The formation of photoreactivable damage by direct excitation of DNA in X-irradiated E. coli cells.

The role of the direct excitation process in the formation of photoreactivable damage (pyrimidine dimers) in E. coli WP2 hcr-exr- cells has been studied. The pyrimidine dimers were detected by photoreactivation following anoxic irradiation by X-rays (220 kVp).

[Role of direct excitation of DNA base molecules in the formation of UV-like damage in Escherichia coli cells irradiated with ionizing radiation].

On the basis of the biophysical model used for theoretical grounding of the importance of the direct excitation of molecules in the formation of photoreactivable lesions it was shown that the experimental data do not contradict the physical concepts. The dependence of the value of the photoreactivation effect upon electron energy is predicted.

[Theoretical analysis of the effect of the photoreactivation of E. coli cells irradiated with gamma quanta].

The assumption that the formation of pyrimidine dimers in E. coli cells, placed in a transient aqueous medium exposed to gamma-quanta, is conditioned by Cerenkov radiation laid the basis for the development of a biophysical model to explain the photoreactivation effect observed. The dependence of the effect upon gamma-radiation energy and the volume of the exposed suspension is predicted and compared with experimental data.