Muscle Research         The goal of our muscle research lab is to investigate the assembly and organization of myofilaments within the body wall muscle of the free-living nematode Caenorhabditis elegans. Specifically, we are attempting to identify new proteins critical for organizing the sarcomere adhesion complex and determine how and where these proteins participate in this process. We are taking advantage of a new expression database that we have established for C. elegans developing muscle founded on SAGE and Affymetrix Genechip expression data that identifies 5,000 genes expressed in muscle, including many genes with human homologs for which there is no function identified in either humans or nematodes. Recently we have completed an RNAi sweep of 3,500 genes from this muscle dataset and have identified over 100 genes that affect sarcomere organization and stability when their encoded proteins are reduced. We are concurrently producing functional protein::GFP fusions for each gene in our 5,000 gene dataset to identify the position of these proteins within a muscle cell. Lastly, we are using muscle proteins tagged with GFP in a series of immunoprecipitations followed by Mass Spectroscopy to identify novel proteins associated with components of the sarcomere. Data from all three approaches will be compiled and compared, and should eventually provide a precise description in molecular detail of myofilament assembly and organization within muscle.  Muscle Cell Migration Project In C. elegans myoblasts arise from several different founder cell lineages. These cells initially arrange themselves in two rows along the left and right lateral midlines and at ~290 min of development they migrate dorsally and ventrally to form the four muscle quadrants present upon hatching. As the myoblasts migrate they are still dividing, as are many other cells around them. This means the cell-cell contacts of cells during migration varies from animal to animal. This situation creates an environment where the extracellular matrix (ECM) and cell surface contacts are in constant flux, which begs the questions as to how these cells navigate unerringly to their final destination. A number of ECM and cell surface components are known to affect cell positioning, migration and attachment in other organisms. The C. elegans homologues of these proteins are involved in the same processes, but during late development, and do not appear to have a role during myoblast migration. In an effort to identify the proteins involved in early myoblast migrations we are currently testing genes predicted to be in, or interacting with the ECM using RNAi knockdowns. A two-tiered approach involving fluorescent and 4-D microscopy is being used to identify RNAi treated animals for potential muscle migration and positioning defects.