In our lab, we investigate molecular mechanisms that control the development of sensory nerves. We take advantage of the powerful genetics of the model organism Drosophila (fruit fly) to characterize genes that allow growing nerve processes to connect to other nerve cells and form a functional brain. We have identified the receptor protein Dscam, which is specifically expressed on the surface of growing nerves. Flies that lack Dscam exhibit strong disruptions of many nerve connections and die as embryos. One of the most exciting aspects of the Dscam protein is its enormous number of subtly different isoforms (approximately 38,000) present on developing nerves, suggesting the provocative possibility that these different forms may provide unique “molecular fingerprints” for different nerve fibers.