Time reversal breaking of colloidal particles in cells

TL;DR

This paper demonstrates that the mean back relaxation (MBR) correlation can detect broken time reversal symmetry in colloidal particles within cells, revealing activity scales and the role of microtubules, with implications for understanding cellular energetics.

Contribution

It introduces the use of MBR to identify time reversal symmetry breaking in biological systems and links it to cellular activity and energy dissipation.

Findings

MBR detects broken time reversal symmetry in cell data.

Microtubules are essential for symmetry breaking.

Entropy production correlates with active energies.

Abstract

We investigate signatures of broken time reversal symmetry in stochastic trajectory data, employing the previously introduced three point correlation called mean back relaxation. We specifically investigate data from a simple driven model, as well as from colloidal particles within living or passivated biological cells. Both in the model as well as in cell data, MBR detects broken time reversal symmetry, and furthermore, allows to determine relevant time and length scales of activity. For the cells, we show, by applying various drugs, that it is predominantly the presence of microtubules which is needed for a time reversal symmetry breaking. We employ a bound for entropy production, finding that it is in striking relation to previously determined active energies that quantify violation of the fluctuation dissipation theorem.