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2020-11-29 - Colloque/Présentation - communication orale - Anglais - 39 page(s)

Delroisse Jérôme , Gilbert Rémy, Mallefet Jérôme, Flammang Patrick , "Perceive the light without eyes and brain: insights from the pentaradial echinoderms" in Zoology 2019, Groningen, Holland, 2019

  • 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) In eumetazoans, light is mainly detected through photosensitive proteins, the opsins, which are involved in both vision and nonvisual photoreception. Advances in comparative genomics transformed our understanding of the evolution of opsin-based photoreception. A picture emerged of a core set of opsin-based signalling pathways that can be traced back to the common ancestor of Bilateria, with opsin orthologs being identified in an increasingly wide range of phyla! Although echinoderms have neither brain nor eyes (sensu stricto), most of the investigated species are light sensitive and up to 7 bilaterian-type opsin groups were identified in these organisms. Based on transcriptome and genome data, this research focused on the opsin diversity of the common European sea star Asterias rubens. In addition, the sensitivity of A. rubens to monochromatic light was also investigated based on phototactism and color change assays. The results confirm (i) the ability of the common sea star to perceive light using both ocellar and extra-ocellar opsin-based photoreception and (ii) the co-occurrence of various opsin types, but also (iii) emphasise the complexity of light perception in these marine invertebrates. Overall, this research contributes to the understanding of opsin-based extraocular photoreception in echinoderms, giving precious insights on opsin evolution and functions, and photoreceptor cell organisation in these enigmatic organisms that bridge the gap between the extensively studied vertebrates and protostomian model species.