Search Results (23)

Oxidative stress-induced macrophage activation and vascular injury are major contributors to atherosclerosis, a chronic inflammatory disease associated with approximately 20 million deaths worldwide. This study investigated the antioxidant and anti-inflammatory activities of structurally characterized low-molecular-weight chitosan oligosaccharides (COS) derived from mud crab (Scylla olivacea) shell waste by hydrochloric acid hydrolysis and explored their molecular interactions with inflammation-related targets. Structural characterization by ¹³C-NMR and MALDI-TOF confirmed the identity of COS, while DPPH and ABTS analysis demonstrated concentration-dependent antioxidant activity. In LPS-induced RAW 264.7 macrophages, COS showed no cytotoxicity and significantly reduced nitric oxide production at 80 and 160 µg/mL. Molecular docking predicted favorable interactions of COS with several inflammation-associated proteins, with iNOS and COX-2 exhibiting the most favorable docking scores and extensive hydrogen-bonding and polar interactions. Transcriptomic profiling further revealed broad transcriptional remodeling and enrichment of pathways related to inflammation and atherosclerosis, including TNF, NF-κB, MAPK, Toll-like receptor, and lipid-and-atherosclerosis signaling. COS markedly suppressed inflammatory mediators, particularly Nos2 (iNOS) and Ptgs2 (COX-2) together with multiple cytokines and chemokines, consistent with reduced nitric oxide production and modulation of macrophage activation and foam cell-associated processes. Integration of docking and transcriptomic analyses identified iNOS and COX-2 as convergent candidate anti-inflammatory targets of COS, supporting its ability to attenuate inflammatory signaling through relevant pathways. These findings suggest that COS may modulate macrophage inflammatory responses through coordinated regulation of oxidative stress and inflammation-related signaling pathways. Full article

Processing crabs for meat generates large quantities of waste (secondary raw materials). Internal organs are typically discarded, which causes environmental problems and highlights the need for the integrated use of marine bioresources. The red king crab hepatopancreas is an excellent source of various proteins, including enzymes with different substrate specificities. In this study, an improved method was developed for producing a complex enzyme preparation from the hepatopancreas of red king crab (Paralithodes camtschaticus) harvested by a large industrial enterprise in the Barents Sea. Physicochemical analysis revealed high protein (16%) and lipid (10%) contents in the hepatopancreas. The developed method involves centrifugation to rapidly separate the fat fraction from the aqueous protein fraction and acetone washing to remove residual lipids. The use of low temperatures (0 to 5 °C) for autolysis is justified to prevent a decrease in enzymatic activity of the final preparation. Obtained enzyme preparations were analyzed for protease, collagenase, and endo- and exochitinase activity. They exhibited high proteolytic (A_prot = 252 μmol Tyr⋅g⁻¹⋅min⁻¹), exochitinolytic (A_exo = 0.94 μmol GlcNAc⋅g⁻¹⋅min⁻¹), and collagenolytic (A_col = 210 mIU·mg⁻¹) activities. It has been shown that enzymatic activities depend on seasonality (winter and summer) of the crab catch, which is due to differences in the physiological processes of crabs during seasonal cyclical temperature changes in their natural habitat. The developed process flowsheet for producing an enzyme preparation from the red king crab hepatopancreas can be used as the basis for technology by enterprises engaged in the comprehensive processing of marine bioresources. Full article

Ovarian maturity in live female mud crabs (Scylla paramamosain) strongly affects harvest decisions and market value. Current ovarian maturity assessment relies mainly on expert-dependent methods that are subjective and destructive. Therefore, this study aimed to develop an interpretable, non-destructive image-based framework to classify crab ovarian maturity as immature or mature. A total of 240 crab image sets acquired using ventral external-view, dorsal external-view, and dorsal transillumination imaging were retained for analysis. Six primary morphometric features were semi-manually extracted from these views. External-view images quantified carapace width (CW), abdomen width (AW), abdomen area (AA), and sternum area (SA). Dorsal transillumination images yielded carapace area (CA) and ovary area (OA), an internal cue visualized through the intact carapace. To mitigate body-size variation, three ratio-based features—abdomen–carapace width ratio (ACWR), abdomen–sternum area ratio (ASAR), and ovary–carapace area ratio (OCAR)—were calculated. Between-class comparisons and correlation analyses were performed to guide candidate feature-set construction. Because OA and OCAR were strongly correlated, two reduced feature sets (Reduced 1 and Reduced 2) were designed to compare absolute ovary area with normalized ovary occupancy. Five feature sets—Raw, Ratio, Combined, Reduced 1, and Reduced 2—were evaluated using logistic regression (LR), support vector machine (SVM), and random forest (RF) classifiers. The Combined feature set, integrating all primary and ratio-based features, achieved the strongest mean cross-validated performance when paired with LR. On the held-out test set (n = 40), the final Combined-LR model achieved 0.950 accuracy and 0.997 ROC–AUC. On an independent practical implementation set (n = 40), the model correctly classified 39 specimens, achieving 0.975 accuracy. These findings may support non-destructive ovarian maturity screening and commercial grading in mud crab aquaculture. Full article

