Graf L H, Urlaub G, Chasin L A
Somatic Cell Genet. 1979 Nov;5(6):1031-44. doi: 10.1007/BF01542658.
Purified DNA from wild-type Chinese ovary (CHO) cells has been used to transform three hypoxanthine phosphoribosyltransferase (HPRT) deficient murine cell mutants to the enzyme positive state. Transformants appeared at an overall frequency of 5 x 10(-8) colonies/treated cell and expressed CHO HPRT activity as determined by electrophoresis. One gene recipient, B21, was a newly isolated mutant of LMTK- deficient in both HPRT and thymidine kinase (TK) activities. Transformation of B21 to HPRT+ occurred at 1/5 the frequency of transformation to TK+; the latter was, in turn, an order of magnitude lower than that found in the parental LMTK- cells, 3 x 10(-6). Thus both clonal and marker-specific factors play a role in determining transformability. The specific activity of HPRT in transformant extracts ranged from 0.5 to 5 times the CHO level. The rate of loss of the transformant HPRT+ phenotype, as measured by fluctuation analysis, was 10(-4)/cell/generation. While this value indicates stability compared to many gene transferents, it is much greater than the spontaneous mutation rate at the indigenous locus. The ability to transfer the gene for HPRT into cultured mammalian cells may prove useful for mutational and genetic mapping studies in this well-studied system.
来自野生型中国仓鼠卵巢（CHO）细胞的纯化DNA已被用于将三种次黄嘌呤磷酸核糖基转移酶（HPRT）缺陷型小鼠细胞突变体转化为酶阳性状态。转化体以5×10^(-8)个菌落/处理细胞的总频率出现，并通过电泳测定显示出CHO HPRT活性。一个基因受体B21是新分离的LMTK-突变体，缺乏HPRT和胸苷激酶（TK）活性。B21向HPRT+的转化频率是向TK+转化频率的1/5；而向TK+的转化频率又比亲本LMTK-细胞中的转化频率低一个数量级，亲本LMTK-细胞中的转化频率为3×10^(-6)。因此，克隆因素和标记特异性因素在决定转化能力方面都起作用。转化体提取物中HPRT的比活性范围为CHO水平的0.5至5倍。通过波动分析测量，转化体HPRT+表型的丢失率为10^(-4)/细胞/代。虽然与许多基因转移体相比，这个值表明其具有稳定性，但它比该基因座的自发突变率要高得多。将HPRT基因转移到培养的哺乳动物细胞中的能力可能被证明对这个经过充分研究的系统中的突变和基因定位研究有用。
