Meeting Abstract

P3.155  Sunday, Jan. 6  Distribution of ciliated cells and identification of putative olfactory receptors in a novel chemosensory organ in the nudibranch Tritonia diomedea GALLAGHER, CA*; MURRAY, JA; CAIN, SD; CHOATE, BA; Cal. State U. East Bay; Cal. State U. East Bay; Eastern Oregon U; Cal. State U. East Bay james.murray@csueastbay.edu

Tritonia diomedea has an a pair of rhinophores that are homologous to the posterior tentacles of the ancestral gastropods, and an oral veil that is derived from the anterior tentacles of ancestral gastropods. The rhinophores are distance chemoreceptors that detect odors emitted by prey, predators, and conspecifics. The oral veil is mechanosensory, can distinguish the taste of prey and predator, and has ~18 white tips, 2-5mm long, which serve as finger-like papillae oriented anteriorly that are used to explore items they contact by crawling. In contrast, the two most lateral tips are 5-10mm long, are oriented ventrally during crawling, and have a ciliated groove along the ventro-medial surface. The groove has motile cilia (10-20 micron long tufts of ~100 cilia; tufts at 500/mm²) oriented to transport fluid from the tip towards the base at 2-4 mm/s. The groove is surrounded by skin with 5-10 micron long tufts of ~300 cilia on papillae separated by ~30 microns (~100 tufts per mm²). The groove may be chemosensory and we observed an ~12% increase in the rate of transport of glass beads when the groove was exposed to the odors of prey or predator, but this change is not statistically significant (n=5). Genetic work was carried out to look for the presence of known Aplysia californica olfactory receptor sequences. Primers were designed for the gene sequence known as “olfactory receptor C”. PCR was carried out on the extracted T. diomedea DNA and a matching sequence was found. Cloning work is now underway to attempt to clone the gene sequence found in T. diomedea. Preliminary results indicate that type A and type C olfactory receptors are present in the oral veil and rhinophores. There is a greater concentration of receptors at the proximal base on the ciliary groove.