Cooke A, Harris W J
Mech Ageing Dev. 1982 Jun;19(2):171-80. doi: 10.1016/0047-6374(82)90008-2.
Two lines of normal human embryonic lung fibroblasts, MRC-5 and F2002, were serially subcultured until senescence was attained. When cells were exposed to varying concentrations of the chemical carcinogen 4-nitroquinoline-1-oxide (4-NQO), the rate of DNA synthesis (as measured by thymidine incorporation) was reduced in a dose-dependent fashion in cells from both early and late passages. While the overall amount of incorporation was considerably lower in old cells, the extent of inhibition caused by 4-NQO treatment (relative to appropriate controls) was not related to culture age. Alkaline sucrose density gradient analysis of newly synthesised DNA from cells pre-treated with 4-NQO failed to detect any significant variation in the size of labelled DNA from cells examined immediately after incubation with radioactive thymidine. The shift of this labelled material to high molecular weight in 4-NQO-treated cells also showed no age-related difference.
将两株正常的人胚胎肺成纤维细胞系MRC-5和F2002进行连续传代培养，直至达到衰老状态。当细胞暴露于不同浓度的化学致癌物4-硝基喹啉-1-氧化物（4-NQO）时，DNA合成速率（通过胸腺嘧啶核苷掺入法测定）在早期和晚期传代的细胞中均呈剂量依赖性降低。虽然老细胞中的总体掺入量明显较低，但4-NQO处理引起的抑制程度（相对于适当的对照）与培养年龄无关。对用4-NQO预处理的细胞新合成的DNA进行碱性蔗糖密度梯度分析，未能检测到与放射性胸腺嘧啶核苷孵育后立即检测的细胞中标记DNA大小的任何显著变化。在4-NQO处理的细胞中，这种标记物质向高分子量的转移也未显示出与年龄相关的差异。
