GENES THAT GUIDE GROWTH CONES ALONG THE C-ELEGANS VENTRAL NERVE CORD

During nervous system development, growth cone pioneering and fascicul ation contribute to nerve bundle structure, Pioneer growth cones initi ally navigate along neuroglia to establish an axon scaffold that guide s later extending growth cones. In C. elegans, the growth cone of the PVPR neuron pioneers the left ventral nerve cord bundle, providing a p ath for the embryonic extensions of the PVQL and AVKR growth cones, La ter during larval development, the HSNL growth cone follows cues in th e left ventral nerve cord bundle provided by the PVPR and PVQL axons. Here we show that mutations in the genes enu-l, fax-1, unc-3, unc-30, unc-42 and unc-115 disrupt pathfinding of growth cones along the left ventral nerve cord bundle, Our results indicate that unc-3 and unc-30 function in ventral nerve cord pioneering and that enu-1, fax-1, unc-4 2 and unc-115 function in recognition of the PVPR and PVQL axons by th e AVKR and HSNL growth cones.