[Quantitative description of the process of radiation inactivation of cells. VII. Nature of primary radiation lesions leading to reproductive cell death].

The entity of radiation damage of viruses, bacteria and cells is defined by the organization of genetic structures. Asimmetrical chromosome exchanges have been proposed as the main reason of inactivation of di- and polyploid eukaryotic cells. If a single molecule of DNA is taken for the core of chromosome, the exchange is believed to be a consequence of cross-polymerization of two polypeptid strands of the single DNA molecule. Thus, the double strand break of DNA is necessary to produce aberration. A hypothesis is put forward on the identity of primary lesion of chromosome with the double strand break. The experimental survival curve is approximated according to the formula derived from the model. The yield of primary lesions of chromosomes is proposed to be equal to that of double strand breaks of chromosomes in order to examine the validity of the hypothesis. The optimal interaction distance of primary lesions in correspondence with parameters of the survival curve is equal to 0.8 mkm. This estimation is in good agreement with the microdosimetrical data, and the proposed hypothesis is not contradicted.