Title:
Trapping by an “entropic” force: from the origin of life to boosted cell migration
Yusuke T. MAEDA1, 2
1Department of Physics, Graduate School of Science, Kyushu University
2PRESTO, Japan Science and Technology Agency
Abstract:
Temperature differences at large scales, kilometers or more, are present in our planet and essential for plate tectonics and meteorological phenomena. As the earth is blessed with temperature, it has revolutionized our life: the French physicist Nicolas Léonard Sadi Carnot showed the operation of the heat engine in two temperature systems at the industrial revolution, which led to the second law of thermodynamics. Heat can serve as a source of mechanical power, however, little is known about the thermodynamic forces at the molecular and cellular scales.
At the scale of millimeters or microns, temperature differences induce the motion of molecules, which is known as thermophoresis. Thermophoresis depletes a polymer such as polyethylene glycol (PEG) from the hot region and builds a concentration gradient. In such a solution, solutes of small volume fraction experience both thermophoresis and an “entropic” force dependent on concentration contrasts of PEG. We found that the interplay of two effects allows DNA and RNA to localize as a ring-like structure which diameter monotonically decreases with their size following a behavior analogous to gel electrophoresis [1,2]. Moreover, we found that that the transport of those molecules depends on its folding structures, e.g. globule or condensed, flexible or rigid. Thus trapping and selection of molecules could be physically feasible in a simple way. Non-equilibrium transport of DNA and RNA might be relevant to the origin of life: Separation of RNA from the large pool of molecules might occur at the thermal vent of the deep ocean where temperature gradient is present.
In the second half of this talk, we will show that the interplay between temperature and concentration gradients can enhance the velocity of cell migration for eukaryotic amoeba cells, Dictyostelium discoideum. The transport driven by polymer solute contrasts has little material dependence and thereby boosts the spontaneous cell migration in a concentration dependent manner. We will discuss about the potential application of our findings in biology, especially for the manipulation of molecules and cells [3]
References:
[1] YT Maeda, A Buguin, A Libchaber. Phys. Rev. Lett. 107, 038301 (2011)
[2] YT Maeda, T Tlusty, A Libchaber. Proc. Natl. Acad. Sci. USA 109, 17972 (2012)
[3] YT Maeda. Applied Physics Letters, 103, 243704 (2013)
