Epigenetic Regulation and Maternal-to-Zygotic Transition in Dwarf Surf Clam (Mulinia lateralis): Insights from Chromatin State Profiling and Transcriptomics

Bivalve mollusks are a major and economically important group within the phylum Mollusca. However, research on the fundamental biology of their embryonic development remains limited. The dwarf surf clam <i>Mulinia lateralis</i> has recently gained recognition as an ideal model for bivalve embryological studies due to its short life cycle and high reproductive capacity. In this study, we explored the epigenetic mechanisms driving embryogenesis in <i>M. lateralis</i> by analyzing chromatin states and transcriptomic data, with a particular focus on the maternal-to-zygotic transition (MZT). For the first time in <i>M. lateralis</i>, we successfully applied the CUT&Tag technique to generate high-resolution profiles of H3K4me1, H3K4me3, H3K27me3, and H3K27ac at key developmental stages. Our findings revealed extensive histone modification reprogramming, underscoring dynamic chromatin changes occurring during early embryonic development. By integrating chromatin profiling with transcriptomic analysis, we identified the timing of the MZT in <i>M. lateralis</i>, pinpointing its occurrence between the morula and gastrula stages, and uncovered candidate genes essential for embryogenesis. This study enhances our understanding of epigenetic regulation in bivalve embryogenesis and provides a novel methodological framework for marine invertebrate research. By establishing <i>M. lateralis</i> as a valuable model, our work not only contributes to the refinement of bivalve aquaculture strategies but also lays the foundation for future functional studies of developmental genes and comparative analyses across bivalve species.