Collagen as the Major Edible Component of Sea Cucumber (Stichopus japonicus)

Study on the adsorption and migration rule of Sichuan pepper characteristic volatile compounds during the cooking process in the sea cucumber body wall

The natural flavor of sea cucumber is generally not easily accepted by consumers. In this study, the effect of different cooking conditions on the adsorption of the characteristic flavor of Sichuan pepper by sea cucumber was investigated by response surface methodology, and the optimal cooking conditions were identified. A total of 45 volatiles were identified based on gas chromatography-mass spectrometry, of which 27 were key flavor actives. Low-field nuclear magnetic resonance and textural analysis showed that the addition of Sichuan pepper during the cooking process affected the water migration and the textural properties of sea cucumbers. It was shown that the addition of Sichuan pepper could significantly improve the flavor and other quality characteristics of sea cucumber. This study has important practical guiding significance for the flavor improvement and product innovation of sea cucumber food.

The characteristic terpenes in sea cucumber soaked in star anise solution were characterized by HS-SPME-GC-MS and PCA analysis

The quality of sea cucumber is closely associated with its processing technology. In this study, the response surface methodology (RSM) was employed to optimize the thermal process conditions for seasoned sea cucumber, while gas chromatography-mass spectrometry (GC-MS) technique identified 25 characteristic compounds. Terpenes and their oxygen derivatives constituted approximately 70% of all compounds detected. Among these, trans-anethole emerged as the predominant volatile aroma compound in seasoned sea cucumber at a concentration of 39.99 ± 4.52 mg/g, followed by p-anisaldehyde, cis-anethole, linalool, estragole, and d-limonene. Principal component analysis (PCA) revealed that trans-anethole, cis-anethole, estragole, and d-limonene collectively contributed over 45.0% to the flavor profile of sea cucumber. This investigation provides an initial exploration into the alterations in volatile compounds within star anise-seasoned seasoned sea cucumber, thereby establishing a foundation for instant sea cucumbers' flavor processing.

Establishment of a targeted proteomics method for the quantification of collagen chain: Revealing the chain stoichiometry of heterotypic collagen fibrils in sea cucumber

Collagen is the most abundant and important structural biomacromolecule in sea cucumbers. The sea cucumber collagen fibrils were previously confirmed to be heterotypic, nevertheless, the stoichiometry of collagen α-chains governing the complexity of collagen fibrils is still poorly understood. Herein, four representative collagen α-chains in sea cucumber including two clade A fibrillar collagens, one clade B fibrillar collagen, and one fibril-associated collagen with interrupted triple helices were selected. After the screening of signature peptides and optimization of multiple reaction monitoring (MRM) acquisition parameters including fragmentation, collision energy, and ion transition, a feasible MRM-based method was established. Consequently, the stoichiometry of the four collagen chains was determined to be approximately 100:54:3:4 based on the method. The assembly forms of sea cucumber collagen fibrils were further hypothesized according to the chain stoichiometry. This study facilitated the quantification of collagen and understanding of the collagen constituents in sea cucumber.

A comparative investigation of anionic polysaccharides on the structure and gastrointestinal digestion of collagen fibrils

Collagen, the most abundant and widely distributed functional protein in mammals, typically assembles into collagen fibrils through side-by-side packing. The purpose of this study was to comparatively investigate the fate of sea cucumber collagen fibrils in the gastrointestinal tract when interacting with different anionic polysaccharides (fucoidan (FUC), Kappa-carrageenan (K-car), sodium alginate (SA)). Results revealed that the gel properties and viscosity values of collagen fibrils were notably enhanced, and the rate of structural alteration in collagen fibrils was reduced when K-car and SA were introduced. Conversely, in the presence of FUC, collagen fibril viscosity decreased, and the secondary structure of collagen fibrils underwent changes. FUC was found to diminish the structural stability of collagen fibrils and accelerate the gastric digestion rate, which was further exacerbated by thermal treatment. All these anionic polysaccharides were observed to facilitate the formation of collagen peptide aggregates by binding to polysaccharides during intestinal digestion. This study bridged the knowledge gap regarding the impact of anionic polysaccharides on the gastrointestinal digestion of collagen fibrils, potentially paving the way for broader applications of collagen in the food industry.

