Estrogen-mediated early life stage mortality in zebrafish ( Danio rerio)

Estrogenic substances have been shown to induce estrogen receptor (ER) regulated genes such as vitellogenin and vitelline envelope proteins. Recently we have shown that estrogen is embryo toxic to fish. In the present study specific polychlorinated biphenyl (PCB) congeners were examined for their effect on early life stage mortality in zebrafish ( Danio rerio). A set of eight PCBs, two hydroxylated PCBs and 17β-estradiol were tested. The PCBs were selected based on multivariate physicochemical characterization of all 154 tetra- through hepta-chlorinated PCBs. Three of the PCBs caused significant embryo mortality. Of these PCBs two more were found to also induce ER transcription. Determination of ER mRNA abundance in developing zebrafish embryos showed that the gene was upregulated at mid-blastula transition and returned to low levels prior to organogenesis. Together these results indicate that estrogenic compounds may interfere with development by interacting with ER.