Effects of irradiation on RNA synthesis primed by calf thymus deoxyribonucleoprotein treated with salt and salt-urea.

1. The effects of ionizing radiation on the activity of calf thymus templates were examined in a Escherichia coli RNA polymerase system. 2. The template activity of native and 2 M NaCl-5M urea-treated deoxyribonucleoproteins was enhanced by relatively low doses of irradiation, while that of 2 M NaCl-treated deoxyribonucleoprotein was not enhanced by irradiation. 3. The template activity of purified DNA was markedly decreased by irradiation, while that of native deoxyribonucleoprotein, 2 M NaCl-treated, and 2 M NaCl-5 M urea-treated ones were slightly decreased at a higher dose range. The doses for 50% inactivation of these templates were 1.3, 210, 140, and approximately 200 krad, respectively.