Fox M, McMillan S, Durrant L, Boyle J M
Mutat Res. 1982 Aug;95(2-3):339-52. doi: 10.1016/0027-5107(82)90269-x.
The relative responses of V79 and V79/79 cells to mutation to 6-thioguanine (6TGR) and ouabain resistance (OUAR) have been compared in unmutagenized cells and after exposure to ethyl methanesulphonate (EMS), N-methyl-N-nitrosourea (MNU) and ultraviolet light. In the V79/79 cell line, the spontaneous frequency of 6TGR colonies but not of OUAR colonies was enhanced compared to that in V79 cells. This appears to be the result of a reduced growth rate and plating efficiency of V79/79 cells and does not reflect a real difference in spontaneous mutability. V79/79 cells were more sensitive than V79 to the cytotoxic effects of all three mutagens, but induced mutation by UV, EMS and MNU to 6TGR was similar in the two cell lines. The lack of a differential response for induced mutation to 6TGR may reflect: (a) differences in selective stringency of thioguanine in the two cell lines, and (b) the greater susceptibility of V79/79 cells to induced chromosome damage. The relative mutability of the two cell lines to OUAR was dependent on the mutagen used. V79 cells were significantly more mutable than V79/79 cells after MNU exposure, but the two cell lines were similar in sensitivity to EMS-induced mutation. After UV-irradiation, however, V79/79 cells were morem utable than V79 cells. The differential response of the two cell lines to MNU suggests that O6-methylguanine is potentially mutagenic in V79 cells but is both potentially lethal and potentially mutagenic in the more sensitive V79/79 cells. The absence of a differential response to EMS-induced mutagenesis suggests that methylated and ethylated bases are repaired differently in Chinese hamster cells. The hypermutability of V79/79 cells by UV-irradiation indicates that thymine dimers are potentially lethal and potentially mutagenic in both cell lines.
已比较了V79细胞和V79/79细胞在未诱变状态下以及暴露于甲基磺酸乙酯（EMS）、N-甲基-N-亚硝基脲（MNU）和紫外线后对6-硫鸟嘌呤抗性（6TGR）和哇巴因抗性（OUAR）突变的相对反应。在V79/79细胞系中，与V79细胞相比，6TGR菌落的自发频率增加，但OUAR菌落的自发频率未增加。这似乎是V79/79细胞生长速率和接种效率降低的结果，并不反映自发突变率的真正差异。V79/79细胞对所有三种诱变剂的细胞毒性作用比V79细胞更敏感，但紫外线、EMS和MNU诱导的6TGR突变在这两种细胞系中相似。对6TGR诱导突变缺乏差异反应可能反映：（a）两种细胞系中硫鸟嘌呤选择严格性的差异，以及（b）V79/79细胞对诱导的染色体损伤更敏感。两种细胞系对OUAR的相对突变率取决于所使用的诱变剂。MNU暴露后，V79细胞比V79/79细胞的突变率显著更高，但两种细胞系对EMS诱导突变的敏感性相似。然而，紫外线照射后，V79/79细胞比V79细胞更易突变。两种细胞系对MNU的差异反应表明，O6-甲基鸟嘌呤在V79细胞中可能具有诱变作用，但在更敏感的V79/79细胞中既可能具有致死性又可能具有诱变作用。对EMS诱导诱变缺乏差异反应表明，甲基化和乙基化碱基在中国仓鼠细胞中的修复方式不同。紫外线照射使V79/79细胞超突变表明，胸腺嘧啶二聚体在两种细胞系中都可能具有致死性和诱变作用。
