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Medientyp:
E-Artikel
Titel:
The Complexity of Radiation-Induced DNA Damage as Revealed by Exposure to Cell Extracts
Beteiligte:
Cunniffe, Siobhan;
O'Neill, Peter
Erschienen:
Radiation Research Society, 1999
Erschienen in:
Radiation Research, 152 (1999) 4, Seite 421-427
Sprache:
Englisch
ISSN:
0033-7587;
1938-5404
Entstehung:
Anmerkungen:
Beschreibung:
The rejoining of single-strand breaks (SSBs) induced in plasmid DNA in the presence of <tex-math>$10\ {\rm mmol}\ {\rm dm}^{-3}$</tex-math> Tris scavenger by aluminum K (<tex-math>${\rm Al}_{{\rm K}}$</tex-math>) ultrasoft X rays has been compared with that for SSBs induced by γ radiation. The <tex-math>${\rm Al}_{{\rm K}}$</tex-math> ultrasoft X rays interact to produce low-energy secondary electrons, which are thought to be the main contributors to the formation of complex damage by low-LET radiations. The rejoining of radiation-induced SSBs was investigated using human whole cell extracts. The efficiency of rejoining of SSBs induced by <tex-math>${\rm Al}_{{\rm K}}$</tex-math> ultrasoft X rays is less than that observed for γ-ray-induced SSBs. From the similarity of the extent of rejoining of SSBs induced by γ rays under aerobic and anaerobic conditions, the chemical nature of the stand break termini does not significantly influence SSB rejoining. A simple nick induced in plasmid DNA by gpII protein is rejoined rapidly compared with the slower rejoining processes for radiation-induced SSBs. Therefore, ligation is not rate-determining in processing radiation-induced SSBs. This study provides further evidence that nonrejoining of radiation-induced SSBs reflects the complexity of DNA damage. From comparison of the extent of rejoining of SSBs induced by different radiations, it is inferred that double-strand breaks represent only a minor component of the overall yield of complex damage.