B6.Cg-Otop1^tlt/J

Stock number: 001104
Product name: tilted
Research areas: Neurobiology Research, Sensorineural Research

Description

These mice carry a spontaneous mutation at the Otop1 locus characterized by a head tilt and lack of otoconia in both the utricle and saccule.

Detailed description

Mice homozygous for the Otop1^tlt mutation are viable and fertile. They can be identified outwardly by a tilt in the head posture, which is reported to be detectable in 50-75% of homozygotes. Auditory brainstem responses at four months of age are normal. Although these mice are not deaf and do not show degeneration of the cochlea or vestibular organs, most completely lack otoconia in both the utricle and saccule and thus have problems with spatial orientation. A few giant otoconia have been observed infrequently in a small minority of these mutants, but generally there is agenesis of otoconia. The macular epithelium and otolithic membrane are intact despite the lack of otoconia. Homozygotes are unable to orient themselves in water to find the surface and thus are categorized as non-swimming since they would drown without rescue. Approximately 2% of these homozygotes are able to find the water surface despite somersaults, backflips, or other abnormal motions indicative of failed perception of gravity. Penetrance of the Otop1^tlt mutation is reported to be nearly 100% although there is some variation in expressivity. 2D-PAGE of sensory epithelium and otoconial membrane from Otop1^tlt homozygotes fails to detect otoconin 90, the principal otoconial matrix protein. (Lane 1986 and 1987; Ornitz et al., 1998; Hurle et al., 2001 and 2003.)

Development

The recessive tlt mutation arose spontaneously in 1983 on the STOCK p^6H/p^d background in the laboratory of Eva Eicher at The Jackson Laboratory. Otop1^tlt was backcrossed onto the C57BL/6J background via backcross-intercross. In 1986 C57BL/6J females were bred to homozygous males at NE5F1 and the resulting embryos were cryopreserved.

Allele

Symbol: Otop1^tlt
Name: tilted
MGI accession ID: MGI:1856638
Generation method: Spontaneous
Synonyms: tilted head; tlt
Marker symbol: Otop1
Marker name: otopetrin 1
Marker synonyms: A530025J20Rik; tlt
Chromosome: 5
Strain of origin: STOCK Oca2^p-6H/Oca2^p-d
Molecular note: The mutation in the tlt mouse has been identified as a C-to-A transversion at coding nucleotide 452 in the third exon of the gene. This results in a alanine to glutamic acid change at amino acid position 151 (p.A151E).