Bhatnagar Rajat, El-Samad Hana
Department of Biochemistry and Biophysics, California Institute for Quantitative Biosciences, University of California at San Francisco, 1700 4th Street, San Francisco CA 94158.
Center for Systems and Synthetic Biology, University of California at San Francisco, San Francisco CA 94158.
Eur J Control. 2016 Jul;30:68-75. doi: 10.1016/j.ejcon.2016.04.010. Epub 2016 May 13.
Biological systems must sense and adapt to changes in their environment. Molecular networks capable of such adaptation belong to two well-known classes, feed-forward and feedback structures, but the fundamental limitations and tradeoffs of these two classes remain unknown. Here we study the advantages and limitations of the feedforward class using three-node circuits representative of these architectures. The feedforward model we investigate displays a tradeoff between the sensitivity of the response (its peak response) and its precision (its error in its return to steady-state). We suggest two ways in which this tradeoff can be alleviated: (1) by introducing a nonlinearity in the production of a specific node in the network, or (2) by adding a feedback loop to the input. We present analytical and numerical examples to support our findings.
生物系统必须感知并适应其环境的变化。能够进行这种适应的分子网络属于两个著名的类别，即前馈和反馈结构，但这两类结构的基本局限性和权衡关系仍然未知。在这里，我们使用代表这些架构的三节点电路来研究前馈类的优点和局限性。我们研究的前馈模型显示了响应灵敏度（其峰值响应）与其精度（其恢复到稳态时的误差）之间的权衡。我们提出了两种可以减轻这种权衡的方法：（1）通过在网络中特定节点的产生过程中引入非线性，或（2）通过向输入添加反馈回路。我们提供分析和数值示例来支持我们的发现。
