Toxicogenomics effects of sewage on juvenile Chinook salmon (Oncorhynchus tshawytscha)

As a part of an Environment Canada project, this research used microarrays and Quantitative Polymerase Chain Reaction to evaluate the effects of British Columbia, Canada, sewage on liver gene expression in exposed juvenile chinook (Oncorhynchus tshawytscha) salmon. The studies highlighted the effects of xenoestrogens on gene expression. Xenoestrogens can alter the expression of genes associated with adult fish reproductive processes, particularly those relating to egg production (female-specific): vitellogenin and the vitelline envelope proteins. Examination of genetic males and females indicated very few significant differences in the expression of female-specific genes between the sexes, indicating that gene expression alterations caused by sewage were unrelated to genetic sex in underyearling fish. Gene expression patterns were examined for trends across time and sewage concentrations. Trends found included U-shaped and linear dose response curves. All concentrations of sewage examined caused gene expression alterations, including the very low environmentally relevant concentrations: 0.05%, 0.1%, 0.7%.