Bradley W E, Belouchi A, Messing K
Institut du Cancer de Montréal, Québec, Canada.
Mutat Res. 1988 May;199(1):131-8. doi: 10.1016/0027-5107(88)90238-2.
Frequencies of mutation at the hprt and aprt loci in various CHO cell lines were measured after exposure of the cells to ionizing radiation. In D423 and AA8-16, which are aprt+/- heterozygotes, the ratio of hprt- mutants to aprt- mutants ranged from 0.11 to 0.36. In D422 and AA8-5, which are aprt+/0 cell lines in which only one copy of the gene and its flanking sequences is present these ratios were greater than 5. In contrast, chemical mutagenesis generated mutations at both loci, in all cell lines, at equal frequencies. Southern blot analysis of DNA from hprt- and aprt- mutants of one of the aprt+/- heterozygous lines showed some apparently unaltered genes, some rearrangements and some complete deletions of hprt among hprt- mutants, but only complete deletions of aprt-linked sequences among aprt- mutants. These results strongly suggest that X-ray-induced mutational events are frequently larger than 40 kb (the length of the hprt gene) and that the difference among the frequencies observed at the two loci in the two types of cell lines were due to the presence of essential sequences close the respective target genes. The combined use of these cell lines in screening environmental mutagens should allow qualitative as well as quantitative analysis of the mutagenic potential of environmental agents.
将各种CHO细胞系暴露于电离辐射后，测量了hprt和aprt基因座的突变频率。在aprt +/- 杂合子的D423和AA8 - 16中，hprt - 突变体与aprt - 突变体的比例在0.11至0.36之间。在D422和AA8 - 5中，它们是aprt + /0细胞系，其中仅存在该基因及其侧翼序列的一个拷贝，这些比例大于5。相比之下，化学诱变在所有细胞系中以相等的频率在两个基因座上产生突变。对其中一个aprt +/- 杂合细胞系的hprt - 和aprt - 突变体的DNA进行Southern印迹分析表明，在hprt - 突变体中，一些基因明显未改变，一些发生了重排，一些hprt基因完全缺失，但在aprt - 突变体中仅aprt相关序列完全缺失。这些结果强烈表明，X射线诱导的突变事件通常大于40 kb（hprt基因的长度），并且在两种类型的细胞系中两个基因座观察到的频率差异是由于各自靶基因附近存在必需序列。在筛选环境诱变剂中联合使用这些细胞系应允许对环境因子的诱变潜力进行定性和定量分析。
