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

Schoenaers Dorian, Delroisse Jérôme , Hwang Dong Soo, Harrington Matthew, Flammang Patrick , "The Smooth and the Scaly: Tunic Morphology of two Distant Urochordates, Halocynthia roretzi (Ord. Phlebobranchia) and Ciona intestinalis (Ord. Stolidobranchia)." in 4th International Congress on Invertebrate Morphology, Moscow, Russia, 2017

  • Codes CREF : Biologie (DI3100), Sciences exactes et naturelles (DI1000), 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) Studying an organism’s photogenic structures at the ultrastructural level is a key step in the understanding of its light-emission process. Recently, the photophore ultrastructure of the deep-sea lanternshark Etmopterus spinax Linnaeus, 1758 was described. The photocytes appeared to be divided into three areas including an apical granular area, which contains inclusions and was hypothesized to be the light-producing reaction site. In this study, we investigated the morphological changes occurring within the granular area during the bioluminescent emissions induced by two hormones: prolactin and melatonin. Prolactin provoked the formation of new structures in the granular area, the “grey particles”, whose number was proportional to the amount of light produced by the reaction. An increase in the number of granular inclusions was also detected at the end of the prolactin-induced light emission. Conversely, melatonin induced a decrease in the number of granular inclusions and an increase in their diameter. An effect of hormones was also observed on the iris-like structure where they triggered pigment retraction and hence an increase in the iris aperture diameter. This is consistent with previous findings and is shown for the first time at the cellular level. The possible role of grey particles in E. spinax light-emission mechanism is discussed, while granular inclusion is considered to be E. spinax’s intracellular luminescence site. Regarding typical shark long-lasting glows, a new term (“glowon”) is proposed to characterize this novel membrane-free microsource.