| First Author | Cattanach BM | Year | 1991 |
| Journal | Mouse Genome | Volume | 89 |
| Pages | 271 | Mgi Jnum | J:14304 |
| Mgi Id | MGI:62475 | Citation | Cattanach BM, et al. (1991) Evidence of allelism between rumpshaker and jimpy. Mouse Genome 89:271 |
| abstractText | Full text of Mouse Genome contribution: Evidence of Allelism between Rumpshaker and Jimpy. B M Cattanach and C V Beechey, Genetics Division, MRC Radiobiology Unit, Chilton, Oxon OX11 ORD. The new mutation, rumpshaker (rsh) closely resembles jimpy (jp) in a number of respects but also shows important differences(1). Both mutants are characterised by the development of tremors by about 14 days of age but, while jp males invariably develop seizures and die before 40 days, rsh males are fully viable and their tremors tend to decline with time. Heterozygous rsh females also differ from jp heterozygotes in that they occasionally exhibit transient shaking behaviour. Homozygous rsh females are viable and resemble hemizygous males. Both mutations are X-linked and are associated with hypomyelination of the central nervous system and a decreased proteo-lipid protein (PLP) expression in the myelin sheaths. Despite the differences it has seemed likely that rsh is an allele of jp and represented a mutation of the PLP gene. Limited linkage data with harlequin (Hq) and viable brindled (MoVbr) were consistent with this as rsh was indicated to be located distal to MoVbr (RF=10.13+/-6.2%). Viability problems complicated the Hq-Movbr-rsh linkage tests. Therefore, to investigate the location of rsh further, linkage with the more viable Mo allele, blotchy (Moblo) has been tested and direct allelism tests with jp conducted. Crosses of Moblo+/+rsh females with +rsh/Y males produced the following classes; 90 Moblo+/+rsh females, 82 Moblo+/Y males, 82 +rsh/+rsh females, 96 +rsh/Y males, 5 Moblo rsh/+rsh females, 5 Moblo rsh/Y males, 9 ++/+rsh females and 6 ++/Y males, total 375. All females exhibiting tremors were kept for 2 weeks beyond weaning to ensure rsh heterozygotes showing transient tremors were not confused with the homozygous female class. On this basis the Moblo-rsh RF is 6.67 +/- 1.29%. This does not differ significantly from the earlier estimate with MoVbr (X2=0.0093; P=0.92) . But the upper 95% confidence limit (11.84%) on the best pooled estimate (7.15 +/- 1.30% is less than the current Mo-jp distance shown on the latest Mouse Chromosome Atlas(2) (13cM) and might suggest that rsh and jp are separate loci. Allelism tests of rsh with jp have suggested otherwise, however. Crosses of Ta jp/++ females with +rsh/Y males produced 20 Ta and 4 non-Ta females exhibiting tremors (3 with mild jp-like seizures) and 17 non-Ta and 3 Ta females which showed normal behaviour. The former group were presumed to carry both jp and rsh and the absence of complementation provided the first line of evidence that the two mutations were alleles. This was confirmed when the presumptive Ta jp/+rsh females were backcrossed to +rsh/Y males. Of 224 daughters, all exhibited tremors with approximately 10% having mild seizures. Among 217 sons, 88 were Ta jp/Y, 98 were +rsh/Y, 15 were Ta rsh/Y and 16 were +jp/Y, the rsh and jp classifications being based on the occurrence of seizures and death of jp mice prior to day 40. In total, therefore, there were 441 progeny none of which lacked the shaking behaviour that characterises the rsh and jp mutants and compounds. A further 48 male progeny from rsh/jp females were also classified as either rsh or jp. The absence of wild type progeny (not exhibiting tremors) among 489 young in these crosses therefore strongly suggests that rsh and jp are allelic (upper 95% confidence limit, 1.5%). It is proposed that the rsh gene symbol be amended to jprsh. REFERENCES 1. Griffiths, I.R., Scott, I.. McCulloch, M.C., Barrie, J.A., McPhilemy, K. and Cattanach, B.M. (1990) J. Neurol, 19:273-283. 2. Lyon, M.F. and Kirby, M.G. (1990) 87:128-56. |
