Transcriptome and Proteome of Blastocysts Obtained from Different Activation Protocols

Normal fertilization triggers Ca²⁺ oscillations in the oocyte cytoplasm. Different assisted oocyte activation (AOA) protocols differ markedly in the calcium dynamics, yet their respective impacts on embryo gene expression remain incompletely understood. In this study, we employed strontium chloride (SrCl₂), which induces Ca²⁺ oscillations, A-23187, which induces a single Ca²⁺ rise, and RO-3306, which activates oocytes without a Ca²⁺ rise by directly inhibiting CDK1 activity, to estimate the effect of different parthenogenetic activation protocols on embryo gene expression using fertilized embryos as a control. We compared the data of omics among different blastocysts. The transcriptional profiles of diverse parthenogenetic blastocysts were distinct from those of normal blastocysts, while transcriptional levels among different parthenogenetic blastocysts were relatively similar. Similarly, proteomics analysis revealed different protein expression profiles of diverse parthenogenetic blastocysts compared to those of normal blastocysts, especially proteins related to fatty acid biosynthesis, fatty acid β-oxidation metabolic, mitochondria, RNA splicing, and RNA binding. Some protein expression differences were also observed among different parthenogenetic blastocysts. However, all parthenogenetic blastocysts exhibited similar differentially expressed pathways. Our results show that gene expression in parthenogenetic embryos is distinct from that of normally fertilized embryos, and Ca²⁺ rise, especially Ca²⁺ oscillation, is important for proper gene expression in early embryos.