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The sea cucumber body wall was subjected to enzymatic hydrolysis using papain. The relationship between the enzyme concentration (1–5% w/w protein weight) and hydrolysis time (60–360 min) and the degree of hydrolysis (DH), yield, antioxidant activities, and antiproliferative activity in a HepG2 liver cancer cell line was determined. The surface response methodology showed that the optimum conditions for the enzymatic hydrolysis of sea cucumber were a hydrolysis time of 360 min and 4.3% papain. Under these conditions, a 12.1% yield, 74.52% DH, 89.74% DPPH scavenging activity, 74.92% ABTS scavenging activity, 39.42% H2O2 scavenging activity, 88.71% hydroxyl radical scavenging activity, and 9.89% HepG2 liver cancer cell viability were obtained. The hydrolysate was produced under optimum conditions and characterized in terms of its antiproliferative effect on the HepG2 liver cancer cell line. [ABSTRACT FROM AUTHOR]

The ever-growing demand for sea cucumbers is a threat to these echinoderms and their habitats; however, a way to relieve stock pressure lies in meeting demand through aquaculture. As such, this study aimed to improve the growth and survival percentage of Holothuria arguinensis during larval development, settlement and juvenile growth. Three diets of microalgae (Diet RbPt = Rhodomonas baltica + Phaeodactylum tricornutum; Diet RbSm = Rhodomonas baltica + Skeletonema marinoi; Diet RbCc = Rhodomonas baltica + Chaetoceros calcitrans) were administered daily to the larval phase. Additionally, three substrates were supplied (pvc rolls, wavy pvc plaques and tile) at three different depths in order to determine the most favourable for settlement. Lastly, the potential benefits on growth and survival from introducing macroalgae (Sacchoriza polyschides) in the juvenile diet were assessed over a period of 6 months. Despite larvae under diet RbPt having presented a larger mean width, H. arguinensis fed with Diet RbCc presented a higher settlement survival at the end of the trial. No preferences were noted among the tested substrates, regardless of diet. Lastly, juveniles with added S. polyschides in their diet showed increased growth in mean weight and length when compared to individuals that were not fed with this seaweed. [ABSTRACT FROM AUTHOR]

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Copyright of Food Research & Development is the property of Food Research & Development Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The demand for sea cucumbers from the NE-Atlantic is increasing as a consequence of the depletion of stocks that historically supplied Asian markets. Some species from the NE-Atlantic are already showing overfishing signs due to either inefficient policies or their total absence, and they do not offer any margins of sustainability to sea cucumber fisheries. The current lack of knowledge of biological and ecological traits has led to ineffective protection of those species. Holothuria arguinensis is a good example of a temperate sea cucumber species suffering from the effects of unregulated and illegal harvest. This study aims to determine the temporal and spatial distribution patterns of H. arguinensis, assessing density and size-class structure in a NE-Atlantic population, in SW Portugal, as a function of environmental conditions. Sampling was done every 1.5 months at 6 stations defined according to habitat heterogeneity, following the coastline from the mouth of the Sado estuary to marine coastal areas. At each station, there were two habitats (rocky substrate and sandy areas) sampled through SCUBA diving along 30-m random transects, each with three replicates. Individuals were counted and measured (total length) and individual behavioural parameters, such as sheltering and settlement surface, were recorded. Water column parameters, sediment composition, and substrate cover were also recorded. Generalised Linear Models were fit to the data, modelling density and size distribution of the species with respect to environmental conditions. The results indicate that the distribution of H. arguinensis was mainly determined by its ability to deal with physical environmental stressors (current), rather than the chemical properties of the water column or sediment composition. The hydrodynamic features of the region exert the greatest impact on this species' distribution and help shape habitat usage by different size class groups. [ABSTRACT FROM AUTHOR]

At present, deep-sea enzymes are a research hotspot. In this study, a novel copper–zinc superoxide dismutase (CuZnSOD) was successfully cloned and characterized from a new species of sea cucumber Psychropotes verruciaudatus (PVCuZnSOD). The relative molecular weight of the PVCuZnSOD monomer is 15 kDa. The optimum temperature of PVCuZnSOD is 20 °C, and it maintains high activity in the range of 0–60 °C. It also has high thermal stability when incubated at 37 °C. PVCuZnSOD has a maximum activity of more than 50% in the pH range of 4–11 and a high activity at pH 11. In addition, PVCuZnSOD has strong tolerance to Ni2+, Mg2+, Ba2+, and Ca2+, and it can withstand chemical reagents, such as Tween20, TritonX-100, ethanol, glycerol, isopropanol, DMSO, urea, and GuHCl. PVCuZnSOD also shows great stability to gastrointestinal fluid compared with bovine SOD. These characteristics show that PVCuZnSOD has great application potential in medicine, food, and other products. [ABSTRACT FROM AUTHOR]

