(A) Schematic of a larval zebrafish. Blue dots indicate neuromasts of the lateral-line organs; green lines indicate innervating afferent lateral-line nerves. pLL neuromasts L3, L4, and L5 were analyzed (dashed circles). (B–C) Maximum intensity dorsal top-down 2D projections of confocal images of control or stimulus-exposed neuromast hair cells (blue (B) or orange (C); Parvalbumin immunolabel). Exposed neuromast hair-cell morphology was categorized as ‘normal’ i.e. radial hair-cell organization indistinguishable from control or ‘disrupted’ i.e. asymmetric organization with the hair-cell apical ends oriented posteriorly. (D) Maximum intensity projections of supporting cells (SCs) expressing GFP (green), immunolabeled synaptic ribbons (magenta; Ribeye b) and all cell nuclei (blue; DAPI). Note that SCs underlying displaced hair cells also appear physically disrupted (indicated by white arrows). Scale bars: 5 µm (F) Average percentage of neuromasts with ‘disrupted’ morphology following mechanical stimulation. Each dot represents the percentage of disrupted neuromasts (NM) in a single experimental trial. Disrupted hair-cell morphology was place dependent, with neuromasts more frequently disrupted following sustained stimulus and when localized toward the posterior end of the tail (*p = 0.0386, **p = 0.0049, ***p = 0.0004) (G) Average percentage of exposed neuromasts (NM) with ‘disrupted’ morphology in lhfpl5b mutants, which lack mechanotransduction specifically in lateral-line hair cells, vs. heterozygous WT. lhfpl5b mutants show a similar gradient of neuromast disruption following mechanical injury as WT siblings. Error Bars = SEM.
