Influence of some radiosensitizers on gamma-ray-induced degradation of DNA in the blue-green alga, Anacystis nidulans

The blue-green algae appear to have maintained efficient repair systems. They were sensitized to gamma-irradiation by chemical sensitizers. This work presents evidence for the influence of sensitizers on post-irradiation DNA degradation. Uracil- 14 C labelled A. nidulans were irradiated in the presence of solutions of various radiosensitizers. Loss of radioactivity from the acid-precipitable DNA was used as a measure of DNA breakdown. Iodoacetic acid, p-chloromercuribenzoate, indanetrione, methylhydrazine and iodobenzoic acid were used at optimum concentrations for sensitization (cell survival). Four sensitizers, iodoacetic acid (3 × 10 −4 m ), indanetrione (10 −4 m ), methylhydrazine (10 −4 m ) and iodobenzoic acid (2 × 10 −4 m ) almost completely inhibited post-irradiation breakdown, but p-chloromercuribenzoate (10 −5 m ) had only a slight inhibitory effect. It was concluded that for this alga, DNA degradation could be affected by various sensitizers.