Fig. 1: prdm1a expression is integral to hair cells with mutant phenotypes during development and regeneration.

a 5 dpf representative zebrafish embryo with hair cells expressing Tg(myo6b:H2B-mScarlet) in magenta and support cells expressing Tg(she:H2B-EGFP) in green, respectively. Scale bar= 100 µm. b Modified schematic of the lateral line with hair cells and support cells in magenta and green, respectively²⁰. c Schematic of the zebrafish ear. AC anterior crista, LC lateral crista, PC posterior crista, AM anterior macula, PM posterior macula. d HCR of lateral line neuromasts and cristae of the zebrafish ear with prdm1a probe and Tg(pou4f3:GAP-EGFP) in hair cells. Representative image of one of three larvae. Scale bars= 20 µm. e prdm1a expression in the lateral line during homeostasis, and during regeneration at 30 min and 5 h post-neomycin, with Tg(pou4f3:GAP-EGFP) in hair cells. HC hair cells, SC support cells. Representative images of one of six larvae. f Schematic of Prdm1a protein with major domains and stop codon in prdm1a mutant (black arrow). g Violin plot of prdm1a expression from sibling scRNA-seq, divided by cell type. h Hair cells labeled with Tg(myo6b:H2B-mScarlet) show developmental defects in prdm1a mutant neuromasts at 2 and 7 dpf compared to siblings. Scale bars= 20 µm. i Quantification of hair cells during development in sibling and prdm1a^-/- neuromasts. n = 6–10 fish per timepoint and genotype, 3–4 neuromasts per fish. Dots represent individual neuromasts. n = 27 for 2 dpf sibling, n = 23 for 2 dpf prdm1a^-/-, n = 18 for 3 dpf sibling, n = 22 for 3 dpf prdm1a^-/-, n = 18 for 5 dpf sibling, n = 38 for 5 dpf prdm1a^-/-, n = 8 for 7 dpf sibling, and n = 26 for 7 dpf prdm1a^-/-. Two-way Anova with Tukey’s multiple comparisons test, ***p < 0.001, ****p < 0.0001. The box plots show the interquartile range (IQR), with the median (central line) and hinges (25th and 75th percentiles), and the whiskers extending from the box to the minimum and maximum values. j Hair cells labeled with Tg(myo6b:H2B-mScarlet) show regeneration defects in prdm1a^-/- neuromasts 48 hours after neomycin treatment; 7 dpf. Scale bars= 20 µm. k Quantification of hair cells during regeneration and homeostasis at the same developmental timepoint, in sibling and prdm1a^-/- neuromasts. The percentage of regenerated hair cells compared to homeostasis for each condition is shown above the regeneration counts. n = 6–10 fish per timepoint and genotype, 3–4 neuromasts per fish. n = 8 for 7 dpf sibling, n = 26 for 7 dpf prdm1a^-/-, n = 30 for 48 hr post neomycin sibling, and n = 35 for 48 hr post neomycin prdm1a^-/-. One-way Anova with Tukey’s multiple comparisons test, ****p < 0.0001. The box plots show the interquartile range (IQR), with the median (central line) and hinges (25th and 75th percentiles), and the whiskers extending from the box to the minimum and maximum values. l EdU (green) incorporation and hair cells expressing Tg(myo6b:H2B-mScarlet) (magenta) during development and regeneration in siblings and mutants. Scale bars= 20 µm. Quantification of EdU incorporation in differentiating divisions (m) and amplifying divisions (n) during regeneration in sibling and prdm1a^-/- neuromasts. n = 6–8 fish per treatment and genotype, 3–4 neuromasts per fish. n = 18 for homeostasis sibling, n = 25 for homeostasis prdm1a^-/-, n = 16 for neomycin sibling, n = 25 for neomycin prdm1a^-/-. One-way Anova with Tukey’s multiple comparisons test, ****p < 0.0001. The box plots show the interquartile range (IQR), with the median (central line) and hinges (25th and 75th percentiles), and the whiskers extending from the box to the minimum and maximum values.