[Interlineage differences in murine sensitivity to thiotepa: an experiment with recombinant strains]

The study is devoted to the clastogenic effect of thio-TEPA in raising recombinant strains 1 x C3 in mice (obtained from 101/H x C3H/Sn crossing). By the summer of 1993, 15 strains had reached 10 generations of inbreeding. From five to six siblings of each strain (males and females) aged 6-8 weeks were treated with the mutagen (3 mg per kg, i/p). Strain sensitivity was estimated by the proportion of marrow cells exhibiting chromosome lesions (including gaps). According to this characteristic, the strains were divided into two unequal groups. The first one included 12 less-sensitive strains (chromosome aberrations were present, on average, in 33.5% of the cells, and lay in the range from 27.0 +/- 4.5 to 39.8 +/- 4.9). The second group included three more-sensitive strains with 51.2, 51.7, and 59.5% of the cells being affected (54.1% on average). A similar difference between the groups was found with respect to the number of breaks per cell: 1.15 in resistant strains and 2.88 in sensitive ones. This difference was significant and similar to that found earlier for C3H and 101 strains. Thus, the results obtained support the hypothesis that mice of the 101/H strain carry a gene enhancing sensitivity to chemical mutagens (mut-1). Some strains of the first group were eliminated; the remaining ones will be bred until the 20th generation, when they will be investigated again in more detail.