Meeting Abstract
Diel vertical migration of deep-sea animals represents the largest migration on our planet. Vertically migrating fauna are subjected to a variety of light fields among other environmental conditions that can have notable impacts on sensory mechanisms, including an organism’s visual capabilities. Among deep-sea migrators are oplophorid shrimp, that vertically migrate 100s of meters (m) to feed in shallow waters at night. These species also have bioluminescent light organs called photophores that emit light during shallow-water migrations to aid in a dynamic form of camouflage known as counterillumination. The organs have recently been shown to contain opsins and other genes that infer light sensitivity. Knowledge regarding the impacts of this vertical migratory behavior, and fluctuating environmental conditions, on sensory system (visual/photophore) evolution is unknown. In this study, the oplophorid Systellaspis debilis was either collected pre-sunset (Day) from 450-750 m, or pre-dawn (Night) from 150-330 m to ensure sampling across the vertical distributional range. RNA was then extracted and sequenced from the light sensitive tissues (eyes/photophores). De novo transcriptomes were assembled discretely for each tissue from Day (n=5) and Night (n=5) specimens and analyzed to characterize opsin diversity, visual and light interaction genes within a phylogenetic context. Gene expression analyses were also conducted to quantify expression differences associated with the migration. This study sheds light on the visual system of a deep-sea bioluminescent shrimp and provides additional evidence for photophore light sensitivity. Our findings also suggest opsin coexpression and subsequent fluctuations in opsin expression may play an important role in diversifying the visual responses of this deep-sea vertical migrator.
