Amundson S A, Xia F, Wolfson K, Liber H L
Laboratory of Radiobiology, Harvard School of Public Health, Boston, MA 02115.
Mutat Res. 1993 Apr;286(2):233-41. doi: 10.1016/0027-5107(93)90188-l.
Two human lymphoblastoid cell lineages derived from the same parental line exhibit markedly different survival and mutational responses to X-irradiation, but not to chemical point mutagens. WI-L2-NS (ATCC CRL 8155) and TK6 (ATCC CRL 8015) both are derived from the original WI-L2 isolate described by Levy et al. (1968). Both lines are near diploid with stable and indistinguishable karyotypes (47, X, Y 13 +). However, differences in the extent of heterozygosity of chromosome 17 RFLP markers have been detected in these lines. Relative to TK6, WI-L2-NS and several cell lines subsequently derived from it exhibit enhanced survival after X-ray treatment. This is due partly to a more pronounced shoulder in the dose response curve for WI-L2-NS and partly to a higher D0 than is observed in TK6. X-ray-induced mutant frequencies also are markedly different. At the hprt locus, the overall magnitude of the response is similar in the two cell lines. However, in TK6, a linear equation appears to be the best fit to the data, as compared to a linear quadratic curve for WI-L2-NS. Induced mutant frequencies at the tk locus in heterozygotes derived from WI-L2-NS are 20-50-fold higher than those seen in TK6 and tk heterozygous derivatives of TK6. Analysis of the mutability of the two tk alleles in various tk heterozygotes of WI-L2-NS reveals a similar pattern to that described previously in heterozygotes derived from TK6; 3 times as many mutants were recovered from one tk allele than the other. A possible explanation for the higher survival and induced mutant frequencies seen in WI-L2-NS and its derivatives is the presence in these lines of an error prone repair system not functioning in TK6.
源自同一亲代系的两个人类淋巴母细胞系对X射线照射表现出明显不同的存活和突变反应，但对化学点突变剂则不然。WI-L2-NS（美国典型培养物保藏中心CRL 8155）和TK6（美国典型培养物保藏中心CRL 8015）均源自Levy等人（1968年）描述的原始WI-L2分离株。这两个细胞系均接近二倍体，具有稳定且难以区分的核型（47, X, Y 13 +）。然而，在这些细胞系中已检测到17号染色体RFLP标记杂合程度的差异。相对于TK6，WI-L2-NS及其随后衍生的几个细胞系在X射线处理后存活能力增强。这部分是由于WI-L2-NS的剂量反应曲线中更明显的肩部，部分是由于其D0高于TK6中观察到的D0。X射线诱导的突变频率也明显不同。在hprt基因座，两个细胞系的总体反应幅度相似。然而，在TK6中，线性方程似乎最适合数据，而WI-L2-NS则为线性二次曲线。源自WI-L2-NS的杂合子中tk基因座的诱导突变频率比TK6及其tk杂合衍生物中观察到的高20至50倍。对WI-L2-NS各种tk杂合子中两个tk等位基因突变性的分析揭示了与先前在源自TK6的杂合子中描述的模式相似；从一个tk等位基因中回收的突变体数量是另一个的3倍。WI-L2-NS及其衍生物中观察到的较高存活率和诱导突变频率的一个可能解释是这些细胞系中存在在TK6中不起作用的易错修复系统。
