Akihiko Hara

Department of Marine Biological Sciences, Faculty of Fisheries, Hokkaido University
(3-1-1, Minato, Hakodate, Hokkaido 041-8611 Japan)

Abstract

A new protein is specifically induced in the blood of immature and male fish within one day by treatment with estrogen. This protein, called vitellogenin, is a female-specific yolk protein precursor naturally occuring in the blood of sexually maturing female fish. Recently, vitellogenin has been used as a biomarker for estrogenic contamination of the aquatic environment. In the early 1980s, hermaphrodite fishes were found in UK rivers and scientists hypothesized that sewage effluents might contain substances estrogenic to these fish. In later, field studies elevated concentrations of plasma vitellogenin were measured in male rainbow trout caged in effluent from sewage-treatment works. As it is important to accumulate such basic data in the field, similar work is in progress in UK, US and Japan. In addition to vitellogenin, estrogen also stimulates hepatic synthesis of choriogenins. A recent study suggests that measurement of these eggshell precursor proteins may provide for more sensitive detection of the presence of environmental estrogens than bioassays targerting vitellogenin.

Key words: environmental endocrine disrupters, fish, vitellogenin, choriogenin, estrogen