RESUMEN
A green protocol to extract chitin from crab shells using water soluble ionic liquids (ILs) is here reported. Compared to conventional multistep acid-base extraction methods, this one-pot procedure achieves pulping of recalcitrant crustacean waste shells by employing ammonium acetate, ammonium formate and hydroxylammonium acetate as water-soluble, low-cost and easy to prepare ILs. An extensive parametric analysis of the pulping process has been carried out with different ILs, different ratios, temperature and time. The optimized protocol provides a high-quality chitin comparable, if not better, to commercial chitin. The best results were obtained at 150 °C with ammonium formate prepared in-situ from aqueous ammonia and formic acid: chitin was isolated in a 17 wt% yield (based on dried crab shells as starting biowaste), a degree of acetylation (DA) > 94 %, a crystallinity index of 39-46 %, a molecular weight up to 6.6 × 105 g/mol and a polydispersity of ca 2.0.
Asunto(s)
Exoesqueleto , Braquiuros , Quitina , Animales , Quitina/química , Quitina/aislamiento & purificación , Exoesqueleto/química , Braquiuros/química , Líquidos Iónicos/química , Tecnología Química Verde/métodos , Acetilación , Temperatura , Formiatos/química , Arañas/químicaRESUMEN
Shrimp consumption is in great demand among the seafood used globally. However, this expansion has resulted in the substantial generation and disposal of shrimp shell waste. Through literature search, it has been observed that since 2020, global scholars have shown unprecedented interest in shrimp shell waste and its chitin/chitosan. However, these new insights lack corresponding and comprehensive summarization and analysis. Therefore, this article provides a detailed review of the extraction methods, applications, and the latest research developments on chitin/chitosan from shrimp shells, including micro-nano derivatives, from 2020 to the present. The results indicate that chemical extraction remains the primary technique for the extraction and preparation of chitin/chitosan from shrimp shells. With further refinement and development, adjusting parameters in the chemical extraction process or employing auxiliary techniques such as microwave and radiation enable the customization of target products with different characteristics (e.g., deacetylation degree, molecular weight, and degree of acetylation) according to specific needs. Additionally, in pursuit of environmentally friendly, efficient, and gentle extraction processes, recent research has shifted toward microbial fermentation and green solvent methods for chitin/chitosan extraction. Beyond the traditional antibacterial, film-forming, and encapsulation functionalities, research into the applications of chitosan in biomedical, food processing, new materials, water treatment, and adsorption fields is gradually deepening. Chitin/chitosan derivatives and their modified products have also been a focal point of research in recent years. However, with the rapid expansion, the future development of chitin/chitosan and its derivatives still faces challenges related to the unclear mechanism of action and the complexities associated with industrial scale-up.
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Exoesqueleto , Quitina , Quitosano , Quitina/química , Quitosano/química , Animales , Exoesqueleto/química , Residuos/análisis , Penaeidae/química , Crustáceos/químicaRESUMEN
Agricultural nitrogen (N) contributes a dominant percentage to global N pollution in the coastal zone. Emerging research on N isotopes in bivalve shells has shown value for reconstructing historical increases in estuarine wastewater inputs. However, applications for fertilizer N are understudied. Here, we integrate the study of organic N isotopes, in concert with δ18O and δ13C, in estuarine bivalve shells to investigate spatial and long-term changes in nitrogen inputs and sources. Modern, museum-collected, and subfossil specimens of the genera Mytilus and Ostrea were profiled in a California estuary with an intensely agricultural watershed. Spatial patterns in bivalve isotopic composition reflected gradients in watershed nutrient inputs and productivity parameters. Furthermore, a comparison between modern and historical periods revealed changes in nutrient source or processing over the last 1,000 years. The N isotope values from shells offer perspective on agricultural pollution in estuaries.
