Evidence for hair cell regeneration in the crista ampullaris of the lizard Podarcis sicula.

We studied hair cell regeneration in the crista ampullaris of the lizard Podarcis sicula both in untreated animals and at early and late time intervals following a single high dose of gentamicin. The study was carried out using the S-phase marker 5-bromo-2'-deoxyuridine. Our ultrastructural and immunofluorescence studies showed that both apoptosis and hair cell regeneration happen in the lizard crista ampullaris in untreated animals, and that regenerative processes are greatly accelerated after treatment with the aminoglycoside antibiotic gentamicin. Our observations indicate that hair cell regeneration is strongly implicated in the repair of damaged sensory epithelium, and that new hair cells appear likely to arise from supporting cells.

Calbindin D28K is a component of the organic matrix of lizard Podarcis sicula otoconia.

The factors controlling otoconia growth are not well known but it seems that the type of proteins contained in the otoconia regulates the initiation and/or the subsequent rates of crystal growth determining the morphology and the size of the final crystal. In order to clarify the mechanism of otoconia formation and their turnover, major proteins contained in the otoconia from the maculae of the saccule, utricle and lagena of inner ear of lizard Podarcis sicula were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Coomassie staining of SDS-PAGE resulted in a major broad band of 15 kDa and four other bands of 21, 28, 45 and 97 kDa. The proteins of 15, 21, 28 and 45 kDa were separated by high-pressure liquid chromatography on a C-4-reverse-phase column and the incubation of blots with monoclonal anti-Calbindin D28K antibodies indicated that the band of 28 kDa was Calbindin D28K, a calcium-binding protein.