A STUDY OF THE SUSCEPTIBILITY OF MICE TO VARIOUS STRAINS OF THIO-TEPA- 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 cros sing). By the summer of 1993, 15 strains had reached 10 generations of inbreeding, From five to six siblings of each strain (males and femal es) 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 ex hibiting chromosome lesions (including gaps), According to this charac teristic, the strains were divided into two unequal groups. The first one included 12 less-sensitive strains (chromosome aberrations were pr esent, on average, in 33.5% of the cells, and lay in the range from 27 .0 +/- 4.5 to 39.8 +/- 4.9)1 The second group included three more-sens itive 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 w ith respect to the number of breaks per cell: 1.15 in resistant strain s and 2.88 in sensitive one's. This difference was significant and sim ilar 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 un til the 20th generation, when they will be investigated again in more detail.