Proteinaceous secretion of bioadhesive produced during crawling and settlement of Crassostrea gigas larvae

Valentin Foulon,Kada Boukerma,Philippe Elies,Caroline Fabioux,Sébastien Artigaud,Manon Buscaglia,Pierre Boudry,Fabienne Guérard,Claire Hellio,Benoit Bernay,Bruno Petton

doi:10.1038/s41598-018-33720-4

Abstract

Bioadhesion of marine organisms has been intensively studied over the last decade because of their ability to attach in various wet environmental conditions and the potential this offers for biotechnology applications. Many marine mollusc species are characterized by a two-phase life history: pelagic larvae settle prior to metamorphosis to a benthic stage. The oyster Crassostrea gigas has been extensively studied for its economic and ecological importance. However, the bioadhesive produced by ready to settle larvae of this species has been little studied. The pediveliger stage of oysters is characterized by the genesis of a specific organ essential for adhesion, the foot. Our scanning electron microscopy and histology analysis revealed that in C. gigas the adhesive is produced by several foot glands. This adhesive is composed of numerous fibres of differing structure, suggesting differences in chemical composition and function. Fourier transformed infrared spectroscopy indicated a mainly proteinaceous composition. Proteomic analysis of footprints was able to identify 42 proteins, among which, one uncharacterized protein was selected on the basis of its pediveliger transcriptome specificity and then located by mRNA in situ hybridization, revealing its potential role during substrate exploration before oyster larva settlement.

Highlights

Bioadhesion of marine organisms has been intensively studied over the last decade because of their ability to attach in various wet environmental conditions and the potential this offers for biotechnology applications
Most bivalves secrete adhesive during the settlement stage of their life cycle, which marks the transition between pelagic larval stage and benthic adult stage by metamorphosis[20]
Metamorphosis of C. gigas larvae occurs a few hours later and the foot is totally resorbed after this stage[11]

Summary

Introduction

Bioadhesion of marine organisms has been intensively studied over the last decade because of their ability to attach in various wet environmental conditions and the potential this offers for biotechnology applications. Biofouling, which can be defined as the adhesion and subsequent growth of organisms on a substrate has been extensively described in marine environments[1]. C. gigas larval development commonly lasts about 15 days at 25 °C, depending on temperature and food availability At this stage, pediveliger larvae, with shell lengths of 280 to 300 μm, are characterized by the presence of a foot: an organ specific to the settlement phase in oysters. In other bivalve species that are not definitively fixed to their substrate, the foot is not resorbed during metamorphosis and can develop to become a highly specific organ, like in mussels

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