Previous studies have reported the fatty acid composition of red king crab (Paralithodes camtschaticus) meat; however, no comparative analyses have simultaneously investigated raw (RM) and cooked meat (CM). This study addresses this gap by employing gas–liquid chromatography to analyze the fatty acid profiles of RM and CM from red king crabs from the coastal Barents Sea, Russia. Both products exhibited significant sex-specific differences, with females containing higher levels of fatty acids in their meat than males. Furthermore, males displayed greater dissimilarity between RM and CM compared to females. While nutritional indices were comparable between male and female RM and CM, the cooking process resulted in improved nutritional indices in CM relative to RM. Moreover, the red king crab meat exhibited superior nutritional indices compared to those reported for other, primarily southern, crab species, reflecting a higher polyunsaturated to saturated fatty acid ratio in both RM and CM. Comparisons with the existing literature revealed variability in red king crab meat fatty acid levels across geographical locations and years, suggesting that spatial variations in diet and temporal fluctuations in feeding habits may influence meat quality. Our findings confirm the high nutritional value of red king crab meat, a finding of relevance to both scientific and consumer audiences. Full article

Valorisation of crab by-products by enzymatic hydrolysis (EH) is proving to be a promising strategy to promote sustainable aquaculture and support a circular economy for crustaceans. Crab processing generates significant amounts of by-products that, if not properly managed, pose an environmental and economic challenge. These by-products are rich in chitin, proteins, and bioactive compounds and offer significant untapped potential for the development of functional feed. This review focuses on the application of enzymatically hydrolysed crab by-products as functional feed additives in aquaculture and their effects on fish growth, health management, and, consequently, human health. Recent studies have shown that EH effectively recovers chitin and bioactive peptides and improves the digestibility and bioavailability of nutrients in aquaculture. The inclusion of crude chitin, along with residual proteins and calcium carbonate, in the diet of farmed fish has been associated with increased growth, improved immune responses, and greater disease resistance, emphasising their critical role in fish health management. In addition, these functional additives contribute to the development of innovative aquafeeds with high added value and improved nutritional quality, while reducing environmental waste. Overall, the utilisation of crustacean by-products through enzymatic hydrolysis represents a valuable tool for the sustainable development of crustacean aquaculture, promotes the circular economy, and supports the development of innovative functional feeds while improving the growth and health of farmed fish, which has a positive impact on human health through their consumption. Full article

Background: Macrobrachium amazonicum is an opportunistic and omnivorous species that primarily feeds on plant material. Recent studies have shown that Endo-β-1,4-glucanase and Endo-β-1,4-mannanase are expressed in the transcriptome of adult specimens, while juveniles are capable of digesting nutrients from purified cellulose in their diet. In organisms that degrade raw plant material, laccase plays a key role in oxidizing phenolic compounds found in lignin, leading to its depolymerization and increasing access to cellulose and hemicellulose microfibrils. Objective: In this study, we conducted an in silico identification and characterization of the laccase-encoding gene, as this enzyme is linked to lignin biodegradation in herbivorous crustaceans. Methods: We analyzed the transcriptomes of the hepatopancreas from adult M. amazonicum, sequenced using the Illumina HiSeq 2500 platform. Subsequently, bioinformatics analyses were conducted to predict the conserved regions and active sites associated with laccase activity. Results: A complete open reading frame (ORF) of the laccase protein was identified in all datasets, comprising 609 amino acids. The top 40 similarity hits corresponded exclusively to crustaceans such as prawns, crayfish, and crabs (86.3–51.4%), while the highest divergence was observed in relation to fungi, plants, and bacteria. Three conserved domains were detected, along with the complete set of copper-binding centers (T1Cu, T2Cu, and T3Cu). A notable variable residue was methionine, suggesting a reduced redox potential in M. amazonicum laccase. Conclusion: These findings, combined with recent reports on the nutritional requirements of M. amazonicum, contribute to a deeper understanding of the digestive physiology of this species and offer valuable insights into its ability to utilize plant fibers as energy sources. Full article

