Lieberman M W, Poirier M C
Proc Natl Acad Sci U S A. 1974 Jun;71(6):2461-5. doi: 10.1073/pnas.71.6.2461.
DNA repair synthesis was examined in mouse satellite and mainband DNA derived from confluent Balb/c 3T3 cells damaged with ultraviolet radiation or N-acetoxy-2-acetylaminofluorene. Two different approaches were used: (i) Contact-inhibited cells were treated with hydroxyurea to reduce replicative synthesis to low levels; and (ii) bromodeoxyuridine was used to label newly replicated DNA in cells that had escaped contact inhibition. DNA was separated into mainband and satellite fractions in Ag(+)-Cs(2)SO(4) gradients. After treatment with either ultraviolet radiation or N-acetoxy-2-acetylaminofluorene, repair synthesis occurred to the same extent in mainband and satellite DNA. Repair synthesis increased over an ultraviolet radiation dose range of 30-200 erg/mm(2), and the extent of repair in the two DNA species was similar at each dose level. An analysis of the separated strands of satellite DNA from ultraviolet-irradiated cells indicated that the extent of repair is closely correlated with the availability of pyrimidines for cyclobutyl dimer formation and provided evidence that repair synthesis occurs at the site of damage. Within the precision of our experiments the results suggest that at least one group of highly repetitive, nontranslated DNA sequences is repaired to about the same extent as the rest of the genome.
对来自紫外线照射或N-乙酰氧基-2-乙酰氨基芴处理的汇合Balb/c 3T3细胞的小鼠卫星DNA和主带DNA中的DNA修复合成进行了检测。采用了两种不同的方法：（i）用羟基脲处理接触抑制细胞，将复制性合成降低到低水平；（ii）使用溴脱氧尿苷标记逃脱接触抑制的细胞中新复制的DNA。DNA在Ag(+)-Cs(2)SO(4)梯度中分离为主带和卫星部分。用紫外线或N-乙酰氧基-2-乙酰氨基芴处理后，主带和卫星DNA中的修复合成程度相同。在30-200 erg/mm(2)的紫外线照射剂量范围内，修复合成增加，并且在每个剂量水平下，两种DNA中的修复程度相似。对紫外线照射细胞的卫星DNA单链分析表明，修复程度与环丁烷二聚体形成中嘧啶的可用性密切相关，并提供了修复合成发生在损伤部位的证据。在我们实验的精度范围内，结果表明至少一组高度重复的非翻译DNA序列的修复程度与基因组的其余部分大致相同。
