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There are nearly 1200 species of sea cucumber in the world's seas. Among these creatures included in the Holothuroidea class, 37 species show distribution in the Mediterranean and Aegean Sea. The purpose of this study is to determine the chemical content and biological potent of five sea cucumber species, Holothuria tubulosa, Holothuria poli, Holothuria mammata, Holothuria sanctori and Stichopus regalis which were collected from the Aegean Sea. The detailed flavonoid, phenolic and triterpene contents were determined by LCHR/MS. Cytotoxic activities against several cancer cell lines, MDA-MB-231, PC-3, A549, PANC-1, HEPG2 and a healthy cell line CCD-34LU were performed by MTT method. Antiviral activities of the samples were measured as virucidal activity against avian coronavirus by in ovo. According to the results of LC-HRMS analysis, H. sanctori, H. poli and S. regalis had the richest chemical content diversity in terms of examined triterpene compounds. Fumaric acid was detected as the most abundant substance in all sea cucumber species. H. tubulosa had a highly toxic effect on all the tested cells. The best cytotoxic activity on A549 cells was seen in H. mammata, H. sanctori and H. poli. H. sanctori also showed a significant toxic effect against PANC-1, MDAMB-231, HepG2 and A549 cells, whereas the IC50 value in CCD-34LU cells was above 50 μg/mL for this sample. The n-butanol extracts of sea cucumber species reduced hemagglutination (HA) virus titer between 1-fold to 4-fold in log2-based at all tested concentrations. The best inhibited virus HA titer results were found in H. tubulosa at 5 μg/g. According to these results we have obtained, the extracts of sea cucumbers may be used in many fields such as medicine, food, cosmetics in the future. This study is also very important in terms of being a guide for all studies on the use, processing and production of sea cucumbers and detailed isolation and purification studies on sea cucumber species from Turkiye. [ABSTRACT FROM AUTHOR]

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Microplastics (MPs) have become pervasive in marine ecosystems, exerting detrimental effects on marine life. The concurrent presence and interaction of MPs and heavy metals in aquatic environments could engender more insidious toxicological impacts. This study aimed to elucidate the potential impacts and underlying mechanisms of polystyrene microplastics (PS-MPs), cadmium (Cd), and their combined stress (MPs-Cd) on sea cucumbers (Apostichopus japonicus). It focused on the growth, Cd bioaccumulation, oxidative stress responses, immunoenzymatic activities, and metabolic profiles, specifically considering PS-MPs sizes preferentially ingested by these organisms. The high-dose MPs (MH) treatment group exhibited an increase in cadmium bioavailability within the sea cucumbers. Exposure to PS-MPs or Cd triggered the activation of antioxidant defenses and immune responses. PS-MPs and Cd exhibited a synergistic effect on lysozyme (LZM) activity. A total of 149, 316, 211, 197, 215, 619, 434, and 602 differentially expressed metabolites were identified, distinguishing the low-dose MPs (ML), high-dose MPs (MH), low-dose Cd (LCd), low-dose MPs and low-dose Cd (MLLCd), high-dose MPs and low-dose Cd (MHLCd), high-dose Cd (HCd), low-dose MPs and high-dose Cd (MLHCd), high-dose MPs and high-dose Cd (MHHCd) groups, respectively. Metabolomic analyses revealed disruptions in lipid metabolism, nervous system function, signal transduction, and transport and catabolism pathways following exposure to PS-MPs, Cd, and MPs-Cd. Correlation analyses among key differentially expressed metabolites (DEMs) underscored the interregulation among these metabolic pathways. These results offer new perspectives on the distinct and synergistic toxicological impacts of microplastics and cadmium on aquatic species, highlighting the complex interplay between environmental contaminants and their effects on marine life., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Abstract In the present study, the biochemical composition of some Echinodermata (Holothuroidea, Echinoidea) from the Red Sea, Egypt was investigated. The results showed that the highest percentage of saturated fatty acids (SFA) was in Holothuria nobilis and the lowest percentage was recorded in Holothuria scabra. The highest percentage of monounsaturated fatty acids (MUFA) was recorded in Pearsonothuria graeffei while the lowest percentage was recorded in Holothuria atra. The highest percentage of polyunsaturated fatty acids (PUFA) was recorded in Holothuria nobilis and the lowest percentage was recorded in Holothuria atra. The highest percentage of omega-3 fatty acids was recorded in Stichopus hermanni however, the lowest percentage was recorded in Diadema setosum. The highest percentage of omega-6 fatty acids was recorded in Bohadschia vitiensis where, the lowest percentage was recorded in Holothuria atra. In addition, nonessential amino acid (NEAA) glycine were the highest in all species and serine was the lowest while Essential amino acid (EAA) arginine was the highest and cysteine was the lowest. All of the NEAA recorded highest concentrations in S. hermanni except proline. The recorded essential amino acids were histidine, isoleucine, phenylalanine, and leucine. The latter was high in Pearsonothuria graeffei. Tyrosine, valine, threonine, and arginine were high in Stichopus hermanni. The present study proved that sea cucumbers has great nutritional value.

