Genetic Analysis of Hemostasis and Thrombosis Using Vascular Occlusion

The zebrafish is an excellent model for mammalian hemostasis and thrombosis since it possesses coagulation factors, thrombocyte receptors and responds to anti-coagulant and anti-platelet drugs commonly used in clinical treatment. In this study, exposure of larvae to FeCl(3) or laser irradiation produced a vessel injury that caused a visible vascular occlusion as a result of thrombus formation. Using the time to vascular occlusion as an assay, two screening strategies were tested for their utility in identifying novel genes involved in thrombosis. Morpholino knockdown studies of zebrafish factor VII showed a prolongation of the time to occlusion of the vessel whereas knockdown of the recently discovered factor VIIi resulted in a shortening of the time. Genetic screening of a population of zebrafish identified mutants that showed a prolongation of the time to occlusion. Bulk segregant analysis showed linkage of one mutant to a locus, victoria, on linkage group 7. Thus, the vascular occlusion assay developed in this report measures in vivo thrombus formation and is a powerful tool for identifying novel genes involved in thrombosis.