Sea Cucumber Research Articles

The effect of temperature and sand substrate in tanks on the growth and survival of the warty sea cucumber Neostichopus grammatus

ABSTRACT Water temperature and the presence of sand substrate are considered critical environmental factors affecting the growth of cultured sea cucumbers. This study investigated the effects of water temperatures and the presence or absence of sand substrate in tanks on the growth of N. grammatus fed an equal ration of abalone waste for eight weeks. Sea cucumbers with a mean weight of 8.34 g were used for the study. The treatments used in the study were Ambient water temperature + sand (A + S), Ambient water temperature without sand (A-S), Cold water temperature + sand (C + S), and Cold-water temperature without sand (C–S). The cold/constant water temperature was 16°C and was representative of winter conditions while the ambient/fluctuating water temperature fluctuated between 16.4 and 18.7 °C and was representative of spring conditions. At the end of the study, the sea cucumbers in A + S and C + S treatment groups exhibited an overall weight increase of 21.08% and 6.18%, respectively. The sea cucumbers reared in ambient water temperature exhibited significantly higher mean weight than those reared in cold water (F 1, 66 = 5.69; p = 0.02), and sea cucumbers reared with sand substrate had significantly higher mean weight compared to those without sand substrate (F 1,66 = 19.06; p = <0.001). This study has shown that growth rates of N. grammatus in tanks were higher in ambient temperatures and that stress was reduced in the presence of sand, a habitat that mimics its natural environment. This implies that sand substrate may be necessary for the farming of N. grammatus.

Incorporating physiological knowledge into correlative species distribution models minimizes bias introduced by the choice of calibration area

AbstractCorrelative species distribution models (SDMs) are important tools to estimate species’ geographic distribution across space and time, but their reliability heavily relies on the availability and quality of occurrence data. Estimations can be biased when occurrences do not fully represent the environmental requirement of a species. We tested to what extent species’ physiological knowledge might influence SDM estimations. Focusing on the Japanese sea cucumber Apostichopus japonicus within the coastal ocean of East Asia, we compiled a comprehensive dataset of occurrence records. We then explored the importance of incorporating physiological knowledge into SDMs by calibrating two types of correlative SDMs: a naïve model that solely depends on environmental correlates, and a physiologically informed model that further incorporates physiological information as priors. We further tested the models’ sensitivity to calibration area choices by fitting them with different buffered areas around known presences. Compared with naïve models, the physiologically informed models successfully captured the negative influence of high temperature on A. japonicus and were less sensitive to the choice of calibration area. The naïve models resulted in more optimistic prediction of the changes of potential distributions under climate change (i.e., larger range expansion and less contraction) than the physiologically informed models. Our findings highlight benefits from incorporating physiological information into correlative SDMs, namely mitigating the uncertainties associated with the choice of calibration area. Given these promising features, we encourage future SDM studies to consider species physiological information where available.

Shark Fin City: transitional marine wildlife economies in Global Hong Kong

ABSTRACT Hong Kong has historically been the epicenter of the global shark fin trade. Despite this legacy, recent public outreach campaigns highlighting the effects of consumption on marine ecosystems have precipitated shifts in the market. Fish maw and sea cucumber have emerged as substitutes in wildlife markets, marking an understudied phenomenon from urban geographical perspectives. This article investigates the transitional nature of social value systems underpinning Hong Kong's marine wildlife market through interviews with retailers, conservation organizations, and government officials, as well as visual surveys of market displays. Hong Kong's marine wildlife market, this article contends, brings into sharp relief how transitions in social value systems that substitute one type of non-fungible wildlife commodity for others can amplify biodiversity loss and reproduce expressions of social difference in urban space. The article illuminates how social value systems embedded in urban wildlife markets are related to human health, aging, gifting, and relationship building. Furthermore, it analyzes how the possession, consumption, and display of high-value wildlife commodities in cities reflects classed and gendered forms of social difference. The article further examines the challenges of regulating the market and shaping public values and actions in the face of escalating global biodiversity loss.