Alpha-2-macroglobulin (A2M) is an extracellular macromolecule mainly known for its role as a broad-spectrum protease inhibitor in mammals. However, the immune recognition and regulation mechanisms of A2M in invertebrates are still not well investigated. In the current study, the role of sea cucumber Apostichopus japonicus A2M in the regulation of innate immune responses was explored. We found that AjA2M promotes phagocytosis of Vibrio splendidus in coelomocytes of sea cucumber. Then two major functional structural domains of AjA2M, the thioester domain (TED) and the receptor-binding structural domain (RBD) were cloned. It was found that the AjA2M-TED binds to pathogens while causing Vibrio splendidus aggregation; the AjA2M-RBD interacts with the Glucose Regulated Protein 78 (AjGRP78), subsequently AjGRP78 accelerates the degradation of Vibrio splendidus in lysosomes by facilitating polymerisation and rearrangement of the cytoskeleton. Collectively, the findings together suggest that A2M-GRP78 axis mediates immune signaling pathway of phagocytosis and AjA2M has been characterized to play an essential crucial role in antibacterial immune responses of invertebrates., Competing Interests: Declaration of competing interest The authors declare that they have no conflicts of interest with the contents of this article., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Zinc is an essential micronutrient for organisms involved in regulating various biological processes. This study evaluated the effects of dietary zinc on growth performance, digestive enzyme activities, antioxidant status, and immune responses of sea cucumber Apostichopus japonicus. Five experimental diets were formulated with graded levels of zinc (0, 20, 40, 60, and 80 mg/kg, respectively), and the actual dietary zinc values were 31.4, 51.0, 68.2, 91.9, and 110.8 mg/kg diet, respectively. Sea cucumbers were fed with diets for 2 months. The results showed the growth performance, amylase, and trypsin activities of sea cucumber increased significantly with zinc supplementation, and the best growth performance and enzyme activities were observed at 40 mg/kg zinc diet. Zinc supplementation significantly increased activities of superoxide dismutase, catalase, anti-superoxide anion, and inhibiting hydroxyl radical, while significantly reduced the malondialdehyde content. Furthermore, the higher zinc supplementation levels resulted in significantly upregulated immune-related genes of hsp90, p105, rel, and lsz, suggesting that excessive zinc caused oxidative stress. The broken-line regression analysis of specific growth rate indicated dietary zinc requirement in juvenile sea cucumber was ~ 66.3 mg/kg diet. Overall, dietary zinc contributes to the growth and immune resistance of juvenile sea cucumber, and our study will provide insights into the rational use of dietary zinc in aquaculture., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

In this work, phlorotannin extracts (PhTEs) were isolated from Ascophyllum nodosum. The effects of PhTEs on the textural properties, structural changes and oxidation level of Apostichopus japonicus (A. japonicus) were investigated. The results showed that thermal treatment could lead to the dissolution of TCA-soluble peptides and free hydroxyproline and promote the degradation of A. japonicus. The chemical compositional changes and texture profile analysis results indicated that PhTEs could effectively inhibit the degradation of A. japonicus and improve the hardness and chewiness of A. japonicus. Analysis of multiple spectroscopic methods suggested that the secondary and tertiary conformations tended to be stable after PhTEs were added. In addition, electron spin resonance results indicated that PhTEs could reduce the oxidation level of A. japonicus. These results suggest that the degradation of A. japonicus during mild heat treatment can be regulated by PhTEs, which provides insights for quality control in A. japonicus heat treatment., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Sulfamethoxazole (SMZ) is a frequently detected antibiotic in the environment, and there is a growing concern about its potential toxic effects on aquatic organisms. sea cucumber (Apostichopus japonicas) is a benthic invertebrate whose gut acts as a primary immune defense and serves critical protective barrier. In this study, growth performance, histology, gut microbiota, and metabolomics analyses were performed to investigate the toxic response in the intestine of sea cucumber effects caused by SMZ stress for 56 d by evaluating with different concentrations of SMZ (0, 1.2×10 -3 , and 1.2 mg/L). The weight gain rate of sea cucumbers under SMZ stress showed significant decrease, indicating that the growth of sea cucumbers was hindered. Analysis of the intestinal morphological features indicated that SMZ stimulation resulted in atrophy