This document synthesising knowledge on the northern sea cucumber Cucumaria frondosa was prepared for all stakeholders, including industry participants, government scientists, policymakers, and academic researchers. Its aim is to highlight the uniqueness of this marine resource to guide the industry forward and to emphasize areas that deserve further investigation. Available data from eastern and northern Canada, eastern United States of America, Greenland, northern Europe and the Russian Federation are presented. Topics covered include the taxonomy, distribution, biology, and ecology of the species, the natural threats it faces, the current harvesting, processing and marketing practices, and the prospects for aquaculture development. Relying on a knowledge base gathered over more than 40 years, this contribution compares C. frondosa with other common commercial species of sea cucumbers to tease out the major aspects that set it apart. A final segment provides a number of key recommendations for its management and conservation. [ABSTRACT FROM AUTHOR]

The bioactive secondary metabolites produced by sea cucumbers are very diverse with differences in composition, linkages, molecular weight, and various functional properties. Due to their physicochemical properties, these bioactive molecules in sea cucumbers have found applications in various market segments such as functional foods and cosmetics. Sea cucumber side dishes are a prominent food item in traditional cuisine in East Asian countries such as South Korea, China, and Japan. In addition, many studies have reported that the consumption of sea cucumbers can reduce the risk of cardiovascular disease, the pathogenesis of cancer cells, chronic inflammatory diseases, etc. In particular, many studies have recently reported the potential of sea cucumbers to develop functional products to reduce inflammation, oxidative stress, diabetes, and cancer. Additionally, these bioactive properties associated with sea cucumbers make them ideal compounds for use as functional ingredients in functional food products. However, no report has yet reviewed the properties of sea cucumbers related to functional foods. Therefore, in this review, the primary focus is given to collecting published scientific data (from 2019 to 2023) on the bioactive properties of sea cucumbers relevant to the functional food industry.

This study was conducted to evaluate the effects of Bacillus licheniformis and combined herbs extracts on the physiological and immune characteristics, intestinal microbiota, and vibriosis resistance of sea cucumber Apostichopus japonicus. The sea cucumbers were fed with basal diets supplemented with B. licheniformis (B group), combined herbs extracts (C group), or both (BC group). The BC group exhibited the better growth performance and higher digestive and immune enzyme activities, whereas the lowest parameters appeared in the control group. This revealed that dietary B. licheniformis and combined herbs extracts in combination could improve digestion, food intake, phosphatase-responsiveness, and oxidation resistance more efficiently compared with the other groups. The BC group was also more capable of regulating intestinal flora balance of sea cucumbers by increasing the beneficial bacteria related to energy synthesis and metabolic conversion, and inhibiting the potential pathogens associated with organic damage and metabolic disorders. Furthermore, the BC group showed greater ability of improving disease resistance by reducing the cumulative mortality rates and the counts of Vibrio splendidus. These results collectively demonstrated that dietary B. licheniformis and combined herbs extracts could improve the physiological and immune parameters, optimize the microbial community, and enhance the resistance to vibriosis of sea cucumbers, and the health-promoting effects were more obvious by supplying them in combination. [ABSTRACT FROM AUTHOR]