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Exoesqueleto , Monitoreo del Ambiente , Estuarios , Fertilizantes , Isótopos de Nitrógeno , Animales , Isótopos de Nitrógeno/análisis , Fertilizantes/análisis , Exoesqueleto/química , Contaminantes Químicos del Agua/análisis , California , Nitrógeno/análisis , Bivalvos , Agricultura , MytilusRESUMEN
In this study, deep eutectic solvent (DES) prepared from choline chloride, lactic acid, and one of the four polyols (ethylene glycol, glycerol, xylitol, and sorbitol) were compared and assessed for their effectiveness in extracting chitin from lobster shells. Our results revealed that as the number of hydroxyl groups in polyols increased, the hydrogen bond network within the DESs became denser. However, this led to a corresponding increase in viscosity, which impacted the efficiency of chitin extraction. Among all prepared DESs, choline chloride-lactic acid/glycerol (CCLaGly) exhibited superior extractive ability, resulting in the extraction of pure chitin from lobster shells. The purity, crystallinity, and molecular weight of the extracted chitin using CCLaGly DES were comparable to those of chemically-isolated chitin, with purity reaching 94.76 ± 0.33 %, crystallinity at 78.78 %, and a molecular weight of 655 kDa. Additionally, the physicochemical properties of the DES-extracted chitins were characterized using Fourier-transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy. This study conducted a comparative analysis of polyol effects on chitin extraction from lobster shells, thereby opening a promising avenue for the utilization of various crustacean shells in sustainable biomaterial production.
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Exoesqueleto , Quitina , Disolventes Eutécticos Profundos , Polímeros , Quitina/química , Quitina/aislamiento & purificación , Animales , Polímeros/química , Exoesqueleto/química , Disolventes Eutécticos Profundos/química , Viscosidad , Peso Molecular , Solventes/química , Espectroscopía Infrarroja por Transformada de Fourier , Difracción de Rayos X , Nephropidae/químicaRESUMEN
The direct enzymatic conversion of untreated waste shrimp and crab shells has been a key problem that plagues the large-scale utilization of chitin biological resources. The microorganisms in soil samples were enriched in two stages with powdered chitin (CP) and shrimp shell powder (SSP) as substrates. The enrichment microbiota XHQ10 with SSP degradation ability was obtained. The activities of chitinase and lytic polysaccharide monooxygenase of XHQ10 were 1.46 and 54.62 U/mL. Metagenomic analysis showed that Chitinolyticbacter meiyuanensis, Chitiniphilus shinanonensis, and Chitinimonas koreensis, with excellent chitin degradation performance, were highly enriched in XHQ10. Chitin oligosaccharides (CHOSs) are produced by XHQ10 through enzyme induction and two-stage temperature control technology, which contains CHOSs with a degree of polymerization (DP) more significant than ten and has excellent antioxidant activity. This work is the first study on the direct enzymatic preparation of CHOSs from SSP using enrichment microbiota, which provides a new path for the large-scale utilization of chitin bioresources.
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Exoesqueleto , Quitina , Quitinasas , Microbiota , Oligosacáridos , Quitina/química , Animales , Oligosacáridos/química , Quitinasas/metabolismo , Exoesqueleto/química , Metagenómica/métodos , Temperatura , Polimerizacion , BacteriasRESUMEN
Byssus is a unique external structure in sessile bivalves and is critical for settlement and metamorphosis. However, little is known about the stout byssus in Pteria penguin. We explored the byssus structure and proteins using scanning electron microscopy and proteomics, respectively. The results revealed that P. penguin byssus has a dense and highly aligned fiber inner core, and the outer cuticle contains protein granules embedded in the protein matrix. Proteomic analysis revealed 31 proteins in the byssus, among which 15 differentially expressed proteins were mainly enriched in the EGF/EGF-like and laminin EGF-like domains. Foot proteins were enriched in the EF-hand, immunoglobulin, and fibronectin domains. All these domains can participate in protein-protein and/or protein-metal interactions in the extracellular matrix (ECM), which, together with the seven types of ECM proteins detected in the byssus, supports the hypothesis that the byssus is derived from the ECM. We also found that in vitro acellular structures of the byssus and the shell shared commonalities in their formation processes. These results are useful for further understanding byssus evolution and the characterization of byssus-related proteins. SIGNIFICANCE: This manuscript investigates the structure and the origin of Pteria penguin byssus, given that byssus is vital to provide critical protection for reproduction and even against environmental stresses that affect survival. However, there is rare research on byssus protein composition. Hence, though scanning electron microscopy and proteomic analysis, we discovered that P. penguin byssus possesses the dense and highly aligned fiber inner core, and the outer cuticle has protein granules embedded in the protein matrix. Proteomic analysis showed that there were 31 proteins in the byssus, among which 15 proteins were mainly enriched in the EGF/EGF-like and laminin EGF-like domains. Foot proteins closely related to byssus formation were enriched in EF hand, immunoglobulin, and fibronectin domains. These domains are able to participate in protein-protein and/or protein-metal interactions in the extracellular matrix (ECM), which together with the seven types of ECM proteins detected in byssus support the hypothesis that byssus derive from the ECM. We also found in vitro acellular structures the byssus and the shell share commonalities in their formation processes. These results were useful for further understanding the byssus evolution and the characterization of the byssus-related proteins.
