Two lineage segregation events in mammalian development form the trophectoderm, primitive endoderm, and pluripotent primitive ectoderm. In mouse embryos, Oct4, Cdx2, Nanog, and Gata6 govern these events, but it is unknown whether this is conserved between mammals. Here, the expression patterns of these genes and their products were determined in porcine oocytes and embryos and in bovine embryos. CDX2 and GATA6 expression in porcine and bovine blastocysts resembled that of mouse, indicating conserved functions. However, NANOG expression was undetectable in porcine oocytes and embryos. Some inner cell mass cells in bovine blastocysts expressed NANOG protein. OCT4 protein was undetectable in porcine morulae, but present in both the trophectoderm and the inner cell mass of blastocysts, suggesting that downregulation of OCT4 in the trophectoderm does not precede trophectoderm formation. Combined, the results indicate differences in lineage segregation between mammals. Developmental Dynamics 237: 918 -927, 2008.

Background: In the developing embryo, total RNA abundance fluctuates caused by functional RNA degradation and zygotic genome activation. These variations in the transcriptome in early development complicate the choice of good reference genes for gene expression studies by quantitative real time polymerase chain reaction.

No abstract

Here we report the culture and differentiation of porcine neural cells derived from the inner cell masses (ICMs) of blastocyst-stage embryos. Manually dissected ICMs were cultured on feeder layers of inactivated mouse embryonic fibroblasts (MEFs). Neural rosette-like structures were selected and passaged mechanically. These structures were transient and disappeared after six passages. After transfer to Matrigel-coated dishes, the cells proliferated for approximately 2 months. Expression of neural progenitor cell (NPC)-specific genes NESTIN, SOX1, SOX2, and MUSASHI as detected by RT-PCR suggests that the cell culture contained neural progenitor-like cells. To further confirm the culture of neural progenitor-like cells, we analyzed their differentiation potential in vitro. The porcine neural cells were able to differentiate into glial fibrillary acidic protein (GFAP)-positive astrocytes and O4-positive oligodendrocytes, identified by quantitative RT-PCR and immunofluorescence. Differentiated cells expressed microtubule-associated protein 2 (MAP2) RNA but were unable to differentiate into neurons. It is concluded that porcine blastocysts have the ability to provide an expandable source of neural cells that can develop into glial subtypes.

Recently, we have performed a whole genome micro‐array analysis on human embryonic stem cells differentiating toward cardiomyocytes, which resulted in the identification of novel genes that were highly up‐regulated during differentiation. Here, we describe one of these novel genes annotated as KIAA0774. The predicted protein contains a leucine‐zipper domain at the C‐terminus and has at least two isoforms (358 and 1354 amino acids). Whole‐mount in situ hybridization confirmed that the mRNA of both the mouse and chicken orthologs of KIAA0774 is expressed during early cardiac development. Hence, we named this protein CAZIP (cardiac zipper protein). Later during embryonic development, Cazip was also expressed in parts of the nervous system. Northern blot and real‐time polymerase chain reaction analysis showed that Cazip is expressed in heart and brain in adult mice. These results suggest a role for CAZIP in development and function of the heart and nervous system in vertebrates. Developmental Dynamics 238:2903–2911, 2009. © 2009 Wiley‐Liss, Inc.