Cell turnover in neuromasts of zebrafish larvae

The numbers and positions of cells undergoing cell death and proliferation in the neuromasts of 10 day old zebrafish larvae were assessed to investiga te the ability of supporting cells to differentiate into hair cells. Evalua tions of cell death and proliferation showed that a subpopulation of cells located in the centre of the neuromast undergo cell death, and a different subpopulation located at the periphery proliferate. This suggests that cell death of hair cells and proliferation of mantle supporting cells occurs as part of normal development, creating constant turnover of hair cells. We s how that the caspase inhibitor zVADfmk reduces cell death while the aminogl ycoside neomycin specifically induces an increased amount of cell death in the central population of cells. Both of these treatments affect the rate o f proliferation of the peripheral subpopulation of cells in the neuromast s uggesting that a feedback mechanism occurs regulating cell death and prolif eration. We propose that the dying population of cells are hair cells and t he proliferating cells are 'mantle' supporting cells, which is in agreement with previous observations suggesting that supporting cells can give rise to hair cells following hair cell death. (C) 2000 Elsevier Science B.V. All rights reserved.