Fig. 1

dtt^y135 mutants have defects in angiogenesis, but not in endothelial specification or in vasculogenesis. (A) Diagram of a zebrafish embryo with the red box highlighting the region shown in B and C, and a blue box highlighting the region shown in D-G. (B,C) Confocal images of trunk vessels in 26 hpf Tg(fli-EGFP)^y1 wild-type sibling (B) and dtt^y135 mutant (C) zebrafish, showing normal formation of the vasculogenic dorsal aorta and posterior cardinal vein but failure to form the angiogenic intersegmental vessels (arrows in B, asterisks show absence in C) in dtt^y135 mutants (lateral views, anterior towards the left). (D,E) The hindbrain vessels imaged in F,G. Primordial hindbrain channels (PHBC) are in blue, basilar artery (BA) is in red and the central arteries (CA) are in black. (F,G) Confocal images of hindbrain vessels in 48 hpf Tg(fli-EGFP)^y1 wild-type sibling (F) and dtt^y135 mutant (G) zebrafish, showing normal formation of vasculogenic primary vessels, including the PHBC and BA, but failure to form the angiogenic CA that penetrate the hindbrain (dorsal views, anterior towards the left). (H,I) In situ hybridization of endothelium in the trunk of 26 hpf wild-type sibling (H) and dtt^y135 mutant (I) zebrafish with a probe for vecdn, showing normal expression levels in dtt^y135 mutants (lateral views, anterior towards the left). ISV are seen in wild-type siblings (arrows in H) but not in dtt^y135 mutants (asterisks in I). (J,K) Transmitted light images of 26 hpf Tg(fli-EGFP)^y1 wild-type sibling (J) and dtt^y135 mutant (K) zebrafish, showing reduced width of yolk extension but otherwise normal morphology of dtt^y135 mutants (J) compared with their wild-type siblings (K). Images are lateral views, anterior towards the left. Endothelial proliferation is reduced in dtt^y135 mutants. (L) Total number of endothelial cells present in the three posteriormost trunk segments, measured in Tg(fli-nEGFP)^y7 transgenic dtt^y135 mutant or wild-type sibling animals, at 26 hpf and 40 hpf. (M) Total number of phosphohistone H3-positive endothelial cells present in the three posteriormost trunk segments, measured in phosphohistone and GFP antibody-probed Tg(fli-nEGFP)^y7 transgenic dtt^y135 mutant or wild-type sibling animals, at 26 hpf and 40 hpf. Data are mean±s.e.m. (N,O) Higher-magnification confocal images of ISV sprouts in wild-type sibling (N) and dtt^y135 mutant (O) embryos at 20 hpf, showing reduced filopodial protrusions in mutants. (P) Total number of filopodia formed by control and mutant sprouts. Scale bars: 50 μm in B,C,F,G; 100 μm in H-K; 20 μm in N,O.