A Model of Chromosome Aberration Induction: Applications to Space Research

A mechanistic model and Monte Carlo code simulating chromosome aberration induction in human lymphocytes is presented. The model is based on the assumption that aberrations arise from clustered DNA lesions (CLs) and that only CL free ends created in neighboring chromosome territories or in the same territory can join and produce exchanges. The lesions are distributed in the cell nucleus according to the radiation track structure. Interphase chromosome territories are modeled as compact intra-nuclear regions with volume proportional to the chromosome DNA content. Both Giemsa staining and FISH painting can be simulated, and background aberrations can be taken into account. The good agreement with in vitro data provides model validation in terms of both the adopted assumptions and the simulation techniques. As an application in the field of space research, the model predictions were compared with aberration yields measured among crewmembers of long-term missions onboard Mir and ISS, assuming an average radiation quality factor of 2.4. The obtained agreement validated the model also for in vivo exposure scenarios and suggested possible applications to the prediction of other relevant aberrations, typically translocations.