Fih-1 negatively modulates angiogenesis during development.

(A) Validation of the morpholino (MO) targeting fih-1. Injection of fih-1 MO interferes with mRNA splicing, leading to the retention of an intron and premature translation termination. (B) Gross morphology of fih-1 MO-injected embryos in comparison with control MO-injected embryos. No obvious gross morphological defects were observed at 55 hpf. (C) At 50 hpf, injection of fih-1 MO did not cause any obvious increase in angiogenic sprouts, however, exuberant angiogenic sprouts emerge from the intersegmental vessels (ISVs) in fih-1 MO-injected embryos at 80 and 122 hpf. (D) Concomitant injection of fih-1 mRNA can rescue exuberant angiogenesis caused by fih-1 MO-injected embryos. On the right column, control (top, n = 12), fih-1 MO (middle, n = 20), or fih-1 MO and fih-1 mRNA (bottom, n = 20) injected embryos. Arrows point to ectopic angiogenic sprouts. Quantification of ectopic angiogenic sprouts per embryo is shown on the right. Asterisk notes statistical significance in the number of ISVs between fih-1 MO and fih-1 MO and fih-1 mRNA injected embryos. Error bars are standard deviation.