Movement of motor and cargo along cilia

Intraflagellar transport (IFT)1 is important in the formation and maintenance of many cilia, such as the motile cilia that drive the swimming of cells and embryos2, the nodal cilia that generate left-right asymmetry in vertebrate embryos3, and the sensory cilia that detect sensory stimuli in some animals4. The heterotrimeric kinesin-II motor protein drives the anterograde transport of macromolecular complexes, called rafts, along microtubule tracks from the base of the cilium to its distal tip5, whereas cytoplasmic dynein moves the rafts back in the retrograde direction6. We have used fluorescence microscopy to visualize for the first time the intracellular transport of a motor and its cargo in vivo. We observed the anterograde movement of green fluorescent protein (GFP)-labelled kinesin-II motors and IFT rafts within sensory cilia on chemosensory neurons in living Caenorhabditis elegans.