Evaluation of endocrine disruptors using chicken fertilized egg

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Various doses of diethylstilbestrol(DES), nonylphenol(NP) and bisphenol A(BPA) were injected into chicken fertilized eggs, and the influences on the viability on day 7 of incubation, hatchability and development of the gonads were examined. Both the viability and hatchability were significantly lower, and a sex-reverse male (phenotypic female having ovary like left gonad regardless of genotypic male) appeared when high dose of DES (1mg) was injected to the eggs. Though high doses of NP or BPA (100mg) was also poisonous for the development of chicken embryos, they had no effect on the male left testis into the ovary. Exposure to high dose of DES, NP and BPA appear to be harmful to the development of embryos in wildlife. The effects of BPA and o,p'- DDT on mRNA expression of vitellogenin (VTG II) in the liver of quail embryo after their sexing were also investigated. RT-PCR analysis detected no mRNA expression of VTG II in the liver of males and females in the control group, whereas distinct VTG II mRNA transcripts were detected in the Estradiol 17β treated female and male groups (183 bp). In BPA treated group, there was a slight expression of VTG II in female embryos. However, no induction of mRNA expression was detected in male embryos. o,p'- DDT treatment induced a remarkable expression of VTG II in female embryos. Moreover, it induced a slight increase in the mRNA levels of VTG II in male embryos at the dose used. Both chemicals have weak estrogenic action.In conclusion, chicken fertilized eggs can be utilized to assess endocrine disruptors, which have estrogenic activity. BPA and o,p'-DDT have weak estrogenic action.