The inactivation of plaque forming ability of T 1 bacteriophage by X- and 60Co-gamma-rays was used to test the protective action of different concentrations of cysteamine and cystamine in broth-suspension, in the dry state. at 300 and at 80°K respectively. Under all experimental conditions the amount of radioprotection given by the disulfide is comparable within a few percent to the protection afforded by the thiol. The protective mechanism by which both compounds act at room temperature or at 80°K is discussed emphasizing evidence in favour of the hypothesis of electron-hydrogen donation. Oxygen reduces the efficiency of this mechanism by competing with the thiol as well as with the disulfide for radiation induced radicals in the phage DNA. Experimental evidence is given for the conclusion that cystamine needs not be reduced by enzymes or radiation to show efficient radioprotection.
Experimental evidence of Er^3+ ion reduction in the radiation-induced degradation of erbium-doped silica fibers
