Department of Physics

Indian Institute Of Technology Madras , Chennai

Equilibrium physics breakdown reveals the active nature of red blood cell flickering - soft matter/biological physics

Speaker : Sachin Krishnan

2017-05-26

Abstract :

From H. Turlier et al. Nature Physics, 12, 513-519 (2016)

Red blood cells, or erythrocytes, are seen to flicker under optical microscopy, a phenomenon initially described as thermal fluctuations of the cell membrane. But recent studies have suggested the involvement of non-equilibrium processes, without definitively ruling out equilibrium interpretations. Using active and passive microrheology to directly compare the membrane response and fluctuations on single erythrocytes, we report here a violation of the fluctuation–dissipation relation, which is a direct demonstration of the non-equilibrium nature of flickering. With an analytical model of the composite erythrocyte membrane and realistic stochastic simulations, we show that several molecular mechanisms may explain the active fluctuations, and we predict their kinetics. We demonstrate that tangential metabolic activity in the network formed by spectrin, a cytoskeletal protein, can generate curvature-mediated active membrane motions. We also show that other active membrane processes represented by direct normal force dipoles may explain the observed membrane activity. Our findings provide solid experimental and theoretical frameworks for future investigations of the origin and function of active motion in cells.

Key Speaker Sachin Krishnan
Guests None
Place Seminar Room
Start Time 12:15 PM
Finish Time 1:15 PM
External Link None