title: Multiple Cytochrome P450 genes: their constitutive overexpression and permethrin induction in insecticide resistant mosquitoes, Culex quinquefasciatus.
abstract: Four cytochrome P450 cDNAs, CYP6AA7, CYP9J40, CYP9J34, and CYP9M10, were isolated from mosquitoes, Culex quinquefasciatus. The P450 gene expression and induction by permethrin were compared for three different mosquito populations bearing different resistance phenotypes, ranging from susceptible (S-Lab), through intermediate (HAmCq(G0), the field parental population) to highly resistant (HAmCq(G8), the 8(th) generation of permethrin selected offspring of HAmCq(G0)). A strong correlation was found for P450 gene expression with the levels of resistance and following permethrin selection at the larval stage of mosquitoes, with the highest expression levels identified in HAmCq(G8), suggesting the importance of CYP6AA7, CYP9J40, CYP9J34, and CYP9M10 in the permethrin resistance of larva mosquitoes. Only CYP6AA7 showed a significant overexpression in HAmCq(G8) adult mosquitoes. Other P450 genes had similar expression levels among the mosquito populations tested, suggesting different P450 genes may be involved in the response to insecticide pressure in different developmental stages. The expression of CYP6AA7, CYP9J34, and CYP9M10 was further induced by permethrin in resistant mosquitoes. Taken together, these results indicate that multiple P450 genes are up-regulated in insecticide resistant mosquitoes through both constitutive overexpression and induction mechanisms, thus increasing the overall expression levels of P450 genes.
authors.affiliation: Department of Entomology and Plant Pathology, Auburn University, Auburn, Alabama, United States of America. liunann@auburn.edu
authors.forename: Nannan
authors.initials: N
authors.lastname: Liu
authors.forename: Ting
authors.initials: T
authors.lastname: Li
authors.forename: William R
authors.initials: WR
authors.lastname: Reid
authors.forename: Ting
authors.initials: T
authors.lastname: Yang
authors.forename: Lee
authors.initials: L
authors.lastname: Zhang
mesh_terms: D000818:Animals; D003465:Culex / Q000201:enzymology / Q000235:genetics*; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics*; D004305:Dose-Response Relationship, Drug; D005260:Female; D020869:Gene Expression Profiling; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D019476:Insect Proteins / Q000235:genetics*; D007305:Insecticide Resistance / Q000235:genetics*; D007306:Insecticides / Q000494:pharmacology; D007527:Isoenzymes / Q000235:genetics; D007814:Larva / Q000235:genetics; D008969:Molecular Sequence Data; D005810:Multigene Family; D026023:Permethrin / Q000494:pharmacology*; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D019476:Insect Proteins; D007306:Insecticides; D007527:Isoenzymes; D026023:Permethrin; D003577:Cytochrome P-450 Enzyme System