Dye-filling of the amphid sheath glia: implications for the functional relationship between sensory neurons and glia in Caenorhabditis elegans.

The nervous system is composed of cells including neurons and glia. It has been believed that the former cells play central roles in various neural functions while the latter ones have only supportive functions for neurons. However, recent findings suggest that glial cells actively participate in neural activities, and the cooperation between neurons and glia is important for nervous system functions. In Caenorhabditis elegans, amphid sensory organs in the head also consist of sensory neurons and glia-like support cells (amphid socket and amphid sheath cells). Ciliary endings of some sensory neurons exposed to the environment detect various chemicals, molecules and signals, and the cilia of some neurons can also take up fluorescent dyes such as DiI. Here, we show that the amphid sheath glia are also stained with DiI and that its uptake by the amphid sheath cells correlates with DiI-filling of sensory neurons, suggesting that the amphid sheath glia might interact with sensory neurons. Furthermore, the localization of the amphid sheath cell reporter F52E1.2SP::YFP is abnormal in che-2 mutants, which have defective cilia. These findings imply that sensory neurons might affect amphid sheath glia functions in the amphid sensory organ of C. elegans.