CELL SENSITIVITY TO IRRADIATION AND DNA-REPAIR PROCESSES .2. THE CELL SENSITIVITY TO IONIZING-RADIATION OF DIFFERENT LETS

  • 1 January 1984
    • journal article
    • research article
    • Vol. 31  (6) , 685-695
Abstract
A new model of DNA single-strand break (SSB) and double-strand break (DSB) induction by radiations of different LET [linear energy transfer] was 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 was calculated. SSB arise from energy depositions in 1 strand of DNA, direct DSB arise from 2 SSB on opposite strands of DNA in the track of 1 particle. DSB induced by .gamma.-radiation are mostly of enzymatic origin, meanwhile DSB induced by high-LET radiation are direct DSB. The dependence of the radiosensitivity .**GRAPHIC**. [1/mean lethal dose] on LET (L) for isogenic mutants of Escherichia coli with different sensitivity to .gamma.-radiation was determined on the bases of the model and considering microscopic energy fluctuations. The shape of .**GRAPHIC**. 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.

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