Coculture of abalone (Haliotis midae) and sea cucumber (Neostichopus grammatus) to reduce tank cleaning frequency in abalone farming

AbstractAbalone farming produces nutrient-rich sludge, and the frequent cleaning and removal of sludge from abalone tanks is labour and capital-intensive. This study aimed to assess the effect of culture methods and tank cleaning frequency on abalone growth, water quality, and sludge characteristics. The study was conducted for 16 weeks. Four treatments were used, namely, abalone cocultured with sea cucumber cleaned once (AS1) and twice weekly (AS2); abalone monoculture cleaned once (A1) and cleaned twice weekly (A2). Abalone (initial avg weight = 40.9 g) were maintained under commercial stocking conditions in flow through systems at a salinity of 35 ppt and fed a commercial formulated diet (Abfeed™) and fresh seaweed (Ulva lacinulata and Gracillaria gracilis). The stocking densities were 200 abalone m−2 and 50 sea cucumbers m−2. The sea cucumbers (initial average weight = 12.5 g) fed on the abalone faeces and leftover feed, which settled at the abalone tank's bottom (sludge). There was a significant interaction between the type of culture and the frequency of cleaning on abalone weight (F (1,476) = 12.41, p &lt; 0.001). Abalone in the A2 treatment group showed higher growth (p = 0.006) than those of the A1 treatment group, while abalone in AS1 had significantly higher growth (p &lt; 0.001) than those in the AS2 treatment group. Also, abalone in AS1 showed higher growth (p = 0.026) than abalone in the A1 treatment. However, abalone in AS1 had growth similar (p = 0.53) to those in A2. The survival rate of the sea cucumbers was high, however, the sea cucumbers experienced a reduction in weight regardless of the treatment. This study showed that growth optimisation in abalone farming can be achieved by cleaning tanks twice instead of once weekly. However, when abalone are cocultured with sea cucumber, tanks need only be cleaned once a week without compromising abalone growth or water quality. The coculture of abalone and sea cucumber results in an additional aquacultured product, a significant reduction in labour and other associated costs of cleaning, without an additional cost of production.

The intestinal mucosal immunity in mice enhanced by crosslinked ready-to-eat sea cucumber via regulating the SIgA secretion and gut microbiota

The protective effects of molecular crosslinked ready-to-eat sea cucumber (RSC) against immunosuppression induced by cyclophosphamide in mice were investigated. After gavage of molecular crosslinked RSC, the SIgA levels of intestinal mucosa in mice were significantly increased by 31.6% (P < 0.01), and the terminal differentiation of IgA+ B cell was promoted with the significant up-regulation of IL-6 and IL-10 levels (P < 0.05). Moreover, the secretion mechanism of plasma cell was mainly promoted through XBP-1s pathway mediated by IRE1 (P < 0.01), rather than ATF-4 and ATF-6 pathway (P > 0.05). In addition, the diversity of intestinal flora was increased, and the imbalance of intestinal flora was improved. The Lachnospiraceae_NK4A136_group dominated in crosslinked group could promote the repair of intestinal mucosa. Therefore, molecular crosslinked RSC can alleviate the intestinal mucosal damage via promoting SIgA secretion and regulating gut microbiota of mice.

Effects of gut bacterial community on differential growth of sea cucumber (Apostichopus japonicus): Molecular mechanisms based on host-gut microbiome co-metabolism

Gut microbiome and their metabolites are increasingly recognized for their pivotal role in regulating the health and growth of the host. The mechanism by which the host-gut microbiome co-metabolism affects the growth rate of sea cucumber (Apostichopus japonicus) remains unclear. In this study, the intestinal wall tissues of fast-growing (FG) and slow-growing (SG) A. japonicus were collected from the full-sib family for 16S amplicon sequencing, metagenomics, metabolomics, and transcriptomics analyses. The results showed a marked variation in the gut bacterial community of A. japonicus with different growth rates. Compared with SG group, FG A. japonicus had a higher abundance of Bacteroidetes. Many of these bacteria were associated with the degradation of polysaccharides, which could potentially affect growth performance. The abundance of Proteobacteria, however, was found to be higher in SG A. japonicus, thereby increasing the potential risk of disease. The metabolome results were further supported by the predicated KEGG functions of the gut microbiomes, lots of metabolites related to the metabolism and biosynthesis of fructose 6-phosphate, arachidonic acid, oleic acid, and dihydroxyacetone phosphate were upregulated in the FG A. japonicus. Furthermore, the genes (IGF1, HK, PK, PCK1) were significantly upregulated in the FG A. japonicus, which were mainly enriched in the metabolic pathways of lipids, amino acids, and carbohydrates. Gut bacterial community via their unique metabolic pathways, which in turn affected the metabolic phenotypes of the organism and eventually led to differences in growth performance of A. japonicus. These findings might help understand the molecular mechanisms of growth gap in sea cucumber, thereby increasing the mariculture production.

