Zdzienicka M Z, Tran Q, van der Schans G P, Simons J W
Department of Radiation Genetics and Chemical Mutagenesis, State University of Leiden, Sylvius Laboratories, The Netherlands.
Mutat Res. 1988 Nov;194(3):239-49. doi: 10.1016/0167-8817(88)90025-9.
A V79 Chinese hamster cell line XR-V15B exhibiting hypersensitivity to X-ray has been isolated and characterized. Additionally to increased X-ray-sensitivity (approximately 8-fold, as judged by D10 values), cross-sensitivity to bleomycin (3-fold increase), 4NQO (3-fold), H2O2, EMS, MMS (2-fold) were observed also. No increased sensitivity to UV and MMC was found. Genetic complementation analysis indicates that XR-V15B belongs to the same complementation group as the X-ray-sensitive (xrs) mutants of Chinese hamster ovary (CHO) cells described by Jeggo (1985). Biochemical analysis of XR-V15B confirms this finding: the mutant showed a decreased ability to rejoin double-strand breaks induced by X-ray as measured by neutral elution. After 4 h of repair more than 50% of the double-strand breaks remain in comparison to 3% in V79 cells. No difference was observed between wild-type and XR-V15B cells in the initial number of single-strand breaks induced, in the kinetics of their rejoining and in the final level of unrejoined single-strand breaks. Treatment with 5-azacytidine did not have an effect on the reversion frequency of XR-V15B, contrary to the results obtained with the xrs mutants. XR-V15B has been grown in continuous culture for more than 3 months without evidence of reversion. The mutation induction by X-ray irradiation at the HPRT locus is not significantly increased in the mutant, but at doses giving the same degree of cell killing, XR-V15B cells are hypomutable.
已分离并鉴定出一种对X射线敏感的V79中国仓鼠细胞系XR-V15B。除了对X射线敏感性增加（根据D10值判断约为8倍）外，还观察到对博来霉素的交叉敏感性（增加3倍）、对4NQO的交叉敏感性（增加3倍）、对H2O2、EMS、MMS的交叉敏感性（增加2倍）。未发现对紫外线和丝裂霉素C的敏感性增加。遗传互补分析表明，XR-V15B与Jeggo（1985年）描述的中国仓鼠卵巢（CHO）细胞的X射线敏感（xrs）突变体属于同一互补组。对XR-V15B的生化分析证实了这一发现：通过中性洗脱测量，该突变体修复X射线诱导的双链断裂的能力下降。修复4小时后，超过50%的双链断裂仍然存在，而V79细胞中这一比例为3%。在诱导的单链断裂初始数量、单链断裂重新连接的动力学以及未重新连接的单链断裂的最终水平方面，野生型细胞和XR-V15B细胞之间未观察到差异。与xrs突变体获得的结果相反，用5-氮杂胞苷处理对XR-V15B的回复频率没有影响。XR-V15B已经连续培养了3个多月，没有回复的迹象。在该突变体中，X射线照射在HPRT位点诱导的突变没有显著增加，但在给予相同程度细胞杀伤的剂量下，XR-V15B细胞的突变率较低。
