A mutation in Drosophila alters normal connectivity between two identified neurones

The mechanisms involved in producing the vast number of specific connections in the nervous system are unknown. As nerve cells grow during development and seek out their targets there must be some sort of molecular cues for axonal guidance and final target recognition. One strategy for identifying such factors is to locate the genes which code for or control the expression of the molecules. To identify these genes, we have chosen a simple network of eight neurones in Drosophila melanogaster, comprising the giant fibre (GF) system1–3, in which we can detect the effect of mutations on connectivity. We report here the isolation of an X-linked, recessive mutation, bendless (ben), which deletes one process of the GF while leaving other portions functionally unaltered.