Ruth Baker University of Oxford Mathematical modelling in developmental biology Wednesday 2nd May 14:05-14:55pm, Eastern Avenue Lecture Theatre. The recent revolution in molecular biology has led to enormous advances in the field, for example the sequencing of whole genomes and the generation of a huge amount of data. However, given all this new information, biologists are still struggling to answer basic questions about how function and form arise from this grand "blue print" for life; how do genes and proteins interact with each other and the environment to create complex, dynamic, living systems? In order to begin to answer some of these questions, we turn to developmental biology to provide us with some paradigms of systems in which physical and chemical processes interact to produce the spatio-temporal cues guiding formation of living systems. These interactions are inherently nonlinear and therefore not amenable to analysis using the verbal models preferred by many biologists. Indeed, the latter mode of thinking, being linear in nature, can lead to incorrect conclusions. Mathematical modelling and computer simulation are powerful tools in generating and testing hypotheses on how observed phenomena arise from the complex interaction of various physical and chemical processes, and in making experimentally testable predictions. In this talk I will discuss two areas on which my research concentrates: segmentation of the vertebrate head-tail axis and morphogen-controlled domain growth. I will outline each biological system, the mathematical modelling techniques used and the possibilities for hypothesis generation and testing.