title: Cross-induction of detoxification genes by environmental xenobiotics and insecticides in the mosquito Aedes aegypti: impact on larval tolerance to chemical insecticides.
abstract: The effect of exposure of Aedes aegypti larvae to sub-lethal doses of the pyrethroid insecticide permethrin, the organophosphate temephos, the herbicide atrazine, the polycyclic aromatic hydrocarbon fluoranthene and the heavy metal copper on their subsequent tolerance to insecticides, detoxification enzyme activities and expression of detoxification genes was investigated. Bioassays revealed a moderate increase in larval tolerance to permethrin following exposure to fluoranthene and copper while larval tolerance to temephos increased moderately after exposure to atrazine, copper and permethrin. Cytochrome P450 monooxygenases activities were induced in larvae exposed to permethrin, fluoranthene and copper while glutathione S-transferase activities were induced after exposure to fluoranthene and repressed after exposure to copper. Microarray screening of the expression patterns of all detoxification genes following exposure to each xenobiotic with the Aedes Detox Chip identified multiple genes induced by xenobiotics and insecticides. Further expression studies using real-time quantitative PCR confirmed the induction of multiple CYP genes and one carboxylesterase gene by insecticides and xenobiotics. Overall, this study reveals the potential of xenobiotics found in polluted mosquito breeding sites to affect their tolerance to insecticides, possibly through the cross-induction of particular detoxification genes. Molecular mechanisms involved and impact on mosquito control strategies are discussed.
authors.affiliation: Laboratoire d'Ecologie Alpine, UMR CNRS-Université Joseph Fourier 5553, Equipe Perturbations Environnementales et Xénobiotiques, Domaine Universitaire de Saint-Martin d'Hères. 2233, rue de la piscine Bât D Biologie, BP 53, 38041 Grenoble Cedex 9, France.
authors.forename: Rodolphe
authors.initials: R
authors.lastname: Poupardin
authors.forename: Stéphane
authors.initials: S
authors.lastname: Reynaud
authors.forename: Clare
authors.initials: C
authors.lastname: Strode
authors.forename: Hilary
authors.initials: H
authors.lastname: Ranson
authors.forename: John
authors.initials: J
authors.lastname: Vontas
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: David
mesh_terms: D000330:Aedes / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D000818:Animals; D001280:Atrazine / Q000493:pharmacokinetics; D003300:Copper / Q000493:pharmacokinetics; D004361:Drug Tolerance; D004785:Environmental Pollutants / Q000493:pharmacokinetics; D005449:Fluorenes / Q000493:pharmacokinetics; D005786:Gene Expression Regulation / Q000187:drug effects*; D008658:Inactivation, Metabolic; D007305:Insecticide Resistance / Q000187:drug effects*; D007306:Insecticides; D007814:Larva / Q000187:drug effects / Q000201:enzymology / Q000235:genetics; D015262:Xenobiotics / Q000493:pharmacokinetics*
chemical_list: D004785:Environmental Pollutants; D005449:Fluorenes; D007306:Insecticides; D015262:Xenobiotics; C007738:fluoranthene; D003300:Copper; D001280:Atrazine