Department of Biology, University of Massachusetts, Amherst, MA 01003 USA,
One of the P[lacW] insertions recovered in a behavioral screen was found to disrupt grooming behavior and had a number of other defects. Weak excision alleles are behaviorally mutant, female sterile and exhibit bristle thinning and bristle loss. Null alleles are pupal lethal and exhibit altered axon projections within the imaginal CNS. P[Gal4] marker lines and an engrailed -LacZ construct were used to characterize the sensory axon projections of tactile and stretch receptor neurons. In mutant animals both types of sensory neuron exhibited altered axon trajectories within the CNS. However, the alterations in axon trajectory did not prevent these axons from reaching their normal termination regions. In the alleles producing these neuronal phenotypes, expression of the cytoplasmic dynein 8kD light chain gene is completely absent suggesting that the dynein light chain is involved in growth cone guidance. We are in the process of characterizing the early in-growth of axons in mutant and wildtype specimens in order to better understand the nature of the defects. The results demonstrate a new function for the cytoplasmic dynein light chain in the regulation of axonogenesis and may provide a point of entry for studies of the role of cellular motors in growth cone guidance. Supported by NSF and NIH.