题目：Information flow in a genetic network.

报告人：William Bialek, Ph.D.

Professor of Physics, Princeton University.

Member of National Academy of Sciences, United States.

时间：2014-10-23（周四），13:30-14:30pm

地点：北京大学新生物楼邓祐才报告厅

联系人：生命科学联合中心， 汤超

Changes in the concentration of transcription factors (TFs) produce changes in the expression levels of target genes. This means that information about TF concentration is being transferred to the expression level, and if we can measure this information we have a quantitative measure of the “control power” of the regulatory system. But the capacity of any system to transmit information is limited by noise, and there are further levels of optimization needed to make full use of this limited capacity. These qualitative ideas have a precise mathematical expression, and I will explain how this theoretical framework can be connected to experiment. I will then look in detail at the early stages of development in the fruit fly embryo, where a small number of transcription factors act as “morphogens” whose concentration carries information about a cell’s position in the embryo. We can follow the flow of this information into the network of “gap genes,” and then to the pair rule genes that generate the famous striped patterns of expression, precursors of the segmented body plan of the fully developed organism. New quantitative experiments and analyses show that the graded expression levels of the gap genes really are sufficient to specify position with single cell resolution, and that the body plan itself has this very high level of precision. The way in which information is distributed along the length of the embryo exhibits the signatures of a system optimized to make full use of its capacity, pointing toward some more general principles.