Cis-Regulatory Elements in the Accord Retrotransposon Result in Tissue-Specific Expression of the Drosophila melanogaster Insecticide Resistance Gene Cyp6g1

摘要

Transposable elements are a major mutation source and powerful agents of adaptive change. Somentransposable element insertions in genomes increase to a high frequency because of the selectivenadvantage the mutant phenotype provides. Cyp6g1-mediated insecticide resistance in Drosophilanmelanogaster is due to the upregulation of the cytochrome P450 gene Cyp6g1, leading to the resistancento a variety of insecticide classes. The upregulation of Cyp6g1 is correlated with the presence of the longnterminal repeat (LTR) of an Accord retrotransposon inserted 291bp upstream of the Cyp6g1 transcriptionnstart site. This resistant allele (DDT-R) is currently at a high frequency in D. melanogaster populationsnaround the world. Here, we characterize the spatial expression of Cyp6g1 in insecticide-resistant andn-susceptible strains. We show that the Accord LTR insertion is indeed the resistance-associated mutationnand demonstrate that the Accord LTR carries regulatory sequences that increase the expression of Cyp6g1nin tissues important for detoxification, the midgut, Malpighian tubules, and the fat body. This studynprovides a significant example of how changes in tissue-specific gene expression caused by transposableelementninsertions can contribute to adaptation.