Xenbase Image ID: 157716

Figure 7. Siamois-Expressing Ventral-Vegetal Cells Induce an Ectopic Spemann Organizer Embryos were injected ventrally at the 4-cell stage with 1 ng of mRNA coding for NLS-~-Gal either alone (A) or in combination with 50 pg of Siamois mRNA (B and C). They were fixed at the tadpole (A and B) or early gastrula (C) stages, stained for I~-Gal activity with X-Gal, and cleared to reveal the position of the stained cells. The diffuse staining throughout the endoderm is due to endogenous ~-Gal activity. The specific NLS-~-Gal staining is nuclear. (A) shows that the progeny of NLS-I~-Gal mRNA injected ventral-vegetal cells is found in the posterior endoderm. (B) shows that the progeny of ventral-vegetal cells injected with Siamois and NLS-I~-Gal mRNA is found in the anterior endoderm. (D) Vegetal view of an early gastrula showing the primary (1 o) and secondary (2 °) dorsal blastopore lips and the position of the progeny of a ventral-vegetal blastomere injected with Siamois and NLS-13-Gal (blue cells underneath the secondary dorsal lip). Image published in: Lemaire P et al. (1995) Copyright © 1995. Image reproduced with permission of the Publisher, Elsevier B. V. Larger Image Printer Friendly View

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