Mathematics

This is a brief summary of a collaborative project with William Bement on patterns of Cdc42 and Rho that arise when the surface of a cell (frog egg, Xenopus oocyte) is wounded. Based on experimental observations and previous discoveries about proteins such as Abr (a GEF/GAP that activates Rho and inactivates Cdc42) were were able to derive a model that captures aspects the phenomena. The model, in turn, inspired several new experiments, notably those where wounds in close proximity were studied. The observed patterns of overlap of influence from neighbouring wounds can be explained by the model.

We first consider the topic of biological patterns and then place it in the context of developmental biology and positional information. The example of the fruit fly (Drosophilla) development is used to motivate the basic questions. We next consider how chemical interaction coupled to diffusion can give rise to pattern formation. We discuss Turing's (1952) theory for pattern formation and derive the conditions for this to happen in a system of two interacting chemicals. Returning to the fruit-fly example, we observe that the mechanism for development (based on reading the level of bicoid protein) has been shown to be distinct from a Turing pattern

We first consider the topic of biological patterns and then place it in the context of developmental biology and positional information. The example of the fruit fly (Drosophilla) development is used to motivate the basic questions. We next consider how chemical interaction coupled to diffusion can give rise to pattern formation. We discuss Turing's (1952) theory for pattern formation and derive the conditions for this to happen in a system of two interacting chemicals. Returning to the fruit-fly example, we observe that the mechanism for development (based on reading the level of bicoid protein) has been shown to be distinct from a Turing pattern

• Combining mechanics and biochemistry
• Application of scaling to deciphering a molecular mechanism
• Actin and cytoskeleton assembly
• Actin dynamics in the (1D) cell lamellipod
• Continuity (Balance) eqs and Reaction-Diffusion eqs (PDEs)
• Bicoid gradients

In order for an immune cell, such as a T-cell to do its job (kill virus infected cells) it must first undergo an activation event. Activation requires the encounter of the cell surface T-cell receptors (TCRs) with bits of protein that are displayed in special complexes (peptide-MHC complexes) on the surface of a target cell. all cells of the body display such p-MHC complexes, but in normal circumstances only those perceived as infected will be destroyed by T-cells in the process of immune surveillance. In this seminar I will describe both theoretical and experimental work aiming to understand the events that culminate in the activation of the T-cell.