哺乳动物细胞中紫外线损伤的切除修复。嘧啶二聚体切除过程中两个步骤的证据。
Excision repair of ultraviolet damage in mammalian cells. Evidence for two steps in the excision of pyrimidine dimers.
作者信息
Williams J I, Cleaver J E
出版信息
Biophys J. 1978 May;22(2):265-79. doi: 10.1016/S0006-3495(78)85488-5.
The incidence of pyrimidine dimer formation and the kinetics of DNA repair in African green monkey kidney CV-1 cells after ultraviolet (UV) irradiation were studied by measuring survival, T4 endonuclease V-sensitive sites, the fraction of pyrimidine dimers in acid-insoluble DNA as determined by thin layer chromatography (TLC), and repair replication. CV-1 cells exhibit a survival curve with extrapolation number n = 7.8 and Do = 2.5 J/m2. Pyrimidine dimers were lost from acid-insoluble DNA more slowly than endonuclease-sensitive sites were lost from or new bases were incorporated into high molecular weight DNA during the course of repair. Growth of CV-1 cultures in [3H]thymidine or X-irradiation (2 or 10 krads) 24 h before UV irradiation had no effect on repair replication induced by 25 J/m2 of UV. These results suggest that pyrimidine dimer excision measurements by TLC are probably unaffected by radiation from high levels of incorporated radionuclides. The endonuclease-sensitive site and TLC measurements can be reconciled by the assumption that pyrimidine dimers are excised from high molecular weight DNA in acid-insoluble oligonucleotides that are slowly degraded to acid-soluble fragments.
通过测量存活率、T4 内切核酸酶 V 敏感位点、经薄层色谱法（TLC）测定的酸不溶性 DNA 中嘧啶二聚体的比例以及修复复制，研究了非洲绿猴肾 CV-1 细胞在紫外线（UV）照射后嘧啶二聚体形成的发生率和 DNA 修复动力学。CV-1 细胞呈现出一条外推数 n = 7.8 且 Do = 2.5 J/m² 的存活曲线。在修复过程中，酸不溶性 DNA 中的嘧啶二聚体丢失的速度比内切核酸酶敏感位点从高分子量 DNA 中丢失或新碱基掺入高分子量 DNA 的速度要慢。在紫外线照射前 24 小时，用 [³H]胸腺嘧啶核苷培养 CV-1 细胞或进行 X 射线照射（2 或 10 千拉德），对 25 J/m²紫外线诱导的修复复制没有影响。这些结果表明，通过 TLC 进行的嘧啶二聚体切除测量可能不受高水平掺入放射性核素辐射的影响。通过假设嘧啶二聚体从高分子量 DNA 中被切除到酸不溶性寡核苷酸中，而这些寡核苷酸会缓慢降解为酸溶性片段，内切核酸酶敏感位点测量和 TLC 测量结果可以得到协调。
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