Sea Cucumber Research Articles

Decadal changes in value of dried sea cucumbers (bêche-de-mer) in Hong Kong markets

Sea cucumbers in their dried form, bêche-de-mer or trepang, have been in high demand for four decades, causing relentless exploitation pressure on fisheries. Key aspects unknown are the temporal trends in prices of different species and potential impacts of external factors. We recorded prices and measured dried specimens of 20 sea cucumber species in 38 retail shops in Hong Kong in 2022 and compared prices obtained for 15 of these species in the same market in 2011 and/or 2016. Two temperate-water species (Apostichopus japonicus and A. nigripunctatus) were the most valuable but declined slightly in price over the 11-year period. All of the tropical species rose in price. Holothuria lessoni emerged as the most valuable tropical species (average: USD$503) and was scarce in the marketplace. Two Indo-Pacific species recently enlisted on CITES Appendix II, H. nobilis and H. whitmaei, were also seldom found in the marketplace and their value had risen greater than inflationary expectations. Also rare in the marketplace was the high-valued Isostichopus badionotus. Larger specimens of A. japonicus and H. scabra demanded exponentially higher prices than small individuals, with implications for fisheries and aquaculture. Significant aquaculture production for both of these species does not appear to have greatly quelled market demand. Despite potential disruptions during the COVID pandemic, overall demand for bêche-de-mer remains strong. The increases in retail prices for certain over-exploited species, potentially exacerbated by trade restrictions from CITES listings, beckons careful resource monitoring by fishery managers and continuing opportunities for aquaculture programs.

MLKL promotes extracellular trap releasing in Vibrio splendidus AJ01-challenged coelomocytes of sea cucumber Apostichopus japonicus

Extracellular traps (ETs) is a novel host-defense mechanism for the immobilization and killing of invading microorganisms, of which pseudokinase mixed lineage kinase-like protein (MLKL) is necessary for ET formation. Here, we aimed to investigate the effects of various stimulations (including classic ET inducers and pathogen) on ET formation in the coelomocytes of invertebrate sea cucumber Apostichopus japonicus. Our results show that stimulation of sea cucumber coelomocytes with phorbol 12-myristate 13-acetate (PMA), zymosan, Vibrio splendidus AJ01, and AJ01 flagella all led to the formation of typical ET fibers, which can be further digested by DNase I. This finding suggests that DNA is an essential component of coelomocyte ETs. Meanwhile, the signals of histones H2A and H2B transferred to extracellular spaces and colocalized with AJ01, which indicates that histones are also crucial components of coelomocyte ETs. Scanning electron microscopy observation and antimicrobial activity analysis successfully revealed that AJ01 was trapped and killed by ET fibers, and this finding implies the antimicrobial role of sea cucumber coelomocyte ETs. More importantly, silencing and inhibition of AjMLKL after AJ01 infection not only considerably depressed ET generation but also increased the survival rate of AJ01. All our results indicate that AjMLKL mediates sea cucumber ET formation and plays critical roles during pathogen infection.

Monitoring the genetic diversity in holothurian populations from the Italian coasts with mitochondrial DNA sequences

Sea cucumbers are deposit feeding members of marine benthic communities. The over-exploitation of sea cucumber natural stocks, especially in the Mediterranean basin, is having negative impacts on the marine ecosystem. This concerns had led the Italian government to take legal actions to preserve these important marine resources. The aim of this study was to evaluate the level of genetic diversity and population structures within two sympatric Holothuria sea cucumber species, H. polii and H. tubulosa, across ten Mediterranean areas along Italy. A 323 bp portion of the COI mitochondrial gene was sequenced in a total of 441 holothurians (251 H. polii, 177 H. tubulosa and 13 from other species). Genetic diversity analyses and analysis of molecular variance (AMOVA) suggest that H. polii and H. tubulosa species are distinct, but within and among populations are homogeneous, indicating active gene flows across the Mediterranean areas investigated. H. polii showed a lower genetic diversity than H. tubulosa, probably related to differences in life history traits. Phylogenetic analyses showed a clear differentiation between the two species, even if six specimens morphologically assigned to a species clustered within the other species, indicating a possible occurrence of hybridization events. These data will be useful in implementing conservation actions for these holothurian genetic resources.

