Sox2 is required for maintenance and regeneration, but not initial development, of hair cells in the zebrafish inner ear.

Sox2 has been variously implicated in maintenance of pluripotent stem cells or, alternatively, early stages of cell differentiation, depending on context. In the developing inner ear, Sox2 initially marks all cells in the nascent sensory epithelium and, in mouse, is required for sensory epithelium formation. Sox2 is eventually downregulated in hair cells but is maintained in support cells, the functional significance of which is unknown.

Otoc1: a novel otoconin-90 ortholog required for otolith mineralization in zebrafish.

Within the vestibular system of virtually all vertebrate species, gravity and linear acceleration are detected via coupling of calcified masses to the cilia of mechanosensory hair cells. The mammalian ear contains thousands of minute biomineralized particles called otoconia, whereas the inner ear of teleost fish contains three large ear stones called otoliths that serve a similar function. Otoconia and otoliths are composed of calcium carbonate crystals condensed on a core protein lattice.

Zebrafish atoh1 genes: classic proneural activity in the inner ear and regulation by Fgf and Notch.

Hair cells of the inner ear develop from an equivalence group marked by expression of the proneural gene Atoh1. In mouse, Atoh1 is necessary for hair cell differentiation, but its role in specifying the equivalence group (proneural function) has been questioned and little is known about its upstream activators. We have addressed these issues in zebrafish.