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Proteómica , Spheniscidae , Animales , Spheniscidae/metabolismo , Proteómica/métodos , Matriz Extracelular/metabolismo , Matriz Extracelular/ultraestructura , Proteínas de la Matriz Extracelular/metabolismo , Proteoma/metabolismo , Proteoma/análisis , Bivalvos/metabolismo , Exoesqueleto/metabolismo , Exoesqueleto/ultraestructura , Exoesqueleto/química , Evolución BiológicaRESUMEN
Biogenic carbonates, including bivalve shells, record past environmental conditions, but their interpretation requires understanding environmental and biological factors that affect trace metal uptake. We examined stable barium (δ138Ba) and radiogenic strontium (87Sr/86Sr) isotope ratios in the aragonite shells of four native freshwater mussel species and two invasive species in five streams and assessed the effects of species identity, growth rate, and river water chemistry on shell isotopic composition. Shells were robust proxies for Sr, accurately reflecting 87Sr/86Sr ratios of river water, regardless of species or growth rate. In contrast, shell δ138Ba values, apart from invasive Corbicula fluminea, departed widely from those of river water and varied according to species and growth rate. Apparent fractionation between river water and the shell (Δ138Bashell-water) reached -0.86, the greatest offset observed for carbonate minerals. The shell deposited during slow growth periods was more enriched in lighter Ba isotopes than the rapidly deposited shell; thus, this phenomenon cannot be explained by aragonite precipitation kinetics. Instead, biological ion transport processes linked to growth rate may be largely responsible for Ba isotope variation. Our results provide information necessary to interpret water chemistry records preserved in shells and provide insights into biomineralization processes and bivalve biochemistry.
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Exoesqueleto , Bario , Bivalvos , Agua Dulce , Isótopos de Estroncio , Animales , Exoesqueleto/química , Agua Dulce/química , Estroncio , Monitoreo del Ambiente , Isótopos , Corbicula/metabolismoRESUMEN
In this current investigation, the experimental performance of a solar still basin was significantly enhanced by incorporating snail shell biomaterials. The outcomes of the snail shell-augmented solar still basin (SSSS) are compared with those of a conventional solar still (CSS). The utilization of snail shells proved to facilitate the reduction of saline water and enhance its temperature, thereby improving the productivity of the SSSS. Cumulatively, the SSSS productivity was improved by 4.3% over CSS. Furthermore, the SSSS outperformed in energy and exergy efficiency of CSS by 4.5 and 3.5%, respectively. Economically, the cost per liter of distillate (CPL) for the CSS was 3.4% higher than SSSS. Moreover, the SSSS showed a shorter estimated payback period (PBP) of 141 days which was 6 days less than CSS. Considering the environmental impact, the observed CO2 emissions from the SSSS were approximately 14.6% higher than CSS over its 10-year lifespan. Notably, the SSSS exhibited a substantial increase in the estimated carbon credit earned (CCE) compared to the CSS. Ultimately, the research underscores the efficacy of incorporating snail shells into solar still basins as a commendable approach to organic waste management, offering economic benefits without compromising environmental considerations.