Mechanisms of Action of Sea Cucumber Triterpene Glycosides Cucumarioside A0-1 and Djakonovioside A Against Human Triple-Negative Breast Cancer.

Breast cancer is the most prevalent form of cancer in women worldwide. Triple-negative breast cancer is the most unfavorable for patients, but it is also the most sensitive to chemotherapy. Triterpene glycosides from sea cucumbers possess a high therapeutic potential as anticancer agents. This study aimed to identify the pathways triggered and regulated in MDA-MB-231 cells (triple-negative breast cancer cell line) by the glycosides cucumarioside A0-1 (Cuc A0-1) and djakonovioside A (Dj A), isolated from the sea cucumber Cucumaria djakonovi. Using flow cytometry, fluorescence microscopy, immunoblotting, and ELISA, the effects of micromolar concentrations of the compounds on cell cycle arrest, induction of apoptosis, the level of reactive oxygen species (ROS), mitochondrial membrane potential (Δψm), and expression of anti- and pro-apoptotic proteins were investigated. The glycosides caused cell cycle arrest, stimulated an increase in ROS production, and decreased Δψm in MDA-MB-231 cells. The depolarization of the mitochondrial membrane caused by cucumarioside A0-1 and djakonovioside A led to an increase in the levels of APAF-1 and cytochrome C. This, in turn, resulted in the activation of caspase-9 and caspase-3 and an increase in the level of their cleaved forms. Glycosides also affected the expression of Bax and Bcl-2 proteins, which are associated with mitochondria-mediated apoptosis in MDA-MB-231 cells. These results indicate that cucumarioside A0-1 and djakonovioside A activate the intrinsic apoptotic pathway in triple-negative breast cancer cells. Additionally, it was found that treatment with Cuc A0-1 resulted in in vivo inhibition of tumor growth and metastasis of murine solid Ehrlich adenocarcinoma.

A potential therapeutic effect of sea cucumber Holothuria polii extract during the intestinal phase of experimental trichinellosis

A potential therapeutic effect of sea cucumber Holothuria polii extract during the intestinal phase of experimental trichinellosis

Sea cucumber, Neostichopus grammatus, density and tank cleaning frequency affect abalone, Haliotis midae, growth in integrated multitrophic aquaculture

AbstractThe integrated multitrophic aquaculture (IMTA) of sea cucumber and abalone has been proposed as a potential bioremediation tool that stimulates increased abalone growth. This study assessed the role of sea cucumber stocking density and frequency of tank cleaning in IMTA on growth, water, and sludge bioremediation. The study was conducted for 16 weeks and was made of four treatments and four replicates; abalone cocultured with sea cucumber (low density—27: 1 g [abalone (ab): sea cucumber (sc)]) with tanks cleaned once a week (L1); abalone cocultured with sea cucumber (low density) with tanks cleaned twice a week (L2); abalone cocultured with sea cucumber (high density—15:1 g [ab:sc]) with tanks cleaned once a week (H1) and abalone cocultured with sea cucumber (high density) with tanks cleaned twice a week (H2). Rearing water nitrite was significantly lower (p = 0.001) at high stocking density of sea cucumbers, but sludge was unaffected. Tanks cleaned once weekly had higher sludge organic matter (p = 0.015) and sludge sulfur content (p = 0.020) and lower sludge carbon (p = 0.003) and nitrogen content (p = 0.049). At the end of the experiment, the stocking density of sea cucumber and frequency of tank cleaning affected abalone mean weight [p = 0.047; p = 0.011, respectively] without a significant interaction (p = 0.517). Abalone in H1 had a higher mean weight and shell length than abalone in L2 and H2 but was similar to those in L1. The stocking density and frequency of cleaning used in this study had no effect on the growth of sea cucumbers [p = 0.150; p = 0.470, respectively]. This study has shown that in an abalone–sea cucumber IMTA system, the stocking density of sea cucumber and the frequency at which tanks are cleaned influence abalone growth and bioremediation of the rearing water. Our result suggests H1 as the best density (ab:sc) and cleaning frequency. The tank cleaning frequency alone affects the tank sludge quality; tanks need not be washed too frequently as, in addition to causing animal stress, cleaning markedly increased carbon and nitrogen level of tank sludge. Both these effects are likely to negatively impact abalone growth.

