Single-nucleotide Resolution Epitranscriptomic Profiling Uncovers Dynamic m⁶A Regulation in Bovine Preimplantation...

RNA N ⁶-methyladenosine (m⁶A) plays a crucial role in regulating gene expression during early embryonic development. However, the m⁶A dynamics at single-nucleotide resolution in preimplantation development remain uncharacterized, and the functional significance of site specific m⁶A modifications in key developmental regulators is largely unknown. Here, using SAC-seq, a single-base resolution, antibody-independent m⁶A profiling method, we generate the first comprehensive m⁶A landscape in bovine oocytes and preimplantation embryos. We identify a previously uncharacterized m⁶A site in RPL12 transcript that is essential for embryonic development. Loss of m⁶A at this site leads to reduced protein synthesis, disrupted expression of translation-related genes, and impaired zygotic genome activation and blastocyst formation. Notably, supplementation with wild-type RPL12 mRNA fails to rescue the developmental arrest, indicating that m⁶A regulation extends beyond transcript abundance. Our findings provide a valuable resource of m⁶A at single-nucleotide resolution in mammalian embryogenesis and uncover a critical mechanism by which precise, site-specific m⁶A regulates translation and developmental competence in early embryos.