Dean, Wendy


Fertilization is followed by complex changes in cytoplasmic composition and extensive chromatin reprogramming which results in the abundant activation of totipotent embryonic genome at embryonic genome activation (EGA). While chromatin reprogramming has been widely studied in several species, only a handful of reports characterize changing transcriptome profiles and resulting metabolic changes in cleavage stage embryos. The aims of the current study were to investigate RNA profiles of in vivo developed (ivv) and in vitro produced (ivt) porcine embryos before (2-cell stage) and after (late 4-cell stage) EGA and determine major metabolic changes that regulate totipotency. The period before EGA was dominated by transcripts responsible for cell cycle regulation, mitosis, RNA translation and processing (including ribosomal machinery), protein catabolism, and chromatin remodelling. Following EGA an increase in the abundance of transcripts involved in transcription, translation, DNA metabolism, histone and chromatin modification, as well as protein catabolism was detected. The further analysis of members of overlapping GO terms revealed that despite that comparable cellular processes are taking place before and after EGA (RNA splicing, protein catabolism), different metabolic pathways are involved. This strongly suggests that a complex metabolic switch accompanies EGA. In vitro conditions significantly altered RNA profiles before EGA, and the character of these changes indicates that they originate from oocyte and are imposed either before oocyte aspiration or during in vitro maturation. IVT embryos have altered content of apoptotic factors, cell cycle regulation factors and spindle components, and transcription factors, which all may contribute to reduced developmental competence of embryos produced in vitro. Overall, our data are in good accordance with previously published, genome-wide profiling data in other species. Moreover, comparison with mouse and human embryos showed striking overlap in functional annotation of transcripts during the EGA, suggesting conserved basic mechanisms regulating establishment of totipotency in mammalian development. © 2013 Østrup et al.


Mathematics and Statistics

Keywords and Phrases

Histone; Transcription Factor; RNA, Animal Cell; Animal Tissue; Apoptosis; Article; Cell Cycle; Cell Cycle Regulation; Chromatin Assembly And Disassembly; Controlled Study; DNA Metabolism; Embryo; Embryo Development; Embryonic Genome Activation; Female; Fertilization In Vitro; Gene Activation; Gene Expression Profiling; Genetic Transcription; Human; Human Versus Animal Comparison; In Vitro Study; In Vivo Study; Metabolic Regulation; Mitosis; Mitosis Spindle; Nonhuman; Oocyte; Protein Degradation; Protein Modification; Riboswitch; RNA Analysis; RNA Processing; RNA Translation; Totipotent Stem Cell; Transcription Regulation; Translation Initiation; Animal; Animal Embryo; Culture Technique; Embryology; Fertilization; Genetics; Genome; Laboratory; Metabolism; Mouse; Reproducibility; RNA Splicing; Sequence Analysis; Species Difference; Swine, Mammalia; Sus, Animals; Culture Techniques; Embryo, Mammalian; Fertilization; Gene Expression Profiling; Genome; Humans; Laboratories; Mice; Reproducibility Of Results; RNA; RNA Splicing; Sequence Analysis, RNA; Species Specificity; Swine

International Standard Serial Number (ISSN)


Document Type

Article - Journal

Document Version

Final Version

File Type





© 2013 The Authors, All rights reserved.

Publication Date

01 Jan 2013