Diverting the Use of Hand-Operated Tablet Press Machines to Bioassays: A Novel Protocol to Test 'Waste' Insoluble Shell Matrices.

To mineralize their shells, molluscs secrete a complex cocktail of proteins-collectively defined as the calcifying shell matrix-that remains occluded in the exoskeleton. Nowadays, protein extracts from shells are recognized as a potential source of bioactive substances, among which signalling molecules, bactericides or protease inhibitors offer the most tangible perspectives in applied sciences, health, and aquaculture. However, one technical obstacle in testing the activity of shell extracts lies in their high insolubility. In this paper, we present a protocol that circumvents this impediment. After an adapted shell protein extraction and the production of two organic fractions-one soluble, one insoluble-we employ a hand-operated tablet press machine to generate well-calibrated tablets composed of 100% insoluble shell matrix. FT-IR monitoring of the quality of the tablets shows that the pressure used in the press machine does not impair the molecular properties of the insoluble extracts. The produced tablets can be directly tested in different biological assays, such as the bactericidal inhibition zone assay in Petri dish, as illustrated here. Diverting the use of the hand-operated tablet press opens new perspectives in the analysis of insoluble shell matrices, for discovering novel bioactive components.

Crystal structure of di-benzyl-ammonium hydrogen (4-amino-phen-yl)arsonate monohydrate.

The title salt, C14H16N+·C6H7AsNO3 -·H2O or [(C6H5CH2)2NH2][H2NC6H4As(OH)O2]·H2O, (I), was synthesized by mixing an aqueous solution of (4-amino-phenyl)-arsonic acid with an ethano-lic solution of di-benzyl-amine at room temperature. Compound I crystallizes in the monoclinic P21/c space group. The three components forming I are linked via N-H⋯O and O-H⋯O inter-molecular hydrogen bonds, resulting in the propagation of an infinite zigzag chain. Additional weak inter-actions between neighbouring chains, such as π-π and N-H⋯O contacts, involving phenyl rings, -NH2 and -As(OH)O3 functions, and H2O, respectively, lead to a three-dimensional network.

Crystal structure of the monoglycidyl ether of isoeugenol.

The title compound, C13H16O3 [GE-isoEu; systematic name: 2-({2-meth-oxy-4-[(E)-1-propen-1-yl]phen-oxy}meth-yl)oxirane], which crystallizes in the triclinic P space group, was synthesized in one step from iso-eugenol, a bio-based phenyl-propanoid, with an excess of epi-chloro-hydrin. Colourless prismatic crystals suitable for X-ray diffraction were obtained from a mixture of ethyl acetate and cyclo-hexane, during purification by column chromatography on silica gel. GE-isoEu, which corresponds to the trans isomer of the monoglycidyl ether of iso-eugenol, is based on a 1,2,4-tris-ubstituted benzene ring by diglycidyl ether, meth-oxy and 1-(E)-propenyl groups, respectively. In the crystal, mol-ecules are organized through offset π-stacking inter-actions. Chemically, GE-isoEu constitutes an inter-mediate in the synthesis protocol of 2-[3-meth-oxy-4-(2-oxiranylmeth-oxy)phen-yl]-3-methyl-oxirane (GEEp-isoEu), a di-epoxy-dized monomer used in the manufacturing of thermosetting resins and intended for the elaboration of bio-composites.

An alternative and effective method for extracting skeletal organic matrix adapted to the red coral Corallium rubrum.

Skeleton formation in corals is a biologically controlled process in which an extracellular organic matrix (OM) is entrapped inside the calcified structure. The analysis of OM requires a time-consuming and tedious extraction that includes grinding, demineralization, multiple rinsing and concentration steps. Here we present an alternative and straightforward method for the red coral Corallium rubrum that requires little equipment and saves steps. The entire skeleton is directly demineralized to produce a tractable material called ghost, which is further rinsed and melted at 80°C in water. The comparative analysis of the standard and alternative methods by electrophoresis, western blot, and FTIR of C. rubrum OM, shows that the 'alternative OM' is of higher quality. Advantages and limitations of both methods are discussed.

