Meeting Abstract

P2-42   -   Extraocular opsin expression in dermal and neural tissues of the nudibranchs Berghia stephanieae and Hermissenda opalescens Newcomb, JM*; Cross, K; Gordon, CA; New England College; New England College; New England College jnewcomb@nec.edu

Extraocular photoreception and light-sensitive opsins have been studied extensively in mollusks such as cephalopods and bivalves, although less is known in other gastropods, especially nudibranchs. Preliminary data, from our lab and our collaborators, suggest that rhabdomeric opsin (r-opsin) is present in epithelial tissues and the brains of several nudibranchs. The purpose of this study was to confirm the presence of extraocular r-opsin in the nudibranchs Berghia stephanieae and Hermissenda opalescens, with two techniques: hybridization chain reaction, with custom RNA probes, and immunohistochemistry, with a commercially available antibody to octopus r-opsin. In contrast to prior experiments done with isolated dermal tissues, entire animals were fixed in this study, resulting in easier identification of dermal structures and the exact location of r-opsin expression. Results confirmed the presence of extraocular r-opsin proteins in dermal tissues of both species, such as the cerata, oral tentacles, and rhinophores. R-opsin was also expressed in extraocular nervous tissue of both species. In the brain of both B. stephanieae and H. opalescens, a large number of neurons expressed r-opsin, especially in the pedal and pleural ganglia. R-opsin was also present in a few peripheral neurons of B. stephanieae, specifically associated with the oral tentacles and rhinophores. These results confirm that r-opsin is present in extraocular tissues of these nudibranchs, and it may play a role in mediating responses to light, independent of the eyes.