These mice carry a spontaneous mutation at the Fign locus characterized by head tossing and circular running. Fidget mice also have insufficient growth of the retinal neural epithelium resulting in small eyes, and skeletal abnormalities, including pelvic girdle dysgenesis, skull bone fusions and polydactyly.Read More +
Mice homozygous for the fidget spontaneous mutation (Fignfi) toss their heads from side to side and tend to run in circles. Homozygous fidgit mice are hypersensitive to sound in early life, but later lose hearing ability. Corneal lesions are common, and hind foot polydactylism occurs. The bony labyrinth is quite defective. Other abnormalities including small eyes, absence of lachrymal glands, dislocation of the hip, and displaced parafloccular lobes of the cerebellum. Viability of homozygotes is usually less than normal and fertility is poor. The STOCK is also carrying the stubby spontaneous mutation (stb). Homozygous stubby mice are recognizable at 4 or 5 days by a domed head and thick short tail. Adult stubby mice have shorter heads, bodies, and legs compared to wildtype mice. Most females are fertile but males do not breed. Male mice do produce normal numbers of motile sperm. Cartilage histology is within normal limits, but chondrogenesis stops earlier than in normal animals.
The fidget mutation was discovered by Gruneberg in a heterozygous stock as reported in 1943 and eventually obtained by The Jackson Laboratory. The strain was cryopreserved in 1985 and again in 2003.
|Gene Symbol and Name||a, nonagouti|
|Strain of Origin||old mutant of the mouse fancy|
|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.|
|Gene Symbol and Name||Fign, fidgetin|
|Strain of Origin||random-bred|
|Molecular Note||The fidget mutation is due to a retrotransposon insertion in intron 2, interfering with normal RNA processing.|
When maintaining a live colony, mice can be bred, with progeny testing, heterozygote x heterozygote for stb in repulsion with fi, and heterozygote x heterozygote for fi in repulsion with stb . These genes are linked on chromosome 2 in the following order: stb Fignfi a. Homozygous stb males are sterile. There is decreased viability in mice homozygous for Fignfi. Homozygous Fignfi males may need to be removed from the cage when the female is pregnant.
When using the fidget mouse strain in a publication, please cite the originating article(s) and include JAX stock #000312 in your Materials and Methods section.