The 'Shellome' of the Crocus Clam Tridacna crocea Emphasizes Essential Components of Mollusk Shell Biomineralization.

Molluscan shells are among the most fascinating research objects because of their diverse morphologies and textures. The formation of these delicate biomineralized structures is a matrix-mediated process. A question that arises is what are the essential components required to build these exoskeletons. In order to understand the molecular mechanisms of molluscan shell formation, it is crucial to identify organic macromolecules in different shells from diverse taxa. In the case of bivalves, however, taxon sampling in previous shell proteomics studies are focused predominantly on representatives of the class Pteriomorphia such as pearl oysters, edible oysters and mussels. In this study, we have characterized the shell organic matrix from the crocus clam, Tridacna crocea, (Heterodonta) using various biochemical techniques, including SDS-PAGE, FT-IR, monosaccharide analysis, and enzyme-linked lectin assay (ELLA). Furthermore, we have identified a number of shell matrix proteins (SMPs) using a comprehensive proteomics approach combined to RNA-seq. The biochemical studies confirmed the presence of proteins, polysaccharides, and sulfates in the T. crocea shell organic matrix. Proteomics analysis revealed that the majority of the T. crocea SMPs are novel and dissimilar to known SMPs identified from the other bivalve species. Meanwhile, the SMP repertoire of the crocus clam also includes proteins with conserved functional domains such as chitin-binding domain, VWA domain, and protease inhibitor domain. We also identified BMSP (Blue Mussel Shell Protein, originally reported from Mytilus), which is widely distributed among molluscan shell matrix proteins. Tridacna SMPs also include low-complexity regions (LCRs) that are absent in the other molluscan genomes, indicating that these genes may have evolved in specific lineage. These results highlight the diversity of the organic molecules - in particular proteins - that are essential for molluscan shell formation.

The shell matrix and microstructure of the Ram's Horn squid: Molecular and structural characterization.

Molluscs are one of the most diversified phyla among metazoans. Most of them produce an external calcified shell, resulting from the secretory activity of a specialized epithelium of the calcifying mantle. This biomineralization process is controlled by a set of extracellular macromolecules, the organic matrix. In spite of several studies, these components are mainly known for bivalves and gastropods. In the present study, we investigated the physical and biochemical properties of the internal planispiral shell of the Ram's Horn squid Spirula spirula. Scanning Electron Microscope investigations of the shell reveal a complex microstructural organization. The saccharides constitute a quantitatively important moiety of the matrix, as shown by Fourier-transform infrared and solid-state nuclear magnetic resonance spectroscopies. NMR identified ß-chitin and additional polysaccharides for a total amount of 80% of the insoluble fraction. Proteomics was applied to both soluble and insoluble matrices and in silico searches were performed, first on heterologous metazoans models, and secondly on an unpublished transcriptome of Spirula spirula. In the first case, several peptides were identified, some of them matching with tyrosinase, chitinase 2, protease inhibitor, or immunoglobulin. In the second case, 39 hits were obtained, including transferrin, a serine protease inhibitor, matrilin, or different histones. The very few similarities with known molluscan shell matrix proteins suggest that Spirula spirula uses a unique set of shell matrix proteins for constructing its internal shell. The absence of similarity with closely related cephalopods demonstrates that there is no obvious phylogenetic signal in the cephalopod skeletal matrix.

The shell matrix of the european thorny oyster, Spondylus gaederopus: microstructural and molecular characterization.