Physicochemical and Biochemical Characterization of Collagen from Stichopus cf. horrens Tissues for Use as Stimuli-Responsive Thin Films

The mutable collagenous tissue (MCT) of sea cucumber, with its ability to rapidly change its stiffness and extensibility in response to different environmental stress conditions, serves as inspiration for the design of new smart functional biomaterials. Collagen, extracted from the body wall of Stichopus cf. horrens, a species commonly found in the Philippines, was characterized for its suitability as stimuli-responsive films. Protein BLAST search showed the presence of sequences commonly found in type VII and IX collagen, suggesting that Stichopus horrens collagen is heterotypic. The maximum transition temperature recorded was 56.0 ± 2 °C, which is higher than those of other known sources of marine collagen. This suggests that S. horrens collagen has better thermal stability and durability. Collagen-based thin films were then prepared, and atomic force microscopy (AFM) imaging showed the visible collagen network comprising the films. The thin films were subjected to thermomechanical analysis with degradation starting at >175 °C. At 100-150 °C, the collagen-based films apparently lose their translucency due to the removal of moisture. Upon exposure to ambient temperature, instead of degrading, the films were able to revert to the original state due to the readsorption of moisture. This study is a demonstration of a smart biomaterial developed from S. cf. horrens collagen with potential applications in food, pharmaceutical, biomedical, and other collagen-based research.

Saponins of North Atlantic Sea Cucumber: Chemistry, Health Benefits, and Future Prospectives

Frondosides are the major saponins (triterpene glycosides) of the North Atlantic sea cucumber (Cucumaria frondosa). Frondosides possess amphiphilic characteristics due to the presence of various hydrophilic sugar moieties and hydrophobic genin (sapogenin). Saponins are abundant in holothurians, including in sea cucumbers that are widely distributed across the northern part of the Atlantic Ocean. Over 300 triterpene glycosides have been isolated, identified, and categorized from many species of sea cucumbers. Furthermore, specific saponins from sea cucumbers are broadly classified on the basis of the fron-dosides that have been widely studied. Recent studies have shown that frondoside-containing extracts from C. frondosa exhibit anticancer, anti-obesity, anti-hyperuricemic, anticoagulant, antioxidant, antimicrobial, antiangiogenic, antithrombotic, anti-inflammatory, antitumor, and immunomodulatory activities. However, the exact mechanism(s) of action of biological activities of frondosides is not clearly understood. The function of some frondosides as chemical defense molecules need to be understood. Therefore, this review discusses the different frondosides of C. frondosa and their potential therapeutic activities in relation to the postulated mechanism(s) of action. In addition, recent advances in emerging extraction techniques of frondosides and other saponins and future perspectives are discussed.

Age-related changes in the ratio of Type I/III collagen and fibril diameter in mouse skin

The content of type I collagen (COL-I) and type III collagen (COL-III) and the ratio between them not only affect the skin elasticity and mechanical strength, but also determine the fibril diameter. In this research, we investigated the age-related changes in COL-I/COL-III ratio with their formed fibril diameter. The experimental result was obtained from high performance liquid chromatography-mass spectrometer, hydroxyproline determination, picrosirius red staining and transmission electron microscopes (TEM), respectively. The result indicated that the COL-I/COL-III ratio in mouse skin increased with aging. From the 0th to 9th week, the COL-I/COLIII ratio increased from 1.3:1 to 4.5:1. From the 9th to the 18th week, it remained between 4.5:1 and 4.9:1. The total content of COL-I and COL-III firstly increased and then decreased with aging. The TEM result showed that the fibril diameter increased with aging. From the 0th to 9th week, the average fibril diameter increased from 40 to 112 nm; From the 9th to 18th weeks, it increased from 112 to 140 nm. After the 9th week. The fibril diameter showed obvious uneven distribution. Thus, the COL-I/COLIII ratio was proportional to the fibril diameter, but inversely proportional to the uniformity of fibril diameter.

