Abstract
A medaka (Oryzias latipes) vitellogenin bioassay is a powerful and useful tool for the screening of estrogenic compounds. In order to establish a rapid and simple method for the screening of estrogenic contaminants in an aquatic environment, we studied the effects of several test conditions on the induction of plasma vitellogenin in male medaka. During the holding period, treatments with animal drugs or NaCl for the prevention of an infective disease did not affect the induction of vitellogenin in male medaka. However, plasma vitellogenin in some male medaka was induced when they were kept with female or in water from a fish-breeding tank. During the testing period, vitellogenin induction in male medaka was not affected by the photoperiod cycle and temperature. However, this induction was affected by the frequency of water changing. In the present paper, we propose a rapid and simple method for the screening of estrogenic contaminants in an aquatic environment using a medaka vitellogenin assay. We also present the exposure test results of 4-nonylphenol and bisphenol A obtained using our simple method.
