Fig. 1

The zebrafish orthologs of syk and zap-70 mediate angioblast migration to form the ISVs. (A) Zebrafish syk and zap-70 have similar domain structures with N-terminal SH2 domains, and a C-terminal tyrosine kinase domain (PTK). (B) Alignment of the nucleotide sequences of syk and zap-70 with orthologs in other species shows a clear grouping of zebrafish syk with the other syk orthologs, and zap-70 with the other zap-70 orthologs. (C) At 30 hpf, ISVs in Tg(fli1a:EGFP)^y1 embryos have reached the dorsal aspect of the somite and are contributing to the DLAV in wild-type embryos. (D–E) Injection of a low dose of syk morpholino (syk^LO, D) or zap-70 morpholino (zap-70^LO, E) results in delayed (arrows) or completely suppressed (asterisk) angioblast migration to form the ISVs. (F) Co-injection of low doses of both morpholinos results in a more severe stalling and suppression of angioblast migration (syk^LO:zap-70^LO). (G–H) Tg(fli1a:EGFP)^y7 embryos with endothelial-expressed nuclear GFP show fewer cells in the ISVs of syk^LO:zap-70^LO embryos. Anterior is to the left in all embryos. DA: dorsal aorta; PCV: posterior cardinal vein; ISV: intersegmental vessel; DLAV: dorsal longitudinal anastomotic vessel; hpf: hours post fertilization.