Proteomic analysis demonstrates that parthenogenetically activated swamp buffalo embryos have dysregulated energy metabolism.

The comprehensive understanding of early embryo development is essential to optimize in vitro culture conditions. Protein expression landscape of parthenogenetically produced embryo remains unexplored. This study aimed to investigate the protein expression dynamics with a particular focus on energy metabolism throughout the early developmental stages of parthenogenetic buffalo embryos. For this purpose, we performed iTRAQ-based quantitative mass spectrometry and identified 280 proteins common in all stages. A total of 933 proteins were identified during the proteomics analysis. The data depicted that morula and blastocyst had distinct protein expression dynamics as compared to 2- to 16-cell-stage embryo. KEGG pathway analysis showed 23 proteins belonging to energy metabolism appeared in the data. Study of energy metabolism-related protein's expression pattern demonstrated that there was asynchrony in proteins related to glycolysis throughout the examined developmental stages. The expression pattern of pyruvate kinase mutase (PKM), an essential protein of glycolysis, indicated a slightly decreasing trend from 2-cell-stage embryo to blastocyst, and it was supported by expression of proteins involved in lactate production (LDHA and LDHB) suggesting the decreasing rate of aerobic glycolysis (Warburg Effect) at morula and blastocyst stage. The increased Warburg Effect is considered as the hallmark of proliferating cells or embryo at the blastocyst stage. Furthermore, the proteins involved in the citric acid cycle also showed down-regulation at the blastocyst stage, indicating a lesser role of oxidative phosphorylation at this stage. Therefore, it could be divulged from the study that there may be an irregular pattern of energy metabolism in early parthenogenetic embryos. Further studies are recommended to understand this phenomenon.