Dynamics of Cell Differentiation

It is well-known that identical living cells within complex multi-celluar organisms (e.g. humans) can respond to environmental signals and perform different, but co-ordinated roles. One of the most striking examples of this is in embryo development. This process is due to ?cell differentiation? and until recently, it was thought this behaviour was only found in complex, multi-cellular organisms. However, recently it has been discovered that simple single-celled organisms such as bacteria, also display cell differentiation and so to some extent can behave as multi-cellular collectives . One of the most striking examples of cell differentiation in bacteria occurs in the formation of biofilms. A biofilm contains billions of individual cells encased in a self-produced polymer glue. Despite each bacterial cell being genetically identical, the community soon differentiates into sub-populations, each carrying out a different role. Just how this complex multi-cellular decision making process occurs is far from understood. Almost all bacteria that occur in the natural environment live in these closely-knit biofilms and they are important to all aspects of our lives e.g. human health, the effective treatment of sewage and even daily dental care: plaque is a bacterial biofilm. The overall aim of this work is to better understand how differences in the way genes within individual bacterial cells respond to environmental signals leads to the segregation of these cells into sub-populations, each of which behaves in an entirely different, but apparently co-ordinated, manner. In this project I will focus on the well-studied bacterium Bacillus subtilis, which is used to produce enzymes for cleaning products (e.g. biological washing powder) and has growing potential as an alternative and environmentally friendly pesticide. Biofilms are so complex and cover such a wide range of scales (it would take 1000 cells laid end-to-end to cross a pin head but biofilms can be centimetres or even metres across) that it is necessary to take an inter-disciplinary ?systems? approach. I intend to use a combination of powerful modern mathematical modelling techniques supported by state-of-the-art molecular biology experimental procedures and will work closely with biofilm expert Dr Nicola-Stanley Wall, University of Dundee. Very recently, I appear to have uncovered an entirely new mathematical theory that may explain cell differentiation. It is this exciting discovery that motivates the work of this proposal.