V. lutrae is an emerging human pathogen attributed to increasing hospitalization cases in humans; however, its biology and epidemiology are under-explored. The present study explored V. lutrae recovery, prevalence, and biology. A two-step enrichment method (i.e., step 1, nourishment; step 2, heat, 80 °C, 20 min) and thiosulfate–citrate–bile salts–sucrose (TCBS) agar were employed for recovering V. lutrae in raw seafood. Bacterial colonies were streaked for purification before 16S rRNA bacterial identification. Confirmed V. lutrae isolates were analyzed for their culture-challenged turbidity and virulence. Of 41 bacterial isolates, 9 confirmed V. lutrae, including regular (33%; nourished 24 h) and heat-resistant (67%; nourished 48 h plus heating) isolates, were exclusively from yellow colonies (i.e., TCBS) and were exclusively recovered from nourished shrimp (78%) and crab (22%) only. The culture and virulence biology revealed that they could diversely tolerate salinity (i.e., 0–17.5% additional NaCl), pasteurization (63 °C, 8 h), oxygen availability, and antibiotic sensitivity (i.e., erythromycin, gentamicin, and vancomycin). Further, this pathogen exhibited no visible hemolytic and alkalization activities. Emerging foodborne pathogens could readily evade the established food safety regime. The present study reveals systematic investigation and diverse phenotypes of V. lutrae to enhance its detection and contribute to public health initiatives. Full article

Human norovirus (HuNoV) is a common cause of outbreaks linked to food. In this study, the effectiveness of a non-thermal method known as high-pressure processing (HPP) on the viable reduction of an HuNoV GII.4 strain on raw crabs was evaluated at three different pressures (200, 400, and 600 MPa). HuNoV viability in raw crabs was investigated by using propidium monoazide/sarkosyl (PMA) as a nucleic acid intercalating dye prior to performing a real-time reverse transcription-polymerase chain reaction (RT-qPCR). The effect of the HPP exposure on pH, sensory, and Hunter colors were also assessed. HuNoV was reduced in raw crabs compared with control to HPP (0.15–1.91 log) in non-PMA and (0.67–2.23 log) in PMA. HuNoV genomic titer reduction was <2 log copy number/µL) when HPP was treated for 5 min without PMA pretreatment, but it was reduced to >2 log copy number/µL after PMA. The pH and Hunter colors of the untreated and HPP-treated raw crabs were significantly different (p < 0.05), but sensory attributes were not significant. The findings indicate that PMA/RT-qPCR could be used to detect HuNoV infectivity without altering the quality of raw crabs after a 5 min treatment with HPP. Therefore, HuNoV GII.4 could be reduced up to 2.23 log in food at a commercially acceptable pressure duration of 600 MPa for 5 min. Full article

Astaxanthin is a xanthophyll carotenoid possessing impressive nutraceutical, antioxidant, and bioactive merits. Traditionally, astaxanthin is extracted from crustacean wastes via solvent extraction methods. However, the rigid structure of shells that comprise complex proteins and chitin challenges the extraction process. This investigation addressed an efficient microbial-assisted method to facilitate astaxanthin recovery from crab exoskeleton waste utilizing chitinolytic and proteolytic microorganisms. Herein, we evaluated the effect of pretreatment of the exoskeleton waste with a newly isolated probiotic strain, Bacillus amyloliquefaciens CPFD8, showing remarkable protease and chitinase activity and a proteolytic Saccharomyces cerevisiae 006-001 before solvent extraction, using acetone/hexane, on astaxanthin recovery. Furthermore, the antioxidant and anti-inflammatory activities of the recovered astaxanthin were inspected. Results revealed that both strains boosted the astaxanthin yield from the crab (Callinectes sapidus) exoskeleton compared with solvent extraction using acetone/hexane. Under optimum conditions, astaxanthin yield was 217 and 91 µg/g crab exoskeleton in samples treated with B. amyloliquefaciens CPFD8 and S. cerevisiae 006-001, respectively. Interestingly, pretreatment of crab exoskeleton waste with B. amyloliquefaciens CPFD8 yielded more than 6-fold astaxanthin compared with the solvent extraction method that yielded just 35 µg/g. This increase could be attributed to the proteolytic activity of B. amyloliquefaciens CPFD8 that rendered deproteinized shell chitin accessible to chitinase, facilitating the penetration of solvents and the recovery of astaxanthin. The recovered astaxanthin exhibited excellent antioxidant activity in scavenging DPPH or ABTS free radicals with IC₅₀ values of 50.93 and 17.56 µg/mL, respectively. In addition, the recovered astaxanthin showed a remarkable anti-inflammatory impact on LPS-induced murine macrophage RAW264.7 cells and significantly inhibited the production of nitric oxide, TNF-α, and IL-6 compared with the untreated control. These findings suggest the potential use of the developed microbial-assisted method utilizing chitinolytic and proteolytic B. amyloliquefaciens CPFD8 to maximize the recovery of bioactive astaxanthin from crab (C. sapidus) exoskeleton waste. Full article

