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Figure 1. Nodal signaling directly controls the expression of XPAPC in Xenopus embryos. A-J: Embryos were collected at stage indicated and in situ hybridized with indicated probe. Embryos were viewed from the vegetal side, with dorsal side up. A: Induction of XPAPC (marked with white triangle) in embryos injected with Xnr2 mRNA at 4-cell stage at the ventral midline. B: LacZ mRNA was injected as lineage tracing and specificity control. C,F: Perturbing nodal signaling with SB-431542 inhibited the expression of XPAPC. C,E: Embryos were treated with SB-431542. D,F: Embryos were treated with DMSO as specificity control. G-J: Gene expression after SB-431542 treatment in Xenopus embryos. In DMSO treated embryos, Xbra expression formed a ring around the margin zone (G), but expression on the dorsal side was lost in SB-431542-treated embryos (H). In contrast, Sizzled expression was not affected (I and J). K: Nodal signaling could induce XPAPC expression directly in animal caps. Induction of XPAPC was not inhibited by CHX treatment, but the induction of Chordin was. Con cap, control animal cap without treatment; WE, whole embryo (Stage 12); No RT, no-reverse-transcriptase control; ODC, ornithine decarboxylase, as loading control. |