Interspecies comparison of the mechanical properties and biochemical composition of byssal threads

Abstract

10 páginas, 5 figuras, 3 tablas ; Several bivalve species produce byssus threads to provide attachment to substrates, with mechanical properties highly variable among species. Here, we examined the distal section of byssal threads produced by a range of bivalve species (Mytilus edulis, Mytilus trossulus, Mytilus galloprovincialis, Mytilus californianus, Pinna nobilis, Perna perna, Xenostrobus securis, Brachidontes solisianus and Isognomon bicolor) collected from different nearshore environments. Morphological and mechanical properties were measured, and biochemical analyses were performed. Multivariate redundancy analyses on mechanical properties revealed that byssal threads of M. californianus, M. galloprovincialis and P. nobilis have very distinct mechanical behaviors compared to the remaining species. Extensibility, strength and force were the main variables separating these species groups, which were highest for M. californianus and lowest for P. nobilis. Furthermore, the analysis of the amino acid composition revealed that I. bicolor and P. nobilis threads are significantly different from the other species, suggesting a different underlying structural strategy. Determination of metal contents showed that the individual concentration of inorganic elements varies but that the dominant elements are conserved between species. Altogether, this bivalve species comparison suggests some molecular bases for the biomechanical characteristics of byssal fibers that may reflect phylogenetic limitations ; This work was supported by the 550 Fonds de Recherche du Québec sur la Nature et les Technologies (FRQNT, team project 2012-551 PR-145239 to I.M.) and the Natural Sciences and Engineering Research Council (NSERC, 552 discovery grant 299100 to RT) of Canada. Z.B. would like to thank the Tunisian government and 553 Ressources Aquatiques Québec (RAQ) for the award of scholarships ; Peer reviewed