Tie1 and Thr794 are required for proper embryonic vascular development in zebrafish.

a-e Zebrafish embryos expressing Fli1:EGFP were injected with a control or Tie1 morpholino (MO) with or without mRNA encoding WT or T794A (TA) mutant Tie1 and effects on vascular development were assessed. b Zebrafish injected with a control MO develop normally and resemble uninjected (Control) embryos. c Tie1 MO-injected embryos display vascular abnormalities. d Co-injection of Tie1 MO and WT mouse Tie1 mRNA rescued the MO phenotype. e Injection of T794A mutant mouse Tie1 mRNA alone resulted in vascular abnormalities similar to those of MO-injected embryos. Arrows indicate blunted intersomitic vessel formation. f Quantification of mutant embryos after injection of Tie1 MO with WT or T794A mutant mRNA, P = 3.0x10^-19 by Chi squared analysis. g Quantification of mutant embryos after injection of Tie1-WT or -TA mRNA alone, P = 1.3x10^-18 by Chi squared analysis.