Molluscs, the largest marine phylum, display extraordinary shell diversity and sophisticated biomineral architectures. However, mineral-associated biomolecules involved in biomineralization are still poorly characterised. We report the first comprehensive structural and biomolecular study of Spondylus gaederopus, a pectinoid bivalve with a peculiar shell texture. Used since prehistoric times, this is the best-known shell of Europe's cultural heritage. We find that Spondylus microstructure is very poor in mineral-bound organics, which are mostly intercrystalline and concentrated at the interface between structural layers. Using high-resolution liquid chromatography tandem mass spectrometry (LC-MS/MS) we characterized several shell protein fractions, isolated following different bleaching treatments. Several peptides were identified as well as six shell proteins, which display features and domains typically found in biomineralized tissues, including the prevalence of intrinsically disordered regions. It is very likely that these sequences only partially represent the full proteome of Spondylus, considering the lack of genomics data for this genus and the fact that most of the reconstructed peptides do not match with any known shell proteins, representing consequently lineage-specific sequences. This work sheds light onto the shell matrix involved in the biomineralization in spondylids. Our proteomics data suggest that Spondylus has evolved a shell-forming toolkit, distinct from that of other better studied pectinoids - fine-tuned to produce shell structures with high mechanical properties, while limited in organic content. This study therefore represents an important milestone for future studies on biomineralized skeletons and provides the first reference dataset for forthcoming molecular studies of Spondylus archaeological artifacts.

Environmentally Friendly Surface Modification Treatment of Flax Fibers by Supercritical Carbon Dioxide.

The present work investigates the effects of an environmentally friendly treatment based on supercritical carbon dioxide (scCO2) on the interfacial adhesion of flax fibers with thermoset matrices. In particular, the influence of this green treatment on the mechanical (by single yarn tensile test), thermal (by TGA), and chemical (by FT-IR) properties of commercially available flax yarns was preliminary addressed. Results showed that scCO2 can significantly modify the biochemical composition of flax fibers, by selectively removing lignin and hemicellulose, without altering their thermal stability and, most importantly, their mechanical properties. Single yarn fragmentation test results highlighted an increased interfacial adhesion after scCO2 treatment, especially for the vinylester matrix, in terms of reduced debonding and critical fragment length values compared to the untreated yarns by 18.9% and 15.1%, respectively. The treatment was less effective for epoxy matrix, for which debonding and critical fragment length values were reduced to a lesser extent, by 3.4% and 3.7%, respectively.

New Eco-Friendly Synthesized Thermosets from Isoeugenol-Based Epoxy Resins.

Epoxy resin plays a key role in composite matrices and DGEBA is the major precursor used. With the aim of favouring the use of bio resources, epoxy resins can be prepared from lignin. In particular, diglycidyl ether of isoeugenol derivatives are good candidates for the replacement of DGEBA. This article presents an effective and eco-friendly way to prepare epoxy resin derived from isoeugenol (BioIgenox), making its upscale possible. BioIgenox has been totally characterized by NMR, FTIR, MS and elemental analyses. Curing of BioIgenox and camphoric anhydride with varying epoxide function/anhydride molar ratios has allowed determining an optimum ratio near 1/0.9 based on DMA and DSC analyses and swelling behaviours. This thermoset exhibits a Tg measured by DMA of 165 °C, a tensile storage modulus at 40 °C of 2.2 GPa and mean 3-point bending stiffness, strength and strain at failure of 3.2 GPa, 120 MPa and 6.6%, respectively. Transposed to BioIgenox/hexahydrophtalic anhydride, this optimized formulation gives a thermoset with a Tg determined by DMA of 140 °C and a storage modulus at 40 °C of 2.6 GPa. The thermal and mechanical properties of these two thermosets are consistent with their use as matrices for structural or semi-structural composites.

'Palaeoshellomics' reveals the use of freshwater mother-of-pearl in prehistory.

The extensive use of mollusc shell as a versatile raw material is testament to its importance in prehistoric times. The consistent choice of certain species for different purposes, including the making of ornaments, is a direct representation of how humans viewed and exploited their environment. The necessary taxonomic information, however, is often impossible to obtain from objects that are small, heavily worked or degraded. Here we propose a novel biogeochemical approach to track the biological origin of prehistoric mollusc shell. We conducted an in-depth study of archaeological ornaments using microstructural, geochemical and biomolecular analyses, including 'palaeoshellomics', the first application of palaeoproteomics to mollusc shells (and indeed to any invertebrate calcified tissue). We reveal the consistent use of locally-sourced freshwater mother-of-pearl for the standardized manufacture of 'double-buttons'. This craft is found throughout Europe between 4200-3800 BCE, highlighting the ornament-makers' profound knowledge of the biogeosphere and the existence of cross-cultural traditions.

