Multi-Color and single-molecule fluorescence imaging of intraflagellar transport in the phasmid chemosensory cilia of c. elegans
Sensory cilia are essential ‘antenna-like’ organelles that protrude out of many eukaryotic cells, acting as signal transducers, enabling cells to sense and respond to the external environment. The model system for this proposed study, chemosensory cilia of C. elegans are well characterised and enable the animal to sense water soluble effectors in the environment for chemotaxis. Cilia consist of an axoneme encapsulated with a signalling protein-rich ciliary membrane. The axoneme, which is a microtubule-based core structure, acts as a template for a specialised intra-cellular transport, intraflagellar transport (IFT). IFT trains are large protein complexes that mediate contacts between motor proteins (IFT kinesins and IFT dynein) and ciliary cargoes, crucial for the formation and maintenance of the cilia, with anterograde IFT trains moving outwards from the ciliary base to deliver ciliary building blocks to the ciliary tip and retrograde IFT trains moving from the ciliary tip to the ciliary base to recycle the waste products. The overarching objective of this project is to grasp the connection between chemosensory function of cilia (initiating chemotaxis), IFT and ciliary length-regulation using single-molecule imaging techniques. In order to achieve this, (i) I will develop a multi-color and single-molecule imaging toolbox to study IFT in the phasmid chemosensory cilia of C. elegans. (ii) Using the toolbox, I will obtain a mechanistic understanding of turnaround dynamics of the IFT machinery (IFT motors and components of the IFT trains), during normal IFT. (iii) A comprehensive understanding of normal IFT will enable discovery of the subtle adjustments made by the IFT machinery, and its effect on the cilia length, in response to chemical cues in the external environment. Ultimately, the goal is to understand how organism level tactic response is interlinked with intracellular transport in the ciliary antennas of individual cells, using C. elegans as a model system.