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Caracoles , Animales , Exoesqueleto/química , Materiales Biocompatibles/química , Luz Solar , Conservación de los Recursos Naturales/métodos , Purificación del Agua/métodosRESUMEN
In this study, hydroxyapatite (HAp) was synthesized from natural biowaste materials, specifically mussel shells, and combined with chitosan (CS) and gentamicin sulfate antibiotic (GA) using an in-situ method. The resulting composite material, designated HAp/CS-GA, has its physicochemical and structural properties characterized by Fourier transform infrared spectroscopy (FTIR) analysis. The structure was confirmed by X-ray diffraction (XRD) analysis. Additionally, field emission scanning electron microscopy (FE-SEM) equipped with the energy dispersive X-ray spectroscopic (EDX) technique was used to determine the surface topography and main components. The composite of HAp/CS-GA was analyzed using a drug release profile by UV-visible spectroscopy (UV-Vis). The fabricated composites antimicrobial behavior was examined against bone infection-causing Gram-positive and Gram-negative bacteria, showing potential activity against Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus compared to Escherichia coli, respectively. Simultaneously, the cytotoxicity of the composite was evaluated by MTT assay using an MG-63 osteoblast-like cell line that exhibited no toxicity in the prepared composite. After a 24 h incubation period, the MG-63 cells on the HAp/CS-GA composite showed good proliferation, according to Hoechst 33258 fluorescence staining results. The results suggested that the composite had excellent biocompatibility and antibacterial activity and enhanced the osteoblast cell proliferation. Therefore, the designed HAp/CS-GA composite would be a promising candidate for bone tissue engineering.
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Exoesqueleto , Antibacterianos , Bivalvos , Regeneración Ósea , Quitosano , Durapatita , Gentamicinas , Gentamicinas/farmacología , Gentamicinas/química , Quitosano/química , Quitosano/farmacología , Antibacterianos/farmacología , Antibacterianos/química , Durapatita/química , Animales , Bivalvos/química , Regeneración Ósea/efectos de los fármacos , Humanos , Exoesqueleto/química , Pruebas de Sensibilidad Microbiana , Línea CelularRESUMEN
This study reports first results on uranium (236U), neptunium (237Np) and plutonium (239Pu and 240Pu) isotopes in shell samples (i.e. oyster, clam and scallop shells) from the coast of the South of China. The 240Pu/239Pu and 236U/238U atom ratios are used for source identification, and the 237Np/239Pu, 237Np/236U and 236U/239Pu non-isotopic atom ratios to study the relative bioaccumulation of Np, Pu and U during the shell formation. The obtained concentration levels are in the 104-106 atoms g-1 range in every case. Clear regional differences are observed in the case of the 240Pu/239Pu atom ratio, with average values lower along the coast of East China Sea (average 0.227 ± 0.120, n = 5) compared to the South China Sea (average 0.258 ± 0.018, n = 7), showing a possible influence of the Pu released at the Pacific Proving Ground nuclear test site. 236U/238U ( × 10-8) atom ratios range from 0.046 ± 0.009 to 0.524 ± 0.135, in agreement with the expected levels in surface seawater from the China Sea. 237Np/239Pu (average 4.1 ± 2.6, n = 13) and 237Np/236U ratios (average 14 ± 10, n = 13) in the oyster shells are clearly enhanced compared to the estimated one in the surface seawater, pointing out higher bioaccumulation of Np compared to Pu and U.
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Plutonio , Monitoreo de Radiación , Uranio , Contaminantes Radiactivos del Agua , China , Plutonio/análisis , Contaminantes Radiactivos del Agua/análisis , Animales , Uranio/análisis , Exoesqueleto/química , NeptunioRESUMEN
Biomaterials like chitosan, hydroxyapatite have been used in biomedical and pharmaceutical field, due to its valuable biochemical and physiological properties. In current work firstly our group has isolated a polysaccharide chitosan along with hydroxyapatite biomaterial from the same source by varying the process condition via greener approach. We have adapted greener approach for the isolation of chitosan within a short period of time and this is the very first report for the isolation of both chitosan and hydroxyapatite simultaneously from the same waste edible garden snail shells. Both these materials were thoroughly characterized by using UV, FT-IR, SEM techniques. Among synthetic colourants, congo red dye is recognized as carcinogens, which are usually used in the textile manufacturing. Interestingly, one of our biomaterial hydroxyapatite has shown good selectivity towards Congo red dye. The sensitivity range was obtained from 10 to 100 µM within the LOD of 101.52 nM. The developed sensor has been tested for various industrial effluents and shown good agreement with our results. Meanwhile these chitosan and hydroxyapatite have also been used as capping agent for the preparation of stable gold nanoparticles.