The interplay between host-specificity and habitat-filtering influences sea cucumber microbiota across an environmental gradient of pollution

Environmental gradients can influence morpho-physiological and life-history differences in natural populations. It is unclear, however, to what extent such gradients can also modulate phenotypic differences in other organismal characteristics such as the structure and function of host-associated microbial communities. In this work, we addressed this question by assessing intra-specific variation in the diversity, structure and function of environmental-associated (sediment and water) and animal-associated (skin and gut) microbiota along an environmental gradient of pollution in one of the most urbanized coastal areas in the world. Using the tropical sea cucumber Holothuria leucospilota, we tested the interplay between deterministic (e.g., environmental/host filtering) and stochastic (e.g., random microbial dispersal) processes underpinning host-microbiome interactions and microbial assemblages. Overall, our results indicate that microbial communities are complex and vary in structure and function between the environment and the animal hosts. However, these differences are modulated by the level of pollution across the gradient with marked clines in alpha and beta diversity. Yet, such clines and overall differences showed opposite directions when comparing environmental- and animal-associated microbial communities. In the sea cucumbers, intrinsic characteristics (e.g., body compartments, biochemistry composition, immune systems), may underpin the observed intra-individual differences in the associated microbiomes, and their divergence from the environmental source. Such regulation favours specific microbial functional pathways that may play an important role in the survival and physiology of the animal host, particularly in high polluted areas. These findings suggest that the interplay between both, environmental and host filtering underpins microbial community assembly in H. leucospilota along the pollution gradient in Hong Kong.

Sea cucumbers and their symbiotic microbiome have evolved to feed on seabed sediments

Sea cucumbers are predominant deposit feeders in benthic ecosystems, providing protective benefits to coral reefs by reducing disease prevalence. However, how they receive sufficient nutrition from seabed sediments remains poorly understood. Here, we investigate Holothuria leucospilota, an ecologically significant tropical sea cucumber, to elucidate digestive mechanisms underlying marine deposit-feeding. Genomic analysis reveals intriguing evolutionary adaptation characterized by an expansion of digestive carbohydrase genes and a contraction of digestive protease genes, suggesting specialization in digesting microalgae. Developmentally, two pivotal dietary shifts, namely, from endogenous nutrition to planktonic feeding, and from planktonic feeding to deposit feeding, induce changes in digestive tract enzyme profiles, with adults mainly expressing carbohydrases and lipases. A nuanced symbiotic relationship exists between gut microbiota and the host, namely, specific resident bacteria supply crucial enzymes for food digestion, while other bacteria are digested and provide assimilable nutrients. Our study further identifies Holothuroidea lineage-specific lysozymes that are restrictedly expressed in the intestines to support bacterial digestion. Overall, this work advances our knowledge of the evolutionary innovations in the sea cucumber digestive system which enable them to efficiently utilize nutrients from seabed sediments and promote food recycling within marine ecosystems.

Metabolomic analysis reveals the potential of fucosylated chondroitin sulfate from sea cucumber in modulating metabolic homeostasis

In this study, we prepared four derivatives of fucosylated chondroitin sulfate (FCS): full-length FCS (flFCS) from Holothuria leucospilota, low molecular weight FCS (lmFCS) derived from flFCS, and their de-branched counterparts, de-branched flFCS (d-flFCS) and de-branched lmFCS (d-lmFCS) via controlled acid treatment. Following structural verification using various analytical techniques, we applied targeted metabolomics to examine the impact of FCS on nutritional efficacy and its structure-activity relationship. Analysis of 225 plasma and feces samples from 75 mice revealed a positive correlation between metabolomic shifts and increased weight gain, underscoring FCS’s potential to enhance nutrient absorption and promote growth. The observed linear relationship between the levels of short-chain fatty acids in plasma and feces suggests that FCS may facilitate catabolic activities in the gastrointestinal tract. The comparative study of different FCS derivatives on mouse growth and metabolic homeostasis regulation led to the conclusion that FCS exhibits greater biological activity with a higher degree of branching and larger molecular weight.

