Cell sensitivity to irradiation and DNA repair processes. II. The cell sensitivity to ionizing radiation of different LETs.
A new model of DNA single-strand break (SSB) and double-strand break (DSB) induction by radiations of different LET has been developed. Utilizing quadratic dependence of the dose that delta-electrons depart in the track of heavy particles the fraction of heavy particle energy deposited in the target of DNA dimensions has been calculated. SSBs arise from energy depositions in one strand of DNA, direct DSBs arise from two SSBs on opposite strands of DNA in the track of one particle. It is concluded that DSBs induced by gamma-radiation are mostly of enzymatic origin, meanwhile DSBs induced by high-LET radiation are direct DSBs. The dependence of the radiosensitivity D0-1 on LET (L) for isogenic mutants of E. coli with different sensitivity to gamma-radiation has been determined on the bases of the model and considering microscopic energy fluctuations. The shape of D0-1 (L) function is formed both by physical characteristics of radiation and by the ability of cells to repair some types of DNA damage. The model provides a basis for further investigation.
D004247:DNA / Q000235:genetics / Q000528:radiation effects*; D004260:DNA Repair; D004277:DNA, Single-Stranded / Q000235:genetics / Q000528:radiation effects; D004735:Energy Transfer; D004926:Escherichia coli / Q000235:genetics / Q000528:radiation effects*; D005720:Gamma Rays; D008433:Mathematics; D008954:Models, Biological; D009154:Mutation; D011829:Radiation Dosage; D011836:Radiation Tolerance; D013997:Time Factors
D004277:DNA, Single-Stranded; D004247:DNA