title: Molecular mechanisms of metabolic resistance to synthetic and natural xenobiotics.
abstract: Xenobiotic resistance in insects has evolved predominantly by increasing the metabolic capability of detoxificative systems and/or reducing xenobiotic target site sensitivity. In contrast to the limited range of nucleotide changes that lead to target site insensitivity, many molecular mechanisms lead to enhancements in xenobiotic metabolism. The genomic changes that lead to amplification, overexpression, and coding sequence variation in the three major groups of genes encoding metabolic enzymes, i.e., cytochrome P450 monooxygenases (P450s), esterases, and glutathione-S-transferases (GSTs), are the focus of this review. A substantial number of the adaptive genomic changes associated with insecticide resistance that have been characterized to date are transposon mediated. Several lines of evidence suggest that P450 genes involved in insecticide resistance, and perhaps insecticide detoxification genes in general, may share an evolutionary association with genes involved in allelochemical metabolism. Differences in the selective regime imposed by allelochemicals and insecticides may account for the relative importance of regulatory or structural mutations in conferring resistance.
authors.affiliation: Department of Entomology and BIO5, University of Arizona, Tucson, Arizona 85721, USA. lxc@email.arizona.edu
authors.forename: Xianchun
authors.initials: X
authors.lastname: Li
authors.forename: Mary A
authors.initials: MA
authors.lastname: Schuler
authors.forename: May R
authors.initials: MR
authors.lastname: Berenbaum
mesh_terms: D000818:Animals; D005075:Biological Evolution; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism; D004251:DNA Transposable Elements; D004950:Esterases / Q000235:genetics / Q000378:metabolism; D005982:Glutathione Transferase / Q000235:genetics / Q000378:metabolism; D007313:Insecta / Q000201:enzymology* / Q000235:genetics; D007305:Insecticide Resistance / Q000502:physiology*; D050216:Metabolic Detoxication, Phase I / Q000502:physiology*; D050217:Metabolic Detoxication, Phase II / Q000502:physiology*; D010944:Plants / Q000378:metabolism; D015262:Xenobiotics / Q000378:metabolism*
chemical_list: D004251:DNA Transposable Elements; D015262:Xenobiotics; D003577:Cytochrome P-450 Enzyme System; D005982:Glutathione Transferase; D004950:Esterases