Meuth M, Gonçalves O, Thom P
Somatic Cell Genet. 1982 Jul;8(4):423-32. doi: 10.1007/BF01538705.
Thy- mutants, in addition to being resistant to arabinosyl cytosine (arcC), show cross-resistance to 5-fluorouracil (5FU). When Chinese hamster ovary (CHO) cells were exposed to a selection system using both araC and 5FU, the resistant clones isolated were identical to thy- mutants by the following criteria: (1) all were auxotrophic for thymidine with a high reversion frequency to thymidine prototrophy; (2) those tested had a high level of dCTP relative to wild-type cells, while dTTP and dATP levels were unaffected, and (3) all tested had a 7- to 50-fold higher rate of spontaneous mutation than the wild-type strain for at least one independent genetic marker. Although spontaneous thy- mutants were rare, the frequencies of thy- mutants in untreated and mutagenized cultures are consistent with the conclusion that the thy- phenotype is the consequence of a single mutation in CHO cells.
Thy-突变体除了对阿糖胞苷（arcC）具有抗性外，还对5-氟尿嘧啶（5FU）表现出交叉抗性。当中国仓鼠卵巢（CHO）细胞暴露于同时使用阿糖胞苷和5FU的选择系统时，通过以下标准分离出的抗性克隆与thy-突变体相同：（1）所有克隆对胸苷均为营养缺陷型，且向胸苷原养型的回复频率很高；（2）测试的克隆相对于野生型细胞具有高水平的dCTP，而dTTP和dATP水平不受影响，并且（3）对于至少一个独立的遗传标记，所有测试的克隆自发突变率比野生型菌株高7至50倍。尽管自发的thy-突变体很少见，但未处理和诱变培养物中thy-突变体的频率与thy-表型是CHO细胞中单个突变的结果这一结论一致。
