Torocyte shapes of red blood cell daughter vesicles

The shape of the newly described torocyte red blood cell endovesicles induc ed by octaethyleneglycol dodecylether (C12E8) is characterized. A possible explanation for the origin and stability of the observed torocyte endovesic les is suggested. Three partly complementary mechanisms are outlined, all o riginating from the interaction of C12E8 molecules with the membrane. The f irst is a preferential intercalation of the C12E8 molecule into the inner m embrane layer, resulting in a membrane invagination which may finally close , forming an inside-out endovesicle. The second is a preference of the C12E 8-induced membrane inclusions (clusters) for small local curvature which wo uld favour torocyte endovesicle shape with large regions of small or even n egative membrane mean curvatures, the C12E8 membrane inclusion being define d as a complex composed of the embedded C12E8 molecule and some adjacent ph ospholipid molecules which are significantly distorted due to the presence of the embedded C12E8 molecule. The preference of the C12E8 inclusions for zero or negative local curvature may also lead to the nonhomogeneous latera l distribution of the C12E8 inclusions resulting in their accumulation in t he membrane of torocyte endovesicles. The third possible mechanism is orien tational ordering of the C12E8-induced inclusions in the regions of torocyt e endovesicles with high local membrane curvature deviator. (C) 2000 Elsevi er Science S.A, All rights reserved.