of the sea cucumber gut. In the 1.2×10 -3 mg/L concentration, the thickness of muscle and mucosal layers was reduced by 12.40% and 21.39%, while in the 1.2 mg/L concentration, the reductions were 35.08% and 26.98%. The abundance and diversity of sea cucumber intestinal bacteria decreased significantly (P < 0.05) under the influence of SMZ. Notably, the intestinal bacteria of sea cucumber became homogenized with the increase in SMZ concentration, and the relative abundance of Ralstonia reached 81.64% under the stress of 1.2 mg/L concentration. The SMZ stress significantly impacted host metabolism and disrupted balance, particularly in L-threonine, L-tyrosine, neuronic acid, piperine, and docosapentaenoic acid. SMZ leads to dysregulation of metabolites, resulting in growth inhibition and potential inflammatory responses that could adversely affect the normal activities of aquatic organisms. Further metabolic pathway enrichment analyses demonstrated that impaired biosynthesis of unsaturated fatty acids and aminoacyl-tRNA biosynthesis metabolic pathway were major reasons for SMZ stress-induced intestinal bacteria dysbiosis. This research aims to provide some theoretical evidence for the ecological hazard assessment of antibiotics in water., Competing Interests: Declaration of Competing Interest The authors declare that they have no competing interests., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

A new genus of Holothuroidea, Notostichopus, from Australia is described and its phylogenetic relationship examined. The new genus is based on two species within the family Stichopodidae, previously attributed to Stichopus. Notostichopus is characterized by the absence of rosette ossicles and the presence of table ossicles with at most one crossbeam in dorsal body wall. The two species revised here (N. ludwigi and N. ellipes) are distributed in the shallow, tropical, and temperate waters of Australia. Phylogenetic analyses indicate that this genus is closely related to the genera Isostichopus and Stichopus but is distinct based on ossicles and phylogenetic analyses. We describe the ossicle assemblages of both species. [ABSTRACT FROM AUTHOR]

As an important input of environmental micropollutants into aquaculture environment, feed is now considered to be a critical factor in shaping gastrointestinal evacuation characteristics of animals. We analyzed the gastrointestinal evacuation characteristics and gut bacteria of Apostichopus japonicus within 30 h after feeding in recirculating aquaculture system (RAS) and explored the evacuation mechanism interacting by bacteria. The Gauss model was the most precise gastrointestinal evacuation curve, and 80% of gastrointestinal evacuation time was 27.81 h after feeding. Linear discriminant analysis effect size analysis revealed that gut microbial abundance associated significantly with time (P < 0.05), and 42 biomarkers that could predict gastrointestinal evacuation were totally detected, such as Lutibacter and Vibrio. Biomarkers at 25 h after feeding were related to harmful bacteria. A dynamic response between gastrointestinal content ratio and gut microbial abundance was detected. Taken together, we could discharge sewage about 25 h after feeding and carry out the next round of feeding activities., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Selecting high-quality seeds with long-term advantages in behavior, intestinal health, and growth are the key to improve production efficiency of sea cucumber aquaculture. It is proposed to distinguish the seed quality of sea cucumbers by color morphs. In the present study, we carried out a 6-week experiment to investigate behavior, intestinal health, and growth of small sea cucumbers Apostichopus japonicus in different color morphs. We found that dark-colored seeds of sea cucumber were significantly more adhesive than those with light-colored seeds. This indicates that the dark-colored seeds of A. japonicus are more adaptive in complex environments in stock enhancement. Food consumption and defecation outputs of dark-colored seeds were significantly higher than those of light-colored seeds. In addition, the feces of dark-colored seeds of sea cucumber had significantly lower crude protein content and better intestinal morphology, but there was no advantage in digestive enzyme activities. This suggests that there are potential digestive benefits in dark-colored seeds. Further, dark-colored seeds of A. japonicus showed significantly better intestinal microbiota composition and faster growth rate than that of light-colored seeds. In conclusion, the present results prove that dark-colored seeds of sea cucumber have long-term advantages in behavior, intestinal health and growth. Overall, this study provides important information for the early selection of seeds and the consequent production efficiency in sea cucumber aquaculture., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

