Theoretical modeling of cellular shapes and dynamics
Biophysics of Cellular Membranes
My main interest is in the physics of biological membranes. These are wonderful examples of self-assembled systems: this means that ordered macroscopic arrangements of many individual molecules occur spontaneously. A similar thing happens in the crystallization process, but in the membranes we have an ordered liquid phase, and the forces that cause it are non-covalent. These properties allow membranes to remain dynamic at room temperatures, while maintaining their overall shape. Biological membranes are made up of lipid molecules, that form a bilayer in water. Such membranes envelope all living cells.
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| Cell membrane | ||
We have so far worked on developing a unified model to describe the mechanical properties of the membrane of the red-blood cell (RBC). Being one of the simplest cells in the body, it has been extensively studied by biophysicists over the past 20 years. What makes this system complex and interesting is the fact that its membrane has a two-dimensional cytoskeleton attached to the outer bilayer. The cytoskeleton determines the elastic properties of the membrane, which in turn control the amplitude of thermal fluctuations and overall cell shape. In our work we focus on the dynamics of the cytoskeleton, that are driven by ATP-induced processes.
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| Red-Blood Cells | ||
A popular article on the Red Blood Cell research: English, Hebrew.
The living cell, and its membranes, are therefore beautiful examples of non-equilibrium systems. These are challenging systems for physicists to describe.
The implications of this work range from the combat of malaria, problems of high blood-pressure, anemia etc. We are currently working to test some of the predictions of the model in experiments done in Weizmann using AFM (Itay Rousso) and single molecule Fluorescence studies (Gilad Haran).
Cell shapes are driven by active processes: This opens the door to a new type of matter which is out-of-equilibrium but can still develop "active-themordynamic" phases:
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Superfluid and Supersolid Helium
1) Defects in solid Helium and their motion: a super-solid?
2) Ion motion in solid Helium
3) Phase nucleation in a quantum system
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| The observation using Neutron scattering of a new optic-like mode at the energy predicted by our model for a dipolar Off-Diagonal-Long-Range-Order in the bcc phase of Helium |
T. Markovich, E. Polturak, J. Bossy, and E. Farhi.
Phys. Rev. Lett. 88, 195301 (2002).
O. Pelleg, J. Bossy, E. Farhi, M. Shay, V. Sorkin, and E. Polturak.
Phys. Rev. B 73, 180301 (2006).