[Spontaneous and induced chromosome aberrations in the bone marrow cells of different strains of mice during aging].

Sensitivity of bone marrow cell chromosomes to alkylating agent thiophosphamide and to gamma-irradiation has been studied in the course of ageing in 101/H, A/He, CBA, BALB/c and C57BL/6 mice. The effects of both the kinds of mutagenic treatment and of the genotype of the animals on the age-dependent changes in sensitivity of bone marrow cell chromosomes were found. Following gamma-irradiation under our experimental conditions, no variation in the output of chromosomal aberrations was observed between the strains studied. Following thiophosphamide treatment, aged mice of strains 101/H, A/He and CBA showed an increased chromosome instability as compared to young ones. In C57BL/6 mice the level of induced chromosome aberrations was found to be age-independent. Following thiophosphamide treatment, cells with multiple chromosome lesions were found in the bone marrow. The higher instability of aged animals in some strains was mainly due to a sharp increase in the number of such cells. In the intact mice of all the strains studied no age-dependent increase in the number of cells showing structural chromosome aberrations was observed, while accumulation of aneuploid cells varied with genotype.