DNA base and strand damage in X-irradiated monkey CV-1 cells: influence of pretreatment using small doses of radiation.
DNA base and strand damage in X-irradiated monkey CV-1 cells: influence of pretreatment using small doses of radiation.
复制标题
X 照射猴 CV-1 细胞中的 DNA 碱基和链损伤：小剂量辐射预处理的影响。
DOI：
10.1080/09553009014551421
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发表时间：
1990
影响因子：
2.6
通讯作者：
Mendez,F
中科院分区：
文献类型：
--
作者：
Bases,R;Hamori,I;Piazza,L;Maio,J;Mendez,F
用限制性内切酶ⅢofE消化5‘-32P末端标记的α片段，测定照射后的猴CV-1细胞DNA碱基损伤。测定了酶敏感位点的频率和碱基序列位置。从辐射后的DNA中释放出位于嘧啶和鸟嘌呤序列位点的片段。修复一半的单链断裂的时间约为1.5小时，碱基损伤的修复较慢，修复后4小时仍可检测到一半以上的损伤碱基。当小辐射剂量先于产生可测量的DNA链断裂和碱基损伤所需的大辐射剂量时，DNA片段释放模式发生了两个重要变化。在320Gy前几小时孵育的细胞经5Gy射线照射后，在高分辨率变性凝胶中检测到的带有3‘-磷酸末端的小DNA片段的丰度增加了五倍。这些增加在剂量低至0.2Gy时可被检测到，并伴随着在碱基序列中特定位置出现中等迁移率的新物种的DNA片段。这些模式类似于用核酸内切酶III消化强照射细胞的DNA所产生的模式。
Base damage in αDNA from irradiated monkey CV-1 cells was determined by measuring release of 5′-32P-end labelled DNA fragments after digestion with endonuclease III ofE. coli.The frequency and base sequence locations of the enzyme-sensitive sites were determined. Fragments were released from irradiated DNA at sequence sites of pyrimidines and guanines. The time for repair of half the single strand breaks was approximately 1·5 h. Repair of base damage as judged from loss of enzyme-sensitive sites in DNA was slower, with more than half of the damaged bases still detectable after 4 h of repair. Two important changes in the pattern of fragment release from DNA were produced when small radiation doses preceded the large ones needed to produce measurable DNA strand breaks and base damage. 5 Gy to cells incubated several hours before 320 Gy increased by five-fold the abundance of small DNA fragments with 3′-phosphoryl termini detected in high-resolution denaturing gels. These increases were detectable with doses as small as 0·2 Gy and were accompanied by the appearance of new species of DNA fragments of intermediate mobility at specific locations in the base sequence. The patterns resemble those produced by digesting DNA from heavily irradiated cells with endonuclease III.