Effects of Storage Method on the Quality of Processed Sea Cucumbers (Apostichopus japonicus)

This research aimed to establish an effective storage method to maintain the quality of processed sea cucumbers. In this study, sea cucumbers were stored by various methods including the storage of live sea cucumbers (seawater treatment, oxygen treatment, and ascorbic acid treatment) and the storage of dead sea cucumbers (frozen treatment). The sea cucumber quality was monitored after storage and boiling. The weightlessness rate and WHC of the frozen group increased to 86.96% ± 0.83% and 93.29% ± 0.32%, respectively. Frozen sea cucumbers shrunk with the meat's textural properties deteriorated. During the live sea cucumber storage, the tissue protein degraded from day 3 to day 7 which led to the promotion of TVB-N. Among these, the oxygen group showed the smallest TVB-N increase from day 0 (3.78 ± 0.60 mg 100 g^-1) to day 7 (10.40 ± 0.12 mg 100 g^-1). The oxygen group exhibited the most moderate change in weightlessness rate (4.24% ± 0.45%) and the most moderate texture parameters decline, such as the hardness of 32.52%, chewiness of 78.98 ± 5.10 N, and adhesion of 0.84 ± 0.00. The oxygen method showed the best condition of sea cucumber after 5 days of storage.

The Phospholipid Molecular Species Profile of Apostichopus japonicus Tissues Modifies through Exposure to n-3 Polyunsaturated Fatty Acid-Deficient Diet

The sea cucumber Apostichopus japonicus, being a target species of commercial fisheries and aquaculture, is also used as a source of biologically active compounds with high pharmacological potential. By the methods of high-performance liquid chromatography with high resolution mass spectrometry, we analyzed the major structural phospholipids (PL)—glycerophosphoethanolamines (PE), glycerophosphocholines (PC), glycerophosphoserines (PS), and glycerophosphoinositols (PI)—in tissues of wild and cultured sea cucumbers. The intestines of the wild and cultured animals differed from the other tissues by an elevated content of molecular species of PE, PC, and PS with 22:6n-3 fatty acid. The respiratory trees of the studied animals contained a high level of odd-chain PI and PI with 20:4n-6. The exposure to n-3 PUFA-deficient diet resulted in substantial changes in the molecular species profile of PL of the wild and cultured animals. The cultured sea cucumbers showed a significant decrease in the 20:5n-3 content in all four studied PL classes. A replacement of 20:5n-3 by 20:4n-6 occurred in PE, PC, and PI. The decrease in the level of molecular species of PS with 20:5n-3 was compensated by an increase in the level of monounsaturated long-chain PS. The diet of cultured sea cucumbers is a crucial factor for enhancing the nutritional properties of the product obtained from them.

Extraction and characterization of bovine collagen type and its effects on cell behaviors

Collagen Type V (Col. V) plays an essential role in cell behaviors and has attracted increasing attention in recent years. High-purity Col. V is needed for evaluating its biological properties. In this research, the enzymatic hydrolysis process was combined with ultrafiltration to purify Col. V from the bovine cornea. The purity of Col. V was determined to be above 90% by both sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and high-performance liquid chromatography methods. The effect of Col. V on cell behaviors was evaluated. The circular dichroism spectroscopy results demonstrated that the extracted Col. V exhibited a complete triple helix structure. SDS-PAGE suggested that the molecular weight of Col. V was 440 kDa. The self-assembly experiment revealed that the proportion of Col. V in the collagen mixture can affect the Col. I fiber diameter. The cell culture results implied that Col. V can inhibit fibroblasts (L929) proliferation. The L929 showed maximum mobility when the addition of Col. V was 30%. Thus, Col. V has the effect of inhibiting L929 proliferation and promoting migration. The high-purity Col. V provides useful information for further understanding its biological implications.

Thermal-Induced Autolysis Enzymes Inactivation, Protein Degradation and Physical Properties of Sea Cucumber, Cucumaria frondosa

The main objective is to effectively denature the autolysis enzymes of C. frondosa on the premise of avoiding the quality deterioration caused by overheating. The effects of the different thermal treatments (blanching at 40–80 °C for 45 min, boiling and steaming at 100 °C for 15–120 min) on the cooking yield, moisture content, protein degradation, texture, and enzyme inactivation were studied, and the inner relationship was investigated by multivariate analysis. The autolysis enzymes of C. frondosa were thermally stable and cannot be denatured completely by blanching. Boiling and steaming could efficiently inactivate the enzymes but overheating for 60–120 min reduced the cooking yield and texture quality. Boiling at 100 °C for 45 min was suitable for pre-treatment, with cooking yield of 70.3% and protein content of 78.5%. Steaming at 100 °C for at least 30 min was preferable for long-term storage and instant food, in which the relative activity was only 3.2% with better palatability.

