During development, neurons (nerve cells) develop elaborate processes that may extend over long distances to reach highly specific local targets. The mechanisms that determine such accurate pathfinding and connectivity are not fully known. The fruitfly, Drosophila, has provided valuable data on such development, and the ease of producing genetic crosses and mutations provides approaches to the molecular mechanisms involved. Ground-based studies show in great detail how particular motor neurons develop specific connections with specific muscles. With this very detailed background from identified single cells, this project uses the space flight of Neurolab as a unique opportunity to test, by lacking normal gravity, how gravity may be a subtle cue important in developing such neuronal outgrowths and connections normally. Drosophila has the advantages for space flight of having very low mass and needing minimal care, so this study can involve very large numbers of individuals to assay developmental variability. Results of this study will be important for developmental neuroscience, and also will raise issues important for developmental biology in general. Contribution to this project represents the NSF Biological Sciences Directorate's participation in the NASA/Interagency Neurolab activity on the space shuttle orbiter, which in turn is part of Decade of the Brain activities.
