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(18-48) Xenoestrogenic and toxic effects of methoxychlor on zebrafish (Danio rerio). Versonnen, Bram*,1, Janssen, Colin1, 1 Ghent University, Laboratory of Environmental Toxicology and Aquatic Ecology, Jozef Plateaustraat 22, Ghent, Belgium ABSTRACT- Juvenile and adult zebrafish and their eggs were exposed to the endocrine disrupting pesticide methoxychlor (MEX). Survival, hatching, length, weight and condition of larvae were examined as indicators of toxic stress, and vitellogenin (VTG) content and gonadosomatic indices were used to determine xenoestrogenic effects. Fifty and 500 ng MEX/l did not affect the weight, length and condition of juvenile zebrafish. These concentrations did, however, induce significant effects on egg hatching and juvenile survival. Protein electrophoresis and RT-PCR on whole body fluid extracted from juveniles exposed to MEX, were performed to investigate the potential use of these techniques as tools to detect xenoestrogenic effects (relative VTG content). However, with both techniques VTG was detected in controls and exposed juveniles. Protein electrophoresis of plasma taken from adult fish exposed to MEX revealed elevated VTG concentrations. In conclusion, zebrafish juveniles and embryo′s are sensitive to toxic effects of methoxychlor, but due to the unexpected presence of VTG in both controls and exposed fish, the use of VTG measurement in juvenile zebrafish to detect effects of (xeno)estrogens may not be appropriate. Adult fish do exhibit a concentration related VTG induction after MEX exposure. Key words: endocrine disruption, methoxychlor, vitellogenin, zebrafish |
