| First Author | Cattanach BM | Year | 1989 |
| Journal | Mouse News Lett | Volume | 83 |
| Pages | 160 | Mgi Jnum | J:14235 |
| Mgi Id | MGI:62407 | Citation | Cattanach BM, et al. (1989) Ta25H, a presumptive X Chromosome deletion. Mouse News Lett 83:160 |
| abstractText | Full text of MNL contribution: 5. Ta-25H, a presumptive X chromosome deletion. Ta-25H, a mutation at the Ta locus that is centrally located on the X chromosome was detected in the F-1 generation of a specific locus mutation experiment following 6 Gy spermatogonial irradiation (Cattanach and Rasberry, MNL 75, 25-26, 1986). The o r i g i n a l mutant was a female and displayed the typical striped Ta+ phenotype attributable to the X-inactivation process. Crossed with a C3H/HeH x 101/H F-1 male the female produced Ta+, + and exceptional hemizygous Ta daughters, but only +sons. Litter size was low (mean 1.6 over 5 litters) but this was shown t o be largely due to an autosomal translocation unconnected with the Ta mutation. Cytological analysis of the exceptional homozygous Ta daughters revealed that they were chromosomally XY and, at autopsy, they were found to have abdominally-located testes, rather than ovaries. No other reproductive organs were present. A mutation at the Tfm as well as the Ta locus was therefore indicated, so suggesting that a deletion covering the two loci might be involved. Breeding tests on the Ta-25H+ descendents of the original mutant have yielded 30 Ta-25H+ females, 65+ females, 31 Ta-25HY females and 70+ males. There is therefore a shortage of both the heterozygous and hemizygous Ta-25H mice and, when the data from heterozygotes for the autosomal translocation were excluded, the litter size of Ta-25H+ females was often lower than that of their + sibs (5.2 c .f. 7.1). A further novel feature of the mutant is that the heterozygotes frequently show a range of defects which are not seen in hemizygotes. These include extra incisors (3-4 instead of 2) on one or other jaw, shortened, distorted and domed heads, a syndactyly predominantly involving digits 1 and 2 and indications of a polydactyly in the region of the hallux. It is not clear how only the heterozygotes should be so affected. It may be concluded from the mosaic phenotypes of the heterozygote that the randomness of X-inactivation has not been affected. If Ta-25H represents a deletion it is clear that the inactivation centre (Xce) has not been deleted. This would place Xce either proximal to tfm and Ta or more distally towards Pgk-1. (Cattanach, Rasberry, Evans and Burtenshaw) |
