Bifurcation in cellular evolution

TL;DR

This paper models cellular metabolism as a dynamical system linked to a network, showing that gradual network changes cause a phase transition that abruptly shifts cell behavior from stagnation to growth.

Contribution

It demonstrates how network topology changes induce bifurcations in cellular dynamics, revealing a percolation-like transition in metabolic evolution.

Findings

Network evolution leads to a giant connected component.

Percolation causes a bifurcation in intracellular dynamics.

Cellular state switches from stagnation to exponential growth.

Abstract

Aspects of cell metabolism are modeled by ordinary differential equations describing the change of intracellular chemical concentrations. There is a correspondence between this dynamical system and a complex network. As in the classic Erd\H{o}s--R\'enyi model, the reaction network can evolve by the iterative addition of edges to the underlying graph. In the biochemical context, each added reaction implies a metabolic mutation. In this work it is shown that modifications to the graph topology by gradually adding mutations lead here too to the formation of a giant connected component, i.e., to a percolation--like phase transition. It triggers an abrupt change in the functionality of the corresponding network. This percolation is mapped into a bifurcation in the intracellular dynamics. It acts as a shortcut in biological evolution, so that the most probable metabolic state for the cell is suddenly switched from cellular stagnation to exponential growth.