Abstract
Vitellogenin (Vtg) is a female specific plasma protein and thc major precursor of egg yolk protein in oviparous vertebrates. The protein serves as a useful biomarker for exposure to estrogenic compounds. To assess possible environmental endocrine disruption in Niigata Prefecture, we examined plasma Vtg concentration of wild Koi carp (Cyprinus carpio) collected at 3 sites on the Shinano River basin and the wetland sites of Sakata and Toyanogata from 1998 to 2000. In the male Koi carp, relatively high Vtg levels (1μg/ml or more) were observed in 5 of 15 males at the site A (Niigata City area) and 2 of 24 males at the site C (Ojiya City area) on the Shinano River basin, and the plasma Vtg levels were independent of gonadosomatic index. In the female carp, the plasma Vtg levels markedly vary depending on sexual maturation and reproductive stage.
