[HeLa细胞转录和非转录DNA中γ诱导单链断裂的修复]
[The repair of gamma-induced single-stranded breaks in the transcribed and nontranscribed DNA of HeLa cells].
作者信息
Igusheva O A, Bil'din V N, Zhestianikov V D
出版信息
Tsitologiia. 1993;35(11-12):54-63.
The repair of gamma-ray-induced DNA single-strand breaks (SSB) in transcribed (Alu-enriched DNA, proto-oncogene c-myc) and non-transcribed (human satellite III) DNA of HeLa cells has been investigated. A special methodical approach has been developed. The method involved alkaline sucrose sedimentation followed by Southern hybridization in situ of 32P labelled plasmids (probes) containing sequences analysed with total DNA distributed through sucrose gradient fractions. The degree of the probes hybridization with cellular DNA was the criteria of the damage and that of DNA repair. The induction of DNA SSB after irradiation (100 Gy) in Alu-enriched DNA and c-myc gene was shown to be 1.3-1.4 time more often while than in satellite DNA, and 1.4 time lower compared to that in total DNA. The rate of DNA repair was different: the most part of lesions was eliminated in the first 10-20 minutes in all cases. For this time 60-67, 50-66, 35-50 and 45-50% DNA SSB were eliminated from transcribed DNA (c-myc, Alu), non-transcribed DNA (satellite III) and total DNA, respectively. Thus, the preferable (fast) repair of gamma-ray-induced DNA SSB takes place in transcribed DNA compared to that in non-transcribed DNA of HeLa cells.
对HeLa细胞转录的（富含Alu的DNA、原癌基因c-myc）和非转录的（人类卫星III）DNA中γ射线诱导的DNA单链断裂（SSB）修复进行了研究。开发了一种特殊的方法。该方法包括碱性蔗糖沉降，然后对含有经蔗糖梯度分级分离的总DNA分析的序列的32P标记质粒（探针）进行原位Southern杂交。探针与细胞DNA的杂交程度是损伤和DNA修复的标准。结果表明，照射（100 Gy）后，富含Alu的DNA和c-myc基因中DNA SSB的诱导频率比卫星DNA高1.3 - 1.4倍，与总DNA相比低1.4倍。DNA修复速率不同：在所有情况下，大部分损伤在最初的10 - 20分钟内被消除。在这段时间内，转录DNA（c-myc、Alu）、非转录DNA（卫星III）和总DNA中分别有60 - 67%、50 - 66%、35 - 50%和45 - 50%的DNA SSB被消除。因此，与HeLa细胞的非转录DNA相比，γ射线诱导的DNA SSB在转录DNA中优先（快速）修复。
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