Meeting Abstract
Opsins are photosensitive proteins that mediate the detection of light in photoreceptive tissues. Although they were originally thought to be restricted to the eye, opsins are now known to be expressed in numerous extraocular tissues across animal taxa. Nematostella vectensis (the starlet sea anemone) is eyeless yet exhibits two demonstrable light-sensitive behaviors: larval phototaxis and photoinducible spawning. The genome of N. vectensis encodes over 20 unique opsin genes; whether they play a role in mediating either larval or adult photosensitive behaviors is unknown. We combined molecular techniques with behavioral assays to characterize photosensitivity in N. vectensis. Most of the opsins examined were expressed in the pharynx and/or mesenteries while others were dispersed in the body wall epithelium or localized to the distal tips of the tentacles. Interestingly, closely related opsins had dissimilar expression patterns, suggesting that duplication and functional divergence have been important mediators of opsin diversification in this lineage. To investigate the role of opsins in mediating light-sensitive behavior, we used morpholinos and pharmacological inhibitors of opsin signaling pathways to manipulate opsin function in vivo. Wild type larvae exhibit chaotic phototaxis, swimming up in the water column in response to light; knockdown of opsin function resulted in a reduced capacity for this behavior. Additionally, the normal photoinducible spawning response of adult female polyps was inhibited upon disruption of opsin signaling. Together, these data suggest a role for opsins in regulating diverse photosensitive behaviors in an eyeless organism.
