Green M H, Lowe J E, Arlett C F, Harcourt S A, Burke J F, James M R, Lehmann A R, Povey S M
MRC Cell Mutation Unit, University of Sussex, Falmer, Brighton, UK.
J Cell Sci Suppl. 1987;6:127-37. doi: 10.1242/jcs.1984.supplement_6.8.
Genomic DNA from normal human or mouse cells was transfected together with the selectable marker gpt into the simian virus 40-transformed ataxia telangiectasia fibroblast line, AT5BIVA. From a series of experiments involving over 400,000 clones selected for the gpt marker, one unambiguously radiation-resistant clone (clone 67) was recovered following selection with repeated cycles of gamma irradiation. The normal level of radiation resistance of clone 67 has been maintained for at least 11 months in the absence of further selection by radiation. The resistant clone contains one copy of the gpt gene. Its DNA synthesis following gamma-irradiation is inhibited to an extent intermediate between that of ataxia telangiectasia and normal cells. Three out of four thioguanine-resistant derivatives of clone 67 have either lost or do not express the gpt sequence and show almost the same sensitivity to gamma irradiation as the original AT5BIVA line. This suggests that the radiation resistance of clone 67 may be linked to the gpt sequence and may have arisen as a consequence of the transfection, rather than as the result of an independent mutation to radiation resistance.
将来自正常人或小鼠细胞的基因组DNA与选择标记gpt一起转染到猿猴病毒40转化的共济失调毛细血管扩张成纤维细胞系AT5BIVA中。在一系列涉及为gpt标记选择的超过400,000个克隆的实验中，在用γ射线反复照射进行选择后，获得了一个明确抗辐射的克隆（克隆67）。在没有通过辐射进一步选择的情况下，克隆67的正常抗辐射水平已维持至少11个月。抗性克隆含有一份gpt基因。其在γ射线照射后的DNA合成受到抑制，抑制程度介于共济失调毛细血管扩张细胞和正常细胞之间。克隆67的四个硫代鸟嘌呤抗性衍生物中有三个要么丢失了gpt序列，要么不表达gpt序列，并且对γ射线照射的敏感性几乎与原始AT5BIVA细胞系相同。这表明克隆67的抗辐射性可能与gpt序列有关，并且可能是转染的结果，而不是独立发生抗辐射突变的结果。
