Central afferent projections of proprioceptive sensory neurons in Drosophila revealed with the enhancer-trap technique.

We have used a GAL4 enhancer-trap line coupled with an upstream activation sequence (UAS)-linked lacZ reporter construct to visualise and describe the central projections of proprioceptive sensory neurons of the thorax and abdomen in Drosophila. In the legs, lacZ expression is restricted to sensory neurons associated with hair plates, a subset of campaniform sensilla, and with the femoral chordotonal organ; whereas, in the wing, expression is seen only in subsets of campaniform sensilla. In the abdomen, expression is seen in Wheeler's organ and in a segmentally repeated array of internal sensory neurons that have not been previously described. The central projections from all of these neurons are described. The results confirm and expand upon our knowledge of the organisation of sensory neuropils in insects. The enhancer-trap technique provides a potentially powerful tool for describing the organisation of the central nervous system of Drosophila.