As an important form of renewable energy, offshore wind power can effectively reduce dependence on traditional energy sources and decrease carbon emissions. However, operation of wind turbines can generate underwater noise that may have negative impacts on marine benthic organisms in the surrounding area. Sea cucumbers are slow-moving invertebrates that inhabit the ocean, relying on their immune system to adapt to their environment. To evaluate the frequency range of characteristic noise produced by offshore wind turbines, we conducted a field survey. Additionally, we utilized sea cucumbers in simulated experiments to assess their response to the noise produced by offshore wind turbines. We established a control group, a low-frequency noise group simulating offshore wind turbine noise at 125 Hz and 250 Hz, and a high-frequency noise group at 2500 Hz, each lasting for 7 days. Results from measuring immune enzyme activity in the coelomic fluid suggest that noise can reduce the activity of superoxide dismutase enzymes, which may make sea cucumbers more susceptible to oxidative damage caused by free radicals. Exposure to low-frequency noise can have the effect of diminishing the activity of catalase, and this decrease in catalase activity could potentially increase the susceptibility of the sea cucumber's coelom to inflammation. In order to elucidate the hypothetical mechanism of immune response, intestinal tissue was extracted for transcriptome sequencing. The results showed that under 125 Hz low-frequency noise stress, the number of differentially expressed genes was the highest, reaching 1764. Under noise stress, sea cucumber's cell apoptosis and cell motility are reduced, interfering with lipid metabolism process and membrane synthesis. This research provides theoretical support for the environmental safety assessment of offshore wind power construction., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)

Pattern recognition receptors (PRRs) are the first line of immune defense in invertebrates against pathogen infection; they recognize pathogens and transmit signals to downstream immune pathways. Among these, peptidoglycan recognition proteins (PGRPs) are an important family in invertebrates that generally comprise of complicated isoforms. A comprehensive understanding of PGRPs in evolutionarily and economically important marine invertebrates, such as the sea cucumber, Apostichopus japonicus, is crucial. Previous studies have identified two PGRPs in sea cucumber, AjPGRP-S and AjPGRP-S1, and another novel short-type PGRP, AjPGRP-S3, was additionally identified here. The full-length cDNA sequence of AjPGRP-S3 was obtained here by PCR-RACE, followed by which showed its gene expression analyses by in situ hybridization that showed it to be relatively highly expressed in coelomocytes and tube feet. Based on an analysis of the recombinant protein, rAjPGRP-S3, a board-spectrum pathogen recognition ability was noted that covered diverse Gram-negative and -positive bacteria, and fungi. Moreover, according to the results of yeast two-hybridization, it was suggested that rAJPGRP-S3 interacted with multiple immune-related factors, including proteins involved in the complement system, extracellular matrix, vesicle trafficking, and antioxidant system. These findings prove the important functions of AjPGRP-S3 in the transduction of pathogen signals to downstream immune effectors and help explore the functional differences in the AjPGRP isoforms., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

To investigate the ability of Vibrio sp. V33 supplementation on the growth performance, innate immunity, intestinal microbiota, and disease resistance of the juvenile sea cucumber Apostichopus japonicus, a feeding experiment was conducted. Our results revealed that dietary Vibrio sp. V33 could significantly enhanced sea cucumber growth rate, and the immune parameters including total coelomocytes counts (TCC), phagocytosis, respiratory burst, immune-related enzyme activities (acid phosphatase, alkaline phosphatase, superoxide dismutase, catalase, superoxide dismutase, and nitric oxide synthetase) were all markedly improved in coelomocytes of sea cucumbers fed with V33 (P < 0.05). Furthermore, the composition of the bacterial community in the intestinal contents of the sea cucumber was surveyed by 16S rRNA sequencing. Beta diversity analysis indicated that the bacterial compositions of sea cucumbers were significantly different between V33 and Control groups. At the phylum level, Proteobacteria, Actinobacteria, Firmicutes, and Bacteroidetes were the most prevalent phyla in sea cucumber gut microbiota. The abundance of Firmicutes (20.58%), Bacteroidetes (9.77%), and Verrucomicrobia (3.04%) were significantly higher in V33 group when compared with Control. Moreover, genus