Filatov M V, Pantina R A, Noskin L A
St. Petersburg Nuclear Physics Institute, Gatchina, Russian Federation.
Mutat Res. 1998 Jul 17;403(1-2):95-101. doi: 10.1016/s0027-5107(98)00056-6.
A phenomenon of spontaneous DNA instability displays itself as the low level of repair DNA synthesis that takes place during any cell cycle phases. However, there is a problem in detection of very low intensive repair DNA synthesis. This paper suggests two approaches to detect the spontaneous DNA instability. The first method involves a blockade of the DNA gaps sealing by a combination of inhibitors, hydroxyurea and arabinofuranosyl cytosine. An accumulation of single strand gaps leads to production of DNA double strand breaks and results to reproductive inactivation of cells. It was shown that registration of both these events by different methods (such as viscoelastometry of DNA, orthogonal pulse electrophoresis or comet assay for double strand breaks as well as effectiveness of colony growth for cell inactivation) may be used as suitable measure of the spontaneous DNA instability. The second approach bases on photolysis of bromodeoxyuridine incorporated into repair DNA patches during the spontaneous repair DNA synthesis. Long wave UV irradiation of cells containing bromodeoxyuridine labeled DNA stained with Hoechst 33342 causes their inactivation. Experimental results presented confirm that both methods actually detect the spontaneous DNA instability. It takes note of the spontaneous DNA instability varies for cells from different tissues and species and increases during aging.
一种自发的DNA不稳定性现象表现为在任何细胞周期阶段发生的低水平修复DNA合成。然而，检测极低强度的修复DNA合成存在一个问题。本文提出了两种检测自发DNA不稳定性的方法。第一种方法是通过羟基脲和阿糖胞苷抑制剂的组合来阻断DNA缺口的封闭。单链缺口的积累会导致DNA双链断裂的产生，并导致细胞的生殖失活。结果表明，通过不同方法（如DNA的粘弹性测量、正交脉冲电泳或双链断裂的彗星试验以及细胞失活的集落生长有效性）对这两个事件的记录可作为自发DNA不稳定性的合适测量方法。第二种方法基于在自发修复DNA合成过程中对掺入修复DNA片段中的溴脱氧尿苷进行光解。用Hoechst 33342染色的含有溴脱氧尿苷标记DNA的细胞经长波紫外线照射会导致其失活。给出的实验结果证实这两种方法确实能检测到自发DNA不稳定性。需要注意的是，自发DNA不稳定性在不同组织和物种的细胞中有所不同，并且在衰老过程中会增加。
