Table 1.
Putative vertebrate orthologs of C. elegans cell migration genes in neural crest development.
Figure 1.
Vertebrate orthologs of genes essential for cell migration in C. elegans are expressed in premigratory neural crest cells in chicken embryos.
Whole mount in situ hybridization was performed using RNA probes corresponding to orthologs of each nematode gene (upper panel). Of the twenty-five genes examined in this study, fourteen chicken orthologs were expressed in the premigratory neural crest domain in the neural folds, as clearly shown in sections (lower panel); Crk (ced-2), Dock180 (ced-5), p21-Rac1 (ced-10), Chx10 (ceh-10), NR1I3 (daf-12), Fgfr1 (egl-15), Fgf18 (egl-17), Fbln2 (fbl-1), Frizzled10 (lin-17), HoxA4 (lin-39), HoxB6 (mab-5), Grb2 (sem-5), DCC (unc-40) and Kinesin (vab-8). arrow, plane of section; arrowhead, gene expression in neural fold.
Figure 2.
Putative chicken orthologs of nematode cell migration genes are conserved in migrating cranial neural crest cells.
Chicken embryos were subjected to whole mount in situ hybridization using RNA probes corresponding to the vertebrate orthologs of each nematode gene. (A) Whole mount chicken embryos (upper panel) and tissue sections at the midbrain level of each embryo (lower panel) show that ten vertebrate orthologs are expressed in neural crest cells migrating from the neural tube in chicken embryos at HH stage 9–10; Crk (ced-2), Dock180 (ced-5), p21-Rac1 (ced-10), NR1I3 (daf-12), Fgfr1 (egl-15), Fgf18 (egl-17), Fbln2 (fbl-1), HoxB6 (mab-5), Grb2 (sem-5) and Ulk2 (unc-51). Arrowhead indicates migrating neural crest cells. (B) Five vertebrate orthologs are expressed in migrating neural crest cells at the hindbrain level in HH stage 11–13 embryos; Dock180 (ced-5), p21-Rac1 (ced-10), NR1I3 (daf-12), Fgfr1 (egl-15) and Kinesin (vab-8). Arrows indicate gene expression in migrating cranial neural crest cells in rhombomere 4 and/or rhombomere 6.
Figure 3.
(A) Predicted FGFR signaling pathway map showing genes obtained from our comparative analyses in red. Whole mount in situ hybridization using RNA probes corresponding to the genes in black was performed. (B) Table summarizing gene expression in neural crest cells. pNCC, premigratory neural crest cells: mNCC, migratory neural crest cells: -, not detected: +, detected: ++, expressed at high level. (C) Transverse sections of chick embryos showing gene expression in premigratory and/or emigrating neural crest cells at stage HH 8–9 (a–f) and in migrating neural crest cells at the midbrain level at HH stage 9–10 (a′–f′); (a, a′) frs2, (b, b′) gab1, (c, c′) pik3r2, (d, d′) shc1, (e, e′) sos1, (f, f′) sos2. Arrows indicate emigrating neural crest cells (a–d, f) or premigratory neural crest cells (e). Arrowheads indicate head mesenchymal cells (a,a′).