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Eli D. Sone - One of the best experts on this subject based on the ideXlab platform.
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Novel Proteins Identified in the Insoluble Byssal Matrix of the Freshwater Zebra Mussel
Marine Biotechnology, 2014Co-Authors: Arpita Gantayet, David J. Rees, Eli D. SoneAbstract:The freshwater zebra mussel, Dreissena polymorpha , is an invasive, biofouling species that adheres to a variety of substrates underwater, using a proteinaceous anchor called the Byssus. The Byssus consists of a number of threads with adhesive plaques at the tips. It contains the unusual amino acid 3, 4-dihydroxyphenylalanine (DOPA), which is believed to play an important role in adhesion, in addition to providing structural integrity to the Byssus through cross-linking. Extensive DOPA cross-linking, however, renders the zebra mussel Byssus highly resistant to protein extraction, and therefore limits byssal protein identification. We report here on the identification of seven novel byssal proteins in the insoluble byssal matrix following protein extraction from induced, freshly secreted byssal threads with minimal cross-linking. These proteins were identified by LC-MS/MS analysis of tryptic digests of the matrix proteins by spectrum matching against a zebra mussel cDNA library of genes unique to the mussel foot, the organ that secretes the Byssus. All seven proteins were present in both the plaque and thread. Comparisons of the protein sequences revealed common features of zebra mussel byssal proteins, and several recurring sequence motifs. Although their sequences are unique, many of the proteins display similarities to marine mussel byssal proteins, as well as to adhesive and structural proteins from other species. The large expansion of the byssal proteome reported here represents an important step towards understanding zebra mussel adhesion.
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Zebra mussel adhesion: structure of the byssal adhesive apparatus in the freshwater mussel, Dreissena polymorpha.
Journal of Structural Biology, 2012Co-Authors: Nikrooz Farsad, Eli D. SoneAbstract:Abstract The freshwater zebra mussel (Dreissena polymorpha) owes a large part of its success as an invasive species to its ability to attach to a wide variety of substrates. As in marine mussels, this attachment is achieved by a proteinaceous Byssus, a series of threads joined at a stem that connect the mussel to adhesive plaques secreted onto the substrate. Although the zebra mussel Byssus is superficially similar to marine mussels, significant structural and compositional differences suggest that further investigation of the adhesion mechanisms in this freshwater species is warranted. Here we present an ultrastructural examination of the zebra mussel Byssus, with emphasis on interfaces that are critical to its adhesive function. By examining the attached plaques, we show that adhesion is mediated by a uniform electron dense layer on the underside of the plaque. This layer is only 10–20 nm thick and makes direct and continuous contact with the substrate. The plaque itself is fibrous, and curiously can exhibit either a dense or porous morphology. In zebra mussels, a graded interface between the animal and the substrate mussels is achieved by interdigitation of uniform threads with the stem, in contrast to marine mussels, where the threads themselves are non-uniform. Our observations of several novel aspects of zebra mussel byssal ultrastructure may have important implications not only for preventing biofouling by the zebra mussel, but for the development of new bioadhesives as well.
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The Byssus of the zebra mussel (Dreissena polymorpha): spatial variations in protein composition
Biofouling, 2010Co-Authors: Trevor W. Gilbert, Eli D. SoneAbstract:The notorious biofouling organism Dreissena polymorpha (the zebra mussel) attaches to a variety of surfaces using a Byssus, a series of protein threads that connect the animal to adhesive plaques secreted onto hard substrata. Here, the use of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) to characterize the composition of different regions of the Byssus is reported. All parts of the Byssus show mass peaks corresponding to small proteins in the range of 3.7-7 kDa, with distinctive differences between different regions. Indeed, spectra from thread and plaques are almost completely non-overlapping. In addition, several peaks were identified that are unique to the interfacial region of the plaque, and therefore likely represent specialized adhesive proteins. These results indicate a high level of control over the distribution of proteins, presumably with different functions, in the Byssus of this freshwater species.
Matthew J Harrington - One of the best experts on this subject based on the ideXlab platform.
