International Mammalian Genome Society

17th International Mouse Genome Conference

9-12 November 2003, Braunschweig, Germany


POSTER 185 - MODIFIERS OF THE BRONX WALTZER MUTATION IN THE MOUSE

Taylor A
MRC Institute of Hearing Research

Co-Authors: Nogueira C, Steel KP
Institutions: MRC Institute of Hearing Research

bronx waltzer (bv) is a recessive mutation in the mouse which has been localised to chromosome 5 between 111.3Mb and 113.4Mb. Homozygous mice exhibit hyperactivity, head tossing and circling behaviour due to vestibular dysfunction, together with degeneration of inner hair cells (IHCs) in the cochlea resulting in deafness.

When we bred an interspecific backcross between bronx waltzer and Mus castaneus we detected better hearing responses and less severe behavioural abnormalities in some homozygous backcross mutant mice. In order to identify the genetic factor(s) that influence the behaviour and the hearing ability of the bv mice, all 241 backcross mice were subjected to a detailed behavioural investigation and a genome scan was performed. QTL analysis was used to localise modifiers of the bv/bv phenotype. A significant modifier on Chromosome 4 near D4Mit72 (LOD 4.14) that affects ambulation behaviour in an open field was identified. A suggestive modifier (LOD 3.26) affecting the variation in total scores for all the measures was mapped near D4Mit305. For the Preyer reflex, a suggestive modifier near D17Mit46 was identified on chromosome 17 with a LOD of 3.1.

Scanning electron microscopy was carried out on the organ of Corti in homozygous mutants at the extremes of the behavioural scale. A strong correlation was observed between the phenotype and the occurrence of IHC degradation and atypical hair cells. Linkage testing for these hair cell traits revealed a suggestive modifier near D15Mit63 for IHC degradation in the base with a LOD of 2.05.


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