Quantitation of Collagen Type V in Tissues by High-Performance Liquid Chromatography Coupled to Mass Spectrometry

A method for quantifying the bovine collagen type V (Col. V) was established based on high-performance liquid chromatography coupled to mass spectrometry by the marker peptide external standard. High-purity Col. V was extracted by the acid-enzyme hydrolysis process, and the marker peptide of Col. V was identified by LCQ mass spectrometry as GPAGPMGLTGR. A broad linear range (0.01-5.00 μg/mL) with a correlation coefficient of 0.9984 was achieved, and the limit of detection and limit of quantification were found to be 3.00 × 10^-3 and 6.25 × 10^-3 μg/mL, respectively. The method precision was 1.49%. The recovery rate was determined as 97.1-109.6% with a relative standard deviation less than 5%. The proposed method was successfully applied for the determination of Col. V contents in the bovine heart, lung, and cornea, which were 0.72 ± 0.01%, 0.23 ± 0.01%, and 2.89 ± 0.00%, respectively. The results show that the proposed method is more suitable for measuring the content of Col. V in tissue samples compared with the enzyme-linked immunosorbent assay. The marker peptide method has high accuracy and great reproducibility, and will lay a foundation for the extraction and application of Col. V. Impact statement The accurate quantitative method for collagen type V (Col. V) is particularly important in scientific research, disease diagnosis and treatment, and industrial production. In this article, we proposed a high-performance liquid chromatography coupled to mass spectrometry method based on the external standard marker peptide to quantify bovine Col. V. This method shows a higher accuracy and recovery rate than enzyme-linked immunosorbent assay (ELISA), indicating that it is more suitable for measuring the content of Col. V in tissue samples than ELISA. The establishment of this method has laid a solid foundation for the extraction and application of Col. V.

Characterizations and the Mechanism Underlying Osteogenic Activity of Peptides from Enzymatic Hydrolysates of Stichopus japonicus

Sea cucumber (Stichopus japonicus) is a kind of fishery product with high nutritional value. It exhibits a wide range of biological activity and has potential application in the food, pharmaceutical, and biomedical industries. However, there are no reports available on the effects of S. japonicus peptides (SJP) on bone mineral density regulations. The purpose of this work was to analyze the composition and osteogenic activity of SJP and explore its underlying mechanism. The results showed that SJP stimulated cell proliferation, differentiation, and mineralization in a dose-dependent manner. In addition, SJP could promote the proliferation of MC3T3-E1 cells by altering the cell cycle progression and regulating the expression of Cyclins. Besides, SJP activated the WNT/β-catenin pathway and increased the nuclear level of the active form β-catenin. Furthermore, SJP also induced the expression of bone morphogenetic protein (BMP-2) and increase the phosphorylation levels of p38, JNK, and ERK, suggesting that the osteogenic activity of SJP may be achieved through the activation of WNT/β-catenin and BMP/MAPK signal pathways. In vivo, SJP significantly inhibited the serum levels of RANKL, ALP, and TRAP, whereas it increased the levels of osteocalcin and osteoprotegerin in OVX-mice. These results indicate that SJP may have the potential to stimulate bone formation and regeneration, and may be used as a functional food or nutritional supplement to prevent osteoporosis.

Heterologous expression, fermentation strategies and molecular modification of collagen for versatile applications

Collagen is a kind of high macromolecular protein with unique tissue distribution and distinctive functions in the body. At present, most collagen products are extracted from the tissues and organs of mammals or marine fish. However, this method exhibits several disadvantages, including low efficiency and serious waste generation, which makes it difficult to meet the current market demand. With the rapid development of synthetic biology and the deepening of high-density fermentation technology, the collagen preparation by biosynthesis strategy emerges as the times require. Co-expression with the proline hydroxylase gene can solve the problem of non-hydroxylated collagen, but the yield may be affected. Therefore, improving the expression through molecular modification and dynamic regulation of synthesis is an entry point for future research. Due to the defects in certain properties of the natural collagen, modification of properties would be benefit for meeting the requirements of practical application. In this paper, in-depth investigations on recombinant expression, fermentation, and modification studies of collagen are conducted. Also, it summarizes the research progress of collagen in food, medicine, and beauty industry in recent years. Furthermore, the future development trend and application prospect of collagen are discussed, which would provide guidance for its preparation and application.

tRNA copy number and codon usage in the sea cucumber genome provide insights into adaptive translation for saponin biosynthesis