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self healing silk from the sea role of helical hierarchical structure in pinna nobilis Byssus mechanics
Soft Matter, 2019Co-Authors: Delphine Pasche, Nils Horbelt, Frederic Marin, Sebastien Motreuil, Peter Fratzl, Matthew J HarringtonAbstract:The Byssus fibers of Mytilus mussel species have become an important role model in bioinspired materials research due to their impressive properties (e.g. high toughness, self-healing); however, Mytilids represent only a small subset of all Byssus-producing bivalves. Recent studies have revealed that Byssus from other species possess completely different protein composition and hierarchical structure. In this regard, Pinna nobilis Byssus is especially interesting due to its very different morphology, function and its historical use for weaving lightweight golden fabrics, known as sea silk. P. nobilis Byssus was recently discovered to be comprised of globular proteins organized into a helical protein superstructure. In this work, we investigate the relationships between this hierarchical structure and the mechanical properties of P. nobilis Byssus threads, including energy dissipation and self-healing capacity. To achieve this, we performed in-depth mechanical characterization, as well as tensile testing coupled with in situ X-ray scattering. Our findings reveal that P. nobilis Byssus, like Mytilus, possesses self-healing and energy damping behavior and that the initial elastic behavior of P. nobilis Byssus is due to stretching and unraveling of the previously observed helical building blocks comprising the Byssus. These findings have biological relevance for understanding the convergent evolution of mussel Byssus for different species, and also for the field of bio-inspired materials.
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mussel Byssus structure function and fabrication as inspiration for biotechnological production of advanced materials
Biotechnology Journal, 2018Co-Authors: Matthew J Harrington, Franziska Jehle, Tobias PriemelAbstract:Biotechnology offers an exciting avenue toward the sustainable production of high performance proteinaceous polymeric materials. In particular, the mussel Byssus-a high performance adhesive bio-fiber used by mussels to cling on hard surfaces-has become a veritable archetype for bio-inspired self-healing fibers, tough coatings, and versatile wet adhesives. However, successful translation of mussel-inspired design principles into man-made materials hinges upon elucidating structure-function relationships and biological fabrication processes. This review provides a detailed survey of the state-of-the-art understanding of the biochemical structure-function relationships defining Byssus performance with a particular focus on structural hierarchy and metal coordination-based cross-linking. The efforts to mimic the Byssus in man-made materials are then discussed. While there has been a strong push to mimic the Byssus via synthetic chemistry taking a reductionist approach, herein the focus is specifically on recent progress of biotechnology-based strategies that more closely approximate the biochemical complexity of the natural material. As an outlook, an overview of recent research toward understanding the natural Byssus assembly process is provided, as processing remains a critical factor in achieving native-like properties.
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Mussel Byssus Structure‐Function and Fabrication as Inspiration for Biotechnological Production of Advanced Materials
Biotechnology journal, 2018Co-Authors: Matthew J Harrington, Franziska Jehle, Tobias PriemelAbstract:Biotechnology offers an exciting avenue toward the sustainable production of high performance proteinaceous polymeric materials. In particular, the mussel Byssus-a high performance adhesive bio-fiber used by mussels to cling on hard surfaces-has become a veritable archetype for bio-inspired self-healing fibers, tough coatings, and versatile wet adhesives. However, successful translation of mussel-inspired design principles into man-made materials hinges upon elucidating structure-function relationships and biological fabrication processes. This review provides a detailed survey of the state-of-the-art understanding of the biochemical structure-function relationships defining Byssus performance with a particular focus on structural hierarchy and metal coordination-based cross-linking. The efforts to mimic the Byssus in man-made materials are then discussed. While there has been a strong push to mimic the Byssus via synthetic chemistry taking a reductionist approach, herein the focus is specifically on recent progress of biotechnology-based strategies that more closely approximate the biochemical complexity of the natural material. As an outlook, an overview of recent research toward understanding the natural Byssus assembly process is provided, as processing remains a critical factor in achieving native-like properties.
