B6.Cg-Fign^fi/Frk

Stock number: 004275
Product name: fidget
Research areas: Developmental Biology Research, Neurobiology Research, Sensorineural Research

Description

These mice carry a spontaneous mutation at the Fign locus characterized by side-to-side head-shaking and circling behavior, due to reduced or absent semicircular canals.

Detailed description

Mice homozygous for the fidget spontaneous mutation (Fign^fi) 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.

Development

Fidget (fi) was initially described in 1943 by Hans Gruneberg. It arose in an albino strain that Gruneberg described as having been "a pure line at one time"but having been "bred in an uncontrolled manner for some years and probably quite heterogeneous". In 1941 he outcrossed an albino male homozygous for fidget and Tyr^c Myo5a^d and a^t to a CBA female from Strong's stock. In 1943 an F2 male was then backcrossed to an albino stock female and the progeny sibling mated for 10 generations at which time, according to Truslove, an outcross was done to "a derivative of the GFF stock which was not highly inbred". Five generations later (1952) it was outcrossed to C57BL. In 1992 Verity Letts at The Jackson Laboratory obtained from Don Varnum in the laboratory of Joseph Nadeau a female mouse called C57BL/6J- Sp/+ fi/fi. Dr. Letts bred out the splotch mutation yielding this strain.

Allele

Symbol: Fign^fi
Name: fidget
MGI accession ID: MGI:1856870
Generation method: Spontaneous
Synonyms: fi
Marker symbol: Fign
Marker name: fidgetin
Marker synonyms: Fgn
Chromosome: 2
Strain of origin: random-bred
Molecular note: The fidget mutation is due to a retrotransposon insertion in intron 2, interfering with normal RNA processing.