title: Sex-specific induction of CYP6 cytochrome P450 genes in cadmium and lead tolerant Anopheles gambiae.
abstract: BACKGROUND
  Anopheles gambiae, one of the main Afro-tropical mosquito vector of malaria, has adapted to heavy metals in its natural habitat, and developed resistance to most conventional insecticides. Investigations were conducted to establish an association between tolerance to cadmium or lead-heavy metals, and expression of specific genes for cytochrome p450 enzymes associated with pyrethroid resistance in the mosquito.
  
  
  METHODS
  Juvenile aquatic stages of the mosquito were selected for tolerance to cadmiun or lead through chronic exposure of the stages to maximum acceptable toxicant concentrations (MATCs) of the metals. Using real-time quantitative polymerase chain reaction (qPCR), three replicates each of male or female cadmium or lead-tolerant individuals and relevant controls were separately screened for expression of CYP6M2, CYP6P3 and CYP6Z1 genes. The variance in expression levels of the genes amongst the treatments was compared by ANOVA statistical tool.
  
  
  RESULTS
  Expressions of all the genes were significantly lower (P <0.05) in females than in males. Within gender, there 1.3 - 2.3 or 3.1-4.2-fold reduction in expression of the genes in cadmium or lead selected than respective control populations. Expression of all the classes of gene was elevated in cadmium selected female populations relative to their respective controls.
  
  
  CONCLUSIONS
  These findings suggest that tolerance to cadmium or lead in the mosquito can influence response in cytochrome p450 genes associated with metabolism of pyrethroids in the mosquito in a sex-specific manner. This can, in turn, affect sensitivity of the mosquito to pyrethroids and other xenobiotics associated with these genes, with potential implications in mosquito vector control operations.
authors.affiliation: Department of Biochemistry and Molecular Biology, Egerton University, P,O, Box 536, Njoro, Kenya.
authors.forename: Fauzia K
authors.initials: FK
authors.lastname: Musasia
authors.forename: Alfred O
authors.initials: AO
authors.lastname: Isaac
authors.forename: Daniel K
authors.initials: DK
authors.lastname: Masiga
authors.forename: Irene A
authors.initials: IA
authors.lastname: Omedo
authors.forename: Ramadhan
authors.initials: R
authors.lastname: Mwakubambanya
authors.forename: Richard
authors.initials: R
authors.lastname: Ochieng
authors.forename: Paul O
authors.initials: PO
authors.lastname: Mireji
mesh_terms: D000818:Animals; D000852:Anopheles / Q000187:drug effects*; D002104:Cadmium / Q000378:metabolism* / Q000633:toxicity; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis*; D004361:Drug Tolerance; D005260:Female; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects*; D007306:Insecticides / Q000494:pharmacology; D007854:Lead / Q000378:metabolism* / Q000633:toxicity; D008297:Male; D011722:Pyrethrins / Q000494:pharmacology; D060888:Real-Time Polymerase Chain Reaction; D012641:Selection, Genetic; D012737:Sex Factors
chemical_list: D007306:Insecticides; D011722:Pyrethrins; D002104:Cadmium; D007854:Lead; D003577:Cytochrome P-450 Enzyme System