Expression of the Vitellogenin Gene in the Liver of Juvenile Whitefish (Coregonus lavaretus L. s.l.) Exposed to Effluents from Pulp and Paper Mills

Juvenile whitefish (Coregonus lavaretus L. s.l.) were exposed by caging in the field to diluted effluents from three operating pulp, paper, and paperboard mills in Southern Lake Saimaa, Finland. The expression of the vitellogenin gene, used as a biomarker of estrogenic contamination of effluents, was measured using a Northern blotting method. Increased mRNA levels, the most specific and reliable evidence for estrogen receptor-mediated actions in vivo, were found in fish caged in the vicinity of one of three mills studied. This mill was found to discharge wood-derived compounds, such as sterols and resin acids, into Lake Saimaa in amounts considerably exceeding those from the other two mills. The increased vitellogenin gene expression suggests that the effluent is a source of estrogenic contaminants.