SPLTRAK Abstract Submission
Evidence for TRP Channels in the Earthworm, Eisenia hortensis.
Karleigh A. Smith, Eileen Reed, Glen B. McKinney, Sopie A. Gonzalez, Patrick M. DeZego, Emily P. Adams, Cecil J. Saunders, Wayne L. Silver
Department of Biology Wake Forest University, Winston-Salem, NC, United States

The earthworm fulfills an important ecological function, yet little is known about their chemical senses– especially how they detect noxious compounds. This sense, known as chemesthesis, is ubiquitous among most animals and is often mediated by transient receptor potential (TRP) channels.  Here we provide evidence for the presence of several TRP channels homologues, including TRPA1, TRPM8, and TRPV1 in Eisenia hortensis, the European nightcrawler. We used a behavioral assay where increasing concentrations of various TRP channel agonists were mixed into the soil. To characterize the repellant nature of the chemical, the number of earthworms that burrowed in the soil--the typical response in control soil--was compared to the number that left the cup. AITC, a TRPA1 agonist, was added to the soil in increasing concentrations, and earthworms were found to leave the cups in a concentration-dependent manner. However, when earthworms were submerged in the TRPA1 channel blocker, H3-030031, the number of earthworms that left the AITC cup was significantly reduced. This same concentration-dependent response was observed when menthol, a TRPM8 stimulant, was added to the soil. For capsaicin, a TRPV1 stimulant, the earthworms did not leave the cup any concentration of capsaicin that was tested. We also identified molecular evidence of E. hortensis TRPA1, TRPM8, and TRPV1-like channels using gene-specific and rapid amplification of cDNA ends (RACE) PCR. We have identified several sequence fragments that are similar to previously reported TRP channel sequences in related organisms. From our behavioral and molecular results, we provide evidence that the earthworm, Eisenia hortensis, uses TRPA1, TRPV1, and TRPM8 channels homologues to detect several respective TRP channel stimulants.