ELMO interacts with DOCK180 to enhance coelomocyte phagocytosis in Vibrio splendidus challenged Apostichopus japonicus

Engulfment and cell motility protein (ELMO) was identified as a novel, evolutionarily conserved upstream regulator of the RAC signaling pathway in mammals, which was essential for diverse physiological and pathological processes of cells, such as phagocytosis and cell migration. However, the functions and the underlying mechanisms of ELMO1 are generally poorly understood in invertebrates. In this study, we found that the endocytosis and GTP activity were significantly enriched in AjELMO1-interfered coelomocytes of Apostichopus japonicus by RNA-seq. Moreover, overexpression or interference of AjELMO1 significantly altered the coelomocyte phagocytosis levels induced by Vibrio splendidus AJ01, leading to an increase and decrease in the intracellular AJ01 burden by flow cytometry and bacteriophage plate counting in vivo and in vitro. Further functional analysis with different endocytosis inhibitors treatment revealed that AjELMO1 mediated AJ01 internalization via the actin-dependent endocytic pathways through the changes of F-actin/G-actin, but not the clathrin-, macropinocytosisi-, and dynamin-dependent endocytic pathways. The dedicator of cytokinesis protein 1 (AjDOCK180) was identified as an interacting protein of AjELMO1 using co-IP and GST-Pull down followed by mass spectrometry identification. Further function analysis also revealed that AjDOCK180 promotes coelomocyte phagocytosis through the actin endocytosis pathway via the changes in the phagocytosis levels, the intracellular AJ01 burden, and the ratio of F-actin/G-actin in coelomocytes. Additionally, we found that the phagocytic activity in sea cucumber coelomocytes promoted by AjELMO1 can be blocked by interference with AjDOCK180. Altogether, our data demonstrate that AjELMO1-AjDOCK180 is involved in resisting AJ01 infection via medicating coelomocyte phagocytosis through the actin-dependent pathway.

Wicked problem of improving fishery livelihoods through capacity building

Development programs can train fishers in value-adding but factors influencing who is likely to benefit are not well understood. Small-scale fishers worldwide often fall short increasing the value of their catch and wellbeing benefits from their harvests. Here, we sought to improve technical capacity of sea cucumber fishers in postharvest processing and examine intrinsic and extrinsic factors that shape long-term livelihood impacts. Manuals, videos and village-based workshops were used to train hundreds of fishers in 29 villages across seven island regions in Fiji. Our linear mixed models found that trained fishers spent more time processing their catch and were more likely to report increased sale prices. However, the fishery was in decline and so fishers’ weekly incomes did not improve overall. The capacity building led to gender-transformative outcomes by motivating women to increase catch rates and it improved their weekly fishery income. Perceived changes in trading prices and economic dependence on the fishery varied regionally, implying inconsistent trader behaviour. Our study reveals that improving fishery livelihoods can be a “wicked problem” involving a complexity of external factors that hinder livelihood impacts. Capacity-building of fishers was insufficient on its own to markedly improve wellbeing. Income also depended on the fishery stocks, equitable behaviour of traders and access of fishers to raw materials for postharvest processing. Development programs should consider a holistic approach through partnerships with institutions to improve the management of natural resources, value chains and technical capacity of fishers.

