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A Transgenic Insertional Inner Ear Mutation on Mouse Chromosome 1

Authors

  • Rick A. Friedman MD, PhD,

    Corresponding author
    1. House Ear Clinic, Inc., Los Angeles
    • Rick A. Friedman, MD, PhD, House Ear Clinic, Inc., 2100 West Third Street, First Floor, Los Angeles, CA 90057, U.S.A.
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  • Yardit Adir MS,

    1. Department of Surgery, University of California, San Diego, San Diego, California
    2. Department of Otolaryngology, University of California, San Diego, San Diego, California
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  • E. Bryan Crenshaw PhD,

    1. Department of Biology, University of California, San Diego, San Diego, California
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  • Allen F. Ryan PhD,

    1. Department of Surgery, University of California, San Diego, San Diego, California
    2. Department of Otolaryngology, University of California, San Diego, San Diego, California
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  • Michael G. Rosenfeld MD

    1. Department of Biology, University of California, San Diego, San Diego, California
    2. Howard Hughes Medical Institute, University of California, San Diego, San Diego, California
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  • Presented as a Candidate's Thesis to the American Laryngological, Rhinological and Otological Society, Inc. Recipient of the Fowler Award.

    Supported by the American Academy of Otolaryngology—Head and Neck Surgery Foundation, the Deafness Research Foundation, the NIH/NIDCD grants DC00019, DC00139, and DC00028, HHMI and the Veterans Administration Research Service.

Abstract

Objectives/Hypothesis To clone and characterize the integration site of an insertional inner ear mutation, produced in one of fourteen transgenic mouse lines. The insertion of the transgene led to a mutation in a gene(s) necessary for normal development of the vestibular labyrinth.

Study Design Molecular genetic analysis of a transgene integration site.

Methods Molecular cloning, Southern and northern blotting, DNA sequencing and genetic database searching were the methods employed.

Results The integration of the transgene resulted in a dominantly inherited waltzing phenotype and in degeneration of the pars superior. During development, inner ear fluid homeostasis was disrupted. The integration consisted of the insertion of a single copy of the transgene. Flanking DNA was cloned, and mapping indicated that the genomic DNA on either side of the transgene was not contiguous in the wild-type mouse. Localization of unique markers from the two flanks indicated that both were in the proximal region of mouse chromosome 1. However, in the wild-type mouse the markers were separated by 6.3 cM, indicating a sizable rearrangement. Analysis of the mutant DNA indicated that the entire region between the markers was neither deleted nor simply inverted.

Conclusions These results are consistent with a complex rearrangement, including at least four breakpoints and spanning at least 6.3 cM, resulting from the integration of the transgene. This genomic rearrangement disrupted the function of one or more genes critical to the maintenance of fluid homeostasis during development and the normal morphogenesis of the pars superior.

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