Fig. 7

Inhibition of BMP signaling in sulf1 morphants partially rescues somite shape and also restores the lateral stripe of pigmentation, but only if done during somitogenesis. (A–C) Phalloidin labeled whole-mounts of 48 hpf control fish (A), sulf1 morphants treated with DMSO as a vehicle control (B), or sulf1 morphant zebrafish treated with 2 μM LDN193189 beginning at 12 hpf (C). While the sulf1 morphants have somites that are more narrow, rounded and obtuse compared to controls, with smaller and less organized actin fibers, inhibition of BMP signaling with LDN193189 partially rescues the phenotype. The LDN-treated somites appear to be less rounded, and have a reduction in the angle compared to untreated or DMSO-treated morphants. (D and E) Quantification of somite angle (D) and width (E) in control (blue), sulf1 morphants treated with DMSO (red) and sulf1 morphants treated with 2 μM LDN193189 (green) beginning at 12 hpf. While sulf1 morphants have significantly more obtuse and more narrow somites than controls (p<0.001; ANOVA), treatment with LDN leads to a significant decrease in the somite angle (p<0.001; ANOVA) and slight, but significant increase in the width of each somite (p<0.05; ANOVA). (F–H) Brightfield views of 72 hpf control (F) or sulf1 morphant zebrafish treated with DMSO (G) or 2 μM LDN193189 (H) at 12 hpf, showing location and number of melanocytes along the lateral stripe. (I) Quantification of the number of melanocytes along the lateral stripe of control (blue), sulf1 morphants treated with DMSO at 12 hpf (red), sulf1 morphants treated with 2 μM LDN193189 at 12 hpf (solid green), and sulf1 morphants treated with 2 μM LDN at 24 hpf (green checked). sulf1 morphants have a significant decrease in the number of melanocytes along the lateral stripe (p<0.001 compared to control; ANOVA), which can be fully rescued by BMP inhibition with LDN treatment beginning at 12 hpf (p<0.001 compared to DMSO-treated; p>0.05 compared to control; ANOVA). Treatment with LDN at 24 hpf does not rescue the number of melanocytes (p>0.05 compared to DMSO-treated; ANOVA). Scale bars: A–C: 100 μm; F–H: 200 μm.