OBSERVATION OF STABLE SHAPES AND CONFORMAL DIFFUSION IN GENUS-2 VESICLES

The observed equilibrium shapes of phospholipid vesicles of topologica l genus 2 (shapes with two holes) are found to be in agreement with th eoretical predictions on the basis of a minimization of the elastic cu rvature energy for fluid membranes under the constraints of constant a rea, volume, and area difference (between the inner and outer layers o f the membrane). For some particular geometrical characteristics, the shapes of the vesicles change continuously and randomly on a slow time scale (tens of seconds) and thus exhibit conformal diffusion. This ph enomenon is a reflection of the conformal degeneracy of the elastic cu rvature energy. Its observation sets a limit (three constraints) on th e number of physical constraints relevant to the determination of the shapes of vesicles.