EXPRESSION OF THE ESTROGEN RECEPTOR ALPHA GENE IN THE ANAL FIN OF JAPANESE MEDAKA, ORYZIAS LATIPES, BY ENVIRONMENTAL CONCENTRATIONS OF BISPHENOL A

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The anal fin in Japanese medaka, Oryzias latipes, is a typical sexual secondary character. In the present study, we focused on this organ and examined the effects of low doses of a natural estrogen, 17β-estradiol (E_2), and an environmental xenoestrogen, bisphenol A (BPA), in vivo by monitoring estrogen receptor (ER)α gene expression. Groups of adult male and female medaka were immersed in 10^<-9> M E_2 or 10^<-10> to 10^<-8> M BPA and the levels of ERα gene transcripts in the anal fins were measured by semiquantitative reverse transcription polymerase chain reaction (RT-PCR). One day of treatment with each concentration of BPA examined and 10^<-9> M E_2 increased the levels of ERα mRNA in female anal fins by 3-fold as compared with controls. In the male specimens, neither 10^<-9> M E_2 nor 10^<-10> M BPA showed remarkable effects on the anal fins as compared with the results in females, but 10^<-9> and 10^<-8> M BPA increased the levels of ERα mRNA by 2.3- and 3.3-fold with 1 day of exposure, respectively. The present results showed that medaka anal fins may be a sensitive bio-indicator for screening of environmental estrogenic chemicals.
日本トキシコロジー学会の論文
2007-02-16