26.1 Monday, Jan. 5 Opsin diversity and extra-ocular photorecepion in the Metazoa MARLOW, Heather Q.*; SPEISER, Daniel I.; SEAVER, Elaine C.; MARTINDALE, Mark Q.; University of Hawaii at Manoa; Duke University; University of Hawaii at Manoa; University of Hawaii at Manoa email@example.com
Bilaterian animals (protostomes and deuterostomes) sense light through the use of visual opsins, seven-pass transmembrane receptors of the Rhodopsin superfamily. It has been long hypothesized that two families of visual opsin molecules, the rhabdomeric and the ciliary families, were present in the urbilaterian ancestor. These molecules, and their corresponding morphological cell types, assumed independent functions in protostome, and deuterostome photoreception, where protostome eyes have been largely found with rhabdomeric opsins and deuterostome eyes are associated with ciliary opsins. Our examination of the visual opsins in the basal metazoa (cnidarians, trichoplax and sponges) confirm previously published reports which show that cnidarians were the earliest phyla to possess putative light sensitive opsin molecules. We find that a large diversity of visual opsin genes are found in the Nematostella vectensis (anthozoan cnidarian) genome and that these genes are expressed in different subsets of minimally differentiated N. vectensis neurons in the adult (polyp) and larval (planula) stages which lack the large membrane elaborations of rhabdomeric and ciliary photoreceptor cells. In addition, we find previously undescribed opsin diversity in the lophotrochozoan Capitella sp.I (polychaete annelid), which is expressed outside of the adult and larval eyes. These data, as well as our examination of the developmental eye gene regulatory network (PSEDN) in N. vectensis (anthozoan cnidarian) implies that opsins evolved and diversified in light sensitive extra-ocular neurons prior to the emergence of the bilateria and have been co-opted for use in non-homologous visual structures (eyes) many times in the bilateria.