Fig. S1

klf2a vascular expression is blood flow-dependent.

klf2a is expressed in zebrafish embryonic vasculature of a WT embryo at 48hpf. Cessation of blood flow in the trunk vasculature by an occlusion of proximal aorta in the gridlock mutants (indicated by a green arrow) results in a complete loss of klf2a vascular expression distally to the occlusion. Blockage of embryonic heart contractions by tnnt2 MO results in significantly decreased klf2a vascular expression. Pharmacological inhibition of heart contractions by tricaine from 32 to 48hpf results in significantly decreased klf2a vascular expression. Interestingly tricaine also reduces klf2a expression in the heart region and in the cells lateral to the most posterior notochord. Red arrows indicate trunk vasculature, black arrows indicate the cells lateral to most posterior notochord, white arrows indicate pectoral fins, black arrowheads indicate the cardiac outflow tract and white arrowheads indicate cloaca. Numbers in top right corners indicate the number of embryos with similar staining pattern out of all embryos examined. klf2a riboprobe used. Scale bar = 500μm.