International Mammalian Genome Society

The 15th International Mouse Genome Conference (2001)

POSTER 87 - The mutations Diminuendo and Catweasel result in changes in hair cells in the sensory patches of the mouse inner ear

Elizabeth Quint
MRC Institute of Hearing Research
University Park
Nottingham NG7 2RD

Co-Authors: 1)Quint E, 2)Fuchs H, 3)Balling R, 2) de Angelis H, 1) Steel KP
Institutions: 1)MRC Institute of Hearing Research, 2)Institute of Experimental Genetics, GSF National Research Center for Environment and Health, 3)Institute for Mammalian Genetics, GSF National Research Centre for Environment and Health

Although many human deafness loci are known, few of these currently have a homologous animal model.  Recent mouse mutagenesis initiatives have however provided new mutations that promise to be useful models of human deafness and vestibular dysfunction.  We have begun detailed phenotypic and genotypic analyses on two of these new mutant lines, Diminuendo and Catweasel with initial phenotypic assessment focussed on the integrity and patterning of the inner ear sensory patches using scanning electron microscopy.

Mutant mice were obtained from N-ethyl-N-nitrosourea (ENU) mutagenesis, and F1 offspring of mutagenised males were screened for new dominant mutations that affect hearing and/or balance.  The mutant diminuendo exhibits a progressive hearing loss whereby the Preyer reflex (an ear flick in response to sound), which is present from about 2 weeks of age, is lost postnatally.  This corresponds to abnormal organisation of the hair-cell bundles in the early postnatal diminuendo organ of Corti (observed at P3) and a progressive basal to apical loss of inner and outer hair `cells (over the following 4-6 weeks).  The mutant catweasel exhibits behavioural abnormalities, including headtossing, which is suggestive of a vestibular deficit.  In mutant mice there appears to be a regional reduction in hair cell number in the utricle and the stereocilia of existing hair cells appear to be less numerous and thicker than in the littermate controls. 

Backcrosses have been set up to map diminuendo and catweasel onto the mouse genome and, combined with further analysis of the hair cell changes described above, should help establish appropriate candidate genes for these mutations.

This work is supported by the MRC, Defeating Deafness and the EC (contact number QLG2-CT-1999-00988)

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