The vegfaa^bns1 mutants exhibit severe vascular defects. (A) A TALEN was designed to target exon 3 of vegfaa; sequence alignment of the TALEN generated allele. vegfaa^bns1 has a 10 nucleotide deletion leading to a premature stop codon. (B) Cartoon representation of wild-type (WT) Vegfaa isoforms ∼121 and -165 and Vegfaa^bns1. Vegfaa-121 consists of a signal peptide and a knot motif, whereas Vegfaa-165 has an additional heparin and Nrp1 binding domain. vegfaa^bns1 encodes a truncated polypeptide (p.Glu61Metfs*54). (C) Genotyping example of single embryos sampled from a population of vegfaa wt (red), bns1/+ (blue), and bns1/bns1 (green) using high resolution melt analysis (HRMA). (D-E) Brightfield micrographs of 48 hours postfertilization (hpf) WT sibling and vegfaa^bns1 mutant embryos in lateral and dorsal views. Arrows point to pericardial edema and blood pooling in the tail. (F-G) Confocal micrographs of 48 hpf TgBAC(etv2:EGFP) WT sibling and vegfaa^bns1 mutant embryos in lateral (F) and dorsal (G) views. Asterisks denote lack of intersegmental vessels (ISVs), axial vessel (F), and reduced central artery (CtA) sprouting (F-G). Bars represent 100 µm.