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ST: Strahlen- und Medizinphysik

ST 12: Biophysikalische Nanoskopie

ST 12.2: Talk

Wednesday, March 15, 2006, 10:30–10:40, D

Computer modelling of nuclear structure allows accurate estimations of chromosome aberration frequencies — •Gregor Kreth — Kirchhoff Institut für Physik

The spatial organization of the genome in the interphase nucleus has far reaching consequences for radiation biophysics. For example, the existence of chromosome territories (CTs) and their spatial distribution in the human cell nucleus is expected to pose serious constraints on the induction of specific chromosome aberrations by ionizing radiation. E.g. various experiments revealed a non-random arrangement of CTs in human lymphocyte cell nuclei. Such a clearly non random organization of nuclear genome No-dqmacroNo-dq structure has raised the question to what extend this organization favors specific interchange aberration frequencies. The spatial proximity of certain CTs or even of clusters of CTs has to increase the respective exchange yields significantly in comparison to a random association of CTs. Computer simulations of nuclear genome structure based on experimentally known general features allow to predict chromosome aberration yields induced by ionizing radiation. As an example, in this report computer simulated arrangements of CTs in human cell nuclei models (No-dq1-Mbp Spherical Chromatin Domain ModelNo-dq) were assumed to calculate interchange frequencies between all heterologous CT pairs. For the positioning of CTs in the virtual nuclear volume, both a statistical and a gene density correlated arrangement was assumed. Under the assumption of an initial repair rate, the calculated absolute aberration frequencies were found to be in good agreement with an experimental study of Arsuaga et al. 2004.