Rab22a is an important small GTPase protein the molecule that is involved in intracellular transportation and regulation of proteins. It also plays an important role in antigens uptake, transportation, regulation of endosome morphology, and also regulates the transport of antigens to MHC (Major Histocompatibility Complex) molecules. To investigate the role of Rab22a, the intracellular co-localization of chicken Rab22a (cRab22a) molecule and its relationship to BF and chicken invariant chain (cIi) molecules was studied. A 3D protein structure of Rab22a was constructed by using informatics tools (DNASTAR 4.0 and DNAMAN). Based on the model, the corresponding recombinant eukaryotic plasmids were constructed by point mutations in the protein’s structural domains. HEK 293T cells were co-transfected with plasmids pEGFP-C1-cIi to observe the intracellular co-localization. Secondly, the DC2.4 Mouse Dendritic Cell and Murine RAW 264.7 cells were transfected with recombinant plasmids of pmCherry-cRab22a and pmCherry-mRab22a respectively. Subsequently, the intracellular localization of cRab22a in early and late endosomes was observed with specific antibodies against EEA1 and LAMP1 respectively. For gene expression-based studies, the cRab22a gene was down-regulated and up-regulated in HD11 cells, following the detection of transcription levels of the BFa (MHCIa) and cIi genes by real-time quantitative PCR (RT-qPCR). The interactions of the cRab22a gene with BFa and cIi were detected by co-immunoprecipitation (Co-IP) and Western blot. The results showed that the protein structures of chicken and mouse Rab22a were highly homologous (95.4%), and both localize to the early and late endosomes. Ser41 and Tyr74 are key amino acids in the Switch regions of Rab22a which maintain its intracellular localization. The down-regulation of cRab22a gene expression significantly reduced (p < 0.01) the transcription of BFa (MHCIa) and cIi in HD11 cells. However, when the expression of the cRab22a gene was increased 55 times as compared to control cells, the expression of the BFa (MHCIa) gene was increased 1.7 times compared to the control cells (p < 0.01), while the expression of the cIi gene did not significantly differ from control (p > 0.05). Western blot results showed that cRab22a could not directly bind to BFa and cIi. So, cRab22a can regulate BFa and cIi protein molecules indirectly. It is concluded that cRab22a was localized with cIi in the endosome. The Switch regions of cRab22a are the key domains that affect intracellular localization and colocalization of the cIi molecule. Full article

In this study, hydroxyapatite/chitosan (HA/CS) composite coatings were prepared by hydrothermal treatment on the surface of low-modulus Ti–25Nb–8Sn alloy to improve the surface bioactivity of the alloy. HA, the main mineral composition of the human skeleton, has excellent bioactivity and is often used as a surface coating on biometal implants. CS, a natural polymer with good antibacterial, hydrophilic and non-toxic characteristics, is often used as dermal regeneration templates, hemostatic agents and drug delivery systems. In this experiment, a natural crab shell was used as a raw material to prepare the HA/CS composite coating by alkali treatment and hydrothermal reaction at various temperatures. The microstructure, morphology and phase composition of the coating surfaces were analyzed by XRD, SEM, and FTIR, and the sample coated with HA/CS was soaked in simulated body fluid (SBF) to evaluate its bioactivity. The experimental results showed that the HA/CS composite coatings through hydrothermal treatment at various temperatures can be successfully fabricated on the surface of the Ti alloy. HA on the coating surface exhibited mainly spherical particles and contained A- and B-type carbonate. When the hydrothermal temperature was up to 200 °C, the spherical particles were approximately 20–40 nm. An ultrasonic vibration test was used to evaluate the adhesion of the coatings, showing that the CS exhibited significantly improved adhesion capacity to the substrate. After being soaked in SBF for 7 days, apatite was deposited on the entire surfaces of the HA/CS coatings, indicating that the coating possesses excellent bioactivity. Full article

