| First Author | Cattanach BM | Year | 1994 |
| Journal | Mouse Genome | Volume | 92 |
| Issue | 3 | Pages | 503-4 |
| Mgi Jnum | J:27501 | Mgi Id | MGI:74990 |
| Citation | Cattanach BM, et al. (1994) Mutations PaxSp-5H and PaxSp-6H. Mouse Genome 92(3):503-4 |
| abstractText | Full text of Mouse Genome contribution: 4. Two further Sp mutations. Two new splotch mutations, Sp5H and Sp6H have been recovered from specific locus mutation experiments following 6 Gy spermatogonial X-irradiation of F1 hybrid (C3H/HeH x 101/H) males. In the case of Sp6H a pre-treatment with 3 amino benzamide had been given 1/2 h prior to the paternal irradiation. Both mutants were characterised by slightly reduced size at birth and subsequently, but with minimal levels of postnatal loss. Both exhibited only low degrees of the white patching that characterizes the Sp phenotype, the white markings most frequently being confined to the feet and tail, and rarely on the belly. Classification was therefore generally difficult although facilitated by the growth retardation. The recovery rates of Sp5H and Sp6H mutants in crosses with wild type were low (65% and 25% of expected, respectively) and may relate to the low penetrance. Cytogenetic evidence of a small Chr 1 deletion in band C5 has so far provided the sole indication that Sp6H is a mutation at the Sp locus. In the case of Sp5H, no cytogenetic indication of a deletion could be found; evidence that the mutation involved Sp derived from linkage with the Chr 1 markers fuzzy (fz) and leaden (ln). Thus, crosses of + Sp5H + males and females with fz ln homozygotes produced the following phenotypic classes of young; 88fz ln, 75 Sp5H, 20 fz Sp5H, 19 ln, 13 fz, 8 Sp5H ln, 8 fz Sp5H ln and 2 +, total 233. Despite some probable classification errors, linkage was clearly demonstrated and the expected gene order of fz-Sp-ln indicated. The fz-Sp5H RF was estimated to be 21.03 +/- 2.67%, Sp5H-ln, 13.30 +/- 2.22% and the fz-ln RF was 25.75 +/- 2.86%, the latter according reasonably well with the map distance of 30 cM (Lyon and Kirby, 1994). Intercross Sp5H openings indicated a 7.69% pre-implantation loss (cf 8.06% Sp5H x + control) and a 30% early post implantation loss (cf 9.65% control). None of the foetuses exhibited rachischisis or other features of Sp homozygotes. On this basis and the high incidence of early post-implantation loss, it may be deduced that Sp5H mutation, like Sp4H (Cattanach et a1 Mouse Genome, 91: 115-116, 1993) represents a deletion, despite the absence of cytogenetic evidence (Cattanach, Beechey, Rasberry and Evans). (Supported by Euratom Contract Bi:6-143). |
