| Abstrakt: |
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. |
