PARENT SESSION
18 - Endocrine Disruption
8:00 AM to 6:30 PM, Monday, 13 May 2002
Exhibition Area

(18-73) Effects of selected xenoestrogens on zebrafish development and reproduction *.

Ortiz-Zarragoitia, Maren^*,1, Trant, John², Cajaraville, Miren¹, ¹ University of the Basque Country, Bilbao, Basque Country (Spain)² University of Maryland Biotechnology Institute, Baltimore, USA

ABSTRACT- Endocrine disrupting chemicals are a structurally diverse group of compounds that may adversely affect the health of wildlife, or its progenies, by interaction with the endocrine system. Among these are chemicals known as peroxisome proliferators (PPs) that induce an increase in the size and number of peroxisomes and in peroxisomal -oxidation together with the formation of liver tumours in sensitive species. The effects of PPs are mediated by peroxisome proliferator-activated receptors, which belong to the same nuclear receptor family as estrogen receptors. Developmental exposure to estrogenic compounds has been shown to skew sex ratios to female in many fish species including zebrafish. The aim of the present work was to study the effects caused by some xenoestrogens such as the PP dibutylphthalate (DBP) and ethynylestradiol (EE2) after exposure of early life stages of zebrafish. Exposure started on fertilized eggs and continued during a period of 5 weeks until sexual differentiation of gonads, under static renewal conditions. Exposure concentrations of 100 and 25 g/L of DBP and 5 g/L EE2 were used. In a second experiment, adult female fish were exposed during a period of 15 days to 500 and 100 g/L DBP and 5 g/L EE2, and afterwards they were paired with untreated males to study the effects over offspring. Measured endpoints include mortality, number of eggs laid, developmental abnormalities, expression levels of CYP19a and CYP19b aromatases, peroxisomal acyl-CoA oxidase (AOX) and vitellogenin; AOX activity, liver peroxisome stereology and gonad histology. The first results demonstrate that EE2 reduced survival and growth of exposed larvae and the ability of females to spawn. Abnormal larvae were observed in the DBP-exposed group. *Funded by a predoctoral fellowship from the University of the Basque Country to M.O-Z. and projects AMB99-0324 and BEEP (EVK3-CT-2000-00025).

Key words: zebrafish development and reproduction, peroxisome proliferation, endocrine disruption, xenoestrogens