Biochemical characterization of the skeletal matrix of the massive coral, Porites australiensis - The saccharide moieties and their localization.

To construct calcium carbonate skeletons of sophisticated architecture, scleractinian corals secrete an extracellular skeletal organic matrix (SOM) from aboral ectodermal cells. The SOM, which is composed of proteins, saccharides, and lipids, performs functions critical for skeleton formation. Even though polysaccharides constitute the major component of the SOM, its contribution to coral skeleton formation is poorly understood. To this end, we analyzed the SOM of the massive colonial coral, Porites australiensis, the skeleton of which has drawn great research interest because it records environmental conditions throughout the life of the colony. The coral skeleton was extensively cleaned, decalcified with acetic acid, and organic fractions were separated based on solubility. These fractions were analyzed using various techniques, including SDS-PAGE, FT-IR, in vitro crystallization, CHNS analysis, chromatography analysis of monosaccharide and enzyme-linked lectin assay (ELLA). We confirmed the acidic nature of SOM and the presence of sulphate, which is thought to initiate CaCO3 crystallization. In order to analyze glycan structures, we performed ELLA on the soluble SOM for the first time and found that it exhibits strong specificity to Datura stramonium lectin (DSL). Furthermore, using biotinylated DSL with anti-biotin antibody conjugated to nanogold, in situ localization of DSL-binding polysaccharides in the P. australiensis skeleton was performed. Signals were distributed on the surfaces of fiber-like crystals of the skeleton, suggesting that polysaccharides may modulate crystal shape. Our study emphasizes the importance of sugar moieties in biomineralization of scleractinian corals.

Crystal structure of the diglycidyl ether of eugenol.

The diep-oxy monomer, C13H16O4 {DGE-Eu; systematic name: 2-[3-meth-oxy-4-(oxiran-2-ylmeth-oxy)benz-yl]oxirane}, was synthesized from eugenol by a three-step reaction. It consists of a 1,2,4-tris-ubstituted benzene ring substituted by diglycidyl ether, a meth-oxy group and a methyl-oxirane group. The three-membered oxirane rings are inclined to the benzene ring by 61.0 (3) and 27.9 (3)°. The methyl-ene C atom of one of the two terminal epoxide rings is positionally disordered [refined occupancy ratio = 0.69 (1):0.31 (1)]. In the crystal, mol-ecules are linked by C-H⋯O hydrogen bonds, forming layers parallel to the ab plane. The layers are linked by C-H⋯π inter-actions, forming a three-dimensional network.

Crystal structure of 2-methyl-1H-imidazol-3-ium hydrogen oxalate dihydrate.

Single crystals of the title mol-ecular salt, C4H7N2 (+)·HC2O4 (-)·2H2O, were isolated from the reaction of 2-methyl-1H-imidazole and oxalic acid in a 1:1 molar ratio in water. In the crystal, the cations and anions are positioned alternately along an infinite [010] ribbon and linked together through bifurcated N-H⋯(O,O) hydrogen bonds. The water mol-ecules of crystallization link the chains into (10-1) bilayers, with the methyl groups of the cations organized in an isotactic manner.

The Shell of the Invasive Bivalve Species Dreissena polymorpha: Biochemical, Elemental and Textural Investigations.

The zebra mussel Dreissena polymorpha is a well-established invasive model organism. Although extensively used in environmental sciences, virtually nothing is known of the molecular process of its shell calcification. By describing the microstructure, geochemistry and biochemistry/proteomics of the shell, the present study aims at promoting this species as a model organism in biomineralization studies, in order to establish a bridge with ecotoxicology, while sketching evolutionary conclusions. The shell of D. polymorpha exhibits the classical crossed-lamellar/complex crossed lamellar combination found in several heterodont bivalves, in addition to an external thin layer, the characteristics of which differ from what was described in earlier publication. We show that the shell selectively concentrates some heavy metals, in particular uranium, which predisposes D. polymorpha to local bioremediation of this pollutant. We establish the biochemical signature of the shell matrix, demonstrating that it interacts with the in vitro precipitation of calcium carbonate and inhibits calcium carbonate crystal formation, but these two properties are not strongly expressed. This matrix, although overall weakly glycosylated, contains a set of putatively calcium-binding proteins and a set of acidic sulphated proteins. 2D-gels reveal more than fifty proteins, twenty of which we identify by MS-MS analysis. We tentatively link the shell protein profile of D. polymorpha and the peculiar recent evolution of this invasive species of Ponto-Caspian origin, which has spread all across Europe in the last three centuries.

