Regensburg 2019 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 6: Poster I

BP 6.83: Poster

Montag, 1. April 2019, 17:30–19:30, Poster B2

DNA Denaturation Induced by Local Salt Fluctuations in a Microfluidic Water Cycle — •Alan Ianeselli and Dieter Braun — Systems Biophysics, Ludwig Maximilian University Munich (Germany)

The evaporation of aqueous solutions can separate pure water from a salt-rich stock. Here, we used a thermal gradient to power a water cycle in a microfluidic chamber filled with water, salts and DNA, under conditions that mimic the Early Earth. The condensation of water vapor led to the formation of water droplets with a low salt content, which then precipitated and diluted the solution locally. The continuous evaporation, condensation and precipitation resulted in local dilution of solutes at the air-water interface. Since salts play a major role in the stability of nucleic acids, we found that the temporary low salt conditions lowered the melting temperature of dsDNA and slowed down the re-annealing process, leading to persistent strand separation at moderate temperatures. This can be important for many prebiotic replication reactions for RNA or DNA that do not tolerate elevated temperatures. The oscillatory dilution mechanism described here provides a route to overcome the strand separation problem and demonstrates microscale implementations of the hydrological cycle for the molecular evolution.