Talbot Emma L, Parolini Lucia, Kotar Jurij, Di Michele Lorenzo, Cicuta Pietro
Department of Physics, Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, United Kingdom.
Department of Physics, Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, United Kingdom
Proc Natl Acad Sci U S A. 2017 Jan 31;114(5):846-851. doi: 10.1073/pnas.1613525114. Epub 2017 Jan 17.
Domain migration is observed on the surface of ternary giant unilamellar vesicles held in a temperature gradient in conditions where they exhibit coexistence of two liquid phases. The migration localizes domains to the hot side of the vesicle, regardless of whether the domain is composed of the more ordered or disordered phase and regardless of the proximity to chamber boundaries. The distribution of domains is explored for domains that coarsen and for those held apart due to long-range repulsions. After considering several potential mechanisms for the migration, including the temperature preferences for each lipid, the favored curvature for each phase, and the thermophoretic flow around the vesicle, we show that observations are consistent with the general process of minimizing the system's line tension energy, because of the lowering of line interface energy closer to mixing. DNA strands, attached to the lipid bilayer with cholesterol anchors, act as an exemplar "cargo," demonstrating that the directed motion of domains toward higher temperatures provides a route to relocate species that preferentially reside in the domains.
在三元巨型单层囊泡表面观察到域迁移，这些囊泡在温度梯度条件下呈现两种液相共存状态。迁移将域定位到囊泡的热侧，而不管该域是由更有序还是无序相组成，也不管其与腔室边界的距离。研究了因粗化而聚集的域以及因长程排斥而分开的域的分布情况。在考虑了几种潜在的迁移机制后，包括每种脂质的温度偏好、每个相的有利曲率以及囊泡周围的热泳流，我们表明观察结果与系统线张力能最小化的一般过程一致，这是因为靠近混合区域时线界面能降低。用胆固醇锚定附着在脂质双层上的DNA链作为一个典型的“货物”，表明域向更高温度的定向运动为重新定位优先存在于域中的物质提供了一条途径。
