Fig. 1. Tsg and Xolloid ventralize the Xenopus embryo. (A) Uninjected stage 18 control embryos stained for krox20 and otx2. (B) Embryos microinjected at the four-cell stage four times at the animal pole with 100 pg Xolloid, (C) 250 pg mouse Tsg or (D) both mRNAs. Same results were obtained using Xenopus Tsg mRNA (data not shown). For each mRNA combination at least 25 embryos were analyzed. (E-H) LiCl-treated embryos. (E) Radially dorsalized LiCl-treated embryo (n=40; dorsoanterior index, DAI=9.5); (F) embryo microinjected into a single blastomere of the marginal zone at the 16-cell stage with 200 pg Xolloid (26% with trunk/tail structures, n=23, DAI=8); (G) 500 pg Xenopus Tsg (32%, n=33, DAI=8.1); or (H) both mRNAs (51%, n=27, DAI=7). Lineage tracing with lacZ and Red-Gal shows that the cells injected with Xenopus Tsg or Xolloid mRNA contributed mostly to ventroposterior mesoderm in the rescued tail region.
