Figure 1.
The left panel shows an illustration of a Drosophila fly with labeled parts including the haltere and leg. Close-up views show the structure of the campaniform sensilla, highlighting the scabellum, pedicellus, and capitellum. Detailed diagrams depict the mechanosensory organelle (MO) and the tubular bundle (TB) distal to the cilium. The right panel shows the nanoscopic organization of the MO in wild-type (WT) and Kif19A mutant flies. In WT, Kif19A drives directed transport of the mechanoreceptor NompC towards the tip, with local binding limiting diffusion. In Kif19A mutants, the directed transport is reduced, affecting the distribution of NompC.
Fly campaniform sensilla are mechanosensory neurons localized in particular on the leg and haltere of the fly, and contribute to several behaviors. The sensory neurons harbor a specialized ciliary ending with specific shape and molecular organization above the cilium per se. Zooming on the tip, the MO, mechanosensory organelle, on the right panel, the bimodal distribution of the NompC mechanoreceptor is observable. This distribution relies on the activity of Kif19A, which drives active transport toward the tip. The active binding from extracellular clues limits passive diffusion of the protein, and a precise balance between these three factors is responsible for the nanodomain organization of NompC. TB, tubular bundle.