Fig. 5

A SOX18-bound region within the notch1b locus represents a bona fide arterial-specific enhancer. (A) Part of the zebrafish notch1b locus from the UCSC ENCODE Genome Browser. The notch1b gene is in 3′ to 5′ orientation, H3K27ac peaks at 24 hpf are in purple, H3K4me1 peaks at 24 hpf are blue, SOX18Ragged ChIP-seq peaks are red, and the region encompassing the notch1b-15 enhancer is indicated by the purple horizontal bar. (B) The ZED notch1b-15:GFP transgene. Ins, insulator sequences; GATA2 prom, the silent GATA2 promoter; ZED control:RFP, the active cardiac actin enhancer/promoter construct fused to the RFP gene used as a positive control in the ZED vector. (C) The notch1b-15:GFP transgene directs arterial endothelial cell-specific expression in the zebrafish line tg(notch1b-15:GFP). Representative transgenic whole-mount embryos and transverse sections show reporter gene expression, as detected by in situ hybridisation (top row, blue) or GFP fluorescence (bottom rows, green) in arterial endothelial cells throughout embryonic development. nt, neural tube; nc, notochord; DA, dorsal aorta; PCV, posterior cardinal vein; aISV (arrows), arterial intersomitic vessel; DLAV, dorsal longitudinal anastomotic vessel.