title: Characterization of an epsilon-class glutathione S-transferase involved in tolerance in the silkworm larvae after long term exposure to insecticides.
abstract: This study assessed the effect of the pesticides on activity and expression of glutathione S-transferases (GSTs) in the midgut of the silkworm after intense selections by phoxim and fenpropathrin for five and four generations, respectively. GSTs activity towards cumene hydroperoxide (CHP), a substrate of GSH-dependent peroxidase, was significantly increased in the crude homogenate of midguts after long term exposure to the insecticides. An epsilon-class GST gene (BmGSTe2) was identified and showed elevated expression in the midguts of phoxim- and fenpropathrin-selected strains. Expression of BmGSTe2 was only detected in the midgut at transcriptional and translational levels. The recombinant BmGSTE2 possessed peroxidase activity and significantly inhibited by fenpropathrin, phoxim and chlorpyrifos in vitro. These results indicated that BmGSTE2 might be one of the enzymes involved in enhancing larval tolerance to the insecticides used. Furthermore, GST activity and expression level of BmGSTe2 might be used as biomarkers of organophosphorus and pyrethroid insecticide exposures.
authors.affiliation: School of Life Sciences, Chongqing University, Chongqing 400044, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhou
authors.affiliation: School of Life Sciences, Chongqing University, Chongqing 400044, China; College of Life Science, China West Normal University, Nanchong 637002, China.
authors.forename: Shou-Min
authors.initials: SM
authors.lastname: Fang
authors.affiliation: College of Forestry and Life Sciences, Chongqing University of Arts and Sciences, Yongchuan 402160, China.
authors.forename: Ke
authors.initials: K
authors.lastname: Huang
authors.affiliation: School of Life Sciences, Chongqing University, Chongqing 400044, China. Electronic address: yuqy@cqu.edu.cn.
authors.forename: Quan-You
authors.initials: QY
authors.lastname: Yu
authors.affiliation: School of Life Sciences, Chongqing University, Chongqing 400044, China.
authors.forename: Ze
authors.initials: Z
authors.lastname: Zhang
mesh_terms: D000818:Animals; D012831:Bombyx / Q000187:drug effects* / Q000201:enzymology; D004390:Chlorpyrifos / Q000633:toxicity; D004064:Digestive System / Q000378:metabolism; D004361:Drug Tolerance / Q000502:physiology*; D005982:Glutathione Transferase / Q000378:metabolism*; D007306:Insecticides / Q000633:toxicity*; D007814:Larva / Q000187:drug effects* / Q000201:enzymology; D009946:Organothiophosphorus Compounds / Q000633:toxicity; D011722:Pyrethrins / Q000633:toxicity
chemical_list: D007306:Insecticides; D009946:Organothiophosphorus Compounds; D011722:Pyrethrins; C003135:phoxim; C044267:fenpropathrin; D005982:Glutathione Transferase; D004390:Chlorpyrifos
keywords: Biomarker; Bombyx mori; Glutathione S-transferases; Insecticide selection; Tolerance