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Quitosano , Rojo Congo , Durapatita , Quitosano/química , Rojo Congo/química , Animales , Durapatita/química , Caracoles/química , Exoesqueleto/química , Tecnología Química Verde/métodos , Colorantes/química , Colorantes/aislamiento & purificación , Colorantes/análisis , Espectroscopía Infrarroja por Transformada de Fourier , Nanopartículas del Metal/química , Oro/químicaRESUMEN
Microplastics (MPs) pose risks to both aquatic ecosystems and human health. This study investigated MPs in the shells and soft tissues of hard clams (Meretrix taiwanica) cultured in the inland waters of Taiwan. This study further developed two novel risk indices for assessing the potential ecological and health consequences of MPs. Moreover, the metal concentrations in the clam's soft tissues and the associated consumption health risks were investigated. Clamshells contained significant amounts of MPs with an average abundance of 16.6 ± 6.9 MPs/ind., which was higher than in the soft tissues (2.7 ± 1.7 MPs/ind.). The distribution and sizes of MPs in shells and soft tissues were similar, primarily small-sized (<2 mm, >99 %), blue (>65 %), and fibrous (>99 %). Dominant MP polymer types included rayon (83.5 %), polyethylene terephthalate (11.8 %), and polyacrylonitrile (3.6 %). The proposed MP potential ecological risk index indicates a higher potential ecological MP risk in soft tissues (302-423) than in shells (270-278) of the clams. The MP potential hazard risk index showed that the risk of exposure to MP through shellfish consumption decreased with age. The total hazard index (THI) value suggested negligible health hazards from metal exposure through shellfish consumption. Moreover, there was no significant correlation between MPs and metal concentrations in soft tissues, suggesting that metals bound to MPs contribute minimally to the total accumulated metals in clam's soft tissues. This study confirms the presence of MPs in clam shells and provides a novel tool to assess the potential ecological and health risks associated with MPs in shellfish.
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Bivalvos , Microplásticos , Contaminantes Químicos del Agua , Animales , Microplásticos/toxicidad , Microplásticos/análisis , Contaminantes Químicos del Agua/análisis , Medición de Riesgo , Exoesqueleto/química , Metales/análisis , Metales/toxicidad , Taiwán , Monitoreo del AmbienteRESUMEN
Black-spot shell disease is an unresolved disease that decreases pearl quality and threatens pearl oyster survival. In previous studies, the bacterium Tenacibaculum sp. strain Pbs-1 was isolated from diseased Akoya pearl oysters Pinctada fucata, and a rapid, specific, and sensitive loop-mediated isothermal amplification (LAMP) assay for detecting this pathogen was established. This technology has considerable potential for routine diagnosis of strain Pbs-1 in oyster hatcheries and/or pearl farms; therefore, it is vital to identify substances in environmental samples that might inhibit LAMP and to find additives that can reduce the inhibition. In this study, we investigated the effects of six chemicals or proteins, otherwise known as conventional PCR inhibitors, on LAMP, using the DNA of strain Pbs-1 as template: humic acid, urea, iron (III) chloride hexahydrate, melanin, myoglobin, and Ethylenediamine-N,N,N',N'-tetraacetic acid, disodium salt, dihydrate (EDTA; pH 6.5). Next, to reduce the effects of identified inhibitors, we tested the addition of bovine serum albumin (BSA) or T4 gene 32 protein (gp32) to the LAMP assay. When 50 ng of DNA template was used, 4 ng/µL of humic acid, 0.05% melanin, and 10 mM of EDTA (pH 6.5) inhibited the LAMP reaction, whereas myoglobin, urea, and FeCl3 had no effect. When 50 pg of DNA template was used, 4 ng/µL of humic acid, 0.05% melanin, 4 µg/µL of myoglobin, 10 µg/µL of urea, and 10 mM of EDTA inhibited the LAMP reaction. Thus, it was shown that the gene-amplification inhibitory effect of melanin, humic acid, and urea could be reduced by adding BSA or gp32 to the LAMP reaction mixture. This technique could be applied as part of a protocol to prevent mass mortalities of pearl oysters; moreover, the results enhance our knowledge about substances that inhibit LAMP and methods to reduce the inhibition, which have rarely been reported.
