[Characteristics of the expression of t12 mutation in mouse embryos with structural aberrations of chromosome 17].

Developmental profiles of mouse embryos with deletions, duplications of nullisomy for the proximal part AB of chromosome 17, including genes of the T-t complex, were studied in mice with marker translocations Rb (16.17)7Bnr or T(16;17)43H and heterozygous for lethal t12 mutation. The embryos t12t12 and t12t12-(Dp17CDE; Dl16) were shown to be eliminated at the morula stage; embryos t12+, t12+ + or t12t12+ survive during preimplantation and early postimplantation stages: t12 embryos (hemizygous for all genes of the 17AB region, including all t-alleles) have quite normal cleavage, blastulation and implantation, but die soon thereafter. The embryos with nullisomy 17AB combined with deletion 17CDE survive up to the morula stage. These data are in line with previously proposed hypothetical mechanism for mutual activation of homologous chromosomes and their segments during initial stages of embryogenesis in mice. The system of marker chromosomes Rb7Bnr and T43H in combination with various alleles of the T complex might be recommended as a useful tool in analysis of primary developmental effects of different t-alleles in mice.