Effect of vitrification on global gene expression dynamics of bovine elongating embryos

Embryo vitrification involves exposure to high concentrations of cryoprotectants and osmotic stress during cooling and warming. A multitude of these factors have the potential of affecting gene expression. In this study, in vitro produced bovine embryos at the blastocyst stage were submitted to vitrification. Four recipients each were used for transferring non-vitrified (80) and vitrified (80) embryos. Twelve non-vitrified and nine vitrified viable day-14 (D14) embryos were recovered by uterine flushing. RNA-seq analysis of whole embryo or isolated trophectoderm (TE) from vitrified and fresh recovered D14 embryos revealed a total of 927 genes changed their expression as a result of vitrification, among them 782 and 145 genes were up- and down-regulated, respectively. In TE isolates, vitrification resulted in 4,096 and 280 up- and down-regulated genes, respectively. In addition, we found 671 and 61 genes commonly up- and down-regulated in both vitrified whole embryo and TE. Commonly up-regulated pathways by vitrification included epithelial adherens junctions, sirtuin signaling, germ cell-sertoli cell junction, ATM signaling, NER, and protein ubiquitination pathways. The commonly down-regulated pathways included EIF2 signaling, oxidative phosphorylation, mitochondrial dysfunction, regulation of eIF4 and p70S6K signaling, mTOR signaling, sirtuin singling, and NER pathways. Our analysis identified specific pathways and implicated specific gene expression patterns important to cryopreservation affecting embryo developmental competence. Twelve non-vitrified and nine vitrified viable day-14 (D14) embryos were recovered by uterine flushing. RNA-seq analysis was performed using the whole embryo or isolated trophectoderm (TE) from vitrified and fresh recovered D14 embryos.