Mehanske lastnosti celičnih membran in celični procesi (Slovene)

Shapes of axially strained axisymmetric phospholipid vesicles were studied. The phase diagram for stable prolate shapes was obtained for vesicles with and without equatorial mirror symmetry. At high enough force the stable shapes do not have such a symmetry. The results show that the currently accepted model for the description of lipid-bilayer elasticity (generalized bilayer couple model) properly accounts for the formation of membrane tethers under these conditions. The effect of membrane inclusions on vesicle shapes was also studied. A phenomenological model for the curvature and orientation dependent interaction of an inclusion with the rest of the membrane was developed. It was demonstrated that anisotropic membrane inclusions may stabilize vesicle shapes involving narrow necks. Lamprey erithrocytes were studied in collaboration with the Abo Akademie University. The non-axisymmetrical shape of these cells was interpreted on the basis of the relatively low membrane content of band 3 proteins. The lack of the membrane skeleton in microvesicles which are formed under the effect of detergents on human erythrocytes was interpreted on the basis of the accompanying shear deformation of the skeleton. Effects of the encapsulation of vectamidin vesicles into the erythrocyte membrane on the cell shape were investigated. The occurrence of torocytic endovesicles in erythrocytes under the presence of octaetilenglycol was interpreted on the basis of the curvature dependent binding of this compound to the erythrocyte membrane.