Recombinant mussel adhesive protein fp-5 (MAP fp-5) as a bulk bioadhesive and surface coating material

Mussel adhesive proteins (MAPs) attach to all types of inorganic and organic surfaces, even in wet environments. MAP of type 5 (fp-5), in particular, has been considered as a key adhesive material. However, the low availability of fp-5 has hampered its biochemical characterization and practical applications. Here, soluble recombinant fp-5 is mass-produced in Escherichia coli. Tyrosinase-modified recombinant fp-5 showed ～1.11 MPa adhesive shear strength, which is the first report of a bulk-scale adhesive force measurement for purified recombinant of natural MAP type. Surface coatings were also performed through simple dip-coating of various objects. In addition, complex coacervate using recombinant fp-5 and hyaluronic acid was prepared as an efficient adhesive formulation, which greatly improved the bulk adhesive strength. Collectively, it is expected that this work will enhance basic understanding of mussel adhesion and that recombinant fp-5 can be successfully used as a realistic bulk-scale bioadhesive and an efficient surface coating material.     

Byssal hairs in the invasive Asian freshwater bivalve Limnoperna fortunei (Mytilidae) in the Paraná River system with comments on this species in South America

We recorded, for the first time, byssal hairs in the Asian freshwater bivalve Limnoperna fortunei from the Paraná River system. We analysed the presence of hairs and their distribution on the shell in relation to habitat and shell size in 12 sites. Hairs were present in lentic habitats associated with macrophytes or organic matter, but were absent in lotic environments. The proportion of mussels with hairs was negatively correlated with current velocity. Hairs were more frequent and abundant in larger mussels. In general, the hairs are a similar length over the bivalve and almost entirely cover the shells in≥60% in lentic habitats. The projections allow L. fortunei to be camouflaged among the roots of macrophytes or coarse organic matter, assisting in avoiding visual predators. The clear-cut separation of L. fortunei populations into two different groups could be associated with phenotypic plasticity in this species.     

Invasive ecosystem engineers and biotic indices: Giving a wrong impression of water quality improvement?

Benthic component of an ecosystem is considered in ecological status assessment of the key European Directives. Most of the metrics proposed for the benthic quality assessment are biodiversity based. Their robustness and applicability are widely discussed in many recent studies. However an impact of invasive alien species on biotic indices and environmental quality assessments has been largely overlooked by researchers so far. In the current study we assessed Benthic Quality Index (BQI) in a coastal ecosystem, highly affected by the invasive zebra mussel Dreissena polymorpha. Zebra mussel is able of modifying benthic habitats and enhancing local biodiversity. In the analyzed ecosystem it affected benthic species richness, abundance and community structure. As a result the calculated BQI values were significantly higher in the presence of zebra mussel with evident outliers in samples with particularly high zebra mussel abundances. Therefore we found that BQI determined in our study was artificially elevated providing false signal of the ecological status improvement. Based on the results presented, we suggested data correction framework that has been tested on the current dataset and proved to be effective minimizing zebra mussel impact on BQI assessment. Our experience could be applied for other coastal ecosystems invaded by the zebra mussel or any other aquatic invasive species with resembling biological traits and bioinvasion impacts.     

Vulnerability of microcrustaceans to predation by the invasive filter-feeding mussel Limnoperna fortunei (Dunker)

Limnoperna fortunei is an Asian mussel introduced to South America around 1990. One of the most important impacts of this invader is probably its grazing on the plankton. In this study we evaluate the vulnerability of several planktonic microcrustaceans from the Paraná River floodplain to predation by adult L. fortunei. We conducted 2-h laboratory feeding experiments where the bivalves were offered microcrustaceans differing in overall body shape, size, and locomotive abilities. Ingestion and clearance rates for each taxon were estimated. Results suggest that, in addition to detritus and phytoplankton, microcrustaceans may be a very important food item for this invasive mollusc. Limnoperna fortunei can prey on larger organisms (up to 1100?µm) than Dreissena polymorpha, the European and North American invasive mussel.     

Microsatellite loci for dreissenid mussels (Mollusca: Bivalvia: Dreissenidae) and relatives: markers for assessing exotic and native populations

We developed and tested 14 new polymorphic microsatellite loci for dreissenid mussels, including the two species that have invaded many freshwater habitats in Eurasia and North America, where they cause serious industrial fouling damage and ecological alterations. These new loci will aid our understanding of their genetic patterns in invasive populations as well as throughout their native Ponto-Caspian distributions. Eight new loci for the zebra mussel Dreissena polymorpha polymorpha and six for the quagga mussel D. rostriformis bugensis were compared with new results from six previously published loci to generate a robust molecular toolkit for dreissenid mussels and their relatives. Taxa tested include D. p. polymorpha, D. r. bugensis, D. r. grimmi, D. presbensis, the 'living fossil'Congeria kusceri, and the dark false mussel Mytilopsis leucophaeata (the latter also is invasive). Overall, most of the 24 zebra mussel (N = 583) and 13 quagga mussel (N = 269) population samples conformed to Hardy-Weinberg equilibrium expectations for the new loci following sequential Bonferroni correction. The 11 loci (eight new, three previously published) evaluated for D. p. polymorpha averaged 35.1 alleles and 0.72 mean observed heterozygosity per locus, and 25.3 and 0.75 for the nine loci (six new, three previously published) developed for D. r. bugensis. All but three of these loci successfully amplified the other species of Dreissena, and all but one also amplified Congeria and Mytilopsis. All species and populations tested were significantly divergent using the microsatellite data, with neighbour-joining trees reflecting their evolutionary relationships; our results reveal broad utility for resolving their biogeographic, evolutionary, population and ecological patterns.     