Use and management of seagrass ecosystems in southwestern Madagascar

Madagascar’s seagrass meadows are among the least-studied ecosystems in the western Indian Ocean region. To facilitate sustainable management, understanding the traditional uses of seagrass areas in relation to current management policies is necessary. This study assessed the uses of, and policies relevant to, seagrass ecosystems off southwestern Madagascar. We interviewed 131 community members in five coastal villages around the Bay of Ranobe in Toliara Province. Answers to the survey revealed a good level of awareness of seagrass, though 55% of respondents perceived the status of the seagrass areas as deteriorating. Opinions varied on the source or degree of threats to seagrass, but 74.8% of respondents suggested destructive fishing methods or other factors, including natural phenomena and animal grazing. The responses highlight that seagrass meadows serve as areas important for fishing, seaweed cultivation or sea cucumber farming, and the passage of boat/pirogue transportation. There are currently no tangible policies that directly protect or manage the seagrass areas regarding these activities, although some national regulations and local management initiatives are indirectly relevant, notably no-take zones and the local-level codes known as Dina. Development and implementation of a national management plan for seagrass ecosystems is a key gap. This demands the collection of scientific data to support decision-making to ensure long-term provision of the services provided by seagrass meadows. The involvement of coastal communities in the management of seagrass ecosystems will be necessary for the success of any new policies.

Advancing One Health in Urban Seafood Markets: A Genetic and Social Analysis of Dried Sea Cucumber in Three New York City Chinatowns

This study employs a multidisciplinary methodology across natural and social sciences to examine relationships between biodiversity loss at sea and urban consumption with a focus on sea cucumber and dried seafood markets in New York City (NYC). The study identified 34 dried seafood retailers across three NYC Chinatown boroughs: Manhattan, Brooklyn, and Queens. Samples of sea cucumber were collected with Chinese-language labels indicating the commodity was from South America, a region of conservation concern. Comparison samples were taken from sea cucumbers labeled from Mexico and Japan. A mitochondrial DNA barcoding method was used to examine the taxonomic origin of 103 samples. Sequence data were successfully obtained from 74 of the samples, 8 of which were classified as brown sea cucumber (Isostichopus fuscus), an endangered species for which harvest is banned in several locations. Semi-structured interviews with dried seafood retailers and consumers (n = 64), moreover, revealed associations between consuming sea cucumber and enhancing human health and limited knowledge of product origins. Collectively, the findings reveal socio-ecological dynamics wherein endangered species on the market coupled with geographic market labeling practices and varying degrees of retailer and consumer knowledge negatively bear on marine biodiversity. Furthermore, given that brown sea cucumbers are abundant on the market, there is a need for developing genetic markers that can trace geographic origin to determine if species were legally harvested. These results indicate that more robust market labeling, training, genetic research, and public outreach are required to advance One Health in urban seafood markets.

Characterization of the Apoptotic and Antimicrobial Activities of Two Initiator Caspases of Sea Cucumber Apostichopus japonicus

Caspase (CASP) is a protease family that plays a vital role in apoptosis, development, and immune response. Herein, we reported the identification and characterization of two CASPs, AjCASPX1 and AjCASPX2, from the sea cucumber Apostichopus japonicus, an important aquaculture species. AjCASPX1/2 share similar domain organizations with the vertebrate initiator caspases CASP2/9, including the CARD domain and the p20/p10 subunits with conserved functional motifs. However, compared with human CASP2/9, AjCASPX1/2 possess unique structural features in the linker region between p20 and p10. AjCASPX1, but not AjCASPX2, induced marked apoptosis of human cells by activating CASP3/7. The recombinant proteins of AjCASPX2 and the CARD domain of AjCASPX2 were able to bind to a wide range of bacteria, as well as bacterial cell wall components, and inhibit bacterial growth. AjCASPX1, when expressed in Escherichia coli, was able to kill the host bacteria. Under normal conditions, AjCASPX1 and AjCASPX2 expressions were most abundant in sea cucumber muscle and coelomocytes, respectively. After bacterial infection, both AjCASPX1 and AjCASPX2 expressions were significantly upregulated in sea cucumber tissues and cells. Together, these results indicated that AjCASPX1 and AjCASPX2 were initiator caspases with antimicrobial activity and likely functioned in apoptosis and immune defense against pathogen infection.

