Sensory Mechanotransduction and Thermotransduction in Invertebrates

Mechanosensory and thermosensory neurons have a diversity of tasks in invertebrate animals. Mechanosensory neurons must detect mechanical stimuli as harsh as the penetration of a parasitoid wasp ovipositor and as gentle as the brush of bacteria while an animal glides along an agar plate (Sawin et al., 2000; Hwang et al., 2007). Thermosensory neurons must detect temperatures warmer and cooler than preferred temperatures to allow animals to return to appropriate temperatures for proper growth as well as detect tissue-damaging heat to allow animals to avoid immediate danger (Kwon et al., 2008; Klein et al., 2015; Sayeed and Benzer, 1996; Lee et al., 2005; Hamada et al., 2008; Gallio et al., 2011; Tracey et al., 2003; Hwang et al., 2007; Xu et al., 2006). Within these cells, the threshold for detection of mechanical and thermal stimuli is adjusted by changes in the external and internal environment. The detection of food or the release of cytokines by dying cells can alter the cellular response of mechanosensory and thermosensory neurons (Sawin et al., 2000; Hilliard et al., 2005; Babcock et al., 2009; Babcock et al., 2011). Genes that encode transient receptor potential (TRP) channel subunits are members of a large gene family that encodes cation channels with key roles in the function of many types of sensory neurons both as transduction channels that transform a specific stimulus into an electrical signal and as regulators of the cellular response.