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Fig. S1
A) Ipsilateral neighborhood analysis of vessel identity with 4 neighbors in 6 dpf WT embryos (N=3 experiments, 74 embryos, 888 ISVs).
B) Ipsilateral neighborhood analysis of vessel identity with 1 neighbor in 6 dpf WT embryos (N=3 experiments, 74 embryos, 1332 ISVs).
C) Stills from time-lapse movie (Supplementary Movie S2) in Tg[fli1a:GFP]y1;Tg[gata1a:DsRed]sd2 labeling ECs in green and blood cells in red showing formation of a transient perfused three-way connection (C?-C?) as circulating blood cells can be observed in the DA-ISV-secondary sprout-PCV shunt. In panel C?? it is clear that the ISV-PCV connection is disconnected again and the secondary sprout takes part in lymphatic development, whereas strong dorsal flow is established in the arterial ISV.
D) Tg[tp1-MmHbb:kaede]um15 embryo mosaically expressing a pT2Fli1ep-zN1aICD-basflimCherry construct (NICDOE) at 52 hpf. Endogenous Notch activity was blocked by treatment with 25?M DAPT from 24 till 52 hpf in order to observe Notch activation by NICD overexpression.
E) Quantification of the ratio of arterial and venous ISVs containing cells overexpressing Su(H)VP16, a constitutively active variant of the Su(H) transcription factor (Su(H)VP16OE) (N=3 experiments, 29 embryos) or mosaically overexpressing Notch-1bICD (N1bICDOE), the intracellular domain of Notch1b, the paralogue of Notch1a (N=2 experiments, 43 embryos). (*P=0.0001)
F) Stills from time-lapse movie (Supplementary Movie S3) in Tg[fli1a:GFP]y1 embryos mosaically overexpressing a pTol2-zN1aICD-basfli-mCherry construct showing formation of a transient perfused three-way connection between a wild-type secondary sprout and a NICD overexpressing (NICDOE) primary ISV, indicating that Notch activation does not prevent
interaction between primary ISVs and secondary sprouts.