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Técnicas de Amplificación de Ácido Nucleico , Pinctada , Tenacibaculum , Animales , Técnicas de Amplificación de Ácido Nucleico/métodos , Pinctada/microbiología , Pinctada/genética , Tenacibaculum/genética , Tenacibaculum/efectos de los fármacos , Tenacibaculum/aislamiento & purificación , Técnicas de Diagnóstico Molecular/métodos , ADN Bacteriano/genética , Exoesqueleto/microbiología , Exoesqueleto/química , Ácido Edético/farmacología , Sustancias Húmicas , Infecciones por Flavobacteriaceae/microbiología , Infecciones por Flavobacteriaceae/veterinariaRESUMEN
The property of being stubborn and degradation resistant makes nanoplastic (NP) pollution a long-standing remaining challenge. Here, we apply a designed top-down strategy to leverage the natural hierarchical structure of waste crayfish shells with exposed functional groups for efficient NP capture. The crayfish shell-based organic skeleton with improved flexibility, strength (14.37 to 60.13 MPa), and toughness (24.61 to 278.98 MJ m-3) was prepared by purposefully removing the inorganic components of crayfish shells through a simple two-step acid-alkali treatment. Due to the activated functional groups (e.g., -NH2, -CONH-, and -OH) and ordered architectures with macropores and nanofibers, this porous crayfish shell exhibited effective removal capability of NPs (72.92 mg g-1) by physical interception and hydrogen bond/electrostatic interactions. Moreover, the sustainability and stability of this porous crayfish shell were demonstrated by the maintained high-capture performance after five cycles. Finally, we provided a postprocessing approach that could convert both porous crayfish shell and NPs into a tough flat sheet. Thus, our feasible top-down engineering strategy combined with promising posttreatment is a powerful contender for a recycling approach with broad application scenarios and clear economic advantages for simultaneously addressing both waste biomass and NP pollutants.
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Exoesqueleto , Astacoidea , Animales , Adsorción , Porosidad , Exoesqueleto/química , Microplásticos/química , Tamaño de la Partícula , Propiedades de SuperficieRESUMEN
Caudofoveata are molluscs that protect their vermiform body with a scleritome, a mosaic of unconnected blade/lanceolate-shaped aragonite sclerites. For the species Falcidens gutturosus and Scutopus ventrolineatus we studied the crystallographic constitution and crystal orientation texture of the sclerites and the scleritome with electron-backscatter-diffraction (EBSD), laser-confocal-microscopy (LCM) and field-emission electron microscopy (FE-SEM) imaging. Each sclerite is an aragonite single crystal that is completely enveloped by an organic sheath. Adjacent sclerites overlap laterally and vertically are, however, not connected to each other. Sclerites are thickened in their central portion, relative to their periphery. Thickening increases also from sclerite tip towards its base. Accordingly, cross-sections through a sclerite are straight at its tip, curved and bent towards the sclerite base. Irrespective of curved sclerite morphologies, the aragonite lattice within the sclerite is coherent. Sclerite aragonite is not twinned. For each sclerite the crystallographic c-axis is parallel to the morphological long axis of the sclerite, the a-axis is perpendicular to its width and the b-axis is within the width of the sclerite. The single-crystalinity of the sclerites and their mode of organization in the scleritome is outstanding. Sclerite and aragonite arrangement in the scleritome is not given by a specific crystal growth mode, it is inherent to the secreting cells. We discuss that morphological characteristics of the sclerites and crystallographic preferred orientation (texture) of sclerite aragonite is not the result of competitive growth selection. It is generated by the templating effect of the organic substance of the secreting cells and associated extracellular biopolymers.
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Exoesqueleto , Carbonato de Calcio , Moluscos , Animales , Exoesqueleto/química , Exoesqueleto/ultraestructura , Moluscos/química , Carbonato de Calcio/química , Cristalografía , Microscopía Electrónica de RastreoRESUMEN
The Ediacaran-Cambrian transition documents a critical stage in the diversification of animals. The global fossil record documents the appearance of cloudinomorphs and other shelled tubular organisms followed by non-biomineralized small carbonaceous fossils and by the highly diversified small shelly fossils between ~ 550 and 530 Ma. Here, we report diverse microfossils in thin sections and hand samples from the Ediacaran Bocaina Formation, Brazil, separated into five descriptive categories: elongate solid structures (ES); elongate filled structures (EF); two types of equidimensional structures (EQ 1 and 2) and elongate hollow structures with coiled ends (CE). These specimens, interpreted as diversified candidate metazoans, predate the latest Ediacaran biomineralized index macrofossils of the Cloudina-Corumbella-Namacalathus biozone in the overlying Tamengo Formation. Our new carbonate U-Pb ages for the Bocaina Formation, position this novel fossil record at 571 ± 9 Ma (weighted mean age). Thus, our data point to diversification of metazoans, including biomineralized specimens reminiscent of sections of cloudinids, protoconodonts, anabaritids, and hyolithids, in addition to organo-phosphatic surficial coverings of animals, demonstrably earlier than the record of the earliest known skeletonized metazoan fossils.
