Optical changes in unilamellar vesicles experiencing osmotic stress

被引:54
作者
White, G
Pencer, J
Nickel, BG
Wood, JM
Hallett, FR
机构
[1] UNIV GUELPH,DEPT PHYS,GUELPH,ON N1G 2W1,CANADA
[2] UNIV GUELPH,DEPT MICROBIOL,GUELPH,ON N1G 2W1,CANADA
基金
加拿大自然科学与工程研究理事会;
关键词
D O I
10.1016/S0006-3495(96)79461-4
中图分类号
Q6 [生物物理学];
学科分类号
071011 ;
摘要
Membrane properties that vary as a result of isotropic and transmembrane osmolality variations (osmotic stress) are of considerable relevance to mechanisms such as osmoregulation, in which a biological system ''senses'' and responds to changes in the osmotic environment. In this paper the light-scattering behavior of a model system consisting of large unilamellar vesicles of dioleoyl phosphatidyl glycerol (DOPG) is examined as a function of their osmotic environment. Osmotic downshifts lead to marked reductions in the scattered intensity, whereas osmotic upshifts lead to strong intensity increases. It is shown that these changes in the scattering intensity involve changes in the refractive index of the membrane bilayer that result from an alteration in the extent of hydration and/or the phospholipid packing density, By considering the energetics of osmotically stressed vesicles, and from explicit analysis of the Rayleigh-Gans-Debye scattering factors for spherical and ellipsoidal shells, we quantitatively demonstrate that although changes in vesicle volume and shape can arise in response to the imposition of osmotic stress, these factors alone cannot account for the observed changes in scattered intensity.
引用
收藏
页码:2701 / 2715
页数:15
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