Landscape and regulation of new protein translation in the early C. elegans embryo.

Translation of maternal mRNAs is crucial for early embryonic development. In C. elegans, cell fates become determined from the first division without new transcription, making this organism ideal for studying post-transcriptional regulation of lineage specification. Using low-input ribosome profiling combined with RNA sequencing on precisely staged embryos, we measured protein translation during the first four cell cycles of C. elegans development. We uncovered stage-specific patterns of developmentally coordinated translational regulation. We found that mRNA localization correlates with translational efficiency, though initial translational repression in germline precursors occurs prior to P-granule association. The RNA-binding protein OMA-1 emerged as a key regulator of translational efficiency in a stage-specific manner. These findings illuminate how post-transcriptional mechanisms shape the embryonic proteome to direct cell differentiation, with implications for understanding similar regulation across species where maternal factors guide early development.