The retinal determination gene, dachshund, is required for mushroom body cell differentiation

The dachshund gene of Drosophila encodes a putative transcriptional regulat or required for eye and leg development. We show here that dachshund is als o required for normal brain development. The mushroom bodies of dachshund m utants exhibit a marked reduction in the number of alpha lobe axons, a diso rganization of axons extending into horizontal lobes, and aberrant projecti ons into brain areas normally unoccupied by mushroom body processes. The ph enotypes become pronounced during pupariation, suggesting that dachshund fu nction is required during this period. GAL4-mediated expression of dachshun d in the mushroom bodies rescues the mushroom body phenotypes. Moreover, da chshund mutant mushroom body clones in an otherwise wild-type brain exhibit the phenotypes, indicating an autonomous role for dachshund, Although eyel ess, like dachshund, is preferentially expressed in the mushroom body and i s genetically upstream of dachshund for eye development, no interaction of these genes was detected for mushroom body development. Thus, dachshund fun ctions in the developing mushroom body neurons to ensure their proper diffe rentiation.