9729649 PHILLIS Dr. Phillis's research focuses on the role of the "motor protein" dynein in neuronal development and the establishment of the mature anatomy of neuronal axons. Although dynein is well known to be involved in the movement of intracellular components along microtubules, Dr. Phillis's analysis of the gene for cytoplasmic dynein light chain, Cdlc1, in the fruitfly Drosophila has suggested a role for this molecule in shaping the growing tips of axons. This research encompasses three projects, each designed to investigate specific aspects of the cytoplasmic dynein light chain with respect to axon anatomy. The first project involves the analysis of when Cdlc1 mutations affect axon projections during development. Using a set of genetic markers, Dr. Phillis and his colleagues will label specific sensory neurons and their axons as they undergo pathfinding in the central nervous system during development. They will then characterize the development of these axons in Cdlc1 mutants, and compare them with observations of wild type development. This analysis will help determine the timing of onset of axon defects caused by Cdlc1 mutations. In addition, Dr. Phillis's group will create a mutant form of Cdlc1 that can be activated by temperature shifts. With this inducible gene, it will be possible to determine the specific time in development when Cdlc1 function is required for the establishment of proper neuronal anatomy. In a second project, Dr. Phillis's group will characterize the effects of Cdlc1 mutations on neurons grown in primary cell culture, using a microtubule labeling system that allows the analysis of microtubule dynamics in live cells. These experiments will resolve the effects that Cdlc1 mutations have on the growth dynamics of individual neurons, and on the dynamic changes in cytoskeletal architecture that underlie the growth of axon projections. Finally, Dr. Phillis's group will perform a genetic screen for mutations that either enh ance or suppress the effects of Cdlc1 mutations on axonal growth. Subsequent genetic and molecular characterization of genes identified in this analysis will provide a detailed understanding of a series of genes that function with Cdlc1 in neural development.
