Ramakrishnan N, Pradhan D S
Biochim Biophys Acta. 1976 Jun 18;435(2):119-27. doi: 10.1016/0005-2787(76)90242-2.
The residual RNA synthesis in Yoshida ascites tumor cells following exposure to ultraviolet radiation was insensitive to rifampicin AF/013, an inhibitor of initiation of RNA synthesis in eukaryotic cells. On the other hand, residual RNA synthesis in the ascites tumor cells after gamma-irradiation was inhibited by rifampicin AF/013. In vitro synthesis of RNA on ultraviolet-irradiated ascites chromatin likewise was resistant to rifampicin AF/013. Ultraviolet irradiation was found to decrease the number of RNA chain initiation sites on ascites chromatin considerably whereas the number of initiation sites on ascites chromatin increased considerably after gamma irradiation. These results indicate that ultraviolet irradiation may preferentially affect the DNA segments participating in initiation of RNA synthesis.
吉田腹水瘤细胞经紫外线照射后残留的RNA合成对利福平AF/013不敏感，利福平AF/013是真核细胞中RNA合成起始的抑制剂。另一方面，γ射线照射后的腹水瘤细胞中残留的RNA合成受到利福平AF/013的抑制。紫外线照射后的腹水染色质上RNA的体外合成同样对利福平AF/013有抗性。发现紫外线照射可显著减少腹水染色质上RNA链起始位点的数量，而γ射线照射后腹水染色质上的起始位点数量则显著增加。这些结果表明，紫外线照射可能优先影响参与RNA合成起始的DNA片段。