Genomic tRNA copy numbers determine cytoplasmic tRNA abundances, which in turn influence translation efficiency, but the underlying mechanism is not well understood. Using the sea cucumber Apostichopus japonicus as a model, we combined genomic sequence, transcriptome expression and ecological food resource data to study its codon usage adaptation. The results showed that, unlike intragenic non-coding RNAs, transfer RNAs (tRNAs) tended to be transcribed independently. This may be attributed to their specific Pol III promoters that lack transcriptional regulation, which may underlie the correlation between genomic copy number and cytoplasmic abundance of tRNAs. Moreover, codon usage optimization was mostly restrained by a gene's amino acid sequence, which might be a compromise between functionality and translation efficiency for stress responses were highly optimized for most echinoderms, while enzymes for saponin biosynthesis (LAS, CYPs and UGTs) were especially optimized in sea cucumbers, which might promote saponin synthesis as a defence strategy. The genomic tRNA content of A. japonicus was positively correlated with amino acid content in its natural food particles, which should promote its efficiency in protein synthesis. We propose that coevolution between genomic tRNA content and codon usage of sea cucumbers facilitates their saponin synthesis and survival using food resources with low nutrient content.

Amino Acid Profiling with Chemometric Analysis as a Feasible Tool for the Discrimination of Marine-Derived Peptide Powders

Marine-derived peptide powders have suffered from adulteration via the substitution of lower-price peptides or the addition of adulterants in the market. This study aims to establish an effective approach for the discrimination and detection of adulterants for four representative categories of marine-derived peptide powders, namely, oyster peptides, sea cucumber peptides, Antarctic krill peptides, and fish skin peptides, based on amino acid profiling alongside chemometric analysis. The principal component analysis and orthogonal partial least squares discriminant analysis results indicate that four categories of marine-derived peptides could be distinctly classified into four clusters and aggregated with the respective raw materials. Taurine, glycine, lysine, and protein contents were the major discriminants. A reliable classification model was constructed and validated by the prediction dataset, mixture sample dataset, and unclassified sample dataset with accuracy values of 100%, 100%, and 100%, respectively.

Comparative Study of The Yield and Physicochemical Properties of Collagen from Sea Cucumber (Holothuria scabra), Obtained through Dialysis and the Ultrafiltration Membrane

Collagen was extracted from the body wall of sea cucumber (Holothuria scabra) using the pepsin-solubilized collagen method followed by isolation using dialysis and the ultrafiltration membrane. The yield and physicochemical properties of the collagen obtained from both isolation methods, denoted as D-PSC and UF-PSC, were compared. The ultrafiltration method affords a higher yield of collagen (11.39%) than that of the dialysis (5.15%). The isolated collagens have almost the same amino acid composition, while their functional groups, referred to as amide A, B, I, II, and III bands, were in accordance with commercial collagen, as verified by Fourier Transform Infrared (FT-IR) spectroscopy. The UV-Vis absorption peaks at 240 nm and 220 nm, respectively, indicated that the collagens produced are type-I collagen. The D-PSC showed interconnecting sheet-like fibrils, while the UF-PSC exhibited a flaky structure with flat-sheets arranged very close to each other. The higher yield and comparable physicochemical properties of the collagen obtained by ultrafiltration as compared with dialysis indicate that the membrane process has high potential to be used in large-scale collagen production for food and pharmaceutical applications.

Comparative metabolomic analysis of the body wall from four varieties of the sea cucumber Apostichopus japonicus

The sea cucumber, Apostichopus japonicas, is an important economic species with high nutritive value. In recent years, driven by significant market demand, the sea cucumber breeding industry has developed rapidly. Body color and number of papillae are important factors that determine the value and price of sea cucumbers. In this study, metabolite profiling of four sea cucumber varieties (green, white, purple and spiny) was performed using ultra-performance liquid chromatography-quadrupole-time-of-flight-mass spectrometry (UPLC-QTOF-MS) combined with multivariate analysis. Orthogonal partial least-squares discriminant analysis (OPLS-DA) clearly discriminated the body wall metabolites of four sea cucumber varieties. Differential metabolites included fatty acids, phospholipids, and sugars. KEGG metabolic pathway analysis revealed that carbohydrate, protein, and phospholipid metabolism were highly conserved among the varieties. These results provide a comprehensive insight into differences in the metabolite profile of four A. japonicus varieties and a deeper understanding of sea cucumber varieties breeding.

