Samo Kralj, University of Maribor, Impact of intrinsic and extrinsic curvature on membrane shapes

Date: Wed. November 29th, 2017, 12:30 pm-1:30 pm
Location: Rockefeller 221 (Les Foldy Room)

Prof. Samo Kralj

University of Maribor, Maribor & Jožef Stefan Institute, Ljubljana, Slovenia

 

 Impact of intrinsic and extrinsic curvature on membrane shapes

Red blood cells (erythrocytes) are present in almost all vertebrates and their main function is the transport of oxygen to the body tissues. Their shape dominantly influences their functionality. In almost all mammals in normal conditions erythrocytes adopt a disk-like (discocyte) shape which optimizes their flow properties in large vessels and capillaries. Experimentally measured values  of  the  relative volume v of stable discocyte shapes  range in a relatively broad window. However, this experimental fact is not supported by any existing theoretical membrane-shape model. In our study we model the erythrocyte membrane using a hybrid  Helfrich-Landau type mesoscopic approach taking into account in-plane membrane ordering. We demonstrate that the extrinsic membrane energy term efficiently broadens the window of v values where discocyte shapes are stable. A fingerprint of the relative importance of  the  extrinsic  curvature energy term are locations  of  topological defects (TDs)  within  a curved membrane. Favored positions of TDs can be predicted without solving Euler-Lagrange equations via intrinsic and extrinsic geometric potentials, which we derived using the parallel transport method.

host: Charles Rosenblatt