We previously demonstrated that the flagellin of intracellular Vibrio splendidus AJ01 could be specifically identified by tropomodulin (Tmod) and further mediate p53-dependent coelomocyte apoptosis in the sea cucumber Apostichopus japonicus. In higher animals, Tmod serves as a regulator in stabilizing the actin cytoskeleton. However, the mechanism on how AJ01 breaks the AjTmod-stabilized cytoskeleton for internalization remains unclear. Here, we identified a novel AJ01 Type III secretion system (T3SS) effector of leucine-rich repeat-containing serine/threonine-protein kinase (STPKLRR) with five LRR domains and a serine/threonine kinase (STYKc) domain, which could specifically interact with tropomodulin domain of AjTmod. Furthermore, we found that STPKLRR directly phosphorylated AjTmod at serine 52 (S52) to reduce the binding stability between AjTmod and actin. After AjTmod dissociated from actin, the F-actin/G-actin ratio decreased to induce cytoskeletal rearrangement, which in turn promoted the internalization of AJ01. The STPKLRR knocked out strain could not phosphorylated AjTmod and displayed lower internalization capacity and pathogenic effect compared to AJ01. Overall, we demonstrated for the first time that the T3SS effector STPKLRR with kinase activity was a novel virulence factor in Vibrio and mediated self-internalization by targeting host AjTmod phosphorylation dependent cytoskeleton rearrangement, which provided a candidate target to control AJ01 infection in practice. Author summary: Vibrio splendidus AJ01 is the major pathogen for skin ulcer syndrome (SUS) in Apostichopus japonicus, nevertheless, its pathogenic mechanism remains unknown. Eukaryotic-like factors play a crucial role in bacterial virulence by targeting hosts. Despite their significance, the eukaryotic factors in Vibrio splendidus have not been studied, and the mechanism by which they interact with the host remains unclear. In this study, we found an eukaryotic-like factor STPKLRR of V. splendidus for the first time. Furthermore, STPKLRR, selected by T3SS, can phosphorylate Tmod at S52, dissociate the Tmod/actin complex, cause cytoskeleton rearrangement and promote the internalization of V. splendidus. Our findings provide insight into the mechanisms underlying the internalization of V. splendidus and advance our knowledge of the general biology of pathogen-host interactions. [ABSTRACT FROM AUTHOR]

Seasonal low-oxygen in marine ranching in the northern Yellow Sea has been one of the major environmental problems in coastal waters in recent years. Nitrogen (N) and phosphorus (P) are important nutrients, which are susceptible to the concentration of dissolved oxygen (DO). This article studied the effects of low-oxygen on nutrients represented by N and P fractions in marine ranching in the northern Yellow Sea. The results showed that there were significant layer differences in temperature and salinity during the low-oxygen period. In the seawater, the nutrient distribution in the death disaster zone of sea cucumbers and the non-disaster zone was similar, and DO had a strong positive correlation with dissolved inorganic nitrogen (DIN). In the sediment, significant regional differences existed in nutrient concentration, and the concentration of total phosphorus (TP) decreased significantly with the increase in DO content. The results showed that the sources and sinks of nitrogen and phosphorus nutrients were inconsistent in this zone, and migration and transformation of the existing form of nitrogen with the seasonal changes in the water environment was a main factor for N distribution. This study extended the understanding of the effects of seasonal low-oxygen on N and P. [ABSTRACT FROM AUTHOR]

The sea otter (Enhydra lutris) population of Southeast Alaska has been growing at a higher rate than other regions along the Pacific coast. While good for the recovery of this endangered species, rapid population growth of this apex predator can create a human‐wildlife conflict, negatively impacting commercial and subsistence fishing. Previous foraging studies throughout the sea otter range have shown they will reduce invertebrate prey biomass when recolonizing an area. The goal of this study was to examine and quantify the energy content of sea otter diets through direct foraging observations and prey collection. Our study area, Prince of Wales Island in southern Southeast Alaska, exhibits a gradient of sea otter recolonization, thus providing a natural experiment to test diet change in regions with different recolonization histories. Sea otter prey items were collected in three seasons (spring, summer, and winter) to measure caloric value and lipid and protein content. We observed 3523 sea otter dives during the spring and summer. A majority of the sea otter diet consisted of clams. Sea otters in newly recolonized areas had lower diet diversity, higher energetic intake rates (EIR, kcal/min), and prey had higher energy content (kcal/g). Females with pups had the highest diet diversity and the lowest EIR. Sea otter EIR were higher in the fall and winter vs. spring and summer. Sea cucumber energy and lipid content appeared to correspond with times when sea otters consumed the highest proportion of sea cucumbers. These caloric variations are an important component of understanding ecosystem‐level effects sea otters have in the nearshore environment. [ABSTRACT FROM AUTHOR]

