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2017-08-23 - Colloque/Présentation - communication orale - Anglais - 1 page(s)

Delroisse Jérôme , Ullrich-Lüter Esther, Blaue Stefanie, Flammang Patrick , Mallefet Jérôme, "Bioluminescence of a Brittle star, from Luciferase homology to Photocyte Ultrastructure" in 4th International Congress on Invertebrate Morphology, Moscow, Russia, 2017

  • Codes CREF : Biologie moléculaire (DI3111), Biologie (DI3100), Sciences exactes et naturelles (DI1000), Ecologie (DI3123), Zoologie générale (DI3160)
  • Unités de recherche UMONS : Biologie des Organismes Marins et Biomimétisme (S864)
  • Instituts UMONS : Institut des Biosciences (Biosciences)
  • Centres UMONS : Biosys (BIOSYS)

Abstract(s) :

(Anglais) Bioluminescence relies on the oxidation of a luciferin substrate catalysed by a luciferase enzyme. Numerous light emission systems would have co-emerged independently along the tree of life resulting in a plethora of non-homologous luciferases. We used transcriptome and phylogenomic analyses, immunodetections and electron microscopy to identify the luciferase of a luminous echinoderm, the burrowing brittle star Amphiura filiformis, and describe its expression pattern as well as the photocyte ultrastructure. The brittle star luciferase is homologous to the luciferase of the sea pansy Renilla (Cnidaria), contradicting with the traditional viewpoint according to which luciferases would generally be of convergent origins. Enzymes homologous to the Renilla luciferase but unable to trigger light emission were also identified in non-luminous echinoderms and metazoans. Our findings strongly indicate that ancestral non-luciferase enzymes might have been convergently co-opted into luciferases in cnidarians and echinoderms. In these two benthic suspension-feeding species, similar ecological pressures would constitute strong selective forces for the functional shift of these enzymes and the emergence of bioluminescence. In the brittle star, luciferase is specifically localized in the spines that we demonstrated to be the bioluminescent organs in vivo. We investigated the ultrastructure of spine tissues in order to identify photocytes and improve our comprehension of the photogenesis phenomenon in brittle stars. All together our study bring new insights on the bioluminescecne of echinoderms and more generally on luciferase evolution.