| First Author | Cattanach BM | Year | 1993 |
| Journal | Mouse Genome | Volume | 91 |
| Issue | 1 | Pages | 115-16 |
| Mgi Jnum | J:4295 | Mgi Id | MGI:52791 |
| Citation | Cattanach BM, et al. (1993) A further mutation at the splotch locus. Mouse Genome 91(1):115-16 |
| abstractText | Full text of Mouse Genome contribution: Research News: 3. A further mutation at the splotch locus. A new splotch mutation, named Sp4H has been recovered from a specific locus mutation experiment in which C3H/HeH x 101/H F1 hybrid males had been spermatogonially irradiated with a 3 + 3 Gy 24h fractionated X-ray dose. Evidence that the Sp locus was involved derived principally from linkage tests with the chr 1 markers fuzzy (fz) and leaden (ln). Crosses of + Sp4H +/fz + ln females and males with fz ln homozygotes produced the following phenotypic classes of young: 23 + Sp4H +, 30 fz + ln, 6 fz Sp4H + , 20 + + ln, total 79. Consistent with the mutation being a Sp allele, is the estimated RF with fz at 32.9 +/- 5.3%, and the close linkage with ln (no recombinants detected). The phenotype was also generally similar to that of the original Sp mutation but, as with some other Sp alleles (Beechey and Searle, MNL 75:28, 1986), the characteristic Sp white belly spotting was not consistently observed. Only about 50% of Sp4H animals displayed the belly spotting, the remainder showing only a low grade white spotting of the feet and tail suggesting that there might be incomplete penetrance. No evidence of this had been found in the linkage tests, however as no + + + or fz + + young were detected. Nevertheless in all crosses there was a consistent shortage of Sp4H animals (29;50 in the linkage tests, 101:258 in crosses with + mice, and 13:39 in Sp4H intercrosses). Post-natal losses were unexceptional (5%) suggesting that the mutant did not have a reduced viability after birth and openings of + females mated with Sp4H males failed to demonstrate significant pre-natal loss (3%). The cause of the reduced recovery of Sp4H heterozygotes is therefore unexplained but could result from a non-random chr 1 segregation. Openings of Sp4H females that had been mated to Sp4H males indicated that the homozygote dies earlier in embryonic development than homozygotes for Sp mutations other than the Spr deletion. Thus, no abnormal embryos exhibiting rachischisis or other features typical of Sp homozygotes were found; rather all but one of the post- implantation loss detected were represented by resorption sites (18 moles among 69 implants; 26.1% loss). These findings compared with zero post-implantation loss and 1% pre-implantation loss detected in openings of + females mated to Sp4H males. The results suggest that Sp4H, like Spr, might represent a deletion but no evidence of this has been found in detailed cytogenic studies. The compound of Sp4H with Sp has not yet been generated (Cattanach, Rasberry, Burtenshaw and Evans). (This study was supported in part by Euratom contract Bi6-143). |