Mycobacterium was markedly decreased to 0.5% after V33 feeding, while the abundance of genus Rhodococcus was significantly increased by 6.9-fold (P < 0.01) under the same condition, indicating V33 diet might promotes the colonization of beneficial bacteria in the gut of sea cucumber. After Vibrio splendidus challenge, the survival rate of juvenile sea cucumbers fed with V33 diet was significantly higher than that fed with Control diet. All our current results suggested that the Vibrio sp. V33 could used as a probiotic for healthier production of sea cucumbers in aquaculture., Competing Interests: Declaration of competing interest The authors declare no competing financial interest., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Stichopus cf. horrens is an economically important sea cucumber species in Southeast Asia due to their presumed nutritional and medicinal benefits. However, compared to other sea cucumbers such as Apostichopus japonicus, there are no biochemical studies on which compounds contribute to the purported bioactivities of S. cf. horrens. To address this, a high-throughput characterization of the global metabolite profile of the species was performed through LC-MS/MS experiments and utilizing open-access platforms such as GNPS, XCMS, and metaboAnalyst. Bioinformatics-based molecular networking and chemometrics revealed the abundance of phospholipids such as phosphatidylcholines (PCs), phosphatidylethanolamines (PEs), phosphatidylinositols (PIs), and phosphatidylserines (PSs) in the crude samples. Body wall extracts were observed to have higher levels of structural, diacylated PCs, while the viscera have higher relative abundance of single-tail PCs and PEs that could be involved in digestion via nutrient absorption and transport for sea cucumbers. PEs and sphingolipids could also be implicated in the ecological response and morphological transformations of S. cf. horrens in the presence of predatory and other environmental stress. Interestingly, terpenoid glycosides and saponins with reported anti-cancer benefits were significantly localized in the body wall. The sulfated alkanes and sterols present in S. cf. horrens bear similarity to known kairomones and other signaling molecules. All in all, the results provide a baseline metabolomic profile of S. cf. horrens that may further be used for comparative and exploratory studies and suggest the untapped potential of S. cf. horrens as a source of bioactive molecules., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2023 Torreno et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

This study aimed to investigate the effects of Bacillus cereus LS2 on the growth performance, innate immunity, intestinal microbiota, and disease resistance of sea cucumber Apostichopus japonicus. After feeding with LS2 for 30 days, results showed that dietary with LS2 had a significant improvement in the growth rate and immune parameters (including total coelomocytes counts, phagocytosis, respiratory burst, and immune-related enzymes) of juvenile sea cucumbers. Subsequently, transcriptome sequencing and qRT-PCR verification were performed to analyze the potential mechanism of LS2 diet and thus improve the immune response of A. japonicus. GO and KEGG pathway analysis indicated that LS2 can primarily activate the "Lectins" and "complement and coagulation cascades" pathways to modulate the innate immunity of the sea cucumbers. Furthermore, 16S rRNA sequencing was used to analyze the intestinal microbial composition of sea cucumbers after dietary with LS2. Results showed that Proteobacteria, Actinobacteria, Firmicutes, and Bacteroidetes were the most prevalent phyla in A. japonicus intestinal microbiota. The abundance of Actinobacteria (46.20%) and Bacteroidetes (12.80%) were significantly higher in the LS2 group, whereas the relative abundance of Proteobacteria (49.98%) and Firmicutes (14.97%) were higher in the control group. The LDA scores of Nocardiaceae and Rhodococcus were also the highest taxa after the dietary administration of LS2, indicating that Actinobacteria phylum played a pivotal role in the intestinal microbial function of A. japonicus. Overall, these results suggested that feeding with Bacillus LS2 may be beneficial for A. japonicus farming., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