Simple Summary: Sea cucumbers are very sensitive to the influence of environmental factors, and will vomit their intestines and undergo tissue degradation under certain stimuli. In order to determine the effect of endogenous enzymes in the sea cucumber intestine on the body wall during body wall softening, intestine extracts and crude collagen fibers were prepared, respectively. The endogenous enzymes belonging to serine proteases were identified by gelatin zymography. The rheological property results showed that the addition of sea cucumber intestinal extracts reduced the viscosity of crude collagen fibers from 32.7 Pa·s to 5.3 Pa·s. The serine protease inhibitor phenylmethylsulfonyl fluoride inhibited the activity of intestinal extracts, and maintained the viscoelasticity of crude collagen fibers. In this paper, endogenous enzymes in sea cucumber intestinal extracts were identified as serine endopeptidases, which caused softening of the body wall. Sea cucumbers Apostichopus japonicus will vomit their intestines during certain stimulations, and the collagen of the body wall will then be degraded. To define the effect of the sea cucumber intestine extracts on the body wall, the intestinal extracts and crude collagen fibers (CCF) of sea cucumber A. japonicus were prepared. According to the gelatin zymography, the type of endogenous enzymes in intestinal extracts were mainly serine endopeptidases with optimal activities at pH 9.0 and 40 °C. According to the rheology results, the viscosity of 3% CCF decreased from 32.7 Pa·s to 5.3 Pa·s by adding intestine extracts. The serine protease inhibitor phenylmethanesulfonyl fluoride inhibited the activity of intestinal extracts and increased the viscosity of collagen fibers to 25.7 Pa·s. The results proved that serine protease in the intestinal extracts participated in the process of body wall softening in sea cucumbers. [ABSTRACT FROM AUTHOR]

Summary: The thermal processing characteristics of sea cucumber collagen (SCC) are closely related to its triple helix structure, self‐assembly and aggregation ability. The effect of heat treatment on SCC was studied by apparent viscosity, circular dichroism spectra and so on. As heating time increased from 10 to 160 min, apparent viscosity decreased from 400 to 300 mPa·s at 80 °C, indicating the structure of SCC changed. The decrease in SCC self‐assembly and aggregation ability showed the structural change. Positive peak at 220 nm was decreased from 24 to 0 mdeg at 60 °C for 10–160 min, which revealed that SCC triple helix structure was uncoiled and disappeared. Fluorescence intensity was increased and the absorption peak showed a red shift during thermal treatment. Gallic acid crosslinking could improve thermal stability and inhibit the degradation of collagen. It could provide theoretical guidance for sea cucumber processing. [ABSTRACT FROM AUTHOR]

Background and Aim: A bone defect is defined as a critically sized autologous bone and a bone gap. Bone grafting is one of the most commonly used surgical methods to enhance bone regeneration in orthopedic procedures. A composite of collagen, hydroxyapatite (HA), and chitosan (Ch) is suitable as a bone matrix and stimulates ossification. This study aimed to evaluate the use of natural HA-Ch composites derived from sea cucumbers and shrimp shells and quantify the levels of cytokines, polymorphonuclear neutrophils (PMNs), serum liver enzymes, calcium, phosphate, and procollagen type 1 N-terminal propeptide (PINP) in albino rats with femoral bone defects. Materials and Methods: A total of 48 albino rats with femoral bone defects were divided into 4 groups (n = 12 each): (C-) placebo, (C+) polyethylene glycol, (T1) HA, and (T2) HA-Ch groups. Each group was divided into two subgroups (n = 6 each), with euthanization on 7- and 42-day post-treatment, respectively. Procollagen Type 1 N-terminal propeptide and the cytokines interleukin (IL)-4, IL-6, IL-10, and tumor necrosis factor-alpha were quantified using enzyme-linked immunosorbent assay. Flow cytometry was performed to evaluate PMNs. A clinical chemistry analyzer was used to measure the serum levels of liver enzymes, calcium, and phosphate. Results: There was a significant decrease in the level of IL-6 on 7 days and in the level of IL-10 on 42 days in the HA-Ch group. The level of PMNs also decreased significantly on 7 and 42 days in the HA-Ch group. Regarding serum liver enzymes, alkaline phosphatase (ALP) levels in the HA-Ch group increased significantly on 42 days. Calcium and phosphate levels increased significantly on 7 and 42 days in the HA and HA-Ch groups, and PINP levels increased significantly on 7 and 42 days in the HA-Ch group. Conclusion: The HA-Ch composite derived from sea cucumbers and shrimp shells ameliorated femoral bone defects in albino rats. The HA-Ch composite modulated the levels of IL-6, IL-10, PMNs, ALP, calcium, phosphate, and PINP on 7- and 42-day post-treatment. [ABSTRACT FROM AUTHOR]

