Morphogenesis at criticality?

TL;DR

This paper provides evidence that the gene regulatory network in early fruit fly embryos operates at a critical point, exhibiting characteristic fluctuation patterns and correlations predicted by theoretical models.

Contribution

It demonstrates, through analysis of experimental data, that the gap gene network is tuned to criticality, linking theoretical predictions with biological observations.

Findings

Strong correlations in gene fluctuations observed

Slowing of dynamics along certain expression directions

Long-distance correlations in embryo expression patterns

Abstract

Spatial patterns in the early fruit fly embryo emerge from a network of interactions among transcription factors, the gap genes, driven by maternal inputs. Such networks can exhibit many qualitatively different behaviors, separated by critical surfaces. At criticality, we should observe strong correlations in the fluctuations of different genes around their mean expression levels, a slowing of the dynamics along some but not all directions in the space of possible expression levels, correlations of expression fluctuations over long distances in the embryo, and departures from a Gaussian distribution of these fluctuations. Analysis of recent experiments on the gap genes shows that all these signatures are observed, and that the different signatures are related in ways predicted by theory. While there might be other explanations for these individual phenomena, the confluence of evidence suggests that this genetic network is tuned to criticality.