Mattern M R, Zwelling L A, Kerrigan D, Kohn K W
Biochem Biophys Res Commun. 1983 May 16;112(3):1077-84. doi: 10.1016/0006-291x(83)91728-x.
X-ray-induced DNA repair in mouse leukemia (L1210) cells was studied by alkaline elution, which measures the amount of DNA strand breakage, coupled with nucleoid sedimentation, which measures DNA compactness. Two phases of X-ray repair were detected. An initial phase was rapid (t1/2 less than 10 min). During this phase most strand breaks were rejoined and some compaction occurred. After a lag of 1-2 hours, a second phase occurred which exhibited very little or no additional ligation but further compaction of the nucleoid DNA. Both the DNA strand rejoining and initial nucleoid compaction of the first phase were inhibited by 3-ABA2 but not by novobiocin, and the second phase was inhibited by novobiocin but not by 3-ABA. The two phases of reconstitution of nucleoid compactness following X-irradiation are thus distinguishable by their time of occurrence and by their sensitivity to inhibitors of DNA-related enzymes. A coordinated process of ligation followed by compaction may be intrinsic to DNA repair following X-irradiation.
通过碱性洗脱法研究了X射线诱导的小鼠白血病（L1210）细胞中的DNA修复，碱性洗脱法用于测量DNA链断裂的量，并结合核仁沉降法，该方法用于测量DNA的紧密程度。检测到X射线修复的两个阶段。初始阶段很快（半衰期小于10分钟）。在此阶段，大多数链断裂重新连接，并且发生了一些紧密化。在1至2小时的延迟后，出现了第二阶段，该阶段几乎没有或没有额外的连接，但核仁DNA进一步紧密化。第一阶段的DNA链重新连接和初始核仁紧密化均受到3-ABA2的抑制，但不受新生霉素的抑制，而第二阶段受到新生霉素的抑制，但不受3-ABA的抑制。因此，X射线照射后核仁紧密化重建的两个阶段可以通过其发生时间和对DNA相关酶抑制剂的敏感性来区分。连接后紧接着紧密化的协调过程可能是X射线照射后DNA修复所固有的。