Detection of Type I and III collagen in porcine acellular matrix using HPLC-MS

Acellular matrix (ACM) has been widely used as a biomaterial. As the main component of ACM, collagen type and content show influence on the material properties. In this research, the collagen in ACM from different tissues of pig were determined by detection of marker peptides. The marker peptides of Type I and III collagen were identified from the digested collagen standards using ions trap mass spectrometry (LCQ). The relationship between the abundance of marker peptide and collagen concentration was established using triple quadrupole mass spectrometer (TSQ). The contents of Type I and III collagen in ACM from different tissues were determined. The method was further verified by hydroxyproline determination. The results showed that, the sum of Type I and III collagen contents in the ACM from small intestinal submucosa, dermis and Achilles tendon of pig were about 87.59, 81.41 and 61.13%, respectively, which were close to the total collagen contents in these tissues. The results proved that this method could quantitatively detect the collagen with different types in the ACM of various tissues.

Investigation of structural proteins in sea cucumber (Apostichopus japonicus) body wall

Structural proteins play critical roles in the food quality, especially texture properties, of sea cucumbers and their products. Most of the previous studies on sea cucumbers focused on few individual proteins, which limited our understanding of how structural proteins influenced the quality of sea cucumbers. Inspired by the clarification of sea cucumber (Apostichopus japonicus) genome, we established an integrated data of structural proteins in the sea cucumber body wall. A portfolio of 2018 structural proteins was screened out from the sea cucumber annotated proteome by bioinformatics analysis. The portfolio was divided into three divisions, including extracellular matrix proteins, muscle proteins, and proteases, and further classified into 18 categories. The presence of 472 proteins in the sea cucumber body wall was confirmed by using a proteomics approach. Moreover, comparative proteomics analysis revealed the spatial distribution heterogeneity of structural proteins in the sea cucumber body wall at a molecular scale. This study suggested that future researches on sea cucumbers could be performed from an integrated perspective, which would reshape the component map of sea cucumber and provide novel insights into the understanding of how the food quality of sea cucumber was determined on a molecular level.

Sea Cucumber Derived Type I Collagen: A Comprehensive Review

Collagen is the major fibrillar protein in most living organisms. Among the different types of collagen, type I collagen is the most abundant one in tissues of marine invertebrates. Due to the health-related risk factors and religious constraints, use of mammalian derived collagen has been limited. This triggers the search for alternative sources of collagen for both food and non-food applications. In this regard, numerous studies have been conducted on maximizing the utilization of seafood processing by-products and address the need for collagen. However, less attention has been given to marine invertebrates and their by-products. The present review has focused on identifying sea cucumber as a potential source of collagen and discusses the general scope of collagen extraction, isolation, characterization, and physicochemical properties along with opportunities and challenges for utilizing marine-derived collagen.

Effect of geographic variation on the proteome of sea cucumber (Stichopus japonicus)

Sea cucumber is a sensitive organism that is easily challenged by environmental change. The aim of this study was to characterize the proteome of sea cucumbers from 5 main Chinese origins, including Xiamen (XM), Dalian (DL), Weihai (WH), Yantai (YT) and Qingdao (QD). In this work, a tandem mass tag (TMT) labeling proteomic approach was applied to identify and quantify the proteome of sea cucumber. A total of 5051 proteins were identified in the body wall; among those proteins, 1594 proteins (31.6%) were identified as enzyme proteins, and 33 proteins belonged to collagen. In addition, the 10 most highly abundant proteins were further discussed. Among all quantified proteins, 2266 were significantly differentially expressed proteins (SDEPs) across the 5 origins. These SDEPs were related to pigmentation (5 proteins), antioxidant activity (13 proteins), and immune system processes (29 proteins). Based on SDEPs, DL differed the most from QD and XM, as well as WH and YT, as shown in principal component analysis (PCA) and hierarchical clustering. In conclusion, one-fourth of the significantly different proteins found in the sea cucumber body wall among the 5 main Chinese locations indicated the sensitivity of sea cucumber to variations in temperature, environment, and feeding.

