Klocker H, Auer B, Burtscher H J, Hirsch-Kauffmann M, Schweiger M
Mol Gen Genet. 1982;188(2):309-12. doi: 10.1007/BF00332693.
The UV photoproduct, thymine dimer (-TT), is excorporated with a remarkably low rate from the DNA of human fibroblasts grown in cell culture. An UV dose of 18 J/m2 creates 0.045% -TT (related to thymine). Within the first two days of repair logarithmically growing and quiescent fibroblasts exhibit the same repair rates; thereafter, the proportion of -TT/T is lower in growing cells due to recovery of DNA replication. Only about 50% of the lesions are excised within 24 h. In quiescent cells, 13% of the thymine dimers originally present can be detected as late as a week after UV-irradiation. Two distinct first-order rate constants indicate that approximately half of the dimers are less accessible to repair. Repair measured by the nucleoid decondensation technique corresponds to the faster repair rate, whereas the slow repair rate cannot be detected by this method. Saturation of repair is found beyond 27 J/m2. The remarkably slow rate of excision indicates that thymine dimers are not lethal lesions in human fibroblasts.
紫外线光产物胸腺嘧啶二聚体（-TT）从细胞培养中生长的人成纤维细胞DNA中被切除的速率极低。18 J/m2的紫外线剂量产生0.045%的-TT（相对于胸腺嘧啶）。在修复的前两天，对数生长和静止的成纤维细胞表现出相同的修复速率；此后，由于DNA复制的恢复，生长细胞中-TT/T的比例较低。在24小时内只有约50%的损伤被切除。在静止细胞中，最初存在的胸腺嘧啶二聚体中13%在紫外线照射一周后仍可被检测到。两个不同的一级速率常数表明大约一半的二聚体修复难度较大。通过核仁解聚技术测量的修复对应较快的修复速率，而这种方法检测不到慢修复速率。超过27 J/m2时发现修复饱和。切除速率极慢表明胸腺嘧啶二聚体在人成纤维细胞中不是致死性损伤。
