This strain is still segregating for rul which causes a ruffled, sparse fur appearance. This genetic background is homozygous for Robertsonian translocations Rb(1.3)1Bnr, Rb(8.12)5Bnr, and Rb(9.14)6Bnr.
The phenotype of the sfx2J remutation is identifiable at 4-5 weeks of age when the mutants appear smaller than their control littermates and begin to hobble about their cage. Between 5 and 8 weeks of age the mutants develop rear limb paralysis and many die by 8 weeks of age. The phenotypic characteristics of this mutation are similar to the original mutation spontaneous fracture (Gulosfx ) except for the eye phenotype described below that is inherent in the background strain on which the sfx2J mutation arose. Mice homozygous for the sfx2J remutation also had cataracts and rosettes and wavy outer nuclear layer of retinas. The eyes of a female mutant were checked using an opthalmascope and it was found to have cataracts on both eyes (as the strain background has characteristically). It has not yet been determined if the rosettes and wavy outer nuclear layer of the retinas is also characteristic of the background strain.
Mus domesticus trapped in Val Poschiavo were found to have seven Robertsonian translocations. One male descended from this stock was bred with a female from the random-bred Swiss NMRI/Han stock. These F1 offspring were sent from Alfred Gropp at Medizinische Hochschule in Lubeck to Thomas Roderick at The Jackson Laboratory where they were intercrossed and lines were separated at the F2 generation for inbreeding. One of the recombinant inbred lines that resulted was RB156BNR/Ei which is homozygous for Rb(1.3)1Bnr, Rb(8.12)5Bnr, and Rb(9.14)6Bnr. When RB156BNR/Ei reached F?+64 in 1989, a mutation causing a sparse, curly haired phenotype was observed, named ruffled (rul), and the mutant strain was maintained segregating for rul. In 2002 when this mutant strain was at F?+64+47 the spontaneous fracture 2 Jackson mutation arose spontaneously in this strain. It has been maintained via progeny testing to identify heterozygous breeders.
|Allele Type||Spontaneous (Hypomorph)|
|Gene Symbol and Name||Dsp, desmoplakin|
|Strain of Origin||RB156Bnr/Ei|
|Molecular Note||A spontaneous duplication of TGTCAGAA at chromosome 13 position 38,197,110-117 (GRCm38) causes a frameshift beginning in the last exon, resulting in the insertion of 4 novel amino acids followed by a premature stop codon that yields a C-terminal truncation of the protein, which is predicted to have partial function with spectrin repeat elements and chromosome segregation ATPase domain intact but partial loss of the plectrin repeats, and western blot analysis shows an altered mutant isoform.|
|Allele Name||spontaneous fracture 2 Jackson|
|Gene Symbol and Name||Gulo, gulonolactone (L-) oxidase|
|Strain of Origin||RB156Bnr/Ei-Dsprul/GrsrJ|
|General Note|| |
The ruffled mutation in the background strain is still segregating in the RB156BNR/Ei-rul/J- Gulosfx-2J strain and when homozygous causes the Gulosfx-2J mice to have a ruffled looking coat.
The phenotype of this remutation is more severe than the original sfx mutation, suggesting a modifying gene may be present in the RB156BNR/Ei-rul/J background strain.
|Molecular Note||This spontaneous mutation arose at The Jackson Laboratory in 2002. A noncomplementation test with Gulosfx demonstrated that this is an additional allele of Gulo.|