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Functional Biocompatible Matrices from Mussel Byssus Waste
2018Co-Authors: Devis Montroni, Matthew J Harrington, Francesco Valle, Stefania Rapino, Simona Fermani, Matteo Calvaresi, Giuseppe FaliniAbstract:The mussel Byssus is a biorenewable, protein-based material produced by marine mussels, which has attracted the interest of material scientists because of its remarkable mechanical and self-healing properties. Large quantities of Byssus waste material from mussel mariculture are produced every year, which have great potential as a raw starting material for producing sustainable advanced materials. In this work, we developed a facile and scalable method to synthesize whole Byssus-based porous matrices that retain part of the hierarchical organization of the pristine material at the nanoscale. The resulting material is biocompatible and maintains important native Byssus features: metal ion chelation (≥12 mg/g), collagen domains, and hierarchical organization, with tunable properties controlled via metal ion content. Furthermore, these biocompatible matrices showed a dye absorbing efficiency (up to 64 mg/g for anionic dyes) that was similar to or higher than that of the pristine Byssus, a proof of preservation of structural motifs. These findings indicate that biorenewable matrices originating from Byssus waste could have potential use in biomedical engineering and applied material science
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Functional Biocompatible Matrices from Mussel Byssus Waste
ACS Biomaterials Science & Engineering, 2017Co-Authors: Devis Montroni, Matthew J Harrington, Francesco Valle, Stefania Rapino, Simona Fermani, Matteo Calvaresi, Giuseppe FaliniAbstract:The mussel Byssus is a biorenewable, protein-based material produced by marine mussels, which has attracted the interest of material scientists because of its remarkable mechanical and self-healing properties. Large quantities of Byssus waste material from mussel mariculture are produced every year, which have great potential as a raw starting material for producing sustainable advanced materials. In this work, we developed a facile and scalable method to synthesize whole Byssus-based porous matrices that retain part of the hierarchical organization of the pristine material at the nanoscale. The resulting material is biocompatible and maintains important native Byssus features: metal ion chelation (≥12 mg/g), collagen domains, and hierarchical organization, with tunable properties controlled via metal ion content. Furthermore, these biocompatible matrices showed a dye absorbing efficiency (up to 64 mg/g for anionic dyes) that was similar to or higher than that of the pristine Byssus, a proof of preservati...
Piotr Szefer - One of the best experts on this subject based on the ideXlab platform.
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distribution and relationships of trace metals in soft tissue Byssus and shells of mytilus edulis trossulus from the southern baltic
Environmental Pollution, 2002Co-Authors: Piotr Szefer, K. Frelek, Krystyna Szefer, Bojeong Kim, Jan Warzocha, I. Zdrojewska, Ch Lee, Tomasz CiesielskiAbstract:Concentrations of Hg, Cd, Pb, Ag, Cu, Zn, Cr, Ni, Co, Mn, and Fe in soft tissues, shells and Byssus of blue mussel (Mytilus edulis trossulus) from 23 sites along the Polish coast of the Baltic Sea were determined by AAS method. Byssus, as compared with the soft tissue, concentrated more effectively Pb, Cu, Cr, and especially Ag, Ni, Mn and Fe, moderately Hg and Zn and less effectively Cd. Significant inter-regional and inter-size differences in metal concentrations in both soft tissues and Byssus were recorded. Highly significant correlations (P<0.01, P<0.05) were observed between tissue and byssal concentrations of Cd, Pb, Ni and Ag. Factor analysis showed clear separation of both the tissue and byssi samples based on their geographic distribution, possibly reflecting a different rate of deposition of clay minerals at the head of the Pomeranian Bay and the Gulf of Gdansk. The Pomeranian Bay differs from the Gulf of Gdansk in respect to geological structure of bottom sediments as a substrata for the M. edulis trossulus as well as in relation to various sources of metallic pollutants. From the data obtained in the present study and those reported previously the soft tissue and especially Byssus of M. edulis, in contrast to shells, appear to be a significantly better bioindicator for identification of coastal areas exposed to metallic contaminants.
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Distribution and relationships of trace metals in soft tissue, Byssus and shells of Mytilus edulis trossulus from the southern Baltic.
