Comparative sensitivity in Chinese rare minnow (Gobiocypris rarus) and Japanese Medaka (Oryzias latipes) exposed to ethinylestradiol.

Morphological and biochemical indices, including hepatosomatic index, gonadosomatic index, and vitellogenin (VTG) induction, were compared between two teleostean species to determine their relative sensitivity of exposure to 17-alpha -ethinylestradiol (EE2). Chinese rare minnow (Gobiocypris rarus) and Japanese medaka (Oryzias latipes) were exposed to aqueous concentrations of EE2 ranging from 0.2 to 100 ng/L for 21 days. A stronger liver response to EE2 in Chinese rare minnow was observed than that in Japanese medaka. In Japanese medaka, significantly increased male GSI could be observed at 50 and 100 ngEE2/L. The semi-quantitative estimation by integrated optic density following electrophoresis showed that exposure of male Chinese rare minnow and Japanese medaka to EE2 resulted in significant (P<0.05) induction of VTG at 0.2 and 2 ngEE2/l, respectively. It indicated that the sensitivity of Chinese rare minnow to the stress of EE2 is about 10-fold greater than that of Japanese medaka.