Radiation breakage of DNA: a model based on random-walk chromatin structure.
Monte Carlo computer software, called DNAbreak, has recently been developed to analyze observed non-random clustering of DNA double strand breaks in chromatin after exposure to densely ionizing radiation. The software models coarse-grained configurations of chromatin and radiation tracks, small-scale details being suppressed in order to obtain statistical results for larger scales, up to the size of a whole chromosome. We here give an analytic counterpart of the numerical model, useful for benchmarks, for elucidating the numerical results, for analyzing the assumptions of a more general but less mechanistic "randomly-located-clusters" formalism, and, potentially, for speeding up the calculations. The equations characterize multi-track DNA fragment-size distributions in terms of one-track action; an important step in extrapolating high-dose laboratory results to the much lower doses of main interest in environmental or occupational risk estimation. The approach can utilize the experimental information on DNA fragment-size distributions to draw inferences about large-scale chromatin geometry during cell-cycle interphase.
NASA Johnson Space Center, Houston, TX 77058, USA. alponoma@ems.jsc.nasa.gov
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D000818:Animals; D002843:Chromatin / Q000528:radiation effects*; D003198:Computer Simulation; D004247:DNA / Q000528:radiation effects*; D004249:DNA Damage; D006801:Humans; D008954:Models, Biological; D009010:Monte Carlo Method; D011839:Radiation, Ionizing
D002843:Chromatin; D004247:DNA