A skin-inspired anisotropic multidimensional sensor based on low hysteresis organohydrogel with linear sensitivity and excellent robustness for directional perception

Human skin has complex sensors to perceive three-dimensional stimuli from the environment. Skin-inspired flexible sensors with multidimensional and directional perception are desirable for applications in intelligent robots and human–machine interaction. Herein, wearable multidimensional sensors have been fabricated by macroscopically assembling 3D-printed microstructured anisotropic organohydrogel sensory units through robust interfacial adhesion. The organohydrogel is crosslinked using microgels and starch microparticles through non-covalent interactions, and composited with short carbon fibers as conductive fillers. The physical network exhibits low hysteresis against 5000 cyclic loadings, which demonstrates excellent robustness in both mechanical properties and sensory performance. The organohydrogel precursor is printed into a cone-shaped sensor with a pressure sensitivity 50 times higher than that of its bulk counterpart. A sea cucumber epidermis-like microstructured sensor with abundant highly sensitive cone array is assembled with 3D-printed anisotropic gels with highly aligned carbon fibers inside, generating a multidimensional sensor capable of perceiving stimuli along X-, Y-, and Z-axis. The assembled sensor can directionally distinguish external forces and identify human motions. This study demonstrates a promising strategy to fabricate well-structured organohydrogel sensors for applications in electronic skin, biomimetic flexible electronics, and artificial intelligence.

V-type starches for trimethylamine of sea cucumber intestinal peptides: Adsorption kinetics and mechanism

Trimethylamine (TMA), which is known to severely affect consumer acceptance and application, is the main compound of sea cucumber intestinal peptides. Herein, different V-type crystalline starches (V6a/h, V7a/h, V8a/h) were prepared using high amylose maize starch for the adsorption of TMA. After analyzing the structure of V-type starches, the V8-type starch had a smaller and more evenly dispersed particles with additional surface pores and cracks, and reduced relative crystallinity compared with V6- and V7-type starch. The relative crystallinity of V6a-, V6h-, V7a-, V7h-, V8a-, and V8h-type starches was 59.1%, 51.8%, 42.7%, 41.3%, 40.4%, and 40.1%, respectively. Adsorption models for V-type starches and TMA helped to analyze the adsorption kinetics characteristics and investigate the effect of different V-type starches on adsorption. Moreover, its adsorption kinetics process agreed with pseudo-second-order kinetic model (R2 > 0.96). Note that different V-type starches demonstrate good adsorption effects on TMA, and the removal rate is as follows: V8h > V8a > V7h > V7a > V6h > V6a. Herein, we used environmental protection and food-grade V-type starches to effectively adsorb TMA and ensure a theoretical foundation for enhancing the flavor and quality of functional seafoods.

A photonic sensor system for real‐time monitoring of turbidity changes in aquaculture

AbstractObjectiveThe objective of this study was to test the compatibility and performance of a developed photonic sensor system, which can serve as a dependable and practical device for continuous monitoring of turbidity changes in aquaculture tanks.MethodsThe fabricated photonic sensor system consisted of an integrated data logger and sensor probe. The sensor probe exhibited a precise emission of infrared light at a wavelength of 850 nm. Moreover, the sensor evaluates the ambient light across the red‐green‐blue spectrum. To ensure accuracy and reliability, the entire system underwent a thorough calibration process, referencing nephelometric turbidity unit values acquired through a specialized handheld turbidimeter. Rigorous trials were systematically conducted in 600‐L seawater tanks featuring tubular sea cucumber Holothuria tubulosa and Gilt‐head Sea Bream Sparus auratus to ensure the sensitivity and robustness of the photonic sensor system to the aquaculture environment.ResultA calibration curve revealed a significant correlation between the infrared channel values of the sensor (photon counts) and the turbidity values measured by the turbidimeter. The photonic sensor effectively captured turbidity changes in the aquaculture tanks, with significant differences observed between the tanks. The sensor performance was evaluated in trials with Gilt‐head Sea Bream, which showed sensitivity to high turbidity changes. The photonic sensor system accurately reflects turbidity changes continuously using its own active light source, independent of ambient light intensity, which is essential for turbid water conditions or for taking measurements in total darkness.ConclusionThe photonic sensor is a reliable tool for the continuous and accurate monitoring of turbidity changes in aquaculture systems. However, there are specific usage limitations under low‐turbidity conditions that can be improved in further studies.

