[Novel partial t-haplotypes of domestic mouse: characteristics of basic properties]

The paper concerns the description of new partial t-haplotypes. One of them, tN1, arose as a result of recombination from t12. The rest ones, tN2-tN5, arose from t6. All the haplotypes described are viable in homozygotic state and when present with T (Brachyury) cause the offspring to be tailless. The tN1-heterozygous males transmit the chromosome with this haplotype to their offspring at the rate of 33%, the t12/tN1 compounds being subfertile. Transmission of chromosome with tN2-tN5 haplotype from heterozygous males does not deviate from 1:1, the t6/tN2 (-tN5) being fertile. The data obtained point out to additional genes (distorters) in the model of t-haplotype, offered by M. Lyon (1984, 1986), that agrees with suggestion of L. Silver (1985). Recombination analysis showed that tN1-tN5 haplotypes suppress crossing over at the strech of 4-5 cM, distally to the T mutation. In tN1 homozygous stock the short-tailed mice appear at the rate of 6-7%. Manifestation of the fused gene is sufficiently modified in a greater part of the animals having genotype tN1Fu/tN1+. That is likely to be the result of gene interaction in early ontogenesis. It has been shown earlier, that penetrance of Fu gene is reduced in the progeny of Fu/t12 females. The results are in favor of the fact that this effect is connected with the distal part of t12-haplotype, the proximal tN1-haplotype having no such effect.