Mutations that affect the length, fasciculation, or ventral orientation of specific sensory axons in the Drosophila embryo.

In wild-type Drosophila embryos, five lateral chordotonal (lch) axons in each abdominal hemisegment originate from a midlaterally positioned cluster of neurons and grow, fasciculate, and orient ventrally as they connect with targets in the CNS. We have identified 22 recessive lethal mutations in 12 complementation groups, 8 of which are novel, that differentially affect lch axon growth, fasciculation, or ventral orientation. Mutations in 3 loci result in shorter, but fasciculated and ventrally directed axon bundles. Mutations in 4 complementation groups cause lch axon defasciculation. Mutations in 7 complementation groups cause some lch axon bundles to grow dorsally along a trajectory 180 degrees from normal.