The sea cucumber Holothuria (Halodeima) grisea Selenka, 1867 is distributed from Florida (USA) to southern Brazil. Juveniles of this species are very hardly found in the wild. H. (H.) grisea is very common on sandstone reefs in some localities from the northern coast of Brazil. Because seagrass beds are a conspicuous feature in some of these localities, the authors have speculated that juveniles live in these habitats. Following this species' reproduction period, seagrass beds adjacent to sandstone reefs were inspected in search of juveniles from December to May. Sea cucumbers were found in one of them. Individuals were collected from two areas within the seagrass bed and two areas within neighboring rocky shores, and their contracted body lengths were measured. Mean sizes were significantly smaller in the seagrass areas than in reef areas (post-hoc Tuckey test, P < 0.05). Within the seagrass bed, more than 70% of individuals were smaller than 7.5 cm, whereas 84.9 and 93.3% in the two reef areas were larger than 7.5 cm -the first report of an H. (H.) grisea population dominated by juveniles. Therefore, seagrass meadows should be looked at as possible sources of juveniles for adult populations of H. (H.) grisea in the tropical western Atlantic. Also, given the rarity of juvenile sightings for this species anywhere within its distribution range, the results are very meaningful for future research on its ecology and local and regional fishery management. [ABSTRACT FROM AUTHOR]

Ball sea cucumber (Phyllophorella kohkutiensis) is an edible marine animal that is both consumed domestically in Thailand and exported to foreign countries. The chemical compositions (moisture, protein, ash, carbohydrate, lipid) and fatty acid (FA) profiles of fresh and dried samples, with and without tube feet (TF), were investigated. The fresh samples had a high moisture content (86.22 to 87.96%), while the dried samples showed high total protein (70.21 to 78.75%). All samples contained low levels of total lipids (0.01 to 0.10%). The dried samples with TF were found to have the highest total saturated FA with 63.75% of total fatty acid (TFA), while fresh samples without TF had the highest total monounsaturated FA at 23.80% TFA, and total polyunsaturated FA with 21.93% TFA, including arachidonic acid (ARA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). The essential minerals, calcium (Ca) and zinc (Zn) were at 73.38 and 0.047 mg/100 g, respectively. The ball sea cucumber P. kohkutiensis provides good nutritional quality for human consumption. [ABSTRACT FROM AUTHOR]

Holothuria leucospilota and Stichopus chloronotus are among the most widespread tropical sea cucumber species usually harvested for food and medicine in Asian countries, for which natural stocks have collapsed worldwide. Both species can reproduce sexually and asexually, and a better understanding of their reproductive strategy can provide useful information for conservation purposes. To describe the genetic structure and diversity of sympatric populations from these species in space and time, individuals were sampled over different sites and seasons in Reunion Island (Southwestern Indian Ocean). They were genotyped using 24 and 9 specific microsatellite markers for H. leucospilota and S. chloronotus, respectively. Multi-locus genotypes (MLG) and lineages (MLL) were identified, and analyses of population structure were performed among sites and seasons. No repeated MLG nor MLL were found for H. leucospilota, demonstrating the absence of asexual reproduction. Populations of H. leucospilota were not genetically differentiated, acting as a metapopulation, with larval exchanges within the reef. Contrarily, repeated MLGs were found for S. chloronotus and all populations were genetically differentiated. Asexual reproduction seems to reach a high level for this species (mean clonal richness = 0.24). For both species, genetic structure was stable through seasons. Thus, these sympatric fissiparous sea cucumber species use two different strategies of reproduction, which may allow them to reduce interspecific competition. [ABSTRACT FROM AUTHOR]

Saponins are amphiphilic molecules of pharmaceutical interest and most of their biological activities (i.e., cytotoxic, hemolytic, fungicide, etc.) are associated to their membranolytic properties. These molecules are secondary metabolites present in numerous plants and in some marine animals, such as sea cucumbers and starfishes. Structurally, all saponins correspond to the combination of a hydrophilic glycan, consisting of sugar chain(s), linked to a hydrophobic triterpenoidic or steroidic aglycone, named the sapogenin. Saponins present a high structural diversity and their structural characterization remains extremely challenging. Ideally, saponin structures are best established using nuclear magnetic resonance experiments conducted on isolated molecules. However, the extreme structural diversity of saponins makes them challenging from a structural analysis point of view since, most of the time, saponin extracts consist in a huge number of congeners presenting only subtle structural differences. In the present review, we wish to offer an overview of the literature related to the development of mass spectrometry for the study of saponins. This review will demonstrate that most of the past and current mass spectrometry methods, including electron, electrospray and matrix‐assisted laser desorption/ionization ionizations, gas/liquid chromatography coupled to (tandem) mass spectrometry, collision‐induced dissociation including MS3 experiments, multiple reaction monitoring based quantification, ion mobility experiments, and so forth, have been used for saponin investigations with great success on enriched extracts but also directly on tissues using imaging methods. [ABSTRACT FROM AUTHOR]

