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FIGURE 6.
Knockdown of Smad4β leads to reduction of mesodermal and neural markers in the morphant embryos. A, injection of 20-40 ng of Smad4β-MO in two-cell stage embryos led to reduction of the mesodermal markers Brachyury (Xbra), Chordin, MyoD, and Wnt8 at gastrula stages, and the reduction was only slightly enhanced by Smad4α-MO. Smad4α-MO alone or the control MO did not affect marker expression. B, at neurula stages, the notochordal expression of Xbra and the paraxial mesodermal gene MyoD were both reduced in Smad4β morphant embryos. Co-injection of Smad4α-MO and Smad4β-MO resulted in further reduction of these markers. The pan-neural marker Sox2 was also down-regulated in embryos expressing Smad4β-MO. Control MO and Smad4α-MO did not significantly inhibit expression of these genes. C, expression of either Smad4α-MO or Smad4β-MO led to reduction of globin expression in the resulting tadpoles. In A, the embryos were viewed from the vegetal pole of gastrula embryos with the dorsal side to the right. In B, the embryos were viewed from the dorsal side with anterior to the left. In C, the embryos were oriented with the anterior to the left and viewed from the lateral side. |
