Figure 3. Loss of Pald impedes neural crest migration.

Embryos were unilaterally electroporated at HH stage 4–5 with cPaldMO, mmspcPald MO, spcPald MO, or standard control MO (coMO) and reincubated to 8-11 somites (s). (A) Neural crest migration defects visualized by HNK-1 immunofluorescence following Pald knock down. cPald MO-targeted neural crest cells (red; arrowheads) do not migrate as far as HNK-1 positive neural crest cells (green) on the untargeted side. (B, C) A representative example of neural crest migration defects visualized by Sox10 in situ hybridization following Pald knockdown. While mmspcPald MO does not affect neural crest migration (A), spcPald MO-targeted neural crest cells’ migration distance is reduced compared to the untargeted side (B). (D, E) A representative example of neural crest migration defects visualized by Snail2 in situ hybridization following Pald knockdown. While coMO does not affect neural crest migration (D), cPald MO-targeted neural crest cells’ migration distance is reduced compared to the untargeted side (E), transverse section at the level of the line indicated in E’. (B–E) Dorsal views of in situ hybridization in left panel, fluorescent MO targeting in right panel. Asterisk, targeted side of the embryo. (F) Stacked bar graphs depicting the severity and frequency of migration impairment in embryos electroporated with cPald MO, spcPald MO, mmcPald MO, mmspcPald MO, or coMO and visualized by Sox10 (left) or Snail2 (right) in situ hybridization. Migration of neural crest cells is mildly disrupted by electroporation of mmspcPald MO, indicating that 1.0mM spcPald MO is the upper limit of its effective and specific dose.