Violet beauregarde, a Zebrafish Alk1 Mutant
Violet beauregarde mutants appear normal at 1.5 dpf, but by 2 dpf most have cranial vascular abnormalities and reduced or absent caudal blood circulation. Trunk, tail, and major head vessels are initially normal, but by 2-2.5 dpf cranial arterial-venous shunts develop, the major arterial-venous vessels of the head become grossly enlarged, and secondary angiogenic cerebral vessels fail to carry circulation. More information on the circulatory defects in this mutant. We positionally cloned the defective gene from this mutant and shown it to be a zebrafish ortholog of Alk1/acvrl1, a gene linked to a human congenital vascular disorder called "Hereditary hemorrhagic telangiectasia," or HHT. More information on HHT and Alk1, and our Vbg cloning publication.
Lateral view icroangiograms of the head of 3 day old wild type (left ) and vbg mutant (right) animals. Secaondary cranial capillaries are not observed in mutants (arrows)