Fig 1

A) Lateral view of sema3fb expression at 30hpf by ISH. Inset shows expression in the dorsal aorta (DA) and intersegmental arteries (ISAs). B) Schematic representation of the zebrafish vasculature at 30 hpf. Inset: The ISAs sprout from the DA and connect to form the Dorsal Longitudinal Anastomotic Vessel (DLAV) by 30 hpf. C-E) Lateral confocal images of the trunk vasculature (black) of 30 hpf (C) wild type sibling (sib), (D) heterozygous (het) sema3fb^ca305/+ and (E) homozygous (hom) sema3fb^ca305 mutants. Gaps in the DLAV (blue asterisks) and truncated ISA sprouts (yellow arrowhead) are noted. Abbreviations: DA (Dorsal Aorta), and PCV (Posterior Cardinal Vein). Anterior, left; Dorsal, up. Scale bar, 100 μm. F) ISA Sprout length at 30 hpf in wild type (WT) sibs (mean length of 106±10 μm), het sema3fb^ca305/+ (92±19μm), and hom sema3fb^ca305 (91±18μm), ****p<0.0001. G) Percentage of ISA sprouts connecting to form DLAV at 30 hpf. WT sib (mean 83% connected), het sema3fb^ca305/+ (50% connected) and hom sema3fb^ca305 (42% connected), ****p<0.0001. H) Quantification of the cross-sectional diameter of ISA sprout at the level of the horizontal myoseptum (HM; dashed red line). WT sib (mean diameter of 6.9±2 μm), het sema3fb^ca305/+ (8.5±2.7 μm), and hom sema3fb^ca305 (9.2±2.9 μm)., **p<0.0016 and ***p = 0.0002. F-G) N = 3; WT sib = 11 embryos (n = 86 ISAs), het sema3fb^ca305/+ = 22 embryos (n = 163 ISAs), and hom sema3fb^ca305 = 9 embryos (n = 75 ISAs), 2-Way ANOVA Tukey’s multiple comparisons test. Error bars = ±SD.