title: Atrazine induction of cytochrome P450 in Chironomus tentans larvae.
abstract: Cytochrome P450-dependent aldrin epoxidation was characterized in third instar larvae of the aquatic midge, Chironomus tentans. Optimal in vitro assay conditions for the epoxidase were pH 7.6 and 31 degrees C. Activity was linear up to 40 min of incubation time and 0.5 mg microsomal protein per incubation. The activity was concentrated in the microsomal fraction of whole body homogenates and was NADPH-dependent. The effect of atrazine exposure on aldrin epoxidase was measured to determine if this herbicide induces cytochrome P450-dependent activity. Comparisons of control and atrazine-exposed midges indicated increased epoxidase activity as a result of atrazine exposure, and a 45 kDa protein of increased intensity was observed after SDS-PAGE of microsomal protein. The molecular weight of this protein was similar in size to cytochrome P450 enzymes reported for other insects. Heme staining of SDS-PAGE gels and immunochemical studies using a Drosophila melanogaster anti-P450 polyclonal antiserum, further support the cytochrome P450 nature of this inducible 45 kDa protein.
authors.affiliation: Department of Entomology, University of Nebraska, Lincoln 68583, USA.
authors.forename: F
authors.initials: F
authors.lastname: Miota
authors.forename: B D
authors.initials: BD
authors.lastname: Siegfried
authors.forename: M E
authors.initials: ME
authors.lastname: Scharf
authors.forename: M J
authors.initials: MJ
authors.lastname: Lydy
mesh_terms: D000818:Animals; D001280:Atrazine / Q000494:pharmacology*; D015153:Blotting, Western; D002683:Chironomidae / Q000201:enzymology* / Q000254:growth & development; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis*; D004591:Electrophoresis, Polyacrylamide Gel; D004790:Enzyme Induction / Q000187:drug effects; D006540:Herbicides / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D007814:Larva / Q000201:enzymology*; D006899:Mixed Function Oxygenases / Q000378:metabolism; D009249:NADP / Q000494:pharmacology
chemical_list: D006540:Herbicides; D009249:NADP; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; C019647:aldrin epoxidase; D001280:Atrazine