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

Abstract

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-α -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.

Keywords:

• Chinese rare minnow
• Japanese medaka
• sensitivity
• 17-α-ethinylestradiol
• morphological indices
• electrophoresis
• vitellogenin

Acknowledgments

This research program was funded by National Basic Research Program of China (2007CB407304), Hunan Provincial Natural Science Foundation of China (05JJ40031) and Science Foundation of Jishou University.

Notes

^a Expressed as density units of Vtg staining from plasma samples, each value represents the mean of at least 10 samples ± SD.

^b % of control = (EE₂ or Acetone group mean/control group mean)× 100.

*Significant different from control group at P < 0.05.