Figure 9. Smurf1 and Smurf2 control mesendodermal development in early Xenopus embryos.

A) Knockdown of Smurf1 in dorsal tissues resulted in reduction of axial structures and malformation of the head, which was often accompanied by a delay or failure in neural tube closure (32 out of the 58 embryos with the shown phenotype had neural tube closure defects, arrow). In contrast, knockdown of Smurf2 led to enlargement of the endodermal mass in the embryos. When both Smurfs were knocked down, the embryos developed with severe axial defects, microcephaly, and failure in gastrulation. B) Knockdown of either Smurf1 or Smurf2 in the VMZ region induced tail truncation, though the phenotype was more pronounced in the Smurf1 morphants. Double knockdown of both Smurfs aggravated the tail defects. The numbers indicate the embryos showing the depicted phenotype.