Recombination between homologous chromosomes does not play a dominant role in the formation of radiation-induced chromosomal aberrations

Purpose : In mammalian cells, the relevance of homologous recombination in radiation-induced double-strand break (DSB) repair is not yet well understood. In the present work, the role of recombination between homologous chromosomes and homology-directed repair of DSB were studied, using X-ray-induced chromosomal aberrations as an end-point. Materials and methods : Human-hamster hybrid cells containing one or two copies of human chromosome 8 were used. If recombination between homologous chromosomes plays a dominant role in DSB repair, it is expected that X-irradiation of cells with two copies of chromosome 8 would result in a lower frequency of aberrations involving this chromosome compared with cells with only one copy of chromosome 8. The aberrations involving human chromosome 8 were detected by fluorescence in situ hybridization (FISH). Furthermore, a comparison between the hamster cell line XR-C1 (defective in non-homologous repair), CHO-9 (the wild-type cells) and the cell line XR-C1#8 (in which the ...