Transcriptomic Dynamics Associated With In Vitro Oocyte Competence in Pigs

Porcine in vitro embryo production (pIVP) would have a major impact on both livestock production and biomedical research if its efficiency-currently limited by suboptimal oocyte competence-could be improved. This study aimed to characterize transcriptional dynamics across oocyte in vitro maturation (IVM) and fertilization (IVF). Immature oocytes (IMO), mature oocytes (MO) and zygotes (ZY) produced in vitro were analysed by RNA sequencing followed by differential gene expression and functional enrichment analyses. IMO showed higher abundance of zona pellucida (ZP) transcripts (ZP2, ZP3, ZP4), whereas MO were enriched in genes related to cytoskeletal remodelling and calcium signalling (e.g., ITPR1, TGM2), consistent with the acquisition of cytoplasmic competence. After fertilization, ZY exhibited increased representation of transcripts involved in gamete interaction, vesicle trafficking, and maternal-effect complexes (e.g., IZUMO1R, NLRP5, PADI6), reflecting the transition to post-fertilization regulatory support. The chain of transcriptional shifts defines the molecular progression underlying maturation and fertilization competence in the porcine in vitro system.