Honors Theses and Capstones

Effects of Proline and Glycine on the Cnidocyte Discharge of Hydra magnipapillata

Janine R. Appleton, University of New Hampshire


The sense of taste enables animals to utilize environmental cues to detect favorable foods. Through specialized sensory receptors, Cnidarians employ stinging cells called cnidocytes to perform a variety of activities such as locomotion, capturing prey, inducing of feeding responses, and defense. Their discharge is highly regulated by mechanical and chemical signals that are mediated by a complex system including the opsin and taste pathways. Taste 1 Receptors (T1R) have previously been isolated in vertebrates but only until recently, have been noted in invertebrates. Receptors specific to L- amino acids corresponding to the taste sensation of umami, were studied to determine if the pathways of Hydra magnipapillata used for feeding were similar to the systems utilized in vertebrates. Amino acids, Proline and Glycine, were experimented using cnidocyte assays to induce feeding and capture cnidocytes. An optimal concentration of 10mM of Proline and Glycine was tested and found to be significant by eliciting greater cnidocyte discharge as compared to a Control of gelatin with P- Values of 0.003 and 0.0011 respectively. This indicates that amino acids, which have similar receptors in vertebrates, are capable of inducing feeding responses in invertebrates implying that T1Rs operate in similar mechanisms thus predating the current notion of the evolutions and diversification of such genes by around 400 million years.