Department of Entomology, Michigan State University, East Lansing, MI, USA.
USDA-ARS, Corn Insects & Crop Genetics Research Unit, Ames, IA, USA.
Pestic Biochem Physiol. 2019 Sep;159:136-143. doi: 10.1016/j.pestbp.2019.06.008. Epub 2019 Jun 14.
Cytochrome P450s are part of a super-gene family that has undergone gene duplication, divergence, over-expression and, in some cases, loss of function. One such case is the 91-R and 91-C strains of common origin, in Drosophila melanogaster, whereby 91-R (DDT resistant strain) overexpresses Cyp4p1 and Cyp4p2 and both genes are lost in 91-C (DDT susceptible strain). In this study, we used a comparative approach to demonstrate that transcription of Cyp4p1 and Cyp4p2 were constitutively up-regulated in the Drosophila melanogaster strain 91-R as compared to another DDT susceptible strain Canton-S which does not have a loss of function of these genes. Furthermore, significantly increased expression of Cyp4p1 and Cyp4p2 was induced in 91-R in response to sublethal DDT exposure, however, such induction did not occur in the DDT treated Canton-S. Additionally, fixed nucleotide variation within putative transcription factor binding sites of Cyp4p1 and Cyp4p2 promoters were observed between 91-R and Canton-S, however, their impact on transcription remains to be determined. Two GAL4/UAS transgenic strains with integrated heat shock-inducible Cyp4p1- or Cyp4p2-RNAi constructs within wild-type genetic backgrounds were developed. Following heat shock induction of Cyp4p1 and Cyp4p2 knockdown, these transgenic lines showed increased DDT mortality as compared to their corresponding non-heat shock controls. These results provide a functional link of Cyp4p1 and Cyp4p2 in conferring tolerance to DDT exposure.
细胞色素 P450 是一个超级基因家族的一部分，该基因家族经历了基因复制、分化、过表达，在某些情况下还丧失了功能。这种情况在果蝇中表现为同源的 91-R 和 91-C 株系，其中 91-R（滴滴涕抗性株系）过表达 Cyp4p1 和 Cyp4p2，而 91-C（滴滴涕敏感株系）则丢失了这两个基因。在这项研究中，我们使用了一种比较的方法来证明，与另一个没有这些基因功能丧失的滴滴涕敏感株系 Canton-S 相比，果蝇 91-R 株系中 Cyp4p1 和 Cyp4p2 的转录是持续上调的。此外，在 91-R 中，亚致死剂量的滴滴涕暴露会显著诱导 Cyp4p1 和 Cyp4p2 的表达，但在滴滴涕处理的 Canton-S 中不会发生这种诱导。此外，在 91-R 和 Canton-S 之间观察到 Cyp4p1 和 Cyp4p2 启动子中假定转录因子结合位点的固定核苷酸变异，但它们对转录的影响仍有待确定。在野生型遗传背景下，我们开发了两种带有整合的热休克诱导型 Cyp4p1 或 Cyp4p2-RNAi 构建体的 GAL4/UAS 转基因株系。在 Cyp4p1 和 Cyp4p2 敲低的热休克诱导后，与相应的非热休克对照相比，这些转基因株系表现出更高的滴滴涕死亡率。这些结果提供了 Cyp4p1 和 Cyp4p2 在赋予对滴滴涕暴露的耐受性方面的功能联系。
