UL

Application of pulsed electric field (PEF) can reversibly increase the permeability of the cell membrane allowing the access of otherwise impermeable DNA molecules to the inside of the cell. Introduction of foreign DNA molecules encoding immuno-modulatory proteins, antibodies and antigens into cells using PEF, known as Gene Electro-Transfer (GET), is increasingly used for the modulation of the immune system or immunotherapy. While GET based immunotherapy presents itself as a potent application for treatment of cancer and vaccination against infectious diseases, it is suffering from low levels of transgene expressions in vivo. This low efficiency can largely be attributed to our lack of fundamental understanding of the mechanisms by which DNA molecules overcome the barriers of the extra-cellular matrix and the cell membrane in the presence of an electric field. In this action, I aim to provide this required fundamental understanding using principles of polymer physics, soft matter and statistical mechanics. Experiments based on these principles will be conducted in vitro and in vivo to generate results that can be directly compared to theories and models of DNA transport through the extra-cellular matrix and the cell membrane. Understanding the mechanisms within the frameworks of polymer physics will radically improve the efficiency of GET immunotherapy, because it will provide a mechanistic ground for developing optimum protocols within complex tissue environments that can, at the same time, be readily transferred across tissue types and species.

Charged colloidal suspensions consist of charged micron-sized particles dispersed in a solvent with nanometer-sized ions, and they find ample applications in material science, food industry and drug development. The particle charge, together with a diffuse ion cloud that screens this particle charge, is called the electric double layer and it is pivotal in understanding the phase behaviour and interactions in these suspensions. However, no attention has been paid to the topological properties of the electric double layer. While drawing heavily on recent advances in liquid crystalline systems with topologically non-trivial orientational ordering, we propose to explore the topology of electric double layers, which could ultimately lead to enhanced stability of charged colloidal crystals. Specifically, we will focus on particles with topologically non-trivial shapes and explore the coupling between the topological invariants of the particle (such as genus) with the emergent electric double layer, and how this affects interparticle interactions and the phase behaviour. Finally, the goal of this proposal is to obtain a precise control over charged colloidal suspensions that are protected by topological, rather than only energetic binding, opening a fundamental and applied route to a new class of topological soft matter.

The idea of parasite manipulation is well known in animal behaviour, with famous examples like the cordyceps ?zombie? fungus of ants. Yet, the most abundant and diverse parasites on earth do not target animals but rather bacteria. They are the bacteriophages, or phages. My hypothesis is that it is in phages that we will find the most important examples of parasite manipulation, examples that will help us both understand and control bacteria, and their impacts. I will focus on the recently-discovered Regulatory Switch (RS) phage, which reversibly excise and reintegrate into the bacterial chromosome to shift the host between different physiological states. I, and others, have shown that RS phages influence a wide variety of bacterial traits including sporulation, biofilm formation, mutation rates or bacteriocin production. However, we do not understand when, how or why these viruses cause such large changes to bacterial behavior. The goal of my project, therefore, is to understand how and why RS phage evolve as a new candidate model of parasite manipulation. Specifcally, I will answer: 1) When and how do RS phages alter host behavior? 2) What is the molecular basis for the effects of RS phage? 3) Why have RS phage evoved to change bacterial behaviours, and is there evidence of counter strategies in their bacterial hosts? I will work with the bacterium Bacillus subtilis, which is strongly affected by RS phage and a model organism, allowing me to employ the very latest molecular methods. My goal is to demonstrate that parasite manipulation is a major factor in the ecology and evolution of bacteria, whereby many bacteria are essentially puppets of their phage masters. Understanding how phage achieve this manipulation also has the potential for broad impacts in an era when the need to find new ways to control bacteria becomes ever greater.