Schrader T J, Walker I G
Department of Biochemistry, University of Western Ontario, London, Canada.
Mutat Res. 1988 Jul;194(1):65-72. doi: 10.1016/0167-8817(88)90057-0.
Quiescent and concanavalin A-stimulated bovine lymphocytes were subjected to a buoyant density analysis used in excision repair studies. Despite neutral and alkaline rebands to remove replicative contamination, the CsCl gradient profiles of DNA isolated from unstimulated lymphocytes given a 6-h labelling period revealed a small amount of radioactivity in the normal-density region which is indicative of an excision repair process. It amounted to the incorporation of 8,000-20,000 molecules of thymidine per lymphocyte. In a 12-h labelling period the extent of repair incorporation was twice that measured in a 6-h period. The extent of this repair incorporation was not altered significantly during the initial 6 or 12 h of lectin stimulation when DNA-strand breaks normally present in the unstimulated cells are repaired. The same amount of repair activity was found whether the measurements were made on the same day that the lymphocytes were isolated or on the next day following an overnight incubation of the cells in culture medium. These observations indicate that lymphocytes display a spontaneous excision repair activity that proceeds continuously and at a constant rate.
将静止的和伴刀豆球蛋白A刺激的牛淋巴细胞进行用于切除修复研究的浮力密度分析。尽管进行了中性和碱性再带处理以去除复制污染，但对标记6小时的未刺激淋巴细胞分离的DNA进行的氯化铯梯度分析显示，正常密度区域有少量放射性，这表明存在切除修复过程。每个淋巴细胞中相当于掺入了8000 - 20000个胸苷分子。在12小时的标记期内，修复掺入的程度是6小时测量值的两倍。当未刺激细胞中正常存在的DNA链断裂得到修复时，在凝集素刺激的最初6或12小时内，这种修复掺入的程度没有明显改变。无论在分离淋巴细胞的当天进行测量，还是在细胞在培养基中过夜培养后的第二天进行测量，都发现了相同量的修复活性。这些观察结果表明，淋巴细胞表现出一种自发的切除修复活性，该活性持续且以恒定速率进行。
