[The accumulation of single-stranded breaks does not lead to paired DNA damage--the characteristic of the transcribing fragment of the human ribosomal operon that allows its being detected in biological fluids at the death of different body cells].
It was shown by blot-hybridization with corresponding DNA probes after electrophoretic separation of control and experimental samples of human genome DNA that accumulation of single-strand breaks in the chains of double-strand fragment of transcribing range of ribosomal gene (TRrDNA) does not result in double-strand breaks. That differs from the other studied DNA sequences (cluster of histon genes, Alu-repetition, telomeric repetition and satellite III). Single-strand breaks and double-strand breaks were induced by endonucleases and by gamma-radiation. In spite of higher chemical modification of TRrDNA by arylazide and dimethylsulfate (because of high content of GC-pairs), under the following fragmentation TRrDNA was found to be more resistant to double-strand breaks than other studied DNA sequences. At the same time in the range of non-transcribing spacer (NTS) of ribosomal gene, the section with higher sensitivity to double-strand breaks was found. Higher resistance of TRrDNA to double breaks makes it possible to identify these fragments in cell material from different tissue after death or in DNA samples after prolonged storage. Resistance of TRrDNA to formation of double-strand breaks can be used for its detection in biological fluids after cell death, including the death initiated by ionizing radiation.
Veĭko
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Medical and Genetic Research Center, Russian Academy of Medical Sciences, Moscow, Russia. socrates@orc.ru
Spitkovskiĭ
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D002102:Cadaver; D016923:Cell Death / Q000235:genetics / Q000528:radiation effects; D004249:DNA Damage / Q000235:genetics*; D004275:DNA, Ribosomal / Q000097:blood / Q000235:genetics* / Q000528:radiation effects; D004277:DNA, Single-Stranded / Q000097:blood / Q000235:genetics* / Q000528:radiation effects; D005720:Gamma Rays; D006801:Humans; D006868:Hydrolysis; D007962:Leukocytes / Q000737:chemistry / Q000528:radiation effects; D009876:Operon / Q000235:genetics* / Q000528:radiation effects; D014158:Transcription, Genetic / Q000235:genetics* / Q000528:radiation effects
D004275:DNA, Ribosomal; D004277:DNA, Single-Stranded