Genomic and Transcriptional Analysis of the Necroptosis Pathway Elements RIPK and MLKL in Sea Cucumber, Holothuria leucospilota.

Background: Receptor-interacting protein kinases (RIPKs) and mixed-lineage kinase domain-like protein (MLKL) are crucial in regulating innate immune responses and cell death signaling (necroptosis and apoptosis), and are potential candidates for genetic improvement in breeding programs. Knowledge about the RIPK family and MLKL in sea cucumber remains limited. Methods: We searched the genomes of sea cucumber Holothuria leucospilota for genes encoding RIPKs and MLKL, performed phylogenetic tree, motif and functional domain analyses, and examined tissue distribution and embryonic development patterns using qPCR. Results: RIPK5 (Hl-RIPK5), RIPK7 (Hl-RIPK7) and MLKL (Hl-MLKL) were identified in sea cucumber H. leucospilota. Hl-RIPK5 and Hl-RIPK7 were mainly expressed in coelomocytes, suggesting that they play a role in innate immunity, whereas Hl-MLKL exhibited relatively low expression across tissues. During embryonic development, Hl-MLKL was highly expressed from the 2-cell stage to the morula stage, while Hl-RIPK5 and Hl-RIPK7 were primarily expressed after the morula stage, indicating different roles in embryonic development. In primary coelomocytes, Hl-RIPK5 transcriptional activity was significantly depressed by LPS, poly(I:C), or pathogen Vibrio harveyi. Hl-RIPK7 expression levels were unchanged following the same challenges. Hl-MLKL mRNA levels were significantly decreased with poly(I:C) or V. harveyi, but did not change with LPS. Conclusions: These findings provide valuable insights into the evolutionary tree and characterization of RIPK and MLKL genes in sea cucumber, contributing to the broader understanding of the RIPK gene family and MLKL in ancient echinoderms.

Replacing sea mud with attachment of suspension cage can improve growth and gut health for sea cucumber Apostichopus japonicus

During the suspension cage culture procedure, a substantial quantity of attachments from the suspension cage will amass in the tidal flats, resulting in environmental pollution and resource wastage. The aim of the present study was to explore the feasibility of using attachments of suspension cage (ASC) as a raw feed material for sea cucumbers. Different ASC concentrations (0, 25, 50, 75, and 100%) were used in sea cucumber (Apostichopus japonicus) fed for 60 d. Replacing sea mud with 50% ASC significantly improved sea cucumber growth, reduced the feed coefficient, significantly increased the activity of intestinal digestive enzymes, improved the activities of acid phosphatase and alkaline phosphatase, improved the intestinal structure, and enriched intestinal microbiome diversity (P<0.05). Replacing sea mud with 75% and 100% ASC significantly improved sea cucumber total antioxidant capacity and total superoxide dismutase (P<0.05).Furthermore, expressions of c-myc gene, mapk-7 gene and fgfr-1 gene, which all three growth genes, significantly increased in the 50% ASC treatment compared to that in the control; whereas, that of gdf-8 gene, a negative growth regulator, was inhibited (P<0.05). Based on the quadratic regression analysis for the weight gain rate, the appropriate levels of ASC substitution were estimated as to be 44.28%. The results suggested the potential of ASC as a new raw feed material for sea cucumbers.

