Fig. 4. Dose-dependent rescue of the TSG-MO phenotype by human TSG, chordin or noggin. (A) Rescue of TSG-MO phenotypes induced by dorsal MO injection, by coinjection with human TSG mRNA. 10 ng TSG-MO was injected into each dorsal blastomere of four-cell stage embryos, alone or with increasing doses (0.2-1 ng) of human TSG mRNA. While the TSG-MO induced a reduced head and bent body axis in frog tadpoles, these defects were rescued with human TSG, or Xenopus BM40-XTSG (data not shown). (B) Rescue of TSG-MO phenotypes induced by ventral MO injection, by coinjection with human TSG mRNA. TSG-MO and increasing doses of human TSG mRNA were injected as above, except ventral instead of dorsal blastomeres were injected. Human TSG rescued the tail defects induced by ventral expression of TSG-MO. (C) Rescue of dorsal defects by high doses of chordin. TSG-MO was injected with a range of between 0.2 ng and 1 ng of chordin RNA into the dorsal blastomeres of four-cell stage embryos. At high doses, chordin rescued the dorsal defects associated with the TSG-MO. (D) Rescue of the TSG-MO dorsal defects by noggin. TSG-MO was injected with between 2 pg and 10 pg noggin into the dorsal blastomeres of four-cell stage embryos. The head defect induced by TSG-MO was rescued by noggin overexpression. In all panels anterior is to the right and dorsal is up.

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