Time reversal breaking of colloidal particles in cells

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 and in cell data, mean back relaxation (MBR) detects broken time reversal symmetry and, furthermore, allows determining relevant time and length scales of activity. For the cells, by applying various drugs, we show that it is predominantly the presence of microtubules which is needed for a time reversal symmetry breaking. We employ a bound for entropy production and find that it is in striking qualitative agreement with previously determined active energies that quantify violation of the fluctuation dissipation theorem.