Sea cucumber-derived extract can protect skin cells from oxidative DNA damage and mitochondrial degradation, and promote wound healing

Our skin serves as the primary barrier against external environmental insults, the latter of which can cause oxidative stress within cells, while various bioactive peptides sourced from natural resources hold promise in protecting cells against such oxidative stress. In this study, we investigate the efficacy of a low molecular weight extract from the sea cucumber Apostichopus japonicus, denoted as Sample-P, in facilitating cell migration and wound healing under oxidative stress conditions in skin cells. The naturally derived compound is a highly complex mix of peptides exhibiting antioxidative properties, as highlighted through liquid chromatography-mass spectrometry peptide screening and an in vitro antioxidant assay. Our results demonstrate that Sample-P is capable of promoting cell migration while preventing severe stress responses such as visible through mTOR expression. To further identify the molecular pathways underpinning the overall protective mechanism of Sample-P, we have utilised a proteomics approach. Our data reveal that Sample-P regulates protein expression associated with ribosomal pathways, glycolysis/gluconeogenesis and protein processing in the endoplasmic reticulum (ER), which help in preserving DNA integrity and safeguarding cellular organelles, such as mitochondria and the ER, under oxidative stress conditions in skin cells. In summary, in the presence of H2O2, Sample-P exhibits antioxidative properties at both molecular and cellular levels, rendering it a promising candidate for topical skin treatment to wound healing and to address age-related skin conditions.

Organization, density, and content of collagen in the body wall of sea cucumbers Acaudina rosettis and Phyllophorus sp.

Marine collagen has been known to have lower immunogenicity compared to bovine collagen. The primary component in the body wall of sea cucumbers is collagen. This study aimed to investigate the density, bundle organization, and yield of collagen in the two sea cucumber species, Acaudina rosettis and Phyllophorus sp. collected from the Madura Strait, Indonesia. The body wall parts, including the dorsal anterior, dorsal median, dorsal posterior, ventral anterior, ventral median, and ventral posterior, from five samples of each species, were fixed and decalcified. They were histologically processed using the paraffin method before staining them with Van Gieson to visualize collagen in the cross-sections of body wall tissue. Collagen density was determined using the ImageJ software, while collagen bundle organization was examined negatively by utilizing the image editing application. Collagen density data were analyzed using repeated-measures ANOVA (α = 0.05). Collagen content in the body wall of each species was examined using acid solubilization-based collagen extraction, which did not significantly differ between different parts of the body wall in each species (p = 0.161 for A. rosettis, p = 0.095 for Phyllophorus sp.). However, Phyllophorus sp. exhibited a higher collagen density and collagen bundles, which were larger and more organized compared to A. rosettis. The collagen content was higher in A. rosettis (10.07%) compared to Phyllophorus sp. (8.07%). Further study can be performed to explore the potential of collagen from these sea cucumber species for commercial use.

Chemoreceptor MCP4580 of Vibrio splendidus mediates chemotaxis toward L-glutamic acid contributing to bacterial virulence

Chemotaxis has an essential function in flagellar bacteria that allows them to sense and respond to specific environmental signals, enabling their survival and colonization. Vibrio splendidus is an important opportunistic pathogen that infects a wide range of hosts including fish, bivalve, and sea cucumber. Our study demonstrated that V. splendidus AJ01 exhibited chemotaxis toward L-glutamic acid (L-Glu), an abundant amino acid in the intestinal and respiratory tree tissues of the sea cucumber. Bacterial samples collected from two locations in soft agar swimming plates were subjected to RNA-sequencing (RNA-Seq) analysis to identify the methyl-accepting chemotaxis protein (MCP) respond to L-Glu. Among the 40 annotated chemoreceptors, MCP4580 was identified as the MCP that mediates L-Glu-response. Molecular docking and site-directed mutagenesis revealed that L-arginine at residue 81 (R81) and L-glutamine at residue 88 (Q88) in the ligand-binding domain (LBD) are crucial for L-Glu recognition. Bacterial two-hybrid assay (BTH) showed that MCP4580 forms dimers and interacts with the histidine kinase CheA via the coupling protein CheW1 and CheW2. Phosphorylation analysis showed that the binding of L-Glu to MCP4580 results in the inhibition of CheA phosphorylation mainly via CheW1. Notably, sea cucumbers stimulated with each mutant strain of chemotaxis protein exhibited reduced mortality, highlighting the importance of chemotaxis in V. splendidus virulence. The present study provides valuable insights into the molecular components and signal transduction involved in the chemotaxis of V. splendidus toward L-Glu, and highlights the importance of chemotaxis in its virulence.

