Fig 3

A) Lateral images of the trunk vasculature with mosaic endothelial expression of the transgene fli1ep: Lifeact-EGFP highlighting actin (green) and endothelial cytoplasm using Tg(kdrl:mCherry; white) in ISAs at 30 hpf. DLAV gaps (blue asterisks) and truncated ISA sprouts (yellow arrowheads) are marked. Inset shows an enlarged view of single ISAs with Lifeact-EGFP expression that have reached the level of DLAV at 30hpf. Scale bar, 100 ?m. B) Representative still images from time-lapse imaging from 28?30 hpf. Enlarged still images of stage-matched embryos with mosaic Lifeact-EGFP (green) in endothelial cells spanning the ISA and reaching the level of the DLAV by 28 hpf in both wild type and sema3fb^ca305 embryo. Endothelial cytoplasm is shown in red Tg(kdrl:mCherry). White arrowheads indicate filopodia present in connecting ISA sprouts within the boxed regions below the DLAV. C) Quantification of number Lifeact-EGFP positive filopodia on ISAs from 28?30 hpf from embryos of the indicated genotypes. N = 3: WT (14 EGFP positive ISAs/ 30 ISAs total, 6 embryos, mean of 4 filopodia/ISA) and homozygous sema3fb^ca305 (18 EGFP positive ISAs/35s ISAs total, 7 embryos, mean of 7 filopodia/ISA). Unpaired t-test with Welch?s correction,*p = 0.03 and ***p = 0.0002. Error bars = ±SD.