Ferroptosis resists intracellular Vibrio splendidus AJ01 mediated by ferroportin in sea cucumber Apostichopus japonicus

Ferroptosis, a kind of programmed cell death, is characterized with iron-dependent lipid ROS buildup, which is considered as an important cellular immunity in resisting intracellular bacterial infection in mammalian macrophages. In this process, lipid ROS oxidizes the bacterial biofilm to inhibit intracellular bacteria. However, the function of ferroptosis in invertebrate remains unknown. In this study, the existence of ferroptosis in Apostichopus japonicus coelomocytes was confirmed, and its antibacterial mechanism was investigated. First, our results indicated that the expression of glutathione peroxidase (AjGPX4) was significantly inhibited by 0.21-fold (p < 0.01) after injecting A. japonicus with the ferroptosis inducer RSL3, and the contents of MDA (3.93-fold, p < 0.01), ferrous iron (1.40-fold, p < 0.01), and lipid ROS (3.10-fold, p < 0.01) were all significantly increased under this condition and simultaneously accompanied with mitochondrial contraction and disappearance of cristae, indicating the existence of ferroptosis in the coelomocytes of A. japonicus. Subsequently, the contents of ferrous iron (1.40-fold, p < 0.05), MDA (2.10-fold, p < 0.01), ROS (1.70-fold, p < 0.01), and lipid ROS (2.50-fold, p < 0.01) were all significantly increased, whereas the mitochondrial membrane potential and GSH/GSSG were markedly decreased by 0.68-fold (p < 0.05) and 0.69-fold (p < 0.01) under Vibrio splendidus (AJ01) infection. This process could be reversed by the iron-chelating agent deferoxamine mesylate, which indicated that AJ01 could induce coelomocytic ferroptosis. Moreover, the results demonstrated that the intracellular AJ01 load was clearly decreased to 0.49-fold (p < 0.05) and 0.06-fold (p < 0.01) after treating coelomocytes with RSL3 and ferrous iron, which indicated that enhanced ferroptosis could inhibit bacterial growth. Finally, subcellular localization demonstrated that ferrous iron efflux protein ferroportin (AjFPN) and intracellular AJ01 were co-localized in coelomocytes. After AjFPN interference (0.58-fold, p < 0.01), the signals of ferrous iron and lipid ROS levels in intracellular AJ01 were significantly reduced by 0.38-fold (p < 0.01) and 0.48-fold (p < 0.01), indicating that AjFPN was an important factor in the introduction of ferroptosis into intracellular bacteria. Overall, our findings indicated that ferroptosis could resist intracellular AJ01 infection via AjFPN. These findings provide a novel defense mechanism for aquatic animals against intracellular bacterial infection.

Cytotoxic Potential of Berunok Sea Cucumber (Paracaudina australis) Against Breast Cancer Cells (T47D)

Background Sea cucumbers can be explored as alternative raw materials by the pharmaceutical and fishery industries as anticancer agents because they contain potential bioactive compounds. Methods This study aimed to determine the anticancer activity of Paracaudina australis extract against breast cancer cells (T47D) using an MTT assay. The secondary metabolites found in P.australis are steroids, terpenoids, saponins, and phenolics. The Thin-Layer Chromatography test results are indicated by Rf values, and steroid compounds in the ethyl acetate fraction are included in the standard Rf values. The isolates obtained were identified by Gas Chromatography-Mass Spectrometry, Fourier-Transform Infrared Spectroscopy, High-performance liquid chromatography, and UV-Visual spectrophotometry. Results The isolated compounds were Dihydrocholesterol and Cholestan-3-ol, with a molecular formula (C27H48O). The ion weight and molecular mass of the compound were m/z 388,7. Conclusions This compound may be responsible for the anticancer activity of P.australis. The IC50 of Isolate F4 was 25,3 μg/ml, and IC50 of Isolate F7,8 was 13,76 μg/ml.

Comparative Analysis of Gut Bacterial Community Composition in Two Tropical Economic Sea Cucumbers under Different Seasons of Artificial Environment.

