【摘要】 本文在－Ｓ９或＋Ｓ９实验条件下，用ＥＭＳ或ＡＦＢ_１在Ｖ_７９细胞ＨＧＰＲＴ位点测试系统中获得良好的剂量反应关系。分别从未染毒组、ＥＭＳ或ＡＦＢ１染毒组分离１０个ＴＧ抗性突变克隆。经鉴定，抗性突变细胞是ＨＧＰＲＴ位点突变的Ｖ_７９细胞；所建立的诱变性测试方法是可靠的。此外，本文对选择开始后不同时间（０、６、１２或２４小时）加入选择剂的情况进行了研究。结果表明，６小时加入选择剂突变体频率略有升高，但升高无显著性；２４小时加入选择剂突变体频率明显下降，经统计分析差异有显著性。更多还原

【Abstract】 A linear dose-response relationship of gene mutation induced by EMS or AFB1 in the absence or presence of S9 was obtained. 10 thioguanine-resisitant mutant clones of V₇₉ Chinese hamster cells were isolated from untreted cultures and cultures exposed to EMS or AFB₁. The evidences indicated that thioguanine-resistant V₇₉ cells were mutants of the HGPRT locus, and the quantiative method for measuring mutation frequency was reliable.The time of adding selecting agent was studied at 0,6,12 or 24 hours after selection started. The mutant frequency was enhanced a little, but did no show any statistical significance at 6h.When selecting agent was added at 24h after selection started, the frequency was decreased significantly.更多还原