During development of the nervous system, newly generated cells must extend processes over substantial distances to establish contacts with their correct target cells. A central issue in developmental neurobiology is to understand how these processes navigate accurately through the embryo. At the tips of extending processes are growth cones that detect guidance information and, on the basis of this information, orient the direction of process extension. A unique culture system of the exposed grasshopper embryo limb in combination with high-tech imaging will be used to visualize the growth cones of growing neurons and study molecular mechansims involved in growth cone steering. Specifically, the role of actin molecules in growth cone steering will be investigated through the use of fluorescent probes and laser photobleaching techniques. Experimental manipulation of actin in situ will shed light on the relationships of actin to other cytoskeletal components and cell-substrate interactions.
