Hypoxia does not rescue the EHT defects in notch1a or notch1b mutants. (A) qPCR analysis of notch1a, notch1b, and gata2b mRNA levels in 36 hpf WT embryos in normoxia and after hypoxia exposure for 8 hours starting at 28 hpf. (B) qPCR analysis of notch1a, notch1b, and gata2b mRNA levels in 36 hpf WT, hif-1α^−/− and hif-2α^−/− embryos. Values represent mean plus SD (n = 3 biological replicates). Ct values for each gene in WT samples: rpl13 = 17.05; notch1a = 21.22; notch1b = 22.21; gata2b = 28.33. (C-J) Brightfield images of WISH for runx1/cmyb expression in 36 hpf (C-D, and G-H) WT siblings, (E-F) notch1a^−/− , and (I-J) notch1b^−/− embryos in normoxia and after hypoxia exposure for 8 hours starting at 28 hpf (lateral views). Scale bar, 100 μm. (K) Quantification of runx1/cmyb WISH results (C-F), showing the percentages of embryos with WT, increased expression, and decreased expression in each condition. (L) Quantification of runx1/cmyb WISH results (G-J), showing the percentages of embryos with WT, increased expression, and decreased expression in each condition. *P < .05 (Student t test).