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PHYSICAL SCIENCES / BIOLOGICAL SCIENCES / GEOLOGY / EVOLUTION
Extreme accumulation of nucleotides in simulated hydrothermal pore systems
*Biophysics Department, Ludwig-Maximilians Universität München, Amalienstrasse 54, 80799 München, Germany; Geochemistry Group, Institute for Mineralogy and Petrology, Swiss Federal Institute of Technology, ETH-Zürich, 8092 Zürich, Switzerland; and Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91125
Edited by Howard Brenner, Massachusetts Institute of Technology, Cambridge, MA, and approved March 9, 2007 (received for review October 28, 2006)
We simulate molecular transport in elongated hydrothermal pore systems influenced by a thermal gradient. We find extreme accumulation of molecules in a wide variety of plugged pores. The mechanism is able to provide highly concentrated single nucleotides, suitable for operations of an RNA world at the origin of life. It is driven solely by the thermal gradient across a pore. On the one hand, the fluid is shuttled by thermal convection along the pore, whereas on the other hand, the molecules drift across the pore, driven by thermodiffusion. As a result, millimeter-sized pores accumulate even single nucleotides more than 108-fold into micrometer-sized regions. The enhanced concentration of molecules is found in the bulk water near the closed bottom end of the pore. Because the accumulation depends exponentially on the pore length and temperature difference, it is considerably robust with respect to changes in the cleft geometry and the molecular dimensions. Whereas thin pores can concentrate only long polynucleotides, thicker pores accumulate short and long polynucleotides equally well and allow various molecular compositions. This setting also provides a temperature oscillation, shown previously to exponentially replicate DNA in the protein-assisted PCR. Our results indicate that, for life to evolve, complicated active membrane transport is not required for the initial steps. We find that interlinked mineral pores in a thermal gradient provide a compelling high-concentration starting point for the molecular evolution of life.
concentration problem | hydrothermal vents | molecular evolution | origin of life problem | RNA world
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
See Commentary on page 9105.
To whom correspondence should be addressed. E-mail: dieter.braun{at}physik.lmu.de
© 2007 by The National Academy of Sciences of the USA
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