The persistent organic pollutant 2,2',4,4'-Tetrabromodiphenyl ether (BDE-47), a prevalent congener among polybrominated diphenyl ethers (PBDEs), exhibits potent bioaccumulation and toxicity. Despite extensive research into the adverse effects of BDE-47, its neurotoxicity in sea cucumbers remains unexplored. Given the crucial role of the sea cucumber's nervous system in survival and adaptation, evaluating the impacts of BDE-47 is vital for sustainable aquaculture and consumption. In this study, we employed ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Triple-TOF-MS) to analyze metabolomic changes in neuro-related tissues of Apostichopus japonicus exposed to low (0.1 µg/L), medium (1.0 µg/L), and high (10.0 µg/L) BDE-47 concentrations. We identified significantly changed metabolites in each exposure group (87 in low, 79 in medium, and 102 in high), affecting a variety of physiological processes such as steroid hormone balance, nucleotide metabolism, energy metabolism, neurotransmitter levels, and neuroprotection. In addition, we identified concentration-dependent, common, and some other metabolic responses in the neuro-related tissues. Our findings reveal critical insights into the neurotoxic effects of BDE-47 in sea cucumbers and contribute to risk assessment related to BDE-47 exposure in the sea cucumber industry, paving the way for future neurotoxicological research in invertebrates., Competing Interests: Declaration of Competing Interest The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Mass mortality caused by skin ulceration syndrome (SUS) is the bottle-neck for the sustainable aquaculture of the sea cucumber Apostichopus japonicus. In the present study, probiotic Bacillus licheniformis (0.25 × 10 9  CFU/g) was used as the treatment for A. japonicus infected with the SUS that caused by Vibrio harveyi. We found that B. licheniformis significantly reduced the number of infected sea cucumbers 5 days and 7 days after the treatment (group B), compared to those without B. licheniformis treatment (group C) (P < 0.001; P < 0.001). Further, the sea cucumbers fed B. licheniformis had significantly lower mortality at the end of the experiment (<10%) than that of those without the B. licheniformis treatment (>60%) (P < 0.001). These results suggest that the treatment of B. licheniformis is an effective method to reduce the mass mortality resulted from SUS in sea cucumber aquaculture. Further, 3-5 days of treatment significantly improved the adverse symptoms of SUS on the physiology and behavior of sea cucumbers, including the righting behavior, adhesion behavior, food consumption, fecal output and mobility. This indicates B. licheniformis treatment has the advantage in the recovery of sea cucumbers after SUS. Moreover, there was no significant difference observed in the physiology and behavior of sea cucumbers between the SUS infected sea cucumbers after the 7-day treatment of B. licheniformis and the healthy individuals. SUS infected sea cucumbers effectively returned to a stage of normalcy. Further, we found a significantly lower infected rate in sea cucumbers exposed to the culture water of group B (∼5%) than that of those in exposure to the culture water of group C (∼60%). This indicates that the treatment of B. licheniformis efficiently controls the residual pathogenicity of SUS in culture water. The present study demonstrated the effectiveness of B. licheniformis treatment as an environmentally friendly approach to reducing mortality, improving symptoms, and controlling residual pathogenicity in sea cucumber aquaculture., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Aquaculture provides essential food for humans, and the health of farmed species is particularly important for the aquaculture industry. Aquaculture environment could be a sink of plastic debris (PDs) due to the enclosed character and heavy use of plastics. Gut microbiota of aquaculture species could respond to the exogenous pollutants and regulate the health of hosts. Here, variations in gut microbiota of Apostichopus japonicus induced by the ingested nanoplastics (NPs) were investigated by a lab experiment. We selected a NPs concentration gradient of 100 mg/kg and 500 mg/kg to simulate microplastic pollution to A. japonicus, and the significant differences in gut microbiota composition after 21 days of NP exposure were evaluated. According to the high-throughput sequencing from time series samples, a decrease of diversity in gut microbiota of A. japonicus with dietary NPs was observed. In addition, the gut microbiota compositions of sea cucumbers with and without NPs exposure were also distinct, expressing as enrichment of Bacteroidota while reducement of Proteobacteria under NPs stresses. Combined the results of network analysis, the less complexity and stability of gut microbiota in sea cucumbers with dietary NPs were proved. Based on the neutral community model, the ingested NPs elevated the contribution of stochastic processes for the gut microbiota assembly in sea cucumbers. Our study showed that substantial variations in gut microbiota of A. japonicus under NPs stresses, and also explored the underlying mechanisms regulating these changes. This research would offer new meaningful insights into the toxicity of NPs on sea cucumbers, contributing a solid fundament to improve the health of sea cucumbers under NPs stresses., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Inc.)

