Atrazine induction of cytochrome P450 in Chironomus tentans larvae

Authors

Francisca Miota, University of Nebraska-Lincoln
Blair Siegfried, University of Nebraska-LincolnFollow
Michael E. Scharf, University of Nebraska-Lincoln
Michael J. Lydy, Wichita State University, Wichita, KS

Date of this Version

October 2000

Comments

Published in Chemosphere 40 (2000), pp. 285–291. Copyright © 1999 Elsevier Science Ltd. Used by permission.

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°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 mic rosomal 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.