(A) Schematic of neural crest cell (NCC) and RB specification. Both NCCs and RBs are specified in the neural plate border (NPB) of gastrulating embryos. NCC and RB specification share a similar gene regulatory network (GRN) that includes notch/delta and prdm1a expression in the NPB. RBs may transiently express sox10 at low levels (gray). (B–H) Whole-mount confocal images of hybridization chain reaction (HCR) shows expression of xanthoblast (aox5, slc2a15b, gjp8) and RB marker genes (fgf13a, cxcr4b) in wild type (B, D, F, H) and Prdm1a-/- (C, E, G, I) embryos at 24 hr post fertilization (hpf). Hnk-1 staining marks RB cells in all images (note loss of HNK-1 in Prdm1a-/- embryos). Expression of all marker genes is lost from the dorsal neural tube (NT) in Prdm1a-/- embryos that show NCC and RB specification defects. Arrows point to expression of marker genes in dorsal neural tube NCCs (B, D) and RBs (F, H). Expression of genes in regions of the embryo other than the NC and RB is still present. For example, expression of cxcr4b in the ventral neural tube is not altered in the Prdm1a mutant (arrowheads). All images are 3D projections of lateral views of the neural tube taken over the yolk extension of 24 hpf embryos.
