|Opsin detection in the sea urchin Paracentrotus lividus and the sea star Asterias rubens|
Delroisse, J.; Lanterbecq, D.; Eeckhaut, I.; Mallefet, J.; Flammang, P. (2013). Opsin detection in the sea urchin Paracentrotus lividus and the sea star Asterias rubens. Cah. Biol. Mar. 54(4): 721-727
In: Cahiers de Biologie Marine. Station Biologique de Roscoff: Paris. ISSN 0007-9723, more
Echinoderms; Sea-urchins; Sea-stars; Photoreception; Opsin
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Vision in metazoans is permitted by opsin expression in photoreceptor cells. These opsins can be mainly classified into two groups: the ciliary (c) and the rhabdomeric (r) opsins. Based on the r-opsin sequence of the sea urchin Strongylocentrotus purpuratus, degenerate primers were designed and used to amplify homologous opsin genes in the sea urchin Paracentrotus lividus and the sea star Asterias rubens by PCR. Partial r-opsin sequences were obtained for both species. These sequences are more similar between sea urchin species than between sea urchins and sea stars. In parallel, a commercial antibody, raised against the N-terminal domain of the rat rhodopsin, was used to detect c-opsins in Western blot experiments. Putative c-opsins were detected in the oral integument of P. lividus. We also detected c-opsins in the aboral integument of A. rubens, but not in the podia nor in the optic cushions. In all eventualities, it is therefore likely that two types of opsins co-occur in A. rubens and P. lividus as it is the case in S. purpuratus. In A. rubens, one opsin type would be located in the optic cushions (r-opsins) and another in the aboral integument (c-opsin). This could support the idea that sea stars possess two types of vision: the optic cushions, involved in visual perception of the environment, and the aboral integument, involved in non-visual photoreception.