Environmental pollution (Barking Essex : 1987), 2002Co-Authors: Piotr Szefer, K. Frelek, Krystyna Szefer, Ch.-b Lee, Bojeong Kim, Jan Warzocha, I. Zdrojewska, Tomasz CiesielskiAbstract:Concentrations of Hg, Cd, Pb, Ag, Cu, Zn, Cr, Ni, Co, Mn, and Fe in soft tissues, shells and Byssus of blue mussel (Mytilus edulis trossulus) from 23 sites along the Polish coast of the Baltic Sea were determined by AAS method. Byssus, as compared with the soft tissue, concentrated more effectively Pb, Cu, Cr, and especially Ag, Ni, Mn and Fe, moderately Hg and Zn and less effectively Cd. Significant inter-regional and inter-size differences in metal concentrations in both soft tissues and Byssus were recorded. Highly significant correlations (P
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distribution and association of trace metals in soft tissue and Byssus of mytella strigata and other benthal organisms from mazatlan harbour mangrove lagoon of the northwest coast of mexico
Environment International, 1998Co-Authors: Piotr Szefer, J Geldon, Anis Ahmed Ali, Paez F Osuna, A C Ruizfernandes, S Guerrero R GalvanAbstract:Concentrations of Cd, Pb, Zn, Cu, Ag, Cr, Co, Ni, Mn, and Fe in soft tissues and byssal threads of Mytella strigata (Mytilidae) and other benthal organisms (clam Chione subrugosa and algae Enteromorpha intestinalis, Ulva lactuca) from four sampling sites in a tropical mangrove lagoon, on the northwest coast of Mexico, were determined by atomic absorption spectrophotometry (AAS). Some inter-regional differences in metal concentrations, especially concerning Ni, Cu, and Mn in both soft tissue and Byssus, were identified. The concentrations of the majority of the metals analyzed were significantly greater in Byssus than in soft tissue, even as great as an order of magnitude for Pb, Co, Cr, Ni, Mn, and two orders of magnitude for Fe. Significant correlations (p<0.01; p<0.05) were observed between tissue concentrations of Ni-Mn, Cu-Ni (positive), Pb-Ni, Pb-Mn, Mn-Fe (negative) as well as byssal concentrations of Pb-Cr-Fe, Cu-Zn-Mn (positive), Pb-Ni, Ni-Fe, Cd-Zn (negative). Inter-comparison of the present data with those published previously (for Mytilidae from Japanese and Yemeni coastal waters) indicates that the soft tissue (mainly for Cd) and Byssus (especially for Co, Ni) are useful in detecting areas of selected metallic contaminants. Molluscs such as M. strtigata and C. subrugosa appear to be convenient biomonitors for identification of coastal waters exposed to Cd, Pb, Cu, Zn, Cr, Co, Ni, Mn, and Fe in the tropical American region.
Giuseppe Falini - One of the best experts on this subject based on the ideXlab platform.
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Metal ion removal using waste Byssus from aquaculture.
Scientific reports, 2020Co-Authors: Devis Montroni, Giorgia Giusti, Andrea Simoni, Genny Cau, Claudio Ciavatta, Claudio Marzadori, Giuseppe FaliniAbstract:Byssus is a thread-like seafood waste that has a natural high efficiency in anchoring many metal ions thanks to its richness of diverse functional groups. It also has structural stability in extreme chemical, physical and mechanical conditions. The combination of these properties, absent in other waste materials, has novelty suggested its use as matrix for water remediation. Thus, pristine Byssus, upon de-metalation, was studied to remove metal ions from ideal solutions at pH 4 and 7, as model chemical systems of industrial and environmental polluted waters, respectively. The Byssus matrix's uptake of metal ions was determined by ICP-OES and its surface microstructure investigated by SEM. The results showed that the Byssus matrix excellently uptakes metal ions slightly reorganizing its surface micro-structure. As example of its efficiency: 50 mg of Byssus absorbed 21.7 mg·g-1 of Cd2+ from a 10 mM solution at pH 7. The adsorption isotherm models of Freundlich and Langmuir were mainly used to describe the system at pH 7 and pH 4, respectively. In conclusion, we showed that the Byssus, a waste material that is an environmental issue, has the potential to purify polluted industrial and environmental waters from metal ions.
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Hierarchical chitinous matrices Byssus-inspired with mechanical properties tunable by Fe(III) and oxidation.
Carbohydrate polymers, 2020Co-Authors: Devis Montroni, Simona Fermani, Marco Palanca, Kavin Morellato, Luca Cristofolini, Giuseppe FaliniAbstract:Abstract In this study the multi-scale hierarchical structure of the β-chitin matrix from squid pen of Loligo vulgaris was used as substrate to synthesize new bio-inspired materials. Aiming to mimic the Byssus peculiar mechanical properties, we chemically functionalized the β-chitin matrix with catechols, one of the main functional groups of the Byssus. The obtained matrix preserved its multi-scale structural organization and was able to chelate reversibly Fe(III). Thus, it behaved as the Byssus, acting as a metal cross-linkable matrix that upon metalation increased its Young‘s modulus, E (> 10 times). The functionalized matrix was also cross-linked by oxidation provoking an increase of the E (> 10 times) and first failure stress (> 5 times). The oxidation of the functionalized matrix followed by metalation slightly increased the material mechanical properties. In conclusion, we added specific bio-functionalities in a natural matrix tuning its mechanical properties without altering its multi-scale organization.
