Lightning Talk + Poster ESA-SRB-NZSE-CaSR 2026 in conjunction with ENSA

Zygotic ribosome activation establishes autonomous protein synthesis in early embryos (142627)

Hongbin Jin 1 , Yi Li 1 , Tia Siddle 1 , Rachel Ingham 2 , Inwon Lee 3 , Marco Podobnik 1 , Peter Currie 1 , John Carroll 3 , Andres Gambini 4 , Mark Green 2 5 , Jennifer Zenker 1
  1. Australian Regenerative Medicine Institute, Monash University, Clayton, VIC, Australia
  2. School of BioSciences, Faculty of Science, The University of Melbourne, Parkville, VIC, Australia
  3. Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
  4. School of Agriculture and Food Sustainability, The University of Queensland , Gatton, QLD, Australia
  5. Monash IVF, Clayton, VIC, Australia

Background

Just as a newborn baby depends on parental care before becoming independent, early embryos rely entirely on maternal ribosomes inherited from the oocyte to translate mRNAs into proteins. However, when and how embryos achieve autonomous protein synthesis through the transition to zygotically generated ribosomes remains largely unknown.

Methods

In mouse, bovine, and zebrafish embryos, advanced embryo microinjection and live-imaging approaches, including confocal and light-sheet microscopy, were used to visualise the real-time dynamics of fluorescently labelled ribosomes during early development.

Results

We discovered a previously unrecognised and evolutionarily conserved developmental event, termed zygotic ribosome activation, through which embryos acquire translational autonomy. Zygotic ribosome activation consistently occurs after zygotic genome activation (ZGA) in different species, at the 8-cell stage in mouse embryos and the 32-cell stage in bovine embryos, approximately two cell cycles after ZGA in both species. In zebrafish embryos, zygotic ribosome activation occurs approximately 6 hours after ZGA at the bud stage. The timing of zygotic ribosome activation is precisely regulated by the ribosome transporter NMD3, which is required for the nuclear export of newly synthesised zygotic ribosomes. Blockage of zygotic ribosome activation leads to significant developmental delay at the corresponding stage, indicating that this event is a critical developmental milestone in early embryogenesis. Furthermore, disruption of ribosome activation reduces global protein translation levels and impairs pluripotency, resulting in compromised embryo quality and abnormal development.

Conclusion

Zygotic ribosome activation represents a novel developmental checkpoint that establishes translational independence in early embryos. This conserved process across vertebrates and mammals is distinct from the transcriptional autonomy conferred by ZGA. Passage through this checkpoint is required to establish full translational autonomy, thereby ensuring normal embryonic development and maintenance of pluripotency.