Modularity of the segmentation clock and morphogenesis

Area of Science:

• Developmental biology
• Evolutionary biology
• Computational biology

Background:

• Vertebrate trunk segment number exhibits significant diversity, but its evolvability is poorly understood.
• Segment number is determined by pre-somitic mesoderm (PSM) morphogenesis and the segmentation clock, a molecular oscillator within the PSM.

Purpose of the Study:

• To investigate whether the segmentation clock and PSM morphogenesis are developmentally modular.
• To understand how this potential modularity contributes to the evolution of vertebrate segment number.

Main Methods:

• Utilized a computational model of the segmentation clock and PSM.
• Parameterised the model for zebrafish.
• Simulated variations in morphogenetic processes like cell ingression, motility, compaction, and division.

Main Results:

• The segmentation clock demonstrated robustness to variations in PSM morphogenetic processes.
• PSM length and segmentation clock phase coupling strength influenced clock robustness.
• Previous studies showed no significant changes in morphogenesis when perturbing the clock.

Conclusions:

• The segmentation clock and PSM morphogenesis exhibit developmental modularity.
• This modularity supports the hypothesis that independent evolution of these processes underlies the evolvability of vertebrate segment number.