Abstract
The semi-dominantly inherited mouse mutation pardon (Pdo) was isolated due to the lack of a Preyer reflex (ear flick) in response to sound from a large-scale N -ethyl- N -nitrosourea (ENU) mutagenesis programme. Dissection of the middle ear revealed malformations in all three ossicles, rendering the ossicular chain incomplete. Hair cell counts in the apical turn of the organ of Corti revealed a significant 22.7% increase in the number of outer hair cells. Raised compound action potential thresholds in Pdo/+ mutants suggested a combined sensorineural/conductive hearing loss. We show that a missense mutation in the homeobox gene Emx2 is responsible for these defects, identifying a new function for this gene in the development of specific structures in the ear.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Action Potentials / genetics
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Animals
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Auditory Threshold / physiology
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Cochlea / abnormalities
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Cochlea / pathology*
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Cochlea / physiopathology
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Ear Ossicles / abnormalities
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Ear Ossicles / pathology
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Ear Ossicles / physiopathology
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Ear, Middle / abnormalities
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Ear, Middle / pathology*
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Ear, Middle / physiopathology
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Female
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Gene Expression Regulation, Developmental / genetics
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Hair Cells, Auditory, Outer / abnormalities
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Hair Cells, Auditory, Outer / pathology
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Hair Cells, Auditory, Outer / physiopathology
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Hearing Loss, Conductive / genetics
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Hearing Loss, Conductive / pathology*
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Hearing Loss, Conductive / physiopathology
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Hearing Loss, Sensorineural / genetics
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Hearing Loss, Sensorineural / pathology*
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Hearing Loss, Sensorineural / physiopathology
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Homeodomain Proteins / genetics*
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Homeodomain Proteins / metabolism
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Male
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Mice
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Mice, Inbred BALB C
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Mice, Inbred C3H
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Mice, Mutant Strains
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Microscopy, Electron, Scanning
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Molecular Sequence Data
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Mutation, Missense / genetics
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Sequence Homology, Amino Acid
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Transcription Factors
Substances
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Homeodomain Proteins
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Transcription Factors
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empty spiracles homeobox proteins