Effects of Decay of Incorporated H-Thymidine on Bacteria

The killing efficiency due to the decay of incorporated H(3)-thymidine in three mutants of E. coli strain 15: 15(T-), 15(T-L-), and 15(T-U-) has been determined. This efficiency is comparable to that previously determined by others for P(32) decay. The killing efficiency has been determined as a function of H(3)-thymidine specific activity, storage media and storage temperature. We have observed a latent killing effect that causes lethality under certain conditions. The kinetics of latent killing have been examined at several temperatures. Finally, mutation production induced by H(3)-thymidine decays was shown to occur. The results are consistent with the idea that inactivation and mutations may be caused by a process in the nuclear transmutation that is not associated with beta-particle ionization damage.