Biolocomotion and Premelting in Ice

Abstract

Biota are found in glaciers, ice sheets and permafrost. Ice bound micro-organisms evolve in a complex mobile environment facilitated or hindered by a range of bulk and surface interactions. When a particle is embedded in a host solid near its bulk melting temperature, a melted film forms at the surface of the particle in a process known as interfacial premelting. Under a temperature gradient, the particle is driven by a thermomolecular pressure gradient toward regions of higher temperatures in a process called thermal regelation. When the host solid is ice and the particles are biota, thriving in their environment requires the development of strategies, such as producing exopolymeric substances (EPS) and antifreeze glycoproteins (AFP) that enhance the interfacial water. Therefore, thermal regelation is enhanced and modified by a process we term bio-enhanced premelting. Additionally, the motion of bioparticles is influenced by chemical gradients influenced by nutrients within the icy host body. We show how the overall trajectory of bioparticles is controlled by a competition between thermal regelation and directed biolocomotion. By re-casting this class of regelation phenomena in the stochastic framework of active Ornstein-Uhlenbeck dynamics, and using multiple scales analysis, we find that for an attractive (repulsive) nutrient source, that thermal regelation is enhanced (suppressed) by biolocomotion. This phenomena is important in astrobiology, the biosignatures of extremophiles and in terrestrial paleoclimatology.

Marine Science Can Contribute to the Search for Extra-Terrestrial Life

“…Earth glaciers are formed from the gradual and continuous accumulation of snow and store information on past environmental conditions of our planet. Microorganisms inhabiting glaciers provide valuable information on the adaptive strategies of extraterrestrial life potentially inhabiting icy moons [ 136 , 139 , 140 , 141 , 142 ]. Marine hydrothermal and deep-sea habitats are postulated as models for putative life-bearing extreme environments in exo-oceans.…”

Supercriticality, Glassy Dynamics, and the New Insight into Melting/Freezing Discontinuous Transition in Linseed Oil

“…therein. They can be as follows [62,[75][76][77][78][79][80][81][82][83][84][85][86][87][88][89][90]: (i) premelting effects are 'weak' and rangelimited, (ii) they are detected only for some systems, (iii) they are detected for selected physical properties, (iv) there are no reports on their parameterization, except the very recent ref. [72], and (v) no solid-state pretransitional effects for freezing, i.e.…”

“…Despite the apparent limitations and problems, premelting effects are commonly considered the gateway for explaining the nature of melting/freezing discontinuous phase transitions [62,72,[75][76][77][78][79][80][81][82][83][84][85][86][87][88][89][90]. This cognitive situation is qualitatively different from continuous phase transitions: understanding their origins is one of the greatest universalistic successes of 20th-century physics, as concluded in Critical Phenomena Physics [33].…”

“…For melting/freezing discontinuous transitions, such pretransitional effects are (almost) absent, except for the puzzling premelting effects in the solid state [62,[75][76][77][78][79][80][81][82][83][84][85][86][87][88][89][90]. In linseed oil, both premelting and post-freezing effects exist, and the latter are even stronger and longer ranged.…”