性，并且在抗拟除虫菊酯品系（LPR）中（与敏感品系相比）以高9倍的水平（mRNA和蛋白质）表达。在用放线菌素D抑制转录后，测定了抗性和敏感品系中CYP6D1 mRNA的相对稳定性。在两个品系中均检测到CYP6D1 mRNA丰度下降的相同时间进程，这表明LPR中CYP6D1的高表达水平不是由于mRNA稳定性增加所致。使用体外连续转录测定法测量了CYP6D1的转录相对速率。与敏感品系相比，该测定中产生的CYP6D1转录本的相对量在LPR品系中高10倍。这表明CYP6D1转录增加是单加氧酶介导的杀虫剂抗性的根本原因。抗性品系（LPR）中CYP6D1转录速率的增加受两个因素控制：一个在常染色体1上，另一个在常染色体2上。
