Author(s)

Yucheng Tan

Corresponding Author

Yucheng Tan

ABSTRACT

Sensory system, as the initiation of neural activities, allows animals to detect and update dynamic information of the external world. Losing any sensation can threaten survival. Due to the complexity of higher animals' sensory systems, neuroscientists usually use simple animals for basic studies, such as the Caenorhabditis elegans. Two sensations, mechanosensation and chemosensation, allow nematode to detect mechanical (e.g., gentle touch, harsh touch) and chemical stimulations (e.g., odors, salts, oxygen), respectively. Both sensations are felt by related sensory neurons and translate to action potentials which downstream neurons can read. These translational processes were known as mechanotransduction and chemotransduction. This revived introduced C. elegans' sensory system to explain how each transduction is achieved by revealing underlaying molecular mechanisms. Mechanotransduction of C. elegans is functioned by the gating of ion channels on the mechanoreceptor neurons (MRNs). Different mechanical stimulation regarding its force can activate distinct neurons, in addition, to different ion channels. For example, gentle touches are sensed by the DEG/ENaC channels, expressed on the touch receptor neurons (TRNs). Harsh touches are detected by the TRP channels, which are expressed on the harsh touch neurons. Two putative models of mechanotransduction proposed that channels are either tethering with both intracellular microtubules and extracellular matrix or only tethering with microtubules to directly regulate channel gating. Chemotransduction of C. elegans is unitarily mediated by G-protein coupled receptors (GPCRs). Like mechanosensation, different chemosensory neurons are responsible for probing different chemicals. This differentiation is represented by the downstream signalling pathways of initially activated GPCRs. Currently, there are two pathways: the OSM-9/OCR-2 TRPV channel mediated signalling pathway and the cGMP-gated channel mediated signalling pathway.

KEYWORDS

C elegans, sensory system, mechanoreceptor neurons, mechanotransduction, chemotransduction, touch receptor neurons, TRP channels