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Fig. S2. Vent2 is expressed in the posterior endoderm and can repress foregut development from blastula to early somite stages. (A) In situ hybridization of bisected Xenopus embryos (anterior left) shows that vent2 RNA is robustly expressed in the posterior endoderm from gastrula stage 11 to stage 22, in a reciprocal pattern to hhex. Throughout this period of development, wnt8 RNA is expressed in the lateral mesoderm (red arrows) adjacent to the vent2-expressing posterior endoderm. (B) Injection of vent2 RNA (500 pg) into the anterior D1 cells of the 32-cell stage embryo results in repression of foxa2 expression in the foregut endoderm at stage 18. (C) RNA encoding a hormone inducible GR-Vent2 fusion protein, with the hormone-binding domain of the glucocorticoid receptor fused to Vent2, was injected into the D1 anterior cells of 32-cell stage embryos. Dexamethasone (Dex, 10-6 M) was added to the media at the indicated stages, embryos were cultured until stage 35-37 and assayed by for1 and pdx1 in situ hybridization. Ectopic GR-Vent2 can repress foregut development up until stage 20, which is similar to the period when ectopically activated β-catenin can repress foregut development. No effect was observed on uninjected embryos treated with Dex, or on injected embryos without Dex. |
