Berlin 2015 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 32: Evolutionary Game Theory II (joint SOE/BP/DY)
BP 32.9: Vortrag
Dienstag, 17. März 2015, 16:00–16:15, MA 001
Length selection and replication in a thermal flow chamber — •Simon A. Lanzmich1, Lorenz M. R. Keil1, Moritz Kreysing2, and Dieter Braun1 — 1Systems Biophysics, LMU Munich, Germany — 2MPI of Molecular Cell Biology and Genetics, Dresden, Germany
The replication of long nucleic acids is central to life. On the early Earth, suitable non-equilibrium boundary conditions were required to surmount the effects of thermodynamic equilibrium such as dilution and degradation of oligonucleotides. One particularly intractable experimental finding is that short genetic polymers replicate faster and outcompete longer ones, leading to ever shorter sequences and the loss of genetic information. We show in theory and experiment that heat flux across an open chamber in submerged rock concentrates replicating oligonucleotides from a constant feeding flow and selects for longer strands. The thermal gradient triggers a complex interplay of molecular thermophoresis, external flow and laminar convection, where the latter drives strand separation and exponential replication. The measurements are understood quantitatively based on the calculation of stochastic trajectories inside the chamber using a two-dimensional random walk model. This allowed to derive lifetimes and thermal oscillation frequencies of the nucleic acids. In an intermediate range of external velocities, the superposition of flow fields retains strands of 75 bases, while strands half as long die out, inverting above dilemma of the survival of the shortest. The combined feeding, thermal cycling and positive length selection opens the door for stable molecular evolution in the long-term micro-habitat of asymmetrically heated porous rock.