STATISTICAL MECHANICS OF LIVING STATE

本研究的目的是提取表征生命状态的一些统计力学性质。为此，我们研究了从分离的细胞团中再生水蛇的过程。分离的细胞最初是一个无序的系统，它不像多细胞动物那样处于生命状态。随着时间的推移，组成细胞开始相互关联，最终形成一个处于生命状态的系统。这个转变由各种过程组成，其中我们澄清了以下事实：(1)动物首先通过细胞分离过程形成内细胞层和外部细胞层。实验研究了细胞分选的机理，并利用基于差动粘附性的物理模型对其进行了模拟，发现两者的差异提出了一个新的未来问题。(2)细胞分选过程完成后，头、脚等结构正式。在这个过程中对细胞的运动进行了测量，发现细胞本质上并不是为了产生结构而移动，而是重新确定了细胞的作用。(3)测量了再生水合物所需的最小组织大小，并用包括扩散反应机制在内的几个因素解释了临界大小。

The aim of the research project is to extract some statistics-mechanical properties which characterize living states.For this aim we studied regeneration process of hydra from dissociated cell aggregate.A dissociated cell is initially a disorganized system which is not in a living state as a multi-cellular animal.As the time elapses,the constitute cells start having correlation and finally forms a system which is in a living state.This transition is composed of various processes among which we clarified the following facts;(1)An animal first forms an internal and an external cell layer by cell sorting process. The mechanism of cell sorting was experimentally investigated and simulated by a physical model based on differential adhesivily.The difference of the two found proposed a new future problem. (2)After the cell sorting process was finished,the structures such as head and foot were formal. The motion of the cells were measured during this process.It was found that the cells do not essentially move to produce structure,but that the role of cells is newly determined. (3)Minimum tissue size required to regenerate a hydra was measured.The critical size was explained by several factors including a diffusion-reaction mechanism.