Meeting Abstract
106.2 Sunday, Jan. 6 Ctenophore photocytes express a light-sensing opsin as well as bioluminescent photoproteins during development SCHNITZLER, CE*; PANG, K; POWERS, ML; REITZEL, AM; RYAN, JF; SIMMONS, D; TADA, T; YOKOYAMA, S; HADDOCK, SHD; MARTINDALE, MQ; BAXEVANIS, AD; NHGRI/NIH; Sars International Centre for Marine Molecular Biology; Monterey Bay Aquarium Research Institute; Woods Hole Oceanographic Institution; Sars International Centre for Marine Molecular Biology; Kewalo Marine Laboratory/Univ. of Hawaii; Emory University; Emory University; Monterey Bay Aquarium Research Institute; Kewalo Marine Laboratory/Univ. of Hawaii; NHGRI/NIH christine.schnitzler@nih.gov
The recent completion of a draft genome assembly of the ctenophore Mnemiopsis leidyi, a representative of the earliest branch of animals that emit light, has provided an excellent opportunity to examine the genome of an organism that uses photoproteins for bioluminescence. Interestingly, we found that photoprotein transcripts are co-expressed with two putative opsin genes in developing photocytes. Opsin expression was also found in four small groups of neural cells in the floor of the apical sensory organ that coincides with structures described as ciliated lamellate bodies; these structures were suggested to be photoreceptors over 130 years ago. We present evidence that one of the opsin genes functions in vitro, absorbing light at wavelengths that overlap with peak photoprotein light emission. We also present genomic evidence of a complete ciliary phototransduction cascade in Mnemiopsis. These findings led us to hypothesize a novel dual role for ctenophore photocytes in both bioluminescence and opsin-mediated phototransduction. This work provides a foundation for further studies aimed at determining how the bioluminescence cascade operates in Mnemiopsis, as well as whether opsin and other phototransduction pathway genes play a role in either promoting or inhibiting luminescence production under different environmental conditions.
