title: Evolutionary changes in gene expression, coding sequence and copy-number at the Cyp6g1 locus contribute to resistance to multiple insecticides in Drosophila.
abstract: Widespread use of insecticides has led to insecticide resistance in many populations of insects. In some populations, resistance has evolved to multiple pesticides. In Drosophila melanogaster, resistance to multiple classes of insecticide is due to the overexpression of a single cytochrome P450 gene, Cyp6g1. Overexpression of Cyp6g1 appears to have evolved in parallel in Drosophila simulans, a sibling species of D. melanogaster, where it is also associated with insecticide resistance. However, it is not known whether the ability of the CYP6G1 enzyme to provide resistance to multiple insecticides evolved recently in D. melanogaster or if this function is present in all Drosophila species. Here we show that duplication of the Cyp6g1 gene occurred at least four times during the evolution of different Drosophila species, and the ability of CYP6G1 to confer resistance to multiple insecticides exists in D. melanogaster and D. simulans but not in Drosophila willistoni or Drosophila virilis. In D. virilis, which has multiple copies of Cyp6g1, one copy confers resistance to DDT and another to nitenpyram, suggesting that the divergence of protein sequence between copies subsequent to the duplication affected the activity of the enzyme. All orthologs tested conferred resistance to one or more insecticides, suggesting that CYP6G1 had the capacity to provide resistance to anthropogenic chemicals before they existed. Finally, we show that expression of Cyp6g1 in the Malpighian tubules, which contributes to DDT resistance in D. melanogaster, is specific to the D. melanogaster-D. simulans lineage. Our results suggest that a combination of gene duplication, regulatory changes and protein coding changes has taken place at the Cyp6g1 locus during evolution and this locus may play a role in providing resistance to different environmental toxins in different Drosophila species.
authors.affiliation: Department of Genetics, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: Thomas W R
authors.initials: TW
authors.lastname: Harrop
authors.affiliation: Department of Genetics, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria, Australia ; School of Biological Sciences, Monash University, Melbourne, Victoria, Australia.
authors.forename: Tamar
authors.initials: T
authors.lastname: Sztal
authors.affiliation: Department of Genetics, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: Christopher
authors.initials: C
authors.lastname: Lumb
authors.affiliation: Department of Genetics, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: Robert T
authors.initials: RT
authors.lastname: Good
authors.affiliation: Department of Genetics, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: Phillip J
authors.initials: PJ
authors.lastname: Daborn
authors.affiliation: Department of Genetics, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: Philip
authors.initials: P
authors.lastname: Batterham
authors.affiliation: Department of Genetics, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria, Australia ; Howard Hughes Medical Institute and Laboratory of Molecular Biology, University of Wisconsin, Madison, Wisconsin, United States of America.
authors.forename: Henry
authors.initials: H
authors.lastname: Chung
mesh_terms: D000818:Animals; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics*; D056915:DNA Copy Number Variations / Q000187:drug effects / Q000235:genetics*; D029721:Drosophila Proteins / Q000235:genetics*; D004331:Drosophila melanogaster / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D019143:Evolution, Molecular; D020440:Gene Duplication / Q000187:drug effects / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000235:genetics*; D056426:Genetic Loci / Q000187:drug effects / Q000235:genetics*; D007305:Insecticide Resistance / Q000235:genetics*; D016366:Open Reading Frames / Q000187:drug effects / Q000235:genetics; D009928:Organ Specificity; D010641:Phenotype; D013045:Species Specificity
chemical_list: D029721:Drosophila Proteins; D003577:Cytochrome P-450 Enzyme System; C446928:Cyp6g1 protein, Drosophila