Alladi Ramakrishnan Hall

Single cell gene regulation: Expression noise and the evolution of gene regulation

Erik van Nimwegen

Biozentrum, University of Basel, Switzerland

How does gene regulation evolve de novo? In the first part of my talk I will present novel insights into this question that result from an integrated experimental/theoretical study of genome-wide transcriptional noise in E. coli. In particular, by comparing the noise properties of native E. coli promoters with those of synthetic promoters that we evolved in the lab, we found that natural selection must have acted to increase the noise levels of promoters of regulated genes. To explain this observation, we developed a general theory for the interplay between gene regulation and gene expression noise in the evolution of gene regulation. This theory shows that noise propagation from regulators to their targets is often beneficial and can be considered a rudimentary form of gene regulation.

In the second part of my talk I will present a new integrated experimental and computational setup consisting of a dual-input microfluidic device and accompanying image analysis software that allows long-term and highly accurate tracking of growth and gene expression in lineages of single cells. As an example application I will present novel insights into an iconic regulatory system: the induction of the lac operon in E. coli in response to a switch in carbon source from glucose to lactose.