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2L - Immunotoxicity - genotoxicity - ED (WEP/113) Vitellogenin induction in sea bass and fathead minnow - determination of actual estrogen exposure levels. Lamoree, M1, Booij, P1, Henriques, M2, Freitas, S2, Gonçalves, J2, Mañanos, E3, Harris, C4, Brian, J4, Sumpter, J4, 1 IVM Institute for Environmental Studies, Amsterdam, The Netherlands2 CIIMAR Centro de Investigação Marinha e Ambiental, Porto, Portugal3 IATS Instituto de Acuicultura de Torre de la Sal, Ribera de Cabanes, Spain4 Brunel University, Uxbridge, United Kingdom ABSTRACT- Exposure of aquatic wildlife in surface waters - marine and fresh - to (xeno-)estrogens is known to cause reproductive dysfunction. As part of a study regarding the combination effects of mixtures of estrogenic chemicals in marine and freshwater organisms, prescreening studies on vitellogenin induction in juvenile sea bass and adult male fathead minnow were carried out after exposure to estradiol and ethynylestradiol. Adult male fathead minnows were exposed to various concentrations of the human and synthetic estrogens, using a flow through system. Tanks were equilibrated with the chemical for one week prior to introduction of the fish. Fish were exposed for a period of two weeks, at the end of which blood samples were collected and the plasma assayed for VTG concentration using a carp-VTG ELISA (Tyler, CR et al, 1996). In a comparable setup, juvenile sea bass were also exposed to estradiol and ethynylestradiol, for two weeks. Analogous to the freshwater study, blood samples were collected after this period and plasma VTG quantified using a sea bass-VTG ELISA. Actual hormone concentrations in the fish tanks for the marine and freshwater studies were determined by gas chromatography with ion trap detection. Because of the high estrogenic potency of the natural hormones, high sensitivity in the range of 0.1-1 ng/L was required. Accurate dose response curves representing actual - not theoretical - exposure levels plotted against vitellogenin induction were thus obtained. The effect of low concentrations of estrogens in juvenile sea bass was shown for the first time. Key words: vitellogenin induction, estrogens, chemical analysis |