Sea cucumber Holothuria leucospilota is one of the most widespread tropical holothurian species. In this study, eukaryotic organism composition in foregut and hindgut contents of H. leucospilota and surrounding sediments was assessed by 18S rRNA gene high-throughput sequencing. Eukaryon richness and diversity in the habitat sediments were significantly higher than those in foregut and hindgut contents of the sea cucumbers (P<0.05). The foregut content group, hindgut content group, and marine sediment group sequences were respectively assigned to 18.20±1.32, 19.40±1.03, and 21.80±0.37 phyla. In the foregut contents, Nematoda (20.18%±9.59%), Mollusca (16.12%±10.49%), Chlorophyta (10.04%± 4.85%), Annelida (8.72%±10.93%), Streptophyta (8.46%±4.65%), and Diatomea (5.99%±2.01%) were the predominant phyla, which showed the eukaryotic food sources of H. leucospilota were primarily belong to the above phyla. The predominant phyla in the hindgut contents were Streptophyta (45.55%±17.32%), Mollusca (4.93%±4.82%), Arthropoda (5.37%±3.08%), Diatomea (3.88%±2.34%), and Chlorophyta (3.79%±1.59%); and Annelida (37.80%±17.00%), Arthropoda (24.49%±12.53%), Platyhelminthes (7.14%±3.02%), Nematoda (4.14%±0.91%), and Diatomea (5.11%±1.35%) had large contents in the sediments. The comparatively high content of Paris genus in phylum Streptophyta in foregut contents indicated that land plants were one of the primary food sources of H. leucospilota, however the significantly higher contents of Streptophyta in hindgut contents than that in foregut contents might suggest a large part of the terrigenous detritus ingested might not be digested by H. leucospilota. UPGMA and PCoA analysis revealed that eukaryotic organism composition differed significantly between foregut contents of H. leucospilota and ambient sediments, indicating selective feeding feature of H. leucospilota. This study provided useful references for artificial feed of tropical sea cucumbers and enhanced understanding of the ecological roles of detritus-feeding macrobenthos. [ABSTRACT FROM AUTHOR]

At present, sea cucumbers, sea urchins, and other seafood products have become increasingly significant in the seafood aquaculture industry. In traditional fishing operations, divers go underwater for fishing, and the complex underwater environment can cause harm to the divers' bodies. Therefore, the use of underwater robots for seafood fishing has become a current trend. During the fishing process, underwater fishing robots rely on vision to accurately detect sea cucumbers and sea urchins. In this paper, an algorithm for the target detection of sea cucumbers and sea urchins in complex underwater environments is proposed based on the improved YOLOv5s. The following improvements are mainly carried out in YOLOv5s: (1) To enhance the feature extraction ability of the model, the g n C o n v -based self-attentive sublayer HorBlock module is proposed to be added to the backbone network. (2) To obtain the optimal hyperparameters of the model for underwater datasets, hyperparameter evolution based on the genetic algorithm is proposed. (3) The underwater dataset is extended using offline data augmentation. The dataset used in the experiment is created in a real underwater environment. The total number of created datasets is 1536, and the training, validation, and test sets are randomly divided according to the ratio of 7:2:1. The divided dataset is input to the improved YOLOv5s network for training. The experiment shows that the mean average precision (mAP) of the algorithm is 94%, and the mAP of the improved YOLOv5s model rises by 4.5% compared to the original YOLOv5s. The detection speed increases by 4.09 ms, which is in the acceptable range compared to the accuracy improvement. Therefore, the improved YOLOv5s has better detection accuracy and speed in complex underwater environments, and can provide theoretical support for the underwater operations of underwater fishing robots. [ABSTRACT FROM AUTHOR]

