Fig. 4

Prdm16 and Mecom mark dorsally positioned motor neurons (A) Feature plot of prdm16 and mecom expression in 2 dpf MN tSNE showing localization in fast MN clusters as in Figure 2F. (B) prdm16 and mecom in situ hybridization at 30 hpf in zebrafish. Zoomed image indicated by dashed box. Gold arrows indicate MNs. Additional staining in the dorsal spinal cord is labeling of some interneurons (prdm16) and a progenitor domain (mecom). (C) Antibody stain of Prdm16/Mecom within Mnx+ MNs in the zebrafish spinal cord at 2 dpf. Dorsal Prdm16/Mecom+; Mnx− cells are a subpopulation of interneurons. (D) Antibody stain showing overlap in expression between Prdm16/Mecom double antibody and Mecom alone antibody at 2 dpf. (E) Antibody stain showing overlap in expression between GFP+ cells in Tg(prdm16::GFP) line and Prdm16/Mecom double antibody at 2 dpf. (F) Quantification of Prdm16 and/or Mecom-expressing MNs from stains in (C)–(E). Line with bars indicates average with SEM. (G) Image of the spinal cord of a Tg(prdm16::GFP);Tg(olig2:dsRed2) larva at 5 dpf. Gold arrow indicates dorsoventral localization of GFP+ MNs within dsRed2+ population. Left image (L) is lateral view, and right image (T) is transverse view. (H) Soma position plot for GFP+ MNs and all other MNs quantified from five larvae at 5 dpf as in (G). Left plot shows the transverse view. Right plot shows the lateral view. Histograms on the top and sides of the plots indicate the distribution of cells across the axes. Green indicates GFP+;dsRed2+ cells. Magenta indicates GFP−;dsRed+ cells. Although magenta (other MNs) count could include olig2 progenitors or oligodendrocytes, these were largely excluded on the basis of morphology and localization. Scale bars, 10 μm.