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Fósiles , Animales , Brasil , Exoesqueleto/anatomía & histología , Exoesqueleto/química , Evolución Biológica , Paleontología/métodosRESUMEN
The role of the carapace in the uptake and storage of newly accumulated metals was investigated in the green crab exposed to environmentally relevant concentrations of calcium ([Ca] = 389 mg L-1 or 9.7 mmol L-1), zinc ([Zn] = 82 µg L-1 or 1.25 µmol L-1), and nickel ([Ni] = 8.2 µg L-1 or 0.14 µmol L-1) in 12 °C seawater, using radio-tracers (45Ca, 65Zn, 63Ni). After 24-h exposure, carapace exhibited the highest concentration of newly accumulated Ca, whereas carapace and gills exhibited the highest concentrations of both newly accumulated Zn and Ni relative to other tissues. For all three metals, the carapace accounted for >85 % of the total body burden. Acute temperature changes (to 2 °C and 22 °C) revealed the highest overall temperature coefficient Q10 (2.15) for Ca uptake into the carapace, intermediate Q10 for Ni (1.87) and lowest Q10 (1.45) for Zn. New Ca uptake into the carapace continued linearly with time for 24 h, new Zn uptake gradually deviated from linearity, whereas Ni uptake reached a plateau by 6 h. Attachment of a rubber membrane to the dorsal carapace, thereby shielding about 20 % of the total crab surface area from the external water, eliminated both new Zn and Ni incorporation into the shielded carapace, whereas 36 % of new Ca incorporation persisted. When recently euthanized crabs were exposed, new Zn uptake into the carapace remained unchanged, whereas Ca and Ni uptake were reduced by 89 % and 71 %, respectively. We conclude that the carapace is a very important uptake and storage site for all three metals. All of the uptake of new Zn and new Ni, and most of the uptake of new Ca into this tissue comes directly from the external water. For Zn, the mechanism involves only physicochemical processes, whereas for Ca and Ni, life-dependent processes make the major contribution.
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Braquiuros , Calcio , Níquel , Agua de Mar , Contaminantes Químicos del Agua , Zinc , Animales , Braquiuros/metabolismo , Níquel/metabolismo , Zinc/metabolismo , Contaminantes Químicos del Agua/metabolismo , Agua de Mar/química , Calcio/metabolismo , Exoesqueleto/química , Exoesqueleto/metabolismo , Monitoreo del AmbienteRESUMEN
Hydroxyapatite (HAp) stands as an inorganic compound, recognized as a non-toxic, bioactive ceramic, and its composition closely resembles that of bone material. In this study, nHAp was prepared from waste oyster shells, which are biowaste rich in calcium carbonate. nHAp with its unique catalytic property can be used as an adsorbent in various fields, including wastewater treatment. nHAp with an exceptional surface adsorbent with excellent chemical stability, enabling its catalytic function. Nano hydroxyapatite doped with Zinc oxide (ZnO) by wet chemical precipitation and made into a composite with Graphene oxide (GO) by modified hummers method followed by grinding, which was taken as 9:1 ratio (nHAp/ZnO and GO) of weight, enhances its tensile and mechanical strength. The energy band gap of nHAp photocatalyst was evaluated as 3.39 eV and that of the in nHAp/ZnO/GO photocatalyst was narrowed to 1.77 eV. The ternary nanocomposites are very efficient in generating the photogenerated electrons and holes, thereby improving the degradation potential of dye effluents to by-products such as CO2 and H2O. The nanocomposites photocatalyst were characterized by FTIR, XRD, SEM, TEM, EDS, XPS, DRS, and BET techniques. The UV-visible study shows the complete dye degradation efficiency of the prepared nanocomposites photocatalyst. In this study, the prepared nanocomposites nHAp/ZnO/GO have studied their efficiency for the removal of MB dye in a batch process by varying the dosage from 0.1 to 0.5 g, and the effects of dosage variations, pH, kinetic, scavenger study were evaluated at a time interval of 30 min. The removal of dye was found to be 99% at 150 min of 0.3 g dosage and pH = 12 is most favorable as it reached the same percentage at 90 min. The as-prepared nanocomposite nHAp/ZnO/GO fits the kinetic rate constant equation and shows a pseudo-first-order reaction model. This study indicates the suitability for dye removal due to the synergistic effect and electrostatic interaction of the synthesized ternary nanocomposite, which shows the potential, socially active, low-cost-effective, eco-friendly, and safe for photocatalytic degradation of MB from wastewater.
Asunto(s)
Durapatita , Grafito , Azul de Metileno , Ostreidae , Óxido de Zinc , Óxido de Zinc/química , Animales , Durapatita/química , Azul de Metileno/química , Catálisis , Grafito/química , Contaminantes Químicos del Agua/química , Nanocompuestos/química , Adsorción , Exoesqueleto/químicaRESUMEN
Observations from the California Current System (CalCS) indicate that the long-term trend in ocean acidification (OA) and the naturally occurring corrosive conditions for the CaCO3 mineral aragonite (saturation state Ω < 1) have a damaging effect on shelled pteropods, a keystone group of calcifying organisms in the CalCS. Concern is heightened by recent findings suggesting that shell formation and developmental progress are already impacted when Ω falls below 1.5. Here, we quantify the impact of low Ω conditions on pteropods using an individual-based model (IBM) with life-stage-specific mortality, growth, and behavior in a high-resolution regional hindcast simulation of the CalCS between 1984 and 2019. Special attention is paid to attributing this impact to different processes that lead to such low Ω conditions, namely natural variability, long-term trend, and extreme events. We find that much of the observed damage in the CalCS, and specifically >70% of the shell CaCO3 loss, is due to the pteropods' exposure to naturally occurring low Ω conditions as a result of their diel vertical migration (DVM). Over the hindcast period, their exposure to damaging waters (Ω < 1.5) increases from 9% to 49%, doubling their shell CaCO3 loss, and increasing their mortality by ~40%. Most of this increased exposure is due to the shoaling of low Ω waters driven by the long-term trend in OA. Extreme OA events amplify this increase by ~40%. Our approach can quantify the health of pteropod populations under shifting environmental conditions, and attribute changes in fitness or population structure to changes in the stressor landscape across hierarchical time scales.
Asunto(s)
Carbonato de Calcio , Agua de Mar , Carbonato de Calcio/análisis , Animales , Agua de Mar/química , California , Exoesqueleto/química , Concentración de Iones de Hidrógeno , Movimientos del Agua , Gastrópodos/fisiología , Gastrópodos/crecimiento & desarrollo , Cambio ClimáticoRESUMEN
Osteoporosis is a major public health problem with an urgent need for safe and effective therapeutic interventions. The process of shell formation in oysters is similar to that of bone formation in mammals, and oyster extracts have been proven to exert osteoprotective effects. Oyster mantle is the most crucial organ regulating shell formation, in which exosomes play an important role. However, the effects of oyster mantle-derived exosomes (OMEs) on mammalian osteoporosis and the underlying mechanisms remain unknown. The OMEs investigated herein was found to carry abundant osteogenic cargos. They could also survive hostile gastrointestinal conditions and accumulate in the bones following oral administration. Moreover, they promoted osteoblastic differentiation and inhibited osteoclastic differentiation simultaneously. Further mechanistic examination revealed that OMEs likely promoted osteogenic activity by activating PI3K/Akt/ß-catenin pathway in osteoblasts and blunted osteoclastic activity by inhibiting NF-κB pathway in osteoclasts. These favorable pro-osteogenic effects of OMEs were also corroborated in a rat femur defect model. Importantly, oral administration of OMEs effectively attenuated bone loss and improved the bone microstructure in ovariectomy-induced osteoporotic mice, and demonstrating excellent biosafety. The mechanistic insights from our data support that OMEs possess promising therapeutic potential against osteoporosis.