[
European Worm Meeting,
2002]
Signaling molecules and receptors important for axon guidance and fasciculation are likely to be found among extracellular and cell surface molecules. The complete sequence of the C. elegans genome allows the identification of all members of known receptor and adhesion families. One of the largest families of adhesion molecules with a role in nervous system development is the immunoglobulin-superfamily (IgCAM-SF). IgCAM family members can be grouped according to their modular organisation. 28 genes encode transmembrane or GPI-anchored proteins with extracellular IG modules. We are focusing on a core of 17 IgCAMs. Five of them consist of IG- modules only, the remaining twelve have one or more fibronectin III (F3) modules in addition to IG-modules. For 15 of them no function is known. To identify IgCAMs with a putative role in axonal outgrowth we started to analyze expression patterns for these genes. Transgenic animals were generated expressing promoter-GFP fusion constructs for individual IgCAMs. Expression typically is dynamic and not confined to a single tissue. Some IgCAMs (e.g. C26G2.1) show predominantly non-neuronal expression. Many others are expressed mainly in particular subsets of neurons (see also Supplementary Material to Aurelio O. et al. (2002); Science, 295: 686-690). Five IgCAMS (C53B7.1, F41D9.3, K02E10.8, K09E2.4, Y42H9B.2) are expressed in motorneurons or interneurons with axons in the ventral cord. We are currently isolating deletion alleles in these genes from our deletion library to begin a functional analysis.