1,721,231 research outputs found
Corals and global warming: the Mediterranean versus the Red Sea (CoralWarm)
No full textCoralWarm will generate for the first time projections of temperate and subtropical coral survival by integrating sublethal temperature increase effects on metabolic and skeletal processes in Mediterranean and Red Sea key species.
CoralWarm unique approach is from the nano- to the macro-scale, correlating molecular events to environmental processes. This will show new pathways to future investigations on cellular mechanisms linking environmental factors to final phenotype, potentially improving prediction powers and paleoclimatological interpretation.
Biological and chemical expertise will merge, producing new interdisciplinary approaches for ecophysiology and biomineralization.
Field transplantations will be combined with controlled experiments under IPCC scenarios. Corals will be grown in aquaria, exposing the Mediterranean species native to cooler waters to higher temperatures, and the Red Sea ones to gradually increasing above ambient warming seawater. Virtually all state-of-the-art methods will be used, by uniquely combining the investigators’ expertise.
Expected results include responses of algal symbionts’ photosynthesis, host, symbiont and holobiont respiratioIMG_0743n, biomineralization rates and patterns, including colony architecture, and reproduction to temperature and pH gradients and combinations.
Integration of molecular aspects of potential replacement of symbiont clades, changes in skeletal crystallography, with biochemical and physiological aspects of temperature response, will lead to a novel mechanistic model predicting changes in coral ecology and survival prospect.
High-temperature tolerant clades and species will be revealed, allowing future bioremediation actions and establishment of coral refuges, saving corals and coral reefs for future generations
Coral biomineralization: A focus on intra-skeletal organic matrix and calcification
No full textIn the recent years several papers and some reviews have dealt with characterization, localization and influence on the precipitation of calcium carbonate, of the organic matrix from scleractinian corals. In fact, it has been well established that coral calcification is a biological controlled process orchestrated in space and time by the organism also trough the secretion of organic matrix molecules because it has been well established that coral calcification is a biological controlled process, and thus is orchestrated in space and time by the organism also through the secretion of organic matrix molecules. In this review is presented a scientific path on the biomineralization of corals having as focusing point the intra-skeletal organic matrix, the molecules that are associated with mineral (aragonite). The review starts with a an overview on coral tissue, skeleton and tissue skeleton interface, describes the intra-skeletal organic matrix putting attention mainly on the proteins associated to aragonite and finally describes the in vivo and in vitro calcium carbonate precipitation experiments carried out aimed to evaluate the role of the organic matrix. The last paragraph reports studies on the role of the organic matrix in controlling calcification when corals are subject ocean acidification effects. The readers are expected to find a source of inspiration for new studies on the biomineralization of corals that are organic matrix addressed and merge diverse scientific disciplines
Influence of proteins on mechanical properties of a natural chitin-protein composite
Full text linkIn many biogenic materials, chitin chains are assembled in fibrils that are wrapped by a protein fold. In them, the mechanical properties are supposed to be related to intra- and inter- interactions among chitin and proteins. This hypothesis has been poorly investigated. Here, this research theme is studied using the pen of Loligo vulgaris as a model material of chitin-protein composites. Chemical treatments were used to change the interactions involving only the proteic phase, through unfolding and/or degradation processes. Successively, structural and mechanical parameters were examined using spectroscopy, microscopy, X-ray diffractometry, and tensile tests. The data analysis showed that chemical treatments did not modify the structure of the chitin matrix. This allowed to derive from the mechanical test analysis the following conclusions: (i) the maximum stress (σmax) relies on the presence of the disulfide bonds; (ii) the Young's modulus (E) relies on the overall correct folding of the proteins; (iii) the whole removal of proteins induces a decrease of E (> 90%) and σmax (> 80%), and an increase in the maximum elongation. These observations indicate that in the chitin matrix the proteins act as a strengthener, which efficacy is controlled by the presence of disulfide bridges. This reinforcement links the chitin fibrils avoiding them to slide one on the other and maximizing their resistance and stiffness. In conclusion, this knowledge can explain the physio-chemical properties of other biogenic polymeric composites and inspire the design of new materials. STATEMENT OF SIGNIFICANCE: To date, no study has addressed on how proteins influence chitin-composite material's mechanical properties. Here we show that the Young's modulus and the maximum stress mainly rely on protein disulfide bonds, the inter-proteins ones and those controlling the folding of chitin-binding domains. The removal of protein matrix induce a reduction of Young's modulus and maximum stress, leaving the chitin matrix structurally unaltered. The measure of the maximum elongation shows that the chitin fibrils slide on each other only after removing the protein matrix. In conclusion, this research shows that the proteins act as a stiff matrix reinforced by di-sulfide bridges that link crystalline chitin fibrils avoiding them to slide one on the other
Zero pollution: recycling sea byproducts of shellfish farming - Search for bactericidal biomolecules in the shell of mollusks of economic interest.
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Sustainable 3D Scaffolds Based on β-Chitin and Collagen I for Wound Dressing Applications
No full textThe development of greener substitutes for plastics is gaining massive importance in today’s society. This also involves the medical field, where disposable materials are used to grant sterility. Here, a novel protocol using only a water-based solvent for the preparation of bio-based composite foams of actual β-chitin and collagen type I is presented. The influence of the ratio of this chitin polymorph to the collagen on the final material is then studied. The samples with 50:50 and 75:25 ratios produce promising results, such as remarkable water absorption (up to 7000 wt.%), exposed surface (up to 7 m2·g−1), and total pore volume (over 80 vol.%). The materials are also tested using wet mechanical compression, exhibiting a Young’s modulus and tenacity (both calculated between 2% and 25% of deformation) of up to 20 Pa and 9 kPa, respectively. Fibroblasts, keratinocytes, and osteoblasts are grown on these scaffolds. The viability of fibroblasts and keratinocytes is observed for 72 h, whereas the viability of osteoblasts is observed for up to 21 days. Under the two conditions mentioned, cell activity and adhesion work even better than under its counterpart condition of pure collagen. In conclusion, these materials are promising candidates for sustainable regenerative medicine scaffolds or, specifically, as biodegradable wound dressings
Crystallization of Calcium Carbonate in Alginate and Xanthan Hydrogels
No full textCalcium carbonate polymorphs were crystallized in alginate and xanthan hydrogels in which a degree of entanglement was altered by the polysaccharide concentration. Both hydrogels contain functional groups (COOH and OH) attached at diverse proportions on saccharide units. In all systems, the precipitation process was initiated simultaneously with gelation, by the fast mixing of the calcium and carbonate solutions, which contain the polysaccharide molecules at respective concentrations. The initial supersaturation was adjusted to be relatively high in order to ensure the conditions suitable for nucleation of all CaCO3 polymorphs and amorphous phase(s). In the model systems (no polysaccharide), a mixture of calcite, vaterite and amorphous calcium carbonate initially precipitated, but after short time only calcite remained. In the presence of xanthan hydrogels, precipitation of either, calcite single crystals, porous polyhedral aggregates, or calcite/vaterite mixtures were observed after five days of ageing, because of different degrees of gel entanglement. At the highest xanthan concentrations applied, the vaterite content was significantly higher. In the alginate hydrogels, calcite microcrystalline aggregates, rosette-like and/or stuck-like monocrystals and vaterite/calcite mixtures precipitated as well. Time resolved crystallization experiments performed in alginate hydrogels indicated the initial formation of a mixture of calcite, vaterite and amorphous calcium carbonate, which transformed to calcite after 24 h of ageing
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