Biological order, structure and instabilities

Biological order, structure and instabilities.

Dynamic instabilities in biological membranes

A phase-field model for dealing with the elastic bending energies is studied in the context of dynamic instabilities in membranes. We use it to study curvature-driven pearling instability in vesicles induced by the anchorage of amphophilic polymers on the membrane. Within this model, we obtain the morphological changes reported in the experimental literature. The formation of a homogeneous pear...

Mechanical instabilities of biological tubes.

We study theoretically the morphologies of biological tubes affected by various pathologies. When epithelial cells grow, the negative tension produced by their division provokes a buckling instability. Several shapes are investigated: varicose, dilated, sinuous, or sausagelike. They are all found in pathologies of tracheal, renal tubes, or arteries. The final shape depends crucially on the mech...

Theory of Electrodynamic Instabilities in Biological Cells

Electric behavior of biological cells is driven by ion transport through the membrane induced by specific proteins. The cable model classically describes the membrane potential dynamics by analogy with an electrical circuit. We show the failure of this description when the various ion species get different diffusion times. The pertinent parameter which describes the membrane electrical stabilit...

Orientational order and instabilities in suspensions of self-locomoting rods.

The orientational order and dynamics in suspensions of self-locomoting slender rods are investigated numerically. In agreement with previous theoretical predictions, nematic suspensions of swimming particles are found to be unstable at long wavelengths as a result of hydrodynamic fluctuations. Nevertheless, a local nematic ordering is shown to persist over short length scales and to have a sign...