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Functional Biocompatible Matrices from Mussel Byssus Waste
2018Co-Authors: Devis Montroni, Matthew J Harrington, Francesco Valle, Stefania Rapino, Simona Fermani, Matteo Calvaresi, Giuseppe FaliniAbstract:The mussel Byssus is a biorenewable, protein-based material produced by marine mussels, which has attracted the interest of material scientists because of its remarkable mechanical and self-healing properties. Large quantities of Byssus waste material from mussel mariculture are produced every year, which have great potential as a raw starting material for producing sustainable advanced materials. In this work, we developed a facile and scalable method to synthesize whole Byssus-based porous matrices that retain part of the hierarchical organization of the pristine material at the nanoscale. The resulting material is biocompatible and maintains important native Byssus features: metal ion chelation (≥12 mg/g), collagen domains, and hierarchical organization, with tunable properties controlled via metal ion content. Furthermore, these biocompatible matrices showed a dye absorbing efficiency (up to 64 mg/g for anionic dyes) that was similar to or higher than that of the pristine Byssus, a proof of preservation of structural motifs. These findings indicate that biorenewable matrices originating from Byssus waste could have potential use in biomedical engineering and applied material science
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A new twist on sea silk: the peculiar protein ultrastructure of fan shell and pearl oyster Byssus.
Soft Matter, 2018Co-Authors: Delphine Pasche, Nils Horbelt, Frederic Marin, Sebastien Motreuil, Peter Fratzl, Giuseppe Falini, Elena Macías-sánchez, Dong Soo Hwang, Matthew James HarringtonAbstract:Numerous mussel species produce byssal threads - tough proteinaceous fibers, which anchor mussels in aquatic habitats. Byssal threads from Mytilus species, which are comprised of modified collagen proteins - have become a veritable archetype for bio-inspired polymers due to their self-healing properties. However, threads from different species are comparatively much less understood. In particular, the Byssus of Pinna nobilis comprises thousands of fine fibers utilized by humans for millennia to fashion lightweight golden fabrics known as sea silk. P. nobilis is very different from Mytilus from an ecological, morphological and evolutionary point of view and it stands to reason that the structure-function relationships of its Byssus are distinct. Here, we performed compositional analysis, X-ray diffraction (XRD) and transmission electron microscopy (TEM) to investigate byssal threads of P. nobilis, as well as a closely related bivalve species (Atrina pectinata) and a distantly related one (Pinctada fucata). This comparative investigation revealed that all three threads share a similar molecular superstructure comprised of globular proteins organized helically into nanofibrils, which is completely distinct from the Mytilus thread ultrastructure, and more akin to the supramolecular organization of bacterial pili and F-actin. This unexpected discovery hints at a possible divergence in Byssus evolution in Pinnidae mussels, perhaps related to selective pressures in their respective ecological niches.
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Functional Biocompatible Matrices from Mussel Byssus Waste
ACS Biomaterials Science & Engineering, 2017Co-Authors: Devis Montroni, Matthew J Harrington, Francesco Valle, Stefania Rapino, Simona Fermani, Matteo Calvaresi, Giuseppe FaliniAbstract:The mussel Byssus is a biorenewable, protein-based material produced by marine mussels, which has attracted the interest of material scientists because of its remarkable mechanical and self-healing properties. Large quantities of Byssus waste material from mussel mariculture are produced every year, which have great potential as a raw starting material for producing sustainable advanced materials. In this work, we developed a facile and scalable method to synthesize whole Byssus-based porous matrices that retain part of the hierarchical organization of the pristine material at the nanoscale. The resulting material is biocompatible and maintains important native Byssus features: metal ion chelation (≥12 mg/g), collagen domains, and hierarchical organization, with tunable properties controlled via metal ion content. Furthermore, these biocompatible matrices showed a dye absorbing efficiency (up to 64 mg/g for anionic dyes) that was similar to or higher than that of the pristine Byssus, a proof of preservati...
Delphine Pasche - One of the best experts on this subject based on the ideXlab platform.
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« Il faut sauver le soldat Pinna ! » La Grande nacre de Méditerranée, bivalve patrimonial, est en grave danger d’extinction.