Crystal structure of bis-(2-methyl-1H-imidazol-3-ium) di-hydroxidobis(oxalato-κ(2) O (1),O (2))stannate(IV) monohydrate.

In the structure of the hydrated title salt, (C4H7N2)2[Sn(C2O4)2(OH)2]·H2O, the asymmetric unit comprises one stannate(IV) dianion, two organic cations and one water mol-ecule of crystallization. The [Sn(C2O4)2(OH)2](2-) dianion consists of an Sn(IV) atom chelated by two oxalate anions and coordinated by two OH(-) ligands in a cis octa-hedral arrangement. Neighbouring anions are connected through O-H⋯O hydrogen bonds between hydroxide groups and non-coordinating oxalate O atoms into layers expanding parallel to (100). In addition, cations and anions are linked through N-H⋯O hydrogen bonds, and the water mol-ecule bridges two anions with two O-H⋯O hydrogen bonds and is also the acceptor of an N-H⋯O hydrogen bond with one of the cations. Weak C-H⋯O hydrogen bonds are also observed. The intricate hydrogen bonding leads to the formation of a three-dimensional network.

A minimal molecular toolkit for mineral deposition? Biochemistry and proteomics of the test matrix of adult specimens of the sea urchin Paracentrotus lividus.

UNLABELLED: The sea urchin endoskeleton consists of a magnesium-rich biocalcite comprising a small amount of occluded organic macromolecules. This structure constitutes a key-model for understanding the mineral--organics interplay, and for conceiving in vitro bio-inspired materials with tailored properties. Here we employed a deep-clean technique to purify the occluded proteins from adult Paracentrotus lividus tests. We characterized them by 1- and 2D-electrophoreses, ELISA and immunoblotting, and using liquid chromatography coupled with Mass Spectrometry (nanoLC-MS/MS), we identified two metalloenzymes (carbonic anhydrase and MMP), a set of MSP130 family members, several C-type lectins (SM29, SM41, PM27) and cytoskeletal proteins. We demonstrate the effect of the protein extract on the crystals, with an in vitro crystallization assay. We suggest that this small set of biomineralization proteins may represent a 'minimal molecular crystallization toolkit'. SIGNIFICANCE: Biominerals often exhibit superior chemical properties, when compared to their inorganic counterparts. This is due pro parte to the proteins that are occluded in the mineral. However, the limited available studies on biomineralization have not yet succeeded in identifying a minimal set of proteins directly involved in the formation of the biomineral in vivo and sufficiently required for in vitro precipitation. Indeed, the high number of proteins identified by high-throughput screening in the recent years does not encourage the possibility of recreating or tailoring the mineral in vitro. Thus, the identification of biomineralization proteins involved in protein-mineral interactions is highly awaited. In the present study, we used the sea urchin, Paracentrotus lividus (P. lividus), to identify the native proteins directly taking part in protein-mineral interactions. We employed an improved deep-clean technique to extract and purify the native occluded skeletal matrix proteins from the test and identified them by the highly sensitive technique of nanoLC-MS/MS. We show that this minimal set of proteins has a shaping effect on the formation of biocalcite in vitro. This work gives insights on the biomineralization of the sea urchin, while it paves the way for the identification of biomineralization proteins in other biomineralizing systems. Understanding the 'biologically controlled mineralization' will facilitate the in vitro formation and tailoring of biominerals in mild conditions for applications in medicine and materials science.

