The contractile segment of the abneural limbus in the gecko cochlea is enriched in vimentin

Abstract

Previously, we discovered a contractile segment within the cartilaginous abneural limbus of the gecko cochlea, the noncartilaginous abneural limbus (NAL, Ganeshina and Vorobyev, J Comp Neurol 461:539-547, 2003). Here, we demonstrate, by means of SDS-PAGE electrophoresis, the nanoLC-ESI-MSMS technique, immunoblotting, and immunocytochemistry, that the major cytoskeletal protein of the NAL cells is vimentin. Filamentous actin constitutes a minor component of the NAL contractile cell cytoskeleton. Our data indicate that the NAL represents a previously unknown specialization of connective tissue, characterized by the reduction of extracellular matrix and a hypertrophy of the vimentin-based intracellular cytoskeleton. The results are compatible with our hypothesis that the NAL is involved in an adaptation of the cochlear mechanics.