Summer mortality and morbidity are serious environment-related problems in cultured sea cucumbers (Apostichopus japonicus). Air exposure probably worsens the impact of high temperature on cultured sea cucumbers. In this present study, two laboratory experiments were designed to investigate the effects of artificial reefs on mortality, morbidity, crawling, feeding, and adhesion behaviors of small sea cucumbers (~1 g of wet body weight) after air exposure and disease outbreaks at 25 °C, respectively. Significantly lower mortality and morbidity occurred in the group with artificial reefs compared with those in the group without artificial reefs in the two experiments. This present study found that the stressed sea cucumbers cultured inside artificial reefs showed a significantly higher adhesion index, feeding behavior, and crawling frequency than those cultured without artificial reefs. In disease challenge assays, small sea cucumbers cultured inside the artificial reefs showed a significantly higher adhesion index and crawling frequency than those cultured without artificial reefs at 25 °C. Feeding, crawling, and adhesion behaviors of sea cucumbers cultured outside artificial reefs were not significantly different from those cultured without artificial reefs. The experimental results indicate that sea cucumbers with good fitness-related behaviors may be less affected by the disease and more likely to move into the crevices of artificial reefs. Fitness-related behaviors were poor in sea cucumbers cultured outside artificial reefs, so we considered them as affected individuals. Thus, artificial reefs provide a place to reduce the physical contact between unaffected and diseased/affected individuals, showing a potential to reduce disease transmission. Our present study establishes a cost-effective approach to increasing the survival of small sea cucumbers in seed production at high temperatures. [ABSTRACT FROM AUTHOR]

Fishing can drive major ecological change in coastal ecosystems and is typically examined through top‐down trophic impacts. However, the massive removal of biomass can also disrupt key ecological bottom‐up processes, though how these effects shape ecosystems is poorly understood. Here, we examined the ecological roles of two species of commercially exploited sea cucumbers thought to promote primary productivity in nutrient‐poor environments through nutrient provisioning and sediment processing. Using a large‐scale field experiment, we tested whether simulated sea cucumber fishing affected seagrass productivity in a natural system comprising reef and seagrass patches that varied in abundance of vertebrate nutrient providers (i.e., fishes). Our findings were scale‐ and metric‐specific: while we could not detect a change in patch‐level seagrass productivity in response to simulated sea cucumber fishing, individual leaf extension rates were ~15% lower at sites where all sea cucumbers were removed, relative to the highest density, unfished sites. Interestingly, there was no concomitant effect of nutrients from the more abundant reef‐associated fishes, which contribute far more nutrients overall than sea cucumbers. This suggests that sea cucumbers are likely mediating seagrass growth through mechanisms other than direct nutrient provisioning, perhaps through processes associated with sediment processing. Our study demonstrates the potential consequences of under‐regulated and unmonitored sea cucumber fishing on foundation species like seagrasses, while highlighting the importance of taking a community‐based approach to these types of field experiments. [ABSTRACT FROM AUTHOR]

Lung cancer is one of the most lethal malignancies in the world. However, current curative approaches for treating this type of cancer have some weaknesses. Therefore, scientists are attempting to discover new anti-lung cancer agents. Sea cucumber is a marine-derived source for discovering biologically active compounds with anti-lung cancer properties. To explore the anti-lung cancer properties of sea cucumber, we analyzed surveys using VOSviewer software and identified the most frequently used keywords. We then searched the Google Scholar database for compounds with anti-lung cancer properties within that keyword family. Finally, we used AutoDock 4 to identify the compounds with the highest affinity for apoptotic receptors in lung cancer cells. The results showed that triterpene glucosides were the most frequently identified compounds in studies examining the anti-cancer properties of sea cucumbers. Intercedenside C, Scabraside A, and Scabraside B were the three triterpene glycosides with the highest affinity for apoptotic receptors in lung cancer cells. To the best of our knowledge, this is the first time that anti-lung cancer properties of sea cucumber-derived compounds have been examined in in silico conditions. Ultimately, these three components displayed anti-lung cancer properties in in silico conditions and may be used for the manufacture of anti-lung cancer agents in the near future. [ABSTRACT FROM AUTHOR]

Sea cucumber extracts and their bioactive compounds have the potential for stem cell proliferation induction and for their beneficial therapeutic properties. In this study, human umbilical cord mesenchymal stromal/stem cells (hUC-MSCs) were exposed