Crystal structure of the bis-(cyclo-hexyl-ammonium) succinate succinic acid salt adduct.

The crystal structure of the title salt adduct, 2C6H14N(+)·C4H4O4 (2-)·C4H6O4, consists of two cyclo-hexyl-ammonium cations, one succcinate dianion and one neutral succinic acid mol-ecule. Succinate dianions and succinic acid mol-ecules are self-assembled head-to-tail through O-H⋯O hydrogen bonds and adopt a syn-syn configuration, leading to a strand-like arrangement along [101]. The cyclo-hexyl-ammonium cations have a chair conformation and act as multidentate hydrogen-bond donors linking adjacent strands through inter-molecular N-H⋯O inter-actions to both the succinate and the succinic acid components. This results in two-dimensional supra-molecular layered structures lying parallel to (010).

Crystal structure of di-methyl-ammonium hydrogen oxalate hemi(oxalic acid).

Single crystals of the title salt, Me2NH2 (+)·HC2O4 (-)·0.5H2C2O4, were isolated as a side product from the reaction involving Me2NH, H2C2O4 and Sn(n-Bu)3Cl in a 1:2 ratio in methanol or by the reaction of the (Me2NH2)2C2O4 salt and Sn(CH3)3Cl in a 2:1 ratio in ethanol. The asymmetric unit comprises a di-methyl-ammonium cation (Me2NH2 (+)), an hydrogenoxalate anion (HC2O4 (-)), and half a mol-ecule of oxalic acid (H2C2O4) situated about an inversion center. From a supra-molecular point of view, the three components inter-act together via hydrogen bonding. The Me2NH2 (+) cations and the HC2O4 (-) anions are in close proximity through bifurcated N-H⋯(O,O) hydrogen bonds, while the HC2O4 (-) anions are organized into infinite chains via O-H⋯O hydrogen bonds, propagating along the a-axis direction. In addition, the oxalic acid (H2C2O4) mol-ecules play the role of connectors between these chains. Both the carbonyl and hydroxyl groups of each diacid are involved in four inter-molecular inter-actions with two Me2NH2 (+) and two HC2O4 (-) ions of four distinct polymeric chains, via two N-H⋯O and two O-H⋯O hydrogen bonds, respectively. The resulting mol-ecular assembly can be viewed as a two-dimensional bilayer-like arrangement lying parallel to (010), and reinforced by a C-H⋯O hydrogen bond.

Crystal structure of 2-methyl-1H-imidazol-3-ium aqua-tri-chlorido-(oxalato-κ(2) O,O')stannate(IV).

The tin(IV) atom in the complex anion of the title salt, (C4H7N2)[Sn(C2O4)Cl3(H2O)], is in a distorted octa-hedral coordination environment defined by three chlorido ligands, an oxygen atom from a water mol-ecule and two oxygen atoms from a chelating oxalate anion. The organic cation is linked through a bifurcated N-H⋯O hydrogen bond to the free oxygen atoms of the oxalate ligand of the complex [Sn(H2O)Cl3(C2O4)](-) anion. Neighbouring stannate(IV) anions are linked through O-H⋯O hydrogen bonds involving the water mol-ecule and the two non-coordinating oxalate oxygen atoms. In combination with additional N-H⋯Cl hydrogen bonds between cations and anions, a three-dimensional network is spanned.

Crystal structure of bis-(cyclo-hexyl-ammonium) di-phenyl-dioxalatostannate(IV).

Reaction of oxalic acid and di-phenyl-tin dichloride in the presence of cyclo-hexyl-amine led to the formation of the title salt, (C6H14N)2[Sn(C6H5)2(C2O4)2]. The dianion is made up from an Sn(C6H5)2 moiety cis-coordinated by two chelating oxalate anions, leading to an overall distorted octa-hedral coordination geometry of the Sn(IV) atom. The negative charges are compensated by two surrounding cyclo-hexyl-ammonium cations adopting chair conformations each. In the crystal, anions and cations are linked via a network of N-H⋯O hydrogen bonds into a layered arrangement parallel to (101).