Differential Gene Expression Between the Porcine Morula and Blastocyst

Abstract

The survival and development of pre-implantation embryos are determinant factors affecting the outcome of animal reproduction. It is essential to transfer the expression of the genetic material from maternal sources, that is the ovum to the zygote before implantation to ensure successful development. Differentiation and transformation of blastomeres initiated during the morula and blastocyst stages is an important step of the embryonic development prior to implantation. We collected morula and early blastocyst samples from pure-bred Landrace pigs in vivo to study the differential gene expression patterns at these two stages. Total RNA was extracted from individual embryos and two rounds of amplification were employed. Two micrograms of antisense RNA, targets, were prepared and hybridized with each of four custom made oligo microarrays representing 24,000 porcine genes. The analyses of replicate hybridizations showed that among the 24,000 genes, 162 genes were expressed fivefold or greater in the morula compared to early blastocysts and 2126 genes were expressed fivefold or greater in early blastocysts compared to the morula. Of these differentially expressed genes, 1429 genes were functionally annotated with related human Gene Ontology terms. In addition to basic metabolic processes, genes related to signal transduction, transportation and cell differentiation were found in both stages and were up-regulated as embryo development proceeded. Real time polymerase chain reaction was utilized to quantify 12 genes differentially expressed in the 2 embryonic stages and validated the reliability of major evidences shown in microarrays. In conclusion, we have obtained a preliminary landscape of genes differentially expressed during the transition from morula to early blastocysts in pigs and showed a generally increased transcriptional activity, perhaps in preparation for implantation. Our results provide an opportunity to study the functions of these genes in relation to the development and survival of pre-implantation porcine embryos.

Vitrification of in Vivo-derived Porcine Morulae and Blastocysts Alters Metabolic and Stress Response Pathway Alterations

“…Interestingly, when we examined enriched pathways for upregulated genes in vitri ed blastocysts, we observed important biological processes (cellular senescence and cell cycle) and signaling pathways (TGFβ, p53 and FoxO) that regulate the pluripotency of stem cells involved in embryo development and pregnancy. The enrichment of the TGFβ signaling pathway has also been reported in vitri ed porcine COCs [44,45], and upregulation of miRNAs related to this pathway was observed in vitri ed mouse blastocysts [61]. The upregulated genes in the TGFβ signaling pathway were BMPR1B, ID4, SMAD3 and TGFβ1, and there were also DEGs involved in the cell cycle pathway (CDKN1A) and signaling pathways regulating the pluripotency of stem cells (BMPR1B, ID4 and SMAD3).…”

“…The most enriched GO terms in morulae were related to fatty acid and acyl-CoA metabolism. It is known that both fatty acids and acyl-CoA are metabolic switches linked to pluripotency that play an essential role in embryo development [44,45]. In addition, acyl-CoA controls crucial cellular processes such as mitosis, autophagy and energy metabolism, and this control is either direct or is mediated by epigenetic regulation of gene expression [46,47].…”

Maternal

“…Therefore, MLF1 may be a potential regulator of increased cellular apoptosis in DDB1-deficient porcine embryos, however further work is required. The morula is a pivotal period for blastocyst formation, controlled by a significant amount of differentially expressed genes between the morula and blastocyst stage (Hsu et al 2012). In this study, the most changed genes in the DDB1deficient morula were found to be associated with signal transduction, cell adhesion, and stem cell differentiation including YAP1 (also known as YAP).…”

Melatonin improves the vitrification of sheep morulae by modulating transcriptome

“…These pathways regulate the pluripotency and pregnancy of stem cells involved in embryonic development. Enrichment of the signaling pathway has also been reported in vitrified porcine COCs ( 45 , 46 ), as well as in vitrified mouse blastocysts, indicated by increased level of miRNA that was associated with TGFβ upregulation ( 47 ). The FoxO pathway is also activated under stress conditions ( 48 ); FoxO molecules have been found in the inner cell mass of mouse blastocysts ( 49 ) to upregulate target genes, thereby promoting cell cycle stalled genes and increasing resistance to stress.…”