Collective Locomotion of Human Cells, Wound Healing and Their Control by Extracts and Isolated Compounds from Marine Invertebrates

The collective migration of cells is a complex integrated process that represents a common theme joining morphogenesis, tissue regeneration, and tumor biology. It is known that a remarkable amount of secondary metabolites produced by aquatic invertebrates displays active pharmacological properties against a variety of diseases. The aim of this review is to pick up selected studies that report the extraction and identification of crude extracts or isolated compounds that exert a modulatory effect on collective cell locomotion and/or skin tissue reconstitution and recapitulate the molecular, biochemical, and/or physiological aspects, where available, which are associated to the substances under examination, grouping the producing species according to their taxonomic hierarchy. Taken all of the collected data into account, marine invertebrates emerge as a still poorly-exploited valuable resource of natural products that may significantly improve the process of skin regeneration and restrain tumor cell migration, as documented by in vitro and in vivo studies. Therefore, the identification of the most promising invertebrate-derived extracts/molecules for the utilization as new targets for biomedical translation merits further and more detailed investigations.

Northern Sea Cucumber (Cucumaria frondosa): A Potential Candidate for Functional Food, Nutraceutical, and Pharmaceutical Sector

Sea cucumber (Cucumaria frondosa) is the most abundant and widely distributed species in the cold waters of North Atlantic Ocean. C. frondosa contains a wide range of bioactive compounds, mainly collagen, cerebrosides, glycosaminoglycan, chondroitin sulfate, saponins, phenols, and mucopolysaccharides, which demonstrate unique biological and pharmacological properties. In particular, the body wall of this marine invertebrate is the major edible part and contains most of the active constituents, mainly polysaccharides and collagen, which exhibit numerous biological activities, including anticancer, anti-hypertensive, anti-angiogenic, anti-inflammatory, antidiabetic, anti-coagulation, antimicrobial, antioxidation, and anti- osteoclastogenic properties. In particular, triterpene glycosides (frondoside A and other) are the most researched group of compounds due to their potential anticancer activity. This review summarizes the latest information on C. frondosa, mainly geographical distribution, landings specific to Canadian coastlines, processing, commercial products, trade market, bioactive compounds, and potential health benefits in the context of functional foods and nutraceuticals.

Identification of molecular markers for superior quantitative traits in a novel sea cucumber strain by comparative microRNA-mRNA expression profiling

To investigate the adaptability of Apostichopus japonicus (A. japonicus) strain "Anyuan No. 1" in the South China Sea, field monitoring and microRNA-mRNA integrated analyses were conducted between "Anyuan No. 1" and a regular A. japonicus population from Wendeng (Shandong Province, as a control) in the Xiapu farming area in Fujian Province, China. The results showed that "Anyuan No. 1" exhibited greater body weight increase and a higher number of papillae compared to the control during two and a half months of field monitoring. Comparative microRNA (miRNA) and mRNA transcriptome analyses identified 12 differentially expressed miRNAs (DEMs) and 165 differentially expressed genes (DEGs) in "Anyuan No. 1" compared to the control. Long-chain specific acyl-CoA dehydrogenase (ACADL), transmembrane protein 251 (TMEM251), dehydrogenase/reductase SDR family protein 7-like (Dhrs7), insulin-like growth factor-binding protein 7 (IGFBP-7), CDK5 regulatory subunit-associated protein 1 (CDK5RAP1), visual pigment-like receptor peropsin, 39S ribosomal protein, miR-10, miR-153, miR-7, and miR-3529 were identified as gene and miRNA candidates correlated with superior economic traits in "Anyuan No. 1". Collectively, "Anyuan No. 1" is suitable for large-scale cultivation extension due to its better adaptability to the South China Sea area. Furthermore, we identified "miR10-ACADL" as a potential module for further molecular marker-assisted selective breeding of A. japonicus.

Collagen fibrils of sea cucumber (Apostichopus japonicus) are heterotypic

Sea cucumbers attracted increasing interest due to its nutritional functions. Collagen is the most important structural biomacromolecule in sea cucumber body wall, and is highly related to the textual properties and food quality of sea cucumber. In this study, the type of constituent collagens of sea cucumber collagen fibrils was investigated, employing a commercially important species Apostichopus japonicus as the material. Proteomics and bioinformatics analysis revealed that collagen fibrils of A. japonicas are heterotypic. Two clade A and one clade B fibrillar collagens and two FACIT collagens were identified from the fibrils. Besides, the heterogeneity was also revealed in the pepsin-solubilized collagen (PSC) of A. japonicus by using the proteomics strategy. It implied that the previous conclusions on the type of sea cucumber collagen deduced from SDS-PAGE analysis should be rechecked. The results provided novel insight into the composition of sea cucumber collagen fibrils.

