Dell'orco R T, Whittle W L
Mech Ageing Dev. 1978 Oct;8(4):269-79. doi: 10.1016/0047-6374(78)90027-1.
Unscheduled DNA synthesis, used as a measure of excision repair following exposure to ultra-violet irradiation, was determined in confluent and arrested human diploid fibroblasts and correlated with in vitro age. Confluent cultures exhibited identical levels of unscheduled DNA synthesis at all in vitro ages. Cells arrested by lowering the serum concentration of the incubation medium exhibited similar levels of unscheduled DNA synthesis as did confluent cells during the first one-third of the cells' characteristic in vitro lifespan. During the last two-thirds of the lifespan, however, arrested populations exhibited a 30 to 50% increase in the amount of detectable DNA repair. This apparent increase in ability to perform unscheduled DNA synthesis was not time or dose dependent and could not be attributed to alterations in precursor pools. It was postulated that the increase may be correlated with changes in DNA structure.
非预定DNA合成，作为紫外线照射后切除修复的一种衡量指标，在汇合且停滞生长的人二倍体成纤维细胞中进行测定，并与体外培养年龄相关联。汇合培养物在所有体外培养年龄时均表现出相同水平的非预定DNA合成。通过降低培养液中血清浓度而停滞生长的细胞，在其特征性体外寿命的前三分之一时间内，表现出与汇合细胞相似水平的非预定DNA合成。然而，在寿命的后三分之二时间内，停滞生长的细胞群体可检测到的DNA修复量增加了30%至50%。这种进行非预定DNA合成能力的明显增加并非时间或剂量依赖性的，也不能归因于前体库的改变。据推测，这种增加可能与DNA结构的变化相关。
