Summaryaccordion, a zebrafish behavioral mutant, has a muscle relaxation defect due to a mutation in the ATPase Ca 2+

We report a simple and rapid method to label individual neurons in live zebrafish embryos and to examine their gene expression profiles. Injection of plasmid DNA encoding an alpha-tubulin promotor driving GFP expression results in mosaic embryos containing a limited number of GFP-positive neurons. Labeled neurons express GFP in their soma and axon, providing the opportunity to analyze pathfinding behaviors of identified neurons in vivo. Moreover, the presence of only a small subset of GFP tagged neurons permits the rapid anatomical identification of these neurons based on soma position and axonal trajectory. Analysis of injected embryos reveals that most, if not all, spinal cord cell types and many other neuronal cell types elsewhere in the nervous system can be GFP tagged. Finally, by combining GFP labeling of individual neurons with fluorescent in situ hybridization, we demonstrate the potential of this method to elucidate gene expression patterns at single cell resolution.