Summary: | Hair cells are specialized mechanosensory receptors in vertebrates that detect and process auditory and vestibular information with remarkable precision, fidelity and efficiency (Schwander et al., 2010). Most of our knowledge about these cells stems from in vitro preparations using isolated tissue, which creates the need for a relatively simple in vivo vertebrate model to study hair cells. The zebrafish (Danio rerio) is being increasingly used to study the genetic basis of hearing and deafness but also the function and physiology of hair cells (Nicolson, 2005). However, the use of the zebrafish as an in vivo model to study hair cell function is currently limited by our poor understanding of their biophysical properties. The aim of this study was to provide a detailed description of the biophysical properties of zebrafish hair cells both in the lateral line as well as inner ear during early and mature stages of fish development. I have used single cell patch-clamp electrophysiology to measure potassium currents and synaptic transmission in hair cells. I found that hair cells from the lateral line and inner ear show different current types, the expression of which depends upon the position of the cell within the lateral line neuromast or inner ear macula. Moreover, I found that the abundance of hair cell types in the lateral line changes over time, which potentially reflects adaptations to a changing sensory environment for the fish. The synaptic machinery of the lateral line hair cells is comparable in terms of efficiency to its mammalian counterpart, but less sensitive. Lastly, I have also developed an approach to study hair cell properties in vivo in the juvenile fish.
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