Gene expression modulation of ABC transporter genes in response to permethrin in adults of the mosquito malaria vector Anopheles stephensi.

Abstract Living organisms have evolved an array of genes coding for detoxifying enzymes and efflux protein pumps, to cope with endogenous and xenobiotic toxic compounds. The study of the genes activated during toxic exposure is relevant to the area of arthropod vector control, since these genes are one of the targets upon which natural selection acts for the evolution of insecticide resistance. ATP-binding cassette (ABC) transporters participate to insecticide detoxification acting as efflux pumps, that reduce the intracellular concentration of toxic compounds, or of their metabolic derivatives. Here we analyzed the modulation of the expression of six genes coding for ABC transporters, after the exposure of adult females and males of the mosquito Anopheles stephensi , a major malaria vector in Asia, to permethrin. Male and female mosquitoes were exposed to insecticide for one hour, then the expression profiles of the ABC transporter genes Anst ABCB2, Anst ABCB3, Anst ABCB4, Anst ABCBmember6, Anst ABCC11, and Anst ABCG4 were analysed after one and 24 h. Our results showed that three genes ( Anst ABCB2, Anst ABCBmember6, Anst ABCG4) were up-regulated in both sexes; two of these ( Anst ABCBmember6 and Anst ABCG4) have previously been shown to be up-regulated also in larval stages of An. stephensi, supporting a role for these genes in permethrin defence in larvae as well as in adults. Finally, the same ABC transporter genes were activated both in females and males; however, the timing of gene induction was different, with a prompter induction in females than in males.