Accueil > Publications > Recherche par années > Années 1990 > 1991

Spotheim-Maurizot, M ; Franchet, J ; Sabattier, R ; Charlier, M

DNA radiolysis by fast-neutrons .2. Oxygen, thiols and ionic-strength effects

International Journal of Radiation Biology 59 (6) 1313-1324

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Abstract :

Plasmid DNA was irradiated with fast neutrons, and the protection by cysteamine against strand breakage (ssb and dsb) was evaluated in the presence and absence of oxygen. In the absence of cysteamine no radiosensitizing effect of oxygen was observed. In anoxia the protection factors, PF(ssb) and PF(dsb) of 1 mM cysteamine (in 50 mM potassium phosphate solution) were lower than the PFs observed with gamma-irradiation. The results agree with the radical repair model, in which the thiol competes with the oxygen produced inside the anoxic neutron-irradiated system, according to the ’oxygen-in-the-track’ hypothesis. At low ionic strength in air-saturated solutions, positively charged cysteamine protects more efficiently than negatively charged thiolactate.