镉、汞、锌3种重金属的雌激素样作用（Estrogenic Activity of Cadmium, Mercury, and Zinc）

为探讨镉、汞、锌3种重金属的雌激素样作用,采用双杂交酵母法测定了醋酸镉、氯化汞、醋酸锌单独作用时对重组基因酵母β-半乳糖苷酶诱导活性的EC50值.实验结果表明,醋酸镉浓度为1.0×10-5mol·L-(1实验浓度范围10-7~10-2mol·L-1),氯化汞浓度为5.0×10-7mol·L-(1实验浓度范围10-9~10-5mol·L-1),醋酸锌浓度为1.0×10-4mol·L-(1实验浓度范围10-9~10-2mol·L-1)时对酵母β-半乳糖苷酶诱导活性最大,分别达到1.3、0.95和1.1U.不能求出镉、汞、锌单独作用时对β-半乳糖苷酶诱导活性的EC50值.一味计算EC50值不仅难以评价重金属的雌激素活性,而且限制重组受体基因酵母法的普遍运用.一些重金属通过MCF-7细胞法(E-screen)呈阳性,通过重组hERα酵母法YES检测呈阴性,有可能是重金属通过与ERβ作用而产生效应.若构建出含ERβ基因的双杂交酵母菌株,与现有的方法互补将能完善环境雌激素的体外测评系统.

Estrogenic Activity of Cadmium, Mercury, and Zinc

In order to explore the estrogenic activity of cadmium,mercury,and zinc,the activity of β-galactosidase of the recombinant human estrogen receptor-α (hERα)gene yeast induced by mercuric chloride,cadmium acetate,and zinc acetate was determined.Results show that the activity of β-galactosidase of this yeast reaches the maximum at the concentration of 5.0×10~(-7)mol·L~(-1) for mercuric chloride(concentration range:10~(-9)-10~(-5)mol·L~(-1)),1.0×10~(-5)mol·L~(-1) for cadmium acetate(concentration range:10~(-7)～10~(-2)mol·L~(-1))and 1.0×10~(-4)mol·L~(-1)for zinc acetate(concentration range:10~(-9)～10~(-2)mol·L~(-1)),and the activities are 0.95,1.3,and 1.1U,respectively.EC_(50) values of single cadmium,mercury,and zinc to β-galactosidase cannot be calculated.If we estimate the estrogenic activity of the heavy metal just by the EC_(50) value,then it's hard to estimate the estrogenic activity of the heavy metal and the wide use of the recombinant yeast estrogen screen will be impeded.Some heavy metals show positive by E-screen,but negative by YES,likely because they bind to the ERβ.So the environmental estrogens assay in vitro will be improving if the recombinant human estrogen receptor-β(hERβ)gene yeast could be constructed.