Collaborative Research Proposal Buettner/Cassimeris The aim of this research is to develop a quantitative framework for characterizing microtubule dynamics and assessing their contribution to neurite extension and growth cone motility. The experiments to be done will combine both an experimental and theoretical approach. Taking advantage of the expertise of Dr. Cassimeris in imaging fluorescently labelled tubulin in growth cones, the first series of experiments will generate a time series of video images of the assembly of microtubules from labelled tubulin and this will be compared with a similar analysis of the dynamic patterns of microtubule behavior in living growth cones. The theoretical expertise of Dr. Buettner will then allow for the construction of a quantitative theoretical model of the contribution of microtubule assembly to neurite growth and motility. This particular combination of an engineering approach to modelling with state of the art cell biological experiments will yield significant insights into our understanding of the relationships between microtubule dynamics and growth cone mobility during the developement of the nervous system.