単細胞微生物の分子機械回路

Abstract

Microorganisms such as bacteria and paramecia show chemotaxis, thermotaxis and other tactic behaviors. For these behaviors they have an organized system of molecular machines, sensors, processors, transmitters, switches and motors. A theoretical analysis is given to understand what kind of organization of molecular machines they have. The connection from sensors to motors is not direct or deterministic, but indirect and probabilistic. They have a fluctuation generator and set the magnitude of fluctuation at an appropriate level in comparison with sensitivities and time constants of sensors, processors and switches. By such organization, they do not fall into a local best but continue to look for a better place in an inhomogeneous and varying environment.