Larval development of the invasive charru mussel,Mytella strigata (Bivalvia: Mytilidae)

ABSTRACT

The South American charru mussel, Mytella strigata, was recently recorded in Singapore waters, possibly introduced into Southeast Asia through shipping. The mussels have rapidly spread across estuarine coastal mudflats. Adult mussels were collected, spawned in aquaria and larvae were successfully cultured to the juvenile stage in the laboratory. The larval morphology and development of M. strigata is described in this paper. D-shaped veligers were produced within 20 h of fertilization and were approximately 75 µm in shell length. These larvae were capable of settlement two weeks post fertilization. Given an adequate amount of food, they were able to grow up to 1 mm in shell length within 30 days. The larval shell of M. strigata possesses anterodorsal G2 hinge teeth as distinct wavy ledges, with a pitted resilial ridge clearly evident in the juvenile shell.     

Adsorption behavior and enzymatically or chemically induced cross‐linking of a mussel adhesive protein

The adsorption behavior of the mussel adhesive protein Mytilus edulis foot protein‐1 (Mefp‐1) has been investigated on a negatively charged polar SiO₂ surface and an electrically inert non‐polar CH₃‐terminated thiolated gold surface. How the structure of adsorbed Mefp‐1 is changed upon chemically and enzymatically induced cross‐linking using sodium periodate (NaIO₄) and catechol oxidase, both of which transform DOPA residues in Mefp‐1 into highly reactive o‐quinones, was also investigated. The results are compared with those resulting from addition of Cu²⁺ to adsorbed Mefp‐1, which forms complexes with and catalyses oxidation of DOPA residues, previously suggested to participate in the cohesive and adhesive properties of the byssus thread of M. edulis. By combining surface plasmon resonance (SPR) and quartz crystal microbalance/dissipation (QCM‐D) measurements, the effects of these agents were investigated with respect to changes in the amount of coupled water, the viscoelastic properties (rigidity) and the hydrodynamic thickness of the protein adlayers. The layer of Mefp‐1 formed on the bare CH₃‐terminated surface was elongated, flexible and coupled hydrodynamically a substantial amount of water, whereas Mefp‐1 formed a rigidly attached adlayer on the SiO₂ surface. Upon enzymatically and chemically induced cross‐linking of Mefp‐1 formed on the CH₃ surface, the rigidity of the adlayer(s) increased significantly. A similar increase in the rigidity was observed also upon addition of Cu²⁺, suggesting that the high level of metal ions present in the byssus thread might be essential for the cohesive and adhesive properties of this protein. For the mass‐uptake kinetics of enzymatically induced cross‐linking, three different phases were observed and are interpreted as competition between binding of protein and release of coupled water. For the reaction with NaIO₄ and Cu²⁺, only release of water affected the coupled mass. The importance of this type of information for an improved understanding of the strong adhesion and cohesive properties in marine environments is discussed.     

Effects of different biotic substrata on mussel attachment

Surface colonization by invertebrates can be stimulated or inhibited by cues produced by biofilms, conspecifics or other macroorganisms. To study the effects of living substrata on the attachment of the brown mussel, Perna perna, two different approaches were employed: (1) mussels were distributed in sets of Petri dishes consisting of one sterile set (controls), three sets in which marine biofilms were allowed to develop in aquaria for 1, 7 or 15 days and another set that had been immersed in a natural marine environment for 1-day. There was no significant effect of biofilms on attachment, suggesting that neither age nor the source of the biofilm influenced attachment. (2) Mussels were suspended over PVC panels (controls) and over panels on which Balanus trigonus (Crustacea), Schizoporella errata (Bryozoa), Symplegma rubra or Didemnum speciosum (Ascidiacea) were present. Attachment was significantly higher on the controls and on B. trigonus than on colonial taxa such as S. rubra, S. errata and D. speciosum, probably due to antifouling defenses of these species. The results show that the composition of the biological substratum is an important factor affecting mussel behavior.     

Fouling deterrent chemical defence in three muricid gastropod egg masses from the Southeast coast of India

Abstract

The egg masses of the marine muricid gastropod molluscs Chicoreus virgineus, Chicoreus ramosus and Rapana rapiformis were studied for antifouling activities. The minimum inhibitory concentrations of crude extracts for the inhibition of byssal production and attachment of the brown mussel Perna indica were 650 μg ml^?1, 1150 μg ml^?1 and 925 μg ml^?1 from the three muricid gastropods, respectively. Higher LC₅₀ values than EC₅₀ values and 100% recovery of the mussels in the toxicity assay indicated the non-toxic nature of the extracts. The gradient partitioning of the egg mass extracts and subsequent antimicrofouling screening against 40 biofilm bacteria showed wide-spectrum antibacterial activity of the medium polar fraction from C. virgineus; the non-polar fraction from R. rapiformis and both non-polar and medium polar fractions from C. ramosus. The antimicrofouling activity from extracts of the three egg masses was found to be more prominent than antimacrofouling activity. This may be attributed to the targeting of a defence strategy against microbes in order to protect the developing mollusc embryos.