Time-aligned hourglass gastrulation models in rabbit and mouse.

Area of Science:

• Developmental Biology
• Evolutionary Biology
• Genomics

Background:

• The hourglass model proposes developmental convergence within phyla, but its molecular basis in mammals is unclear.
• Understanding mammalian developmental mechanisms is crucial for evolutionary insights.

Purpose of the Study:

• To investigate the molecular mechanisms of developmental convergence in mammals using a comparative approach.
• To analyze single-cell differentiation trajectories during mammalian gastrulation.

Main Methods:

• Comparative analysis of rabbit and mouse embryos at single-cell resolution.
• Modeling gastrulation dynamics from E6.0 to E8.5.
• Utilizing a framework for time-resolved single-cell differentiation-flows analysis.

Main Results:

• Convergence of cell-state compositions observed at embryonic day 7.5 (E7.5) in both species.
• Quantitatively conserved expression of 76 key transcription factors.
• Divergence noted in primordial germ cell programs and lineage specification timing, with rabbits not activating mesoderm genes in germ cells.

Conclusions:

• Mammalian gastrulation exhibits conserved core developmental programs despite species-specific variations.
• Comparative single-cell analysis provides a powerful tool for studying evolutionary developmental dynamics.
• Findings contribute to understanding the evolution of body plan development across mammals.