Gdf3 is required for robust Nodal signaling during germ layer formation and left-right patterning.

Vertebrate embryonic patterning depends on signaling from Nodal, a TGFβ superfamily member. There are three Nodal orthologs in zebrafish; directs left-right asymmetries, while and function earlier to pattern mesendoderm. TGFβ member Vg1 is implicated in mesoderm formation but the role of the zebrafish ortholog, Growth differentiation factor 3 (Gdf3), has not been fully explored. We show that zygotic expression of is dispensable for embryonic development, while maternally deposited is required for mesendoderm formation and dorsal-ventral patterning. We further show that Gdf3 can affect left-right patterning at multiple stages, including proper development of regional cell morphology in Kupffer's vesicle and the establishment of expression in the lateral plate mesoderm. Collectively, our data indicate that is critical for robust Nodal signaling at multiple stages in zebrafish embryonic development.