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2010-10-09 - Colloque/Présentation - communication orale - Anglais - 1 page(s)

Delroisse Jérôme , Flammang Patrick , Mallefet Jérôme, "Fine structure of bioluminescent areas in the ophiuroid Amphiura filiformis" in 7th European Conference on Echinoderms, Göttingen, Germany, 2010

  • Codes CREF : Biologie (DI3100), Sciences exactes et naturelles (DI1000)
  • 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 is present in at least thirteen phyla and in more than seven hundred identified genera of living organisms. Its implications in the biology of marine organisms are multiple and it is considered as the main source of light in deep marine ecosystems. It seems that bioluminescence appeared, at least, forty times in the evolution of organisms. In echinoderms, luminescent species are gathered predominantly in the class Ophiuroidea, which comprises more than 65 species able to emit light. In these organisms, the luminescence is always intrinsic and comes from specialized cells, the photocytes, which may have various localizations in the arms or the disc of the animal. The brittle-star Amphiura filiformis emits a blue light at the level of the arms when it is mechanically stimulated. The structure and accurate localization of the luminous areas are currently unknown in this species. The goal of this work was therefore to localize the light-emitting structures of A. filiformis and to describe their ultrastructure. At first, tests of bioluminescence with the aid of digital videography with intensification of brilliance and macrophotography were realized. No bioluminescence was observed at the level of the disc of the brittle-star. Most visible luminous areas are present at the tip of the dorsal spines of the brittle-star. The ultrastructure of photocytes and surrounding tissues was also considered and compared to that of Amphiura chiajei, a sympatric sister-specie of A. filiformis which is not bioluminescent. Photocyte ultrastructure is studied during different stages of bioluminescence, i.e. before, during and after the emission of light. The obtained results are compared with data concerning photocytes of others luminous brittle-stars species present in literature (Ophiopsila californica, Amphipholis squamata).