2019Co-Authors: Frederic Marin, Delphine Pasche, Daniel Jackson, Matthew James Harrington, Jonathan Perrin, Jérôme Thomas, Alain Garcia, Laurent Gilletta, David Luquet, Sebastien MotreuilAbstract:La Grande nacre Pinna nobilis est le plus grand bivalve de Méditerranée. Espèce endémique, elle est inféodée aux herbiers de posidonies, vivant sous forme de petites populations clairsemées. C’est une espèce patrimoniale : son Byssus a longtemps été collecté pour être utilisé à la confection de gants, bonnets ou étoles. Protégée par une Directive Européenne (1992), P. nobilis fait l’objet d’une surveillance étroite au plan national et international. Or depuis fi n 2016, une épidémie, dont l’origine semble être un parasite protozoaire, décime les populations (jusqu’à 100 % de mortalité). Détectée au départ sur les côtes espagnoles, elle s’étend sur tout le pourtour méditerranéen. Bien que des mesures aient été prises, les prochaines années pourraient voir l’extinction de ce bivalve emblématique. Hormis sa valeur symbolique, P. nobilis est une espèce digne d’intérêt en science des matériaux et composites bioinspirés. En effet, sa coquille comprend deux couches minéralisées, dont l’une, externe, est constituée de grands prismes calcitiques d’aspect monocristallin, simples en apparence, mais présentant une structuration multi-échelle très complexe. Comprendre leur formation et leur croissance est un challenge en biomimétique. Son Byssus forme des fi laments très fi ns remarquablement solides, aux propriétés ultrastructurales différentes de celles du Byssus de moule. Jusqu’à présent, la chimie de ce Byssus reste mystérieuse. L’appréhender est aussi une gageure en physique des matériaux. Ces différents points sont abordés dans cet article.
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self healing silk from the sea role of helical hierarchical structure in pinna nobilis Byssus mechanics
Soft Matter, 2019Co-Authors: Delphine Pasche, Nils Horbelt, Frederic Marin, Sebastien Motreuil, Peter Fratzl, Matthew J HarringtonAbstract:The Byssus fibers of Mytilus mussel species have become an important role model in bioinspired materials research due to their impressive properties (e.g. high toughness, self-healing); however, Mytilids represent only a small subset of all Byssus-producing bivalves. Recent studies have revealed that Byssus from other species possess completely different protein composition and hierarchical structure. In this regard, Pinna nobilis Byssus is especially interesting due to its very different morphology, function and its historical use for weaving lightweight golden fabrics, known as sea silk. P. nobilis Byssus was recently discovered to be comprised of globular proteins organized into a helical protein superstructure. In this work, we investigate the relationships between this hierarchical structure and the mechanical properties of P. nobilis Byssus threads, including energy dissipation and self-healing capacity. To achieve this, we performed in-depth mechanical characterization, as well as tensile testing coupled with in situ X-ray scattering. Our findings reveal that P. nobilis Byssus, like Mytilus, possesses self-healing and energy damping behavior and that the initial elastic behavior of P. nobilis Byssus is due to stretching and unraveling of the previously observed helical building blocks comprising the Byssus. These findings have biological relevance for understanding the convergent evolution of mussel Byssus for different species, and also for the field of bio-inspired materials.
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A new twist on sea silk: the peculiar protein ultrastructure of fan shell and pearl oyster Byssus.
Soft Matter, 2018Co-Authors: Delphine Pasche, Nils Horbelt, Frederic Marin, Sebastien Motreuil, Peter Fratzl, Giuseppe Falini, Elena Macías-sánchez, Dong Soo Hwang, Matthew James HarringtonAbstract:Numerous mussel species produce byssal threads - tough proteinaceous fibers, which anchor mussels in aquatic habitats. Byssal threads from Mytilus species, which are comprised of modified collagen proteins - have become a veritable archetype for bio-inspired polymers due to their self-healing properties. However, threads from different species are comparatively much less understood. In particular, the Byssus of Pinna nobilis comprises thousands of fine fibers utilized by humans for millennia to fashion lightweight golden fabrics known as sea silk. P. nobilis is very different from Mytilus from an ecological, morphological and evolutionary point of view and it stands to reason that the structure-function relationships of its Byssus are distinct. Here, we performed compositional analysis, X-ray diffraction (XRD) and transmission electron microscopy (TEM) to investigate byssal threads of P. nobilis, as well as a closely related bivalve species (Atrina pectinata) and a distantly related one (Pinctada fucata). This comparative investigation revealed that all three threads share a similar molecular superstructure comprised of globular proteins organized helically into nanofibrils, which is completely distinct from the Mytilus thread ultrastructure, and more akin to the supramolecular organization of bacterial pili and F-actin. This unexpected discovery hints at a possible divergence in Byssus evolution in Pinnidae mussels, perhaps related to selective pressures in their respective ecological niches.
