Trout oestrogen receptor sensitivity to xenobiotics as tested by differentbioassays

A recombinant yeast system highly and stably expressing rainbow trout oestr ogen receptor (rtER) was used in parallel with a more elaborated biological system, trout hepatocyte aggregate cultures to examine the oestrogenic pot ency of several chemicals commonly found in the environment. In hepatocyte cultures, the vitellogenin gene, whose expression is principally dependent upon oestradiol, was used as a biomarker. Moreover, competitive binding ass ays were performed to determine direct interaction between rtER and xenobio tics. This paper describes high specificity of our systems for screening po tentially oestrogenic chemicals and determining the mode of action of trout ER with oestrogenic compounds. This work also demonstrates that it is impo rtant to combine bioassays with in vitro approaches to elucidate the mechan ism of xenooestrogen actions. (C) 1999 Elsevier Science B.V. All rights res erved.