Activity development of selected detoxication enzymes during the ontogenesis of the zebrafish (Danio rerio)

Activities of two detoxication enzyme systems, microsomal and soluble gluta thione S-transferases (m-/sGST, EC 2.5.1.18), and Se-dependent glutathione peroxidase (GP-X, EC 1.11.1.9) were monitored during zebrafish (Danio rerio ) development. Starting with the 2-4 cell stage of ontogenesis successively up to adult fish. the presence of these detoxication enzymes could be demo nstrated. Activities increased slowly during development and showed elevati ons corresponding to increased stress conditions. Plain increase occured af ter hatching, possibly caused by the change of the surrounding micromilieu. The juveniles showed highest activities, certainly provoked by new substan ces as from the food. Enzyme activities of adults revealed moderate levels probably due to a dilution of highly concentrated detoxication activities i n the ready developed organs, especially the liver, in the whole body homog enate.