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Fig. 9
Mouse and zebrafish arterial Notch1 expression is dependent on SOX7/18 activity. (A) Transverse sections of whole-mount in situ hybridisation for Notch1 transcript on E8.5 mouse embryos shows a reduction of Notch1 expression (asterisks) in the bulbus cordis (bc) region of the primitive heart and vitelline artery (va) of Sox7/Sox18 double knockouts. (B) At 24 hpf notch1b expression is significantly downregulated in the dorsal aorta (asterisks) of sox7/sox18 double-morphant zebrafish, whereas its signal is unaffected in the neural tube. flt1 expression is comparable between controls and sox7/sox18 double morphants, indicating that the dorsal aorta is correctly formed. (C) notch1b was barely detectable in the dorsal aorta and ISVs of sox7/18 double-knockout zebrafish (asterisks), as compared with the WT, sox7 or sox18 heterozygotes (arrows). The number of embryos showing the illustrated phenotype among the total examined is indicated. DA, dorsal aorta; PCV, posterior cardinal vein.