Xu Li, Wang Jin
State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, P.R. China.
Department of Chemistry and of Physics and Astronomy, State University of New York at Stony Brook, Stony Brook, New York 11794-3400, United States.
J Phys Chem B. 2020 Apr 2;124(13):2549-2559. doi: 10.1021/acs.jpcb.9b11998. Epub 2020 Mar 24.
The underlying interactions in physical and biological systems often lead to a variety of behaviors and emergent states or phases. Under certain conditions, these phases can be transformed from one to another. The phase transition behaviors can be described by the bifurcation or catastrophe where different stable/unstable states can branch out or meet together with the birth of the new and death of the old states. Despite significant efforts, how the bifurcation and catastrophe actually occur dynamically and the associated mechanisms for nonequilibrium systems are still not very clear. As an example, we study the underlying mechanism of cell differentiation through bifurcations. Cell differentiation is one of the key fate decision-making processes that a cell faces. It is crucial for the development of multicellular organisms. Under induction, gene regulation changes, or stochastic fluctuations, the cell fate decision-making processes can exhibit different types of bifurcations or phase transitions. In order to understand the underlying mechanism, it is crucial to find out where and how the bifurcation occurs. However, this is still largely unknown. In this study, we found that the average of the curl flux as a major component of the driving force for the dynamics in addition to the landscape gradient and the associated entropy production rate both reach maximum near the bifurcation. This indicates that the curl flux and entropy production rate may provide the dynamical and thermodynamic origins of the bifurcation/catastrophe or phase transitions for cell differentiation and this possibly applies to many other nonequilibrium active systems.
物理和生物系统中的潜在相互作用通常会导致各种行为以及涌现状态或阶段。在某些条件下，这些阶段可以相互转化。相变行为可以用分岔或突变来描述，其中不同的稳定/不稳定状态可以分支出来或随着新状态的诞生和旧状态的消亡而汇聚在一起。尽管付出了巨大努力，但分岔和突变实际上是如何动态发生的以及非平衡系统的相关机制仍然不是很清楚。例如，我们通过分岔研究细胞分化的潜在机制。细胞分化是细胞面临的关键命运决策过程之一。它对多细胞生物的发育至关重要。在诱导、基因调控变化或随机波动的情况下，细胞命运决策过程可以表现出不同类型的分岔或相变。为了理解潜在机制，找出分岔发生的位置和方式至关重要。然而，这在很大程度上仍然未知。在这项研究中，我们发现除了景观梯度和相关的熵产生率之外，作为动力学驱动力主要成分的旋度通量平均值在分岔附近都达到最大值。这表明旋度通量和熵产生率可能为细胞分化的分岔/突变或相变提供动力学和热力学起源，这可能适用于许多其他非平衡活性系统。
