[Biophysical modeling of dose response for γ-ray induced complex chromosomal aberrations]

Experiments with FISH painting of chromosomes, including full-color mFISH, have revealed unexpectedly high yields of complex chromosomal aberrations (CA). The ratio of complex and simple aberrations observed in the 1st postirradiation mitosis has proved to depend on the cell line, LET and time after irradiation in a complicated way. According to the widely accepted viewpoint, interchanges are formed as a result of interaction between either contacting lesions or those having come into contact on a boundary between chromosome territories. However, the theoretical analysis has shown that the mechanism of CA formation at the boundary between chromosome territories is insufficient to explain the high ratio of complex/simple aberrations induced by γ-rays in human lymphocytes at different doses. In the present work, the origin of high yields of complex CA is investigated by means of biophysical modeling. The hypothesis that CA are formed on nuclear centers is able to explain quantitatively the dose response relationships for both simple and complex interchanges observed by mFISH technique after low-LET irradiation.