Polysaccharides from Enteromorpha prolifera improve growth performance and are involved in regulation of immune responses and microbial communities in the sea cucumber, Apostichopus japonicus (Selenka, 1867)

A 70-day feeding experiment was conducted to investigate the effects of supplementing Apostichopus japonicus with polysaccharides from Enteromorpha prolifera (PEP) on growth performance, biochemical composition, immune responses, and microbial communities. Different proportions of PEP (0, 0.2,1, 5, and 25 g/kg) were respectively added to the basal diet. Dietary 5 g/kg PEP induced an increase in final weights and specific growth rates (SGR), while decreasing the ingestion rate (IR) and feed conversion efficiency (FCE). Moisture contents and crude protein levels of sea cucumber were not significantly affected by PEP supplementation. Superoxide dismutase (SOD) and acid phosphatase (ACP) activities were elevated by dietary 1 g/kg PEP supplementation. Alkaline phosphatase (AKP), total anti-oxidative (T-AOC), lysozyme (LZM), and catalase (CAT) activities were enhanced by dietary 5 g/kg PEP. Sea cucumbers fed with 5 g/kg PEP exhibited higher levels of lys and cystain, and suppressed rel levels. Based on 16S rRNA sequencing, it was found that dietary 5 g/kg PEP increased the relative abundances of Proteobacteria and Firmicutes, while decreasing the relative abundances of Lutibacter and Vibrio. In general overview, dietary 5 g/kg PEP improves growth performance, enhances non-specific immunity, and modulates intestinal microbial composition of A. japonicus.

Establishment of a workflow for high-throughput identification of anti-inflammatory peptides from sea cucumbers

Developing an effective workflow for screening anti-inflammatory peptides is crucial for discovering novel food-derived anti-inflammatory peptides and optimizing the screening and identification process of bioactive peptides. Virtual screening identified three major yolk proteins as target precursor proteins for anti-inflammatory peptides in sea cucumbers. A portfolio of 170 peptides was identified from hydrolysates after 9 h of alcalase treatment by combining antioxidant activity determination and peptidomics analysis. Among these, 12 high-confidence anti-inflammatory peptides were identified through virtual screening. Three of these peptides were shown to effectively inhibit the production of NO and the release of pro-inflammatory cytokines in RAW264.7 cells. Molecular docking demonstrated that these three peptides exerted their anti-inflammatory effects primarily by binding to the active sites of cyclooxygenase-2 and inducible nitric oxide synthase through hydrophobic interactions. This study provided a reference workflow for screening anti-inflammatory peptides, facilitating the discovery of novel anti-inflammatory peptides and the high-value utilization of sea cucumber cooking liquid.

Effects of Selenium, Iron, and Zinc Enrichment on Cultured Sea Cucumber (Apostichopus Japonicus).

Selenium, iron, and zinc (Se, Fe, Zn) are essential trace elements crucial for animal growth, development, and immune protection, but they can be detrimental in excess. This study evaluates the impacts of Se, Fe and Zn on Apostichopus japonicus over a period of nine days, utilizing concentrations ranging from low to high: Se (0.20 µmol/L and 0.82 µmol/L), Fe (4.74 µmol/L and 18.96 µmol/L), Zn (1.88 µmol/L and 7.51 µmol/L). Concentrations of these trace elements in sea cucumbers increased with exposure time. Activities of CAT, SOD, and GSH-PX enzymes were enhanced. Transcriptomic analyses of sea cucumber body wall revealed significant gene expression changes, with differentially expressed genes (DEGs) numbering 294 at high and 945 at low Se concentrations, 906 at high and 210 at low Fe concentrations, and 423 at high and 123 at low Zn concentrations. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses highlighted DEGs enrichment in critical metabolic and immune-related pathways, including DNA replication, arachidonic acid metabolism, and oxidative phosphorylation. These results suggest that energy metabolism and immune regulation are pivotal in managing these elements, potentially enhancing sea cucumber immunity. This study enhances our comprehension of the physiological responses of sea cucumbers to trace elements and provides a theoretical basis for their use in aquaculture.