With the continuous rise of the sea cucumber aquaculture industry in China, the tropical sea cucumber aquaculture industry is also improving. However, research on the gut microorganisms of tropical sea cucumbers in captivity is scarce. In this study, high-throughput sequencing methods were used to analyze the gut microbial composition of Stichopus monotuberculatus and Holothuria scabra in the dry season and wet season of artificial environments. The results showed that 66 phyla were obtained in all samples, of which 59 phyla were obtained in the dry season, and 45 phyla were obtained in the wet season. The Tax4Fun analysis showed that certain gut bacterial communities affect the daily metabolism of two sea cucumber species and are involved in maintaining gut microecological balance in the gut of two sea cucumber species. In addition, compared with differences between species, PCoA and UPGMA clustering analysis showed the gut prokaryotes of the same sea cucumber species varied more in different seasons, indicating that the influence of environment was higher than the feeding choices of sea cucumbers under relatively closed conditions. These results revealed the gut bacterial community composition of S. monotuberculatus and H. scabra and the differences in gut bacterial structure between two sea cucumber species in different seasons were compared, which would provide the foundation for tropical sea cucumber aquaculture in the future.

Chemical Synthesis of Fucosylated Chondroitin Sulfate Tetrasaccharide with Fucosyl Branch at the 6-OH of GalNAc Residue.

Fucosylated chondroitin sulfate is a unique glycosaminoglycan isolated from sea cucumbers, with excellent anticoagulant activity. The fucosyl branch in FCS is generally located at the 3-OH of D-glucuronic acid but, recently, a novel structure with α-L-fucose linked to the 6-OH of N-acetyl-galactosamine has been found. Here, using functionalized monosaccharide building blocks, we prepared novel FCS tetrasaccharides with fucosyl branches both at the 6-OH of GalNAc and 3-OH of GlcA. In the synthesis, the protective group strategy of selective O-sulfation, as well as stereoselective glycosylation, was established, which enabled the efficient synthesis of the specific tetrasaccharide compounds. This research enriches knowledge on the structural types of FCS oligosaccharides and facilitates the exploration of the structure-activity relationship in the future.

Sea Cucumber Plasmalogen Regulates the Lipid Profile in High-Fat Diet Mouse Liver via Lipophagy.

The sea cucumber plasmalogen PlsEtn has been shown to be associated with various chronic diseases related to lipid metabolism. However, the mechanism is unclear. Therefore, the present study used the sea cucumber plasmanylcholine PakCho as a structural contrast to PlsEtn and assessed its effect in 8 week high-fat diet (HFD)-fed mice. The lipidomic approach based on high-resolution mass spectrometry combined with molecular biology techniques was used to evaluate the mechanism of PlsEtn. The results showed that both PlsEtn and PakCho significantly inhibited an increase in mouse body weight and liver total triglyceride and total cholesterol levels caused by HFD. In addition, oil red O staining demonstrated that lipid droplets stored in the liver were degraded. Meanwhile, untargeted lipidomic experiments revealed that total lipids (increased by 42.8 mmol/mg prot; p < 0.05), triglycerides (increased by 38.9 mmol/mg prot; p < 0.01), sphingolipids (increased by 1.5 mmol/mg prot; p < 0.0001), and phospholipids (increased by 2.5 mmol/mg prot; p < 0.05) were all significantly elevated under HFD. PlsEtn resolved lipid metabolism disorders by alleviating the abnormal expression of lipid subclasses. In addition, five lipid molecular species, PE (18:1/20:4), PE (18:1/20:3), PE (18:1/18:3), TG (16:0/16:0/17:0), and TG (15:0/16:0/18:1), were identified as the biomarkers of HFD-induced lipid metabolism disorders. Finally, lipophagy-associated protein expression analysis showed that HFD abnormally activated lipophagy via ULK1 phosphorylation and PlsEtn alleviated lipophagy disorder through lysosomal function promotion. In addition, PlsEtn performed better than PakCho. Taken together, the current study results unraveled the mechanism of PlsEtn in alleviating lipid metabolism disorder and offered a new theoretical foundation for the high-value development of sea cucumber.

Using the socio-ecological system approach to guide the management of sea cucumber fisheries at Barang Lompo Island, South Sulawesi, Indonesia

Using the socio-ecological system approach to guide the management of sea cucumber fisheries at Barang Lompo Island, South Sulawesi, Indonesia

Importance of the ECM-receptor interaction for adaptive response to hypoxia based on integrated transcription and translation analysis.

