Fig. 5

Chemical-genetic ablation of neuromasts blocks neuromast regeneration in most but not all larvae. (A) Larvae from the cross of Et(HG7L) (green) and Tg(−8.0cldnb:NTR-hkiKGR) (green dots) were treated with 2 mM metronidazole (Mtz) ob 3 days post-fertilization (dpf) for 12 h, washed out, cultured, examined, and photographed at designated h post-Mtz treatment (hpMtz) as shown in a series of cartoons. (B–D) Representative stacked images show decreasing size (enclosed by dashed lines) of neuromast (asterisks) during Mtz treatment. (E) A cartoon shows the absence of neuromast with undamaged Schwann cells and lateral nerve. (F) The TUNEL staining clearly labeled apoptotic cells in the Mtz-treated larva, and the lateral nerve (arrow) stayed undamaged. (G) Mtz was used to treat larvae from the cross of Tg (foxD3: GFP) and Tg (−8.0cldnb: NTR-hkiKGR). In a representative stacked image, Schwann cells (arrowhead pointed green rod) appeared intact compared to the disintegrating neuromast (asterisk). The faint broad green signal underneath is stacked signals from underlying tissues. (H–J) After washing out Mtz, most of the interneuromast cells (30/34) in the proximity of ablated neuromasts did not form a new neuromast. (K–M) A few (2/34) larvae had regenerated a neuromast (M) through cluster formation (4/34) (L). Scale bars are the same in all panels but are only shown in (B).