Yi Tau-Mu, Andrews Burton W, Iglesias Pablo A
Department of Developmental and Cell Biology, Center for Complex Biological Systems, Irvine, California, USA.
Methods Enzymol. 2007;422:123-40. doi: 10.1016/S0076-6879(06)22006-8.
Bacteria such as Escherichia coli demonstrate the remarkable ability to migrate up gradients of attractants and down gradients of repellents in a rapid and sensitive fashion. They employ a temporal sensing strategy in which they estimate the concentration of ligand at different time points and continue moving in the same direction if the concentration is increasing in time, and randomly reorient if the concentration is decreasing in time. The key to success is accurate sensing of ligand levels in the presence of extracellular and intracellular disturbances. Research from a control theory perspective has begun to characterize the robustness of the bacterial chemotaxis signal transduction system to these perturbations. Modeling and theory can describe the optimal performance of such a sensor and how it can be achieved, thereby illuminating the design of the network. This chapter describes some basic principles of control theory relevant to the analysis of this sensing system, including sensitivity analysis, Bode plots, integral feedback control, and noise filters (i.e., Kalman filters).
诸如大肠杆菌之类的细菌展现出了以快速且灵敏的方式沿引诱剂梯度向上迁移以及沿驱避剂梯度向下迁移的卓越能力。它们采用一种时间感知策略，即估算不同时间点配体的浓度，若浓度随时间增加则继续沿同一方向移动，若浓度随时间降低则随机重新定向。成功的关键在于在存在细胞外和细胞内干扰的情况下准确感知配体水平。从控制理论角度开展的研究已开始刻画细菌趋化信号转导系统对这些扰动的稳健性。建模与理论能够描述此类传感器的最优性能及其实现方式，从而阐明该网络的设计。本章介绍了与该传感系统分析相关的控制理论的一些基本原理，包括灵敏度分析、波特图、积分反馈控制以及噪声滤波器（即卡尔曼滤波器）。
