Figure 5

Early lineage marker expression in Rbm19^{GtXC768/GtXC768}mutant embryos. Embryos from an Rbm19^GtXC768/+ intercross were sorted based on appearance and designated either wild-type-appearing (Rbm19^GtXC768/+ or Rbm19^+/+) or Rbm19^{GtXC768/GtXC768}mutants. (A) Double immunofluorescence staining for embryonic stem cell markers OCT-3/4 and NANOG reveals uniform expression in cleavage stage embryos, with progressive segregation of immunopositive cells to the inner cell mass in wild-type-appearing E3.5 embryos. In Rbm19^{GtXC768/GtXC768}embryos arrested at the 16-cell stage, the level of OCT-3/4 is diminished, but NANOG expression remains comparable to WT morula. There is no spatial segregation across the mutant embryos for either protein. (B) Double immunofluorescence staining for the trophectoderm marker CDX2 and the nucleolar protein Fibrillarin (positive control). In the wild-type-appearing embryos CDX2 expression was found in a subset of cells corresponding to the prospective trophectoderm, whereas in the Rbm19^{GtXC768/GtXC768}embryos there was no CDX2 expression detectable.