Hot water pretreatment-induced significant metabolite changes in the sea cucumber Apostichopus japonicus

Hot water pretreatment of sea cucumbers potentially changes nutritional benefits. This study aimed to quantify hot water pretreatment-induced changes in metabolite profiles of sea cucumber body walls. ICP-OES, GC-MS, and LC-MS analyses of untreated- (UT-BW), hot water-treated body walls (HW-BW) of Apostichopus japonicus, and the hot water extract (HW-E) determined significant losses of minerals (25-50% w/w), protein (~11% w/w), carbohydrate (33% w/w), saponins (~41% w/w), and spermidine (100%), a potential antipsychotic from hot water-treated samples. Multivariate comparisons of HW-BW with UT-BW and HW-BW with HW-E showed increases in amino acids and fatty acids, suggesting hot water-induced degradation or transformation or easier extraction of protein, lipid or other components. Presence of 80 to 88.5% of compounds in the HW-E and lower DHA, EPA and glycerophospholipids levels in HW-BW suggested extraction of these metabolites. These data indicate that novel processing technologies are required to preserve the full nutritional benefits of sea cucumbers.

Antioxidant and anti-aging effects of a sea cucumber protein hydrolyzate and bioinformatic characterization of its composing peptides

C. elegans-based activity guided and size-based isolation of antioxidant peptide fractions from a sea cucumber protein hydrolyzate and their bioinformatic characterization.

Isolation and identification of zinc-chelating peptides from sea cucumber (Stichopus japonicus) protein hydrolysate

BACKGROUND

Zinc is known to play an essential role in the biological activities in the human body. In this study, a zinc-chelating peptide (ZCP) produced by Alcalase-assisted hydrolysis of the body wall of sea cucumber was isolated and identified. The ZCP was purified stepwise by ultrafiltration, anion-exchange chromatography, and gel filtration chromatography, in conjunction with ultraviolet-visual (UV-visual) spectrophotometry, which was used to analyze each purified fraction.

RESULTS

Analysis of the purified ZCP revealed that its zinc-chelating ability was 33.31%. Analysis of isothermal titration calorimetry suggested that the binding of ZCP and zinc (N ≈ 2) was endothermic, with weak binding affinity. Fourier transform infrared spectroscopy spectra (FTIR) indicated that carboxylic and amide groups in ZCP were the primary binding sites of Zn. Sequencing the result by ultra-performance liquid chromatography-quadrupole/time of flight mass spectrometry (UPLC-Q-TOF-MS/MS) showed that a representative ZCP had the sequence WLTPTYPE with a molecular weight of 1005.5 Da.

CONCLUSION

These results provide a promising foundation for the production of zinc supplements from sea-cucumber-derived ZCPs. © 2019 Society of Chemical Industry.

RNA Sequencing Analysis to Capture the Transcriptome Landscape during Tenderization in Sea Cucumber Apostichopus japonicus

Sea cucumber (Apostichopus japonicus) is an economically significant species in China having great commercial value. It is challenging to maintain the textural properties during thermal processing due to the distinctive physiochemical structure of the A. japonicus body wall (AJBW). In this study, the gene expression profiles associated with tenderization in AJBW were determined at 0 h (CON), 1 h (T_1h), and 3 h (T_3h) after treatment at 37 °C using Illumina HiSeq™ 4000 platform. Seven-hundred-and-twenty-one and 806 differentially expressed genes (DEGs) were identified in comparisons of T_1h vs. CON and T_3h vs. CON, respectively. Among these DEGs, we found that two endogenous proteases-72 kDa type IV collagenase and matrix metalloproteinase 16 precursor-were significantly upregulated that could directly affect the tenderness of AJBW. In addition, 92 genes controlled four types of physiological and biochemical processes such as oxidative stress response (3), immune system process (55), apoptosis (4), and reorganization of the cytoskeleton and extracellular matrix (30). Further, the RT-qPCR results confirmed the accuracy of RNA-sequencing analysis. Our results showed the dynamic changes in global gene expression during tenderization and provided a series of candidate genes that contributed to tenderization in AJBW. This can help further studies on the genetics/molecular mechanisms associated with tenderization.