Interfacial Phenomena in Marine and Freshwater Mussel Adhesion

Abstract

The attachment of mussels to underwater surfaces is one of the best-studied examples of biological adhesion, yet it continues to provide new insights into the phenomenon of wet adhesion. Both marine and freshwater mussels secrete a proteinaceous byssus, which attaches the mussel to a wide variety of surfaces with considerable strength. In marine mussels, Dopa (3,4-dihydroxyphenylalanine)-containing proteins have been shown to play key roles in this process, while less is known about the mechanism of adhesion in freshwater mussels, which contain much less Dopa. This chapter will highlight some of the recent developments in the mechanistic understanding of byssal adhesion, with a focus on the adhesive interface itself. In marine mussels, the extensive foundational work that preceded the last edition of this book has allowed a more recent emphasis on protein function, leading to important new insights regarding redox chemistry at the adhesive interface, the effect of surface chemistry on adhesion, and the role of amino acids other than Dopa in adhesion. Prior to this, adhesion of freshwater mussels will be reviewed. Here, the state of knowledge is much more nascent, with current emphasis still on protein sequencing and distribution. Nevertheless, careful structural characterization of the freshwater mussel adhesion has led to new understandings on the nature of the byssal adhesive interface. Furthermore, the comparison of the separately evolved adhesion strategies of freshwater and marine mussels may lead to new insights into the essential requirements of underwater adhesion.