Amphiphilic Compounds Assemble into Membranous Vesicles in Hydrothermal Hot Spring Water but Not in Seawater.

Daniel Milshteyn,Jeff Havig,David Deamer,Bruce Damer

doi:10.3390/life8020011

Daniel Milshteyn, Jeff Havig + Show 2 more

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https://doi.org/10.3390/life8020011

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Abstract

There is a general assumption that amphiphilic compounds, such as fatty acids, readily form membranous vesicles when dispersed in aqueous phases. However, from earlier studies, it is known that vesicle stability depends strongly on pH, temperature, chain length, ionic concentration and the presence or absence of divalent cations. To test how robust simple amphiphilic compounds are in terms of their ability to assemble into stable vesicles, we chose to study 10- and 12-carbon monocarboxylic acids and a mixture of the latter with its monoglyceride. These were dispersed in hydrothermal water samples drawn directly from hot springs in Yellowstone National Park at two pH ranges, and the results were compared with sea water under the same conditions. We found that the pure acids could form membranous vesicles in hydrothermal pool water, but that a mixture of dodecanoic acid and glycerol monododecanoate was less temperature-sensitive and assembled into relatively stable membranes at both acidic and alkaline pH ranges. Furthermore, the vesicles were able to encapsulate nucleic acids and pyranine, a fluorescent anionic dye. None of the amphiphiles that were tested formed stable vesicles in sea water because the high ionic concentrations disrupted membrane stability.

Highlights

At some point along the pathway to the origin of life, assembly of microscopic compartments containing functional systems of polymers was an essential step [1,2]
The results reported here confirm that a 1:1 mole mixture of dodecanoic acid with monoglyceride (LA–GML)
The main conclusions from themembranous results reported hereinis hydrothermal that, althoughwater pure samples decanoic from and dodecanoic acid are able to form vesicles dodecanoic acid are able to form membranous vesicles in hydrothermal water samples from hydrothermal pools, they are relatively sensitive to temperature and pH

Summary

Introduction

At some point along the pathway to the origin of life, assembly of microscopic compartments containing functional systems of polymers was an essential step [1,2]. There are several problems to overcome if polymers were to be encapsulated in the prebiotic environment. We first note that there are two aqueous phases in which life may have emerged. Because most of the Earth’s water today is in the ocean, it is generally assumed that life began in the sea, and hydrothermal vents have been proposed as a possible site [3,4]. A reasonable assumption is that volcanic land masses emerged above sea level 4 Gya [5]

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