Fig. S6

Loss of endogenous notch1b-15 enhancer mildly phenocopies Notch1b loss-of-function. (A) A representative confocal projection of F₂ homozygous zebrafish notch1b- 15^uq1mf/uq1mf, derived from the F₁ heterozygous notch1b-15uq^1mf/+ in-crosses. No obvious phenotype was observed in the vasculature of F₂ homozygous clutches. Quantification of YFP positive intersomittic vessels connecting between the dorsal longitudinal anastomotic vessel (DLAV) and dorsal aorta (DA) in individual F₂ larvae labeled by tg(fltYFP;lyveDsred) at 3dpf (red arrowheads). Mean ± SEM; Scored sibling WT (+/+), n=19; Het (uq^1mf/+), n=54; Hom (uq^1mf/1mf), n=26; Mann-Whitney. (ns) No significant difference. (B) Representative confocal projections of F₃ homozygous zebrafish notch1b-15^uq1mf/uq1mf, derived from the F₂ homozygous notch1b-15^uq1mf/uq1mf in-crosses. While most F₃ homozygous clutches lack phenotype (top left panel), a sub-population (20-30%) of the larvae showed either ectopic sprouting (asterisks) and/or loss of arterial connections (red arrowheads) between DLAV and DA, as indicated by the loss of YFP expression in tg(fltYFP;lyve1Dsred) background (bottom left panel). Quantification of YFP positive (top right panel) and hyper-sprouting (bottom right panel) intersomitic vessels in individual F₃ larvae labeled by tg(fltYFP;lyveDsred) at 3dpf. Mean ± SEM; Scored WT (+/+), n=55; Hom (uq^1mf/1mf), n=59; Mann-Whitney. (*) p<0.05, (***) p<0.001.