Abstract
Endovesicles induced in human erythrocytes by octaethyleneglycol dodecylether (C12E8) were studied by confocal laser scanning microscopy, using fluorescein isothiocyanate dextran as a nonspecific fluid marker. The endovesicles appeared to consist mainly of a ring-formed toroidal part joined with a central flat membrane segment. The torocyte contour length was several microm. There was usually one torocyte endovesicle per cell. The endovesicles seemed to be located near the cell surface. In sections of C12E8-treated erythrocytes transmission electron microscopy revealed the frequent occurrence of flat membrane structures with a bulby periphery, which apparently are cross sections of torocyte endovesicles. The possible physical mechanisms leading to the observed torocyte endovesicle shape are discussed. The torocyte endovesicles seem to be formed in a process in which an initially stomatocytic invagination loses volume while maintaining a large surface area. Because intercalation of C12E8 in the erythrocyte membrane induces inward membrane bending (stomatocytosis) we assume that C12E8 is preferentially located in the inner lipid layer of the erythrocyte membrane, i.e., in the outer lipid layer of the endovesicle membrane. It is suggested that local disturbances of the lipid molecules in the vicinity of the C12E8 molecules in the outer lipid layer of the endovesicle membrane form membrane inclusions with the effective shape of an inverted truncated cone. If the interaction between the inclusion and the membrane is weak, the membrane of such an endovesicle can be characterized by its negative spontaneous curvature, which may lead to a torocyte endovesicle shape with a small relative volume. Effects of a possible strong interaction between the C12E8-induced membrane inclusions and the membrane on the stability of the torocyte endovesicles are also indicated.
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- Deuticke B. Transformation and restoration of biconcave shape of human erythrocytes induced by amphiphilic agents and changes of ionic environment. Biochim Biophys Acta. 1968 Dec 10;163(4):494–500. doi: 10.1016/0005-2736(68)90078-3. [DOI] [PubMed] [Google Scholar]
- Fournier JB. Nontopological saddle-splay and curvature instabilities from anisotropic membrane inclusions. Phys Rev Lett. 1996 Jun 3;76(23):4436–4439. doi: 10.1103/PhysRevLett.76.4436. [DOI] [PubMed] [Google Scholar]
- Fujii T., Sato T., Tamura A., Wakatsuki M., Kanaho Y. Shape changes of human erythrocytes induced by various amphipathic drugs acting on the membrane of the intact cells. Biochem Pharmacol. 1979 Mar 1;28(5):613–620. doi: 10.1016/0006-2952(79)90144-8. [DOI] [PubMed] [Google Scholar]
- Hägerstrand H., Isomaa B. Amphiphile-induced antihaemolysis is not causally related to shape changes and vesiculation. Chem Biol Interact. 1991;79(3):335–347. doi: 10.1016/0009-2797(91)90113-l. [DOI] [PubMed] [Google Scholar]
- Hägerstrand H., Isomaa B. Morphological characterization of exovesicles and endovesicles released from human erythrocytes following treatment with amphiphiles. Biochim Biophys Acta. 1992 Aug 24;1109(2):117–126. doi: 10.1016/0005-2736(92)90074-v. [DOI] [PubMed] [Google Scholar]
- Hägerstrand H., Isomaa B. Vesiculation induced by amphiphiles in erythrocytes. Biochim Biophys Acta. 1989 Jul 10;982(2):179–186. doi: 10.1016/0005-2736(89)90053-9. [DOI] [PubMed] [Google Scholar]
- Iglic A., Hägerstrand H. Amphiphile-induced spherical microexovesicle corresponds to an extreme local area difference between two monolayers of the membrane bilayer. Med Biol Eng Comput. 1999 Jan;37(1):125–129. doi: 10.1007/BF02513278. [DOI] [PubMed] [Google Scholar]
- Isomaa B., Hägerstrand H., Paatero G. Shape transformations induced by amphiphiles in erythrocytes. Biochim Biophys Acta. 1987 May 12;899(1):93–103. doi: 10.1016/0005-2736(87)90243-4. [DOI] [PubMed] [Google Scholar]
- Kralj-Iglic V., Svetina S., Zeks B. Shapes of bilayer vesicles with membrane embedded molecules. Eur Biophys J. 1996;24(5):311–321. doi: 10.1007/BF00180372. [DOI] [PubMed] [Google Scholar]
- Lipowsky R. The conformation of membranes. Nature. 1991 Feb 7;349(6309):475–481. doi: 10.1038/349475a0. [DOI] [PubMed] [Google Scholar]
- Markin V. S. Lateral organization of membranes and cell shapes. Biophys J. 1981 Oct;36(1):1–19. doi: 10.1016/S0006-3495(81)84713-3. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Miao L, Seifert U, Wortis M, Döbereiner HG. Budding transitions of fluid-bilayer vesicles: The effect of area-difference elasticity. Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics. 1994 Jun;49(6):5389–5407. doi: 10.1103/physreve.49.5389. [DOI] [PubMed] [Google Scholar]
- Otten D., Löbbecke L., Beyer K. Stages of the bilayer-micelle transition in the system phosphatidylcholine-C12E8 as studied by deuterium- and phosphorous-NMR, light scattering, and calorimetry. Biophys J. 1995 Feb;68(2):584–597. doi: 10.1016/S0006-3495(95)80220-1. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Seifert U. Curvature-induced lateral phase segregation in two-component vesicles. Phys Rev Lett. 1993 Mar 1;70(9):1335–1338. doi: 10.1103/PhysRevLett.70.1335. [DOI] [PubMed] [Google Scholar]
- Sheetz M. P., Singer S. J. Biological membranes as bilayer couples. A molecular mechanism of drug-erythrocyte interactions. Proc Natl Acad Sci U S A. 1974 Nov;71(11):4457–4461. doi: 10.1073/pnas.71.11.4457. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Sheetz M. P., Singer S. J. Equilibrium and kinetic effects of drugs on the shapes of human erythrocytes. J Cell Biol. 1976 Jul;70(1):247–251. doi: 10.1083/jcb.70.1.247. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Svetina S., Iglic A., Zeks B. On the role of the elastic properties of closed lamellar membranes in membrane fusion. Ann N Y Acad Sci. 1994 Mar 9;710:179–191. doi: 10.1111/j.1749-6632.1994.tb26626.x. [DOI] [PubMed] [Google Scholar]
- Svetina S., Zeks B. Membrane bending energy and shape determination of phospholipid vesicles and red blood cells. Eur Biophys J. 1989;17(2):101–111. doi: 10.1007/BF00257107. [DOI] [PubMed] [Google Scholar]
- Waugh R. E. Elastic energy of curvature-driven bump formation on red blood cell membrane. Biophys J. 1996 Feb;70(2):1027–1035. doi: 10.1016/S0006-3495(96)79648-0. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Wenk M. R., Alt T., Seelig A., Seelig J. Octyl-beta-D-glucopyranoside partitioning into lipid bilayers: thermodynamics of binding and structural changes of the bilayer. Biophys J. 1997 Apr;72(4):1719–1731. doi: 10.1016/S0006-3495(97)78818-0. [DOI] [PMC free article] [PubMed] [Google Scholar]
