Zebrafish sparse corresponds to an orthologue of c-kit and is required forthe morphogenesis of a subpopulation of melanocytes, but is not essential for hematopoiesis or primordial germ cell development

The relative roles of the Kit receptor in promoting the migration and survi val of amniote melanocytes are unresolved. We show that, in the zebrafish, Danio rerio the pigment pattern mutation sparse corresponds to an orthologu e of c-kit. This finding allows us to further elucidate morphogenetic roles for this c-kit-related gene in melanocyte morphogenesis. Our analyses of z ebrafish melanocyte development demonstrate that the c-kit orthologue ident ified in this study is required both for normal migration and for survival of embryonic melanocytes. We also find that, in contrast to mouse, the zebr afish c-kit gene that we have identified is not essential for hematopoiesis or primordial germ cell development. These unexpected differences may refl ect evolutionary divergence in c-kit functions following gene duplication e vents in teleosts.