Triple sox7;sox18;rbpj knockdown results in the loss of a detectable dorsal aorta. (A) Analysis of GFP expression in tg(fli1a:GFP) zebrafish embryos after injection of control (Upper) and triple sox7;sox18;rbpj MO (Lower) during the migration of angioblasts from the lateral plate mesoderm toward the midline and coalescence into a vascular cord. At 26 hpf, the dorsal aorta (red bracket) and posterior cardinal vein (blue bracket) can be detected in the control MO-injected embryo but not in the triple MO (white bracket highlights single axial vessel). See also Fig. S7 A and B. (B) Lateral view (Upper) and optical transversal sections (Lower, location indicated by white bar) of control, rbpj, sox7;sox18, and sox7;sox18;rbpj MO-injected fli1a:EGFP embryos at 2 dpf. See also Movies S1, S2, S3, and S4 for 3D animations of each embryo. (C–E) Whole-mount in situ hybridization of venous (C) and arterial (D and E) markers on control, rbpj, double sox7;sox1,8 and triple sox7;sox18;rbpj MO at 26 hpf. See also Fig. S8 A–D. Black arrowhead, dorsal aorta; white arrowhead, where dorsal aorta should be; black arrow, posterior cardinal vein; white bracket, single axial vessel; black bracket, notochord. Probes used are depicted in the bottom left of each picture. Values on the bottom right indicate number of embryos with the predominant and displayed phenotype per total number of embryos analyzed. In all cases, 0.125 pmol of sox7 and sox18 and 0.15 pmol of rbpj MO were used.