Schwartz S A
Nucleic Acids Res. 1979 Feb;6(2):745-55. doi: 10.1093/nar/6.2.745.
In order to characterize the molecular mechanism responsible for the BrdU-mediated activation of endogenous retrovirus from normal rat embryo cells, the previously reported selective distribution of bromouracil in DNA was correlated with the corresponding organization of the nucleo-protein complex in regard to nucleosome structure and template - active and -inactive chromatin. Following micrococcal nuclease digestion of chromatin labeled with either [(3)H]thymidine or [(3)H]BrdU, the amount and specific activities of the respective nucleosomal DNA were indistinguishable. Comparable findings were obtained following direct examination of the nuclease-sensitive, "spacer" DNA. However, when each chromatin type was fractionated into template-active and -inactive components, it was evident that [(3)H]bromouracil was nonrandomly more concentrated in the template-active portion in comparison to the random distribution of [(3)H]thymine moieties. Furthermore, it was apparent that the template-active chromatin fraction was substantially enriched in the nucleotide sequences of rat DNA known to be sensitive to the virogenic action of BrdU.
为了阐明负责BrdU介导的正常大鼠胚胎细胞内源性逆转录病毒激活的分子机制，先前报道的溴尿嘧啶在DNA中的选择性分布与核蛋白复合物在核小体结构以及模板活性和非活性染色质方面的相应组织相关。在用[³H]胸腺嘧啶或[³H]BrdU标记的染色质经微球菌核酸酶消化后，各自核小体DNA的量和比活性没有区别。对核酸酶敏感的“间隔”DNA进行直接检查后也得到了类似的结果。然而，当将每种染色质类型分离为模板活性和非活性成分时，很明显，与[³H]胸腺嘧啶部分的随机分布相比，[³H]溴尿嘧啶非随机地更集中在模板活性部分。此外，很明显，模板活性染色质部分在已知对BrdU的病毒发生作用敏感的大鼠DNA核苷酸序列中大量富集。
