6th ESACP Congress, Heidelberg, April 7-11, 1999

A087
INFLUENCE OF IONIZING RADIATION: CALCULATION OF CHROMOSOME ABERRATIONS APPLYING SIMULATED CELL NUCEAR MODELS
Kreth G 1 2, Münkel Ch 3, Langowski J 3 2, Cremer T 4 2, Cremer C 1 2

1) Institut für angewandte Physik, Universität Heidelberg 2) Interdisziplinäres Zentrum fuer Wissenschaftliches Rechnen (IWR), Universitüt Heidelberg (3) Deutsches Krebsforschungszentrum, Heidelberg (4) Institut für Anthropologie und Humangenetik, Universitüt München, Germany

To understand the correlation between the three dimensional structure of the human cell nucleus and the formation of chromosome aberrations induced by ionizing radiation, simulated cell nuclear models are applied to calculate relative damage rates (e.g. translocation rates). For this goal the complete human genome was approximated by polymer chains situated in a spherical "nuclear" volume which are folded in a territorial or a non-territorial way, corresponding to different model assumptions. By the comparison with observed translocation rates of Hiroshima A-bomb survivors, a very good agreement was obtained with the calculated rates for both territorial and non-territorial models. Except for one extreme model case, there were no differences in the relative translocation rates of autosomes between territorial and non-territorial models. Obiviously, these relative rates depend only on the effective cross section surface of the chromosomes and the distance of the damaged chromatin sites. By the modification of one specific territorial model (Spherical 1Mbp-Chromatin Granule Domain model), the relative translocation probability for the active and the inactive X-chromosome (Xi) was determined too. For Xi, a smaller damage probability was predicted in good agreement with observed results.