Assessment of Environmental Endocrine Disruption with Plasma Concentration of Vitellogenin in Koi Carp (Cyprinus Carpio)

Yuji TSUKADA

Yoshio KERA�@Ryo-hei YAMADA�@Shouji TAKAHASHI

Vitellogenin (Vtg) is a female specific plasma protein and the major precursor of egg yolk protein in oviparous vertebrates including fish. The protein serves as a useful biomarker for exposure of male or juvenile fish to estrogenic compounds.
To assess possible estrogenic activity of effluent from sewage treatment works, juvenile Koi carp (Cyprinus Carpio) were in situ exposed to the effluent by maintaining the fish in a cage deployed at a point downstream from the effluent outfall. The exposure of the fish significantly increased the plasma Vtg concentration of the fish within 10-14 days. The results suggest that the effluent from a sewage treatment works had a weak but enough estrogenic activity at a biologically significant level.
Chemical analyses for several compounds with estrogenic activity in the water samples at the exposure point suggest that natural estrogens, such as �@estradiol-17�� and estrone, were possible candidate compounds responsible for the observed increase in the plasma Vtg levels.
The effect of estradiol-17�� or estrone on the plasma Vtg level of the carp were confirmed by subsequent indoor aquaria experiments. In addition, the preset study showed that the hepatic Vtg concentration was an alternative biomarker for endocrine disruption by estrogenic compounds.