Journal of Neuroscience, Vol 11, 1524-1530, Copyright © 1991 by Society for Neuroscience
Wocko, a neurological mutant generated in a transgenic mouse pedigree
EB Crenshaw 3d, A Ryan, SR Dillon, K Kalla and MG Rosenfeld
Department of Biology, University of California at San Diego, La Jolla 92093-0648.
Naturally occurring mutations involving the nervous system have provided
virtually all of our current understanding of the genetic regulation of
neural development (Caviness and Rakic, 1978). The difficulty of isolating
the corresponding genes, however, has precluded a molecular analysis of
these mutants. Insertional mutagenesis, induced by microinjection of DNA
into fertilized ova to produce transgenic animals, provides a molecular tag
that marks the site of the mutational event. In this article, we describe a
transgenic neurological mutation, designated wocko (Wo), which disrupts the
development of the inner ear. These mutant mice display a dominant
behavioral phenotype that consists of circling, hyperactivity, and head
tossing, reminiscent of the shaker/waltzer class of mutants, and they
display a recessive homozygous sublethal phenotype. Anatomical analyses
showed that both structural and neural components of the vestibular system
were disrupted, while analyses of mutant fetuses showed that these
morphological abnormalities were due to aberrant development. Although low
levels of transgene expression were detected using a sensitive PCR assay,
several nonmutant pedigrees that contain the same construct also expressed
the transgene in the inner ear, suggesting that low levels of transgene
expression alone were not responsible for the wocko phenotype. Because the
integrated transgene provides a marker to clone the wocko mutation, the
analysis of this mutant will give unique insight into the molecular
genetics of inner ear development and into a broad class of neurological
mutations that affect the inner ear.