A Local, Self-Organizing Reaction-Diffusion Model Can Explain Somite Patterning in Embryos.

Area of Science:

• Developmental biology
• Systems biology
• Mathematical modeling

Background:

• Somitogenesis involves a differentiation front that halts segmentation clock gene oscillations, forming periodic expression stripes.
• The established "clock and wavefront" model proposes long-range molecular gradients control this front's movement and stripe placement.

Purpose of the Study:

• To introduce and validate a novel model for somitogenesis based on local interactions.
• To challenge the prevailing clock and wavefront model by proposing an alternative mechanism.

Main Methods:

• Development of a progressive oscillatory reaction-diffusion (PORD) system model.
• Comparison of PORD model predictions with experimental data, including FGF-inhibition and tissue-cutting experiments.

Main Results:

• The PORD model describes posterior front movement as an emergent phenomenon driven by short-range interactions, not global positional information.
• The PORD model successfully explains size regulation in somitogenesis, a feature not adequately addressed by previous models.
• Experimental results from FGF-inhibition and tissue-cutting favor the PORD model over the clock and wavefront model.

Conclusions:

• The progressive oscillatory reaction-diffusion (PORD) model offers a new framework for understanding embryonic segmentation.
• Somitogenesis can be explained by local interactions and emergent properties rather than solely by global positional cues.
• The PORD model provides a more accurate explanation for experimental observations in somitogenesis, including size regulation.