This will be a double session with two talks of 25min each.
1. Using populations of engineered cells to regulate extracellular chemical concentrations
Jordan Ang (Imperial)
We are working to construct a synthetic gene network intended to allow a population of engineered bacterial cells to actively regulate the extracellular concentration of a small molecule. To accomplish this, the cells will be equipped with both the ability to sense the extracellular concentration level of the molecule, as well as the ability to synthesize and secrete the molecule itself. An intercellular control circuit linking sensing to biochemical synthesis will effectively couple the cell population’s overall secretion rate to the extracellular small molecule concentration. By tuning the control circuit design around the strategy of integral feedback control, our aim is to best allow for the automatic and precise adjustment of the secretion rate in response to static perturbations to the extracellular concentration.
The nature of biochemical networks, however, can make the implementation of even basic control structures challenging. In this talk, I’ll focus on some of the challenges associated with our design and the strategies we are using to work with them.
2. Decision-making in short and long-term osmotic adaptation in yeast.
Alejandro Granados (Imperial/U. Edinburgh)
The ability of biological systems to interact with the environment and survive depends upon the detection of specific signals and organization of adequate physiological responses. At the cellular level, information from environment is processed using molecular networks that orchestrate the appropriate response, which often includes changes gene expression. The high osmolarity glycerol (HOG) pathway in yeast serves as a prototype signaling system for eukaryotes. Its main function is to sense changes in osmotic pressure and coordinate a wide range of molecular processes that lead to adaptation of cell volume. The signaling properties of the HOG pathway have been widely studied both experimentally and theoretically. An integrative framework, however, that connects the dynamic properties of the HOG pathway to its ability to process information is still missing. Moreover, experimental conditions used previously are unlikely to be experienced by yeast in the wild and might lead to incomplete conclusions. Yeast osmoregulation is a decision-making system that must respond at short times to enable survival and at longer times to enable adaptation. Using microfluidic experiments and techniques from control theory, we are determining how the HOG network performs these two tasks when facing dynamic environments.