Meeting Abstract

145.4  Monday, Jan. 7  Functional divergence? Comparing opsin expression in extra-ocular tissues and eyes of the scallop (Pectinidae). KRAUSE, A/J*; SERB, J/M; Iowa State University; Iowa State University ajkrause@iastate.edu

Photosensitivity plays a role in vision, entrainment of the circadian clock, and phototaxis, ultimately affecting the life history and fitness of many species. While we often think of the eye as the primary light perceiving organ, extra-ocular photosensitivity (EOP) is common in animals and many species maintain photosensitivity despite their eyeless condition. Presumably, the key photoreceptive protein in animals in both ocular and EOP structures is a member of the opsin family, a group of seven transmembrane G-protein coupled receptors, but the relationship between opsins used in these specific photo-sensing systems is largely unexplored. Recently, we isolated two copies of Gq-opsin from eyes of the common bay scallop, Argopecten irradians (Pectinidae). One of the copies has been previously reported in scallops, while the second copy differs by 45% in amino acid sequence. Surprisingly, both copies contain a lysine residue required for chromophore binding and photosensitivity suggesting both proteins are functional. To test the hypothesis that a gene duplication event resulted in tissue-specific functional divergence of scallop opsins, we determined the evolutionary relationship and examined spatial expression patterns of the two A. irradians Gq-opsin copies. Using in situ hybridization techniques, we determined both copies are expressed in the nerves of mantle tissue as well as ocular tissues. Our results suggest a scallop’s mirror-type eyes and the EOP in surrounding mantle tissue may be sensitive to similar spectrums of light.