Apostichopus japonicus is a marine invertebrate with high economic value. Analysis of the effects of age on the structure of this species is important for understanding the status of the population and conservation. In this study, metabolite analysis of the body walls of A. japonicus of three different ages (1, 2, and 3 years) was performed using LC-MS/MS. Metabolite analysis was performed for the KEGG metabolic pathway. The partial least squares-discriminant analysis is clearly distinguished metabolites in the three groups of A. japonicus. A total of 59, 222, and 179 different metabolites were detected in the age 3 vs age 2, age 3 vs age 1, and age 2 vs age 1 controls, respectively (P < 0.05). These metabolic differences involved several metabolic pathways, including phenylalanine metabolism, taurine and hypotaurine metabolism, sulfur metabolism et al. Thiamin, riboflavin, lipoic acid, acetyl l-carnitine levels increase with age, trans-10-heptadecenoic acid, stearic acid, pentadecanoic acid, dibutyl sebacate, and 8,15-diHETE levels decrease with age, which these metabolites can be used as potential markers to determine the age of A. japonicus. Our results provide the foundation for determining the age of A. japonicus and are important for the conservation of germplasm resources of A. japonicus., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Inc.)

Bisphenols are known as endocrine disruptor that affect the development, and growth of marine creatures, including human. There were plenty of manuscripts evaluated the toxicology of bisphenol A (BPA) and its analogues such as bisphenol F (BPF), bisphenol AF (BPAF), and bisphenol S (BPS), but limits of them studied the effects of bisphenol analogues on echinoderms. In this study, we used metabolomics to investigate the metabolic response of sea cucumber (Apostichopus japonicus) exposed to BPAF, and the activities of glutathione (GSH), catalase (CAT), and superoxide dismutase (SOD) were determined. The results demonstrated alterations in lipid metabolism, glycerophospholipid metabolism, and biosynthesis of amino acids following BPAF treatment. Sea cucumbers upregulated the glycerophospholipid metabolism to repair the destruction of intestine cellular homeostasis. Six metabolites were selected as the potential biomarkers for the exposure of BPAF. This study revealed the metabolic response and oxidative response of sea cucumber arising from BPAF exposure, and provided theoretical support for the risk assessment of bisphenol analogues on economically important echinoderms, such as A. japonicus., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Microplastic pollution has been widely detected across the global ocean, posing a major threat to a wide variety of marine biota. To date, the deleterious impacts of microplastics have predominantly been linked to their direct exposure, while the potential risks posed by the leachates emanating from microplastics have received comparatively less attention. Here, the toxicity of virgin plasticized polyvinyl chloride (PVC) microspheres and their leachates were evaluated on the embryo-larval development of sea cucumber Apostichopus japonicus using an in-vitro assay. Results showed that a significant toxic effect of both PVC microspheres and their leachates on the embryo development and larval growth of sea cucumbers follows a dose-dependent and time-dependent pattern. Nonetheless, the toxicity of PVC leachates surpasses that of the microspheres themselves. Abnormal developmental phenotypes, such as aberrant gastrulation, misaligned mesenchymal cells, and delayed arm development, were also observed in embryos and larvae treated with PVC. Further chemical analyses of PVC microspheres and leachates revealed the existence of five distinct phthalate esters (PAEs), with DIBP (diisobutyl phthalate) and DBP (dibutyl phthalate) exhibiting higher concentrations in the PVC leachates. This finding suggests that the elevated toxicity of plastic leachate may be attributed to the leaching of phthalate additives from the plastic particles., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Ye Zhao reports financial support was provided by National Natural Science Foundation of China., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Marine microplastic (MP) pollution is becoming a serious problem and their potentially toxic effects on marine organisms have attracted much attention. Sea cucumber is very important for the safety and health of marine ecosystems. However, there have been relatively few studies on the effects of microplastic pollution on sea cucumbers at environmentally-related concentrations and under controlled conditions. Therefore, this study evaluated the effects of polyethylene terephthalate (PET) microplastics (particle sizes: 0.5-45 μm, 2-200 μm, and 20-300 μm; and three concentration levels for each particle size, approximately 10 3 , 10 4 , and 10 5 particles/kg) on the basic biological indicators, intestinal digestive enzymes, and intestinal flora of Apostichopus japonicus after a 28-day feeding experiment. This study showed that environmentally-related and high concentrations of microplastics had little effect on A. japonicus. This study provides valuable reference information about the effects of marine microplastic pollution on sea cucumbers., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:Linbin Zhang reports financial support was provided by National Natural Science Foundation of China., (Copyright © 2023 Elsevier Ltd. All rights reserved.)