酵母SUP4-o突变检测系统及铬遗传毒性分析

Genotoxicity investigation of tri- and hexavalent chromium using a yeast SUP4-o mutation assay

目的:应用酵母SUP4-o突变检测系统来评价两种价态铬(Cr^(3+),Cr^(6+))的遗传毒性。方法:用电转化法将YCpMP2质粒转入MKP-o(SJPt576)得到SJR576-p菌株。用相同浓度(150μmol/L)三氯化铬和重铬酸钾(Cr^(3+),Cr^(6+))分别处理酵母SJR576-p细胞74 h,取适量培养细胞均匀涂布刀豆氨酸抗性筛选平板和尿嘧啶缺陷合成培养基(SC-Ura),计数克隆数。结果:150μmol/L三氯化铬和重铬酸钾处理导致SUP4-o正向突变频率分别为2.6×10^(-5)和2.3×10^(-5),比对照提高约5倍,两种价态铬之间无显著性差异(P>0.05)。结论:真核酵母SUP4-o突变检测系统对可疑遗传毒性化合物的分析具有多个可筛选的性状和遗传操作的简便性。三价铬也能够造成酵母细胞遗传物质的损伤,具有一定的遗传毒性。

OBJECTIVE： To evaluate genotoxicities of chromium （tri- and hexavalent states） using a new yeast mutation SUP4-o assay system. METHODS： YCpMP2 plasmid was transferred into MKP-o （SJR576） to obtain SJR576-p strain by electroporation. After treatment of the yeast cell SJR576-p with the same concentrations of Cr^3＋ and Cr^6＋ for 24 h,the cells were coated on canavanine resistance screening plates in uracil synthetic medium （SC-Ura）,and the number of clones were subsequently counted. RESULTS： Compared with the untreated controls,the mutation rates of the treated groups with potassium dichromate and chromium trichloride increased five times. The values were about 23 and 26 parts per million,respectively. While there was no significant difference between the groups treated with Cr^3＋ and Cr^6＋. CONCLUSION： Our data suggest that Cr^3＋ can cause DNA damage and genotoxicity. Additionally,the yeast SUP4-o mutation assay system is useful for detecting genotoxicity.