Budin Itay, Bruckner Raphael J, Szostak Jack W
Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
J Am Chem Soc. 2009 Jul 22;131(28):9628-9. doi: 10.1021/ja9029818.
Many of the properties of bilayer membranes composed of simple single-chain amphiphiles seem to be well-suited for a potential role as primitive cell membranes. However, the spontaneous formation of membranes from such amphiphiles is a concentration-dependent process in which a significant critical aggregate concentration (cac) must be reached. Since most scenarios for the prebiotic synthesis of fatty acids and related amphiphiles would result in dilute solutions well below the cac, the identification of mechanisms that would lead to increased local amphiphile concentrations is an important aspect of defining reasonable conditions for the origin of cellular life. Narrow, vertically oriented channels within the mineral precipitates of hydrothermal vent towers have previously been proposed to act as natural Clusius-Dickel thermal diffusion columns, in which a strong transverse thermal gradient concentrates dilute molecules through the coupling of thermophoresis and convection. Here we experimentally demonstrate that a microcapillary acting as a thermal diffusion column can concentrate a solution of oleic acid. Upon concentration, self-assembly of large vesicles occurs in regions where the cac is exceeded. We detected vesicle formation by fluorescence microscopy of encapsulated dye cargoes, which simultaneously concentrated in our channels. Our findings suggest a novel means by which simple physical processes could have led to the spontaneous formation of cell-like structures from a dilute prebiotic reservoir.
由简单单链两亲分子组成的双层膜的许多特性似乎非常适合作为原始细胞膜发挥潜在作用。然而，此类两亲分子自发形成膜是一个浓度依赖性过程，必须达到显著的临界聚集浓度（cac）。由于脂肪酸和相关两亲分子的大多数益生元合成场景会产生远低于cac的稀溶液，因此确定能导致局部两亲分子浓度增加的机制是定义细胞生命起源合理条件的一个重要方面。热液喷口塔的矿物沉淀物中的狭窄垂直定向通道此前被认为可作为天然的克卢修斯 - 迪克尔热扩散柱，其中强烈的横向热梯度通过热泳和对流的耦合使稀分子浓缩。在此，我们通过实验证明，作为热扩散柱的微毛细管可以浓缩油酸溶液。浓缩后，在超过cac的区域会发生大囊泡的自组装。我们通过对封装染料货物的荧光显微镜观察检测到囊泡形成，这些染料货物同时在我们的通道中浓缩。我们的发现表明了一种新的方式，通过这种方式简单的物理过程可能导致从稀益生元库中自发形成细胞样结构。
