Influence of Delipation on the Energy Metabolism in Pig Parthenogenetically Activated Embryos

This study was designed not only to measure the effect of delipation on the developmental viability of pig parthenogenetically activated (PA) embryos, but also to evaluate the changes of mitochondria DNA (mtDNA), reactive oxygen species (ROS) level, adenosine triphosphate (ATP) content and gene (Acsl3, Acadsb, Acaa2, Glut1) expression level at different stages after delipation. Results showed that no effect was observed on the cleavage ability, but significant lower blastocyst rate was obtained in delipated embryos. Copy number of mtDNA decreased gradually from MII to four-cell stages and subsequently kept consistent with blastocyst stage both in delipated and control embryos, but the copy number of mtDNA in delipated embryos was similar to that in the control groups no matter at which developmental stage was observed. Both in delipated and control embryos, ATP content progressive decreased from one-cell to blastocyst stages, while just at one-cell stage, a significant decrease of ATP level was observed in delipated embryos compared with that of control. The level of ROS increased obviously after delipation at cleavage stage, but no difference was seen at blastocyst stage. Finally, the expression level of genes related to fatty acids beta-oxidation (Acadsb and Acaa2) was decreased, while the expression level of genes related to glucose metabolism (Glut 1) was upregulated after delipation. In conclusion, the reduction of lipids in pig oocytes will affect the developmental competence of pig PA embryos by disturbed energy metabolism and ROS stress.