Low dissolved oxygen (LO) conditions represent a major environmental challenge to marine life, especially benthic animals. For these organisms, drastic declines in oxygen availability (hypoxic events) can trigger mass mortality events and thus, act as agents of selection influencing the evolution of adaptations. In sea cucumbers, one of the most successful groups of benthic invertebrates, the exposure to hypoxic conditions triggers adaptive adjustments in metabolic rates and behaviour. It is unclear, however, how these adaptive responses are regulated and the genetic mechanisms underpinning them. Here, we addressed this knowledge gap by assessing the genetic regulation (transcription and translation) of hypoxia exposure in the sea cucumber Apostichopus japonicus. Transcriptional and translational gene expression profiles under short- and long-term exposure to low oxygen conditions are tightly associated with extracellular matrix (ECM)-receptor interaction in which laminin and collagen likely have important functions. Finding revealed that genes with a high translational efficiency (TE) had a relatively short upstream open reading frame (uORF) and a high uORF normalized minimal free energy, suggesting that sea cucumbers may respond to hypoxic stress via altered TE. These results provide valuable insights into the regulatory mechanisms that confer adaptive capacity to holothurians to survive oxygen deficiency conditions and may also be used to inform the development of strategies for mitigating the harmful effects of hypoxia on other marine invertebrates facing similar challenges.

Simulated Digestion of Red Sea Cucumber (Parastichopus tremulus): A Study of Protein Quality and Antioxidant Activity

Sea cucumbers from unharvested areas, are underutilized resources which may have the potential to become a future food resource. The aim of this study was to evaluate protein quality and investigate the changes in antioxidant activity from frozen and freeze-dried red sea cucumber (Parastichopus tremulus) subjected to digestion, using an in vitro digestion model. P. tremulus constituted high moisture content (90%), comparable protein (4%) and ash (4%) content, and low lipid (1%) content. The biochemical components in freeze-dried samples were largely retained during the freeze-drying process. Frozen samples showed significantly higher (p &lt; 0.05) antioxidant activity compared to freeze-dried samples (calculated on a dry weight basis). The quantity of essential amino acids was high (31%) and corresponds to the Food and Agriculture Organization of the United Nations reference protein. Frozen samples showed an increase in antioxidant activity during digestion measured by three different antioxidant assays. Freeze-dried samples only showed an increase in one of the antioxidant assays. Correlations (p &lt; 0.05) were found between specific free amino acids and antioxidant activity. The amount of free amino acids exceeded the threshold to taste bitter, umami, sour, and sweet flavors. This study showed that P. tremulus constitutes good protein quality, performed antioxidant activity, and has the potential to be used as a flavor-enhancing ingredient.

Immune responses of sea cucumber (Apostichopus japonicus) to combined environmental stress from high temperature and oil pollution

Context High temperature and oil pollution are typical examples of environmental stress to sea cucumber (Apostichopus japonicus) in northern China. Aims Evaluate the combined effects of high temperature and oil pollution on the immune responses of sea cucumbers. Methods In this study, we investigated the immune responses in the respiratory tree of sea cucumber subjected to the optimal temperature (16°C), high temperature (26°C), Oman crude oil (OCO) water-accommodated fractions (WAF) at 16°C (WAF + 16°C) and OCO WAF at 26°C (WAF + 26°C) for 48 h. Key results All three treatments significantly up-regulated total antioxidant capacity and disturbed active oxygen species homeostasis in sea cucumbers. Moreover, all three treatments caused immune-enzyme activity disorders, manifested by a significant increase in acid–alkaline phosphatase and nitric oxide synthase activities and a noticeable decline in lysozyme activity. Conclusions Combining the integrated biomarker-response index (WAF + 26°C &gt; 26°C &gt; WAF + 16°C), the combined stress could result in a more adverse effect on the immune responses of sea cucumbers than do high temperature or oil pollution alone, which might further exacerbate the health challenges for sea cucumbers in response to environmental stress. Implications This study has provided an insight into the immune impacts in benthic organisms caused by high temperature and oil pollution.