FIRST INSIGHTS INTO THE COMPOSITION OF ADHESIVE SECRETED BY CRASSOSTREA GIGAS LARVAE DURING SETTLEMENT

Valentin Foulon¹, Bruno Petton², Sébastien Artigaud¹, Manon Buscaglia¹, Fabienne Guérard¹, Claire Hellio¹, Pierre Boudry²

¹Laboratoire des Sciences de l’Environnement Marin (LEMAR), UMR 6539 CNRS UBO IRD Ifremer – Institut Universitaire Européen de la Mer, Technopôle Brest-Iroise – Rue Dumont d’Urville, 29280 Plouzané, France

²Ifremer, Laboratoire des Sciences de l’Environnement Marin (LEMAR), UMR 6539 CNRS UBO IRD Ifremer, ZI de la Pointe du Diable, CS 10070, F-29280 Plouzané, France

First adhesion stages of oyster Crassostrea gigas larvae are very poorly documented. Oyster larvae start their life by a pelagic phase, leading to the pediveliger stage which is characterized by the apparition of their foot, a specific organ which is essential for adhesion. Pediveliger larvae stop swimming, fall to the bottom and explore the substrate with their foot which have a sensitive and locomotive function: this is the crawling phase. When a favourable zone is detected, the foot discharges an adhesive between the shell and the substrate which strongly stick larvae definitely. Histological preparations were realised with the aim to localize the adhesive production site. Several glands were observed and similarities were detected with other species such as Ostrea edulis. Adhesive was studied by optic and electronic microscopy, revealing numerous fibres of different structures supposing different composition and functions.  Infra-red spectrometry, and X-ray spectrometry were used to determine the global composition of adhesive; thus proteins and potentially sulphated polysaccharides were detected. Proteomic analysis was performed and revealed 70 proteins potentially involved in adhesion. Among these proteins, candidates were selected for cellular localisation by in situ hybridization. Complete characterization of proteins is in progress, with the aim of developing new marine adhesive.