Problems with Methods used to Screen Estrogenic Chemicals by Yeast Two- Hybrid Assays

We developed a yeast two-hybrid assay using a human-type estrogen receptor (hERα) to screen test chemicals reporting weak estrogenic activity at high concentrations. As a result of exposure to several test chemicals, viable yeast cells showed a decrease in num-ber compared with a control. It was shown that this phenomenon was due to fungicidal effects of the test chemicals within the yeast cell or to inhibition of yeast cell proliferation. Therefore, in performing a yeast two-hybrid assay, it is necessary to monitor yeast cell pro-liferation by methods such as the measurement of the number of viable cells, and it is necessary to screen test chemicals within a concentration range where these chemicals show neither fungicidal effects towards the yeast cell nor inhibition of yeast cell proliferation. Key words —– — yeast two-hybrid assay, endocrine disruptor, estrogenic chemica