Fluctuations of cell geometry and their non-equilibrium thermodynamics in living epithelial tissue

TL;DR

This study investigates the non-equilibrium thermodynamics of living epithelial tissue by measuring entropy production and cell geometry fluctuations, revealing controlled entropy flow during tissue development.

Contribution

It introduces a method to quantify entropy production in living tissue through high-resolution imaging and cell shape analysis, highlighting controlled thermodynamic processes.

Findings

Irreversible cell geometry dynamics observed without entropy change

Energy flow into cell geometry degrees of freedom

Living tissue controls entropy production and partitioning

Abstract

We measure different contributions to entropy production in a living functional epithelial tissue. We do this by extracting the functional dynamics of development while at the same time quantifying fluctuations. Using the translucent Drosophila melanogaster pupal epithelium as an ideal tissue for high resolution live imaging [1], we measure the entropy associated with the stochastic geometry of cells in the epithelium. This is done using a detailed analysis of the dynamics of the shape and orientation of individual cells which enables separation of local and global aspects of the tissue behaviour. We find intriguingly that we can observe irreversible dynamics in the cell geometries but without a change in the entropy associated with those degrees of freedom, showing that there is a flow of energy into those degrees of freedom. Hence the living system is controlling how the entropy is being produced and partitioned into its different parts.