The living cell is an active, self-organized medium comprising molecular processes fuelled by energy. Our group is interested in the organization, flow and processing of mass (molecules), mechanical stress, energy (mitochondria) and information (signaling) in living cells and tissues. These fluxes are coupled via interconnected networks of molecules en-gaged in biochemical reactions played out in this active dynamical medium. The structure of these networks allow for a coarse-grained approach involving new physical principles, unique to the living state. We are interested in the evolution of these molecular and force networks.

These new physical principles are a consequence of the novel response of cellular systems to local active (energy consuming) forces which maintain it away from equilibrium. These active forces arising from (i) the coupled dynamics of the cytoskeleton, motors and cytoskeletal regulatory proteins, and (ii) the active dynamics of fission and fusion of or ganelles, regulate the flux of mass, stress, energy and information. We have been engaged in developing a theoretical framework, called active hydrodynamics, to address the relationship between fluxes and forces in a variety of contexts, where activity plays a significant role. Using this framework we study the mechanical response, pattern formation, symmetry breaking and hydrodynamic instabilities in both in-vivo and in-vitro reconstituted active systems.

1. Goswami D, K. Gowrishankar, S. Bilgrami, S. Ghosh, R. Raghupathy, R. Chadda, R. Vishwakarma, M. Rao and S. Mayor, (2008), Nanoclusters of GPI-anchored proteins are formed by cortical actin-driven activity , Cell 135:1085-1097.

2. S. Ramaswamy and M. Rao, (2007), Active filament hydrodynamics : instabilities, oundary conditions and rheology, New J. Phys. 9:423.

3. Y. Hatwalne, S. Ramaswamy, M. Rao, and R.A. Simha, (2004), Rheology of active-particle suspensions , Phys. Rev. Lett. 92:118101.

4. S. Mayor and M. Rao, (2004), Rafts: Scale-dependent, active lipid organization at he cell surface , Traffic 5:231-240.

5. Sharma P, Varma R, RC Sarasij, Ira, K. Gousset, G. Krishnamoorthy, M. Rao and  Mayor, (2004), Nanoscale organization of multiple GPI-Anchored proteins in living cell  membranes , Cell 116:577-589.

6. M. Rao and Sarasij RC, (2001), Active fusion and fission processes on a fluid memrane , Phys. Rev. Lett. 87:128101.