Study of the maintenance mechanism of individuality by random cellular motion and its regulation

要了解人的生存状态，不仅需要了解硬件，还需要了解整个身体工作所依赖的软件。换句话说，要理解维持个性的机制，必须知道处于单细胞状态的细胞和处于多细胞状态的细胞之间的关系。作为最不发达的多细胞物种，九头蛇和网柄盘藻就是很好的研究对象。在几天内就可以从分离的细胞团中再生出九头蛇。鞭毛虫通过饥饿从个体阿米巴中产生细胞聚集和鼻涕虫。随机运动及其控制被认为对多细胞状态的形成起着重要的作用。本研究的主要结果是：1)详细研究了九头蛇细胞聚集体中单个细胞的运动，阐明了细胞集合的统计特性。这些结果有助于了解细胞分选机制。2)盘基网柄菌细胞人工聚集在两个玻璃板之间，在几分钟内就出现了花纹。这种模式与细胞内的氧浓度增加有关。这一模式可能是生物系统分化的第一个前驱模式。

To understand the living state it is necessary to know not only the hardwares but also the softwares by which the whole body works. In other words to understand the mechanism by which individuality is maintained, one must know the relation between the cells in the monocellular state and the cells in the multicellular state. Hydra and dictyostelium, which are the most underdeveloped multicellular species, are the good subjects for this purpose. Hydra can be regenerated from dissociated cell aggregate in a few days. Dictyostelium makes cell aggregation and slugs from individual amoebae by starvation. The random motion and the control of this random motion are considered to play an important role for the formation of the multicellular state.The main results of this research are1) The motion of the individual cells in a cell aggregation of hydra was studied in detail and the statistical properties of the ensmble of cells are clarified. The results were useful for understanding of cell sorting mechanism.2) The cells aggregated of Dictyostelium discoideum artificially between the two glass plate was found to show a patterning in a few minutes. This patterning is related to the oxygen concentration within the cell aggragate. This pattern may be the first prepattern of differentiation in biological system.