Further data on the radiation injury of MS2 phages

The injury of phage RNA caused by UV-irradiation was examined. Results are compared with data found by other authors on R 17 phages and synthesized polynucleotides. Authors' previously described interpretation of the injury of the phage RNA is further discussed, showing that reversible and irreversible injuries in the model correspond to dimerization and uracilhydration, respectively. By quantitative measurements and computerized calculations the ratio of reversible and irreversible photoproducts is determined for low and high doses, as well. It has been concluded that in case of sufficiently high doses the quantity of irreversible photoproducts is dominant. This model has been constructed mainly to interpret biological inactivation, it seems however, to be applicable for the comparison of the biological effect and the radiochemical experience. (B.A.)