These mice carry a spontaneous mutation at the Scn8a locus characterized by progressive skeletal muscle weakness, progressive atrophy of skeletal muscle, and terminal sprouting of motor nerves. The strain also carries Krt71Ca (caracul) that produces curved vibrissae and wavy hair in young mice.
Genetic Background | Generation |
---|---|
|
Allele Type | Gene Symbol | Gene Name |
---|---|---|
Spontaneous | a | nonagouti |
Allele Type | Gene Symbol | Gene Name |
---|---|---|
Spontaneous | Krt71 | keratin 71 |
Allele Type | Gene Symbol | Gene Name |
---|---|---|
Spontaneous | Scn8a | sodium channel, voltage-gated, type VIII, alpha |
Mice homozygous for the motor end plate disease-Jackson spontaneous mutation (Scn8amed-J) have a phenotype that resembles the original mutation (Scn8amed). Homozygous motor end plate disease mutant mice show progressive skeletal muscle weakness beginning 8 to 10 days postnatally and usually die within 2 weeks of onset. Other disease characteristics include progressive atrophy of skeletal muscle, marked terminal sprouting of motor nerves along with slower conduction velocity and prolonged refraction, and eventually failure of muscle fibers to show end-plate potentials or action potentials in response to nerve stimulation. Heterozygotes may show mild manifestations of the disease during the first 2 weeks of life but symptoms disappear with age. Both homozygotes and heterozygotes exhibit immunological aberrations.
Allele Name | nonagouti |
---|---|
Allele Type | Spontaneous |
Allele Synonym(s) | |
Gene Symbol and Name | a, nonagouti |
Gene Synonym(s) | |
Strain of Origin | old mutant of the mouse fancy |
Chromosome | 2 |
General Note | Insertion of the LV30 retrotransposon without the beta4 retrovirus sequence does not cause the nonagouti phenotype. J:278039 |
Molecular Note | Characterization of this allele shows an insertion of DNA comprised of a 5.5kb virus-like element, VL30, into the first intron of the agouti gene. The VL30 element itself contains an additional 5.5 kb sequence, flanked by 526 bp of direct repeats (beta4 retroviral sequence). The host integration site is the same as for at-2Gso and Aw-38J and includes a duplication of four nucleotides of host DNA and a deletion of 2 bp from the end of each repeat. Northern analysis of mRNA from skin of homozygotes shows a smaller agouti message and levels 8 fold lower than found in wild-type. |
Allele Name | caracul |
---|---|
Allele Type | Spontaneous |
Allele Synonym(s) | Ca |
Gene Symbol and Name | Krt71, keratin 71 |
Gene Synonym(s) | |
Strain of Origin | Swiss stock |
Chromosome | 15 |
Molecular Note | Sequence analysis identified the transversion of an C-to-A at coding nucleotide 1292, resulting in an alanine to aspartic acid missense mutation at codon 431 (p.A431D). |
Allele Name | motor end plate disease Jackson |
---|---|
Allele Type | Spontaneous |
Allele Synonym(s) | medJ; seal |
Gene Symbol and Name | Scn8a, sodium channel, voltage-gated, type VIII, alpha |
Gene Synonym(s) | |
Strain of Origin | STOCK Krt71Ca |
Chromosome | 15 |
General Note | This Scn8amed remutation occurred at The Jackson Laboratory on the same chromosome as the very closely linked gene Krt71 in a stock carrying a mutation in that gene (J:6191). Homozygotes resemble Scn8amed homozygotes. Heterozygotes may show mild manifestations of the disease during the first 2 weeks but they recover. Both homozygotes and heterozygotes exhibit immunological aberrations: reduced PFC response to sheep red blood cells in 14- to 16-day old mice, with reduced suppressor cell function and precocious maturation of the cytotoxic response to allogeneic cells at 21 to 23 days. The reduction in the PFC response disappears in older heterozygotes but remains in the few homozygotes that survive beyond 6 weeks of age (J:6824). The molecular defect in Scn8a is a 4 bp deletion in the splice donor site of exon 3 that causes exon skipping and protein truncation (J:34154). A very low level of correctly spliced transcripts has been detected, indicating that Scn8amed-J is a severe hypomorph (J:53340). The modifier locus Scnm1 on chromosome 3 influences the phenotype of homozygotes for the Scn8amed-J allele (J:53340). C57BL/6J mice carry the susceptible allele of Scnm1 which results in juvenile death. Other inbred strains carry a resistant allele and on these strains, homozygotes exhibit muscle weakness and dystonia. |
Molecular Note | A 4-base pair deletion within the 5' donor site of exon 3 results in splicing from exon 1 to exon 4. The mutant transcript has an altered reading frame with premature stop codon close to the N terminus of the protein. A very low level of correctly spliced transcripts has been detected. |
Ca and Scn8a are linked on chromosome 15 and are maintained in coupling in this strain.
When using the motor end plate disease Jackson mouse strain in a publication, please cite the originating article(s) and include JAX stock #000304 in your Materials and Methods section.
Facility Barrier Level Descriptions
Service/Product | Description | Price |
---|---|---|
Heterozygous or Wild-type for Krt71<Ca>, Heterozygous or Wild-type for Scn8a<med-J> |
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The Jackson Laboratory has rigorous genetic quality control and mutant gene genotyping programs to ensure the genetic background of JAX® Mice strains as well as the genotypes of strains with identified molecular mutations. JAX® Mice strains are only made available to researchers after meeting our standards. However, the phenotype of each strain may not be fully characterized and/or captured in the strain data sheets. Therefore, we cannot guarantee a strain's phenotype will meet all expectations. To ensure that JAX® Mice will meet the needs of individual research projects or when requesting a strain that is new to your research, we suggest ordering and performing tests on a small number of mice to determine suitability for your particular project. We do not guarantee breeding performance and therefore suggest that investigators order more than one breeding pair to avoid delays in their research.
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