Comparative study of DNA radiolysis by fast neutrons and gamma-rays.
The effect of fast neutrons on cells is different from that of gamma-rays: the relative (to gamma) biological effect (RBE) is higher than one and the oxygen enhancement ratio (OER) is lower than that of gamma-rays. We searched for differences between the effects of the two radiations on DNA, the critical target of radiations. Using a model plasmid DNA we observed that for the same absorbed dose, fast neutrons induce twice fewer single strand breaks (SSB) and 1.5 more double strand breaks (DSB) than gamma-rays. A transition metal ion, the Cu++, is a better sensitizer of DNA breakage with fast neutrons than with gamma-rays. In anoxia, cysteamine, a positively charged thiol, is a better radioprotector against neutrons than against gamma-rays. In presence of cysteamine, the OER is lower for neutrons than for gamma-rays. These results are discussed in terms of different physical properties of the two types of radiation.
Spotheim-Maurizot
M
M
Centre de Biophysique Moléculaire, CNRS, Orléans, France.
Savoye
C
C
Sabattier
R
R
Charlier
M
M
D003300:Copper / Q000494:pharmacology; D003543:Cysteamine / Q000494:pharmacology; D004247:DNA / Q000187:drug effects / Q000528:radiation effects*; D004249:DNA Damage; D004260:DNA Repair; D005214:Fast Neutrons; D005720:Gamma Rays; D006801:Humans; D008954:Models, Biological; D010100:Oxygen / Q000494:pharmacology; D010957:Plasmids / Q000187:drug effects / Q000528:radiation effects; D011837:Radiation-Protective Agents / Q000494:pharmacology; D012062:Relative Biological Effectiveness
D011837:Radiation-Protective Agents; D003543:Cysteamine; D003300:Copper; D004247:DNA; D010100:Oxygen