Effects of stress and effluent on vitellogenin production in fathead minnows

Vitellogenin is a protein produced in female fish in response to estradiol production during normal cycles of oogenesis. It is also present in male fish to some extent, but is usually inactive. Vitellogenin can be used as a biomarker for measuring exposure of fish to exogenous estrogens or estrogen mimics. The effects of effluent flow, of the Jackson Pike wastewater treatment plant in Columbus, Ohio, on the production of vitellogenin are being determined in male fathead minnows. Expectations are that the amount of vitellogenin will be affected by the level of stress, because fathead minnows produce cortisol in time of stress, and the production of cortisol is known to reduce the amount of vitellogenin production. The study was begun in October of 2002, with forty male fathead minnows, ten fish per basket. Two baskets were placed in the center of the stream at the waste treatment effluent and two were placed 320 meters upstream. Fish in one basket at each site were fed twice a week in order to reduce stress and cortisol production; the other fish were not fed. Initial blood samples were taken two days after placement in the stream by sacrificing five fish from each basket. The final samples will be taken three weeks after placement. The plasma from each fish will be used in an ELISA test to measure vitellogenin levels.