Every year, close to 8 million tons of waste crab, shrimp and lobster shells are produced globally, as well as 10 million tons of waste oyster, clam, scallop and mussel shells. The disposed shells are frequently dumped at sea or sent to landfill, where they modify soils, waters and marine ecosystems. Waste shells are a major by-product, which should become a new raw material to be used to the best of their potential. There are a number of applications for waste shells in many fields, such as agriculture, medicine, chemical production, construction, environmental protection, cosmetic industry, food and feed industry, and a plethora of other (often niche) applications, which are being developed by the day. This review provides a broad picture of crustacean and mollusc shell waste management and reutilization possibilities, reviewing well established, current, and potential strategies, particularly from the standpoint of sustainability challenges and energy demand. Full article

Carcinoscorpius rotundicauda (C. rotundicauda) is one of the four species of horseshoe crabs (HSCs). The HSC hemocytes store defense molecules that are released upon encountering invading pathogens. The HSCs rely on this innate immunity to continue its existence as a living fossil for more than 480 million years. To gain insight into the innate mechanisms involved, transcriptomic analysis was performed on isolated C. rotundicauda hemocytes challenged with lipopolysaccharides (LPS), the main components of the outer cell membrane of gram-negative bacteria. RNA-sequencing with Illumina HiSeq platform resulted in 232,628,086 and 245,448,176 raw reads corresponding to 190,326,253 and 201,180,020 high-quality mappable reads from control and LPS-stimulated hemocytes, respectively. Following LPS-stimulation, 79 genes were significantly upregulated and 265 genes were downregulated. The differentially expressed genes (DEGs) were related to multiple immune functional categories and pathways such as those of the cytoskeleton, Toll and Imd, apoptosis, MAP kinase (MAPK), inositol phosphate metabolism, phagosome, leucocyte endothelial migration, and gram-negative bacterial infection, among others. This study provides important information about the mechanisms of response to LPS, which is relevant for the understanding the HSCs’ immune response. Full article

Polybius henslowii, an abundant yet unexploited species of swimming crab, was investigated as a potential source of α-chitin and calcium lactate using deep eutectic solvents (DES) as extracting solvents. Choline chloride–malonic acid (CCMA) and choline chloride–lactic acid (CCLA) were used to obtain high purity α-chitin from ball-milled P. henslowii exoskeleton in 2 h at 120 °C, with yields of 12.05 ± 2.54% and 12.8 ± 1.54%, respectively. The physical and chemical characteristics of the obtained chitins were assessed using CHN elemental analysis, attenuated total reflectance–Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy. Furthermore, the CCLA solvent was reusable three times with little effect on the extract purity, and calcium lactate was produced at the end of the recycling cycles. The ensuing calcium lactate was also characterized in terms of chemical and physical properties. The obtained chitin is a promising raw material for downstream processing and the double valorization pathway with the obtention of calcium salts may increase the viability of a DES-based approach for the processing of mineralized substrates. Full article

Crickets are gaining worldwide attention as a nutrient source with a low environmental impact. We considered crickets as a new source of chitin raw material. Chitin isolated from crickets was successfully converted to nanochitin by pulverization. First, chitin was obtained from cricket powder in a 2.6% yield through a series of chemical treatments. Chitin identification was confirmed by FT-IR and ¹³C NMR. The chitin had an α-type crystal structure and a deacetylation degree of 12%. Next, it was pulverized in a disk mill to obtain nanochitin. Cricket nanochitin was of a whisker shape, with an average fiber width of 10.1 nm. It was larger than that of crab shells, while the hydrodynamic diameter and crystal size were smaller. Such differences in shape affected the physical properties of the dispersion. The transmittance was higher than that of crab nanochitin due to the size effect, and the viscosity was smaller. Moreover, the dry non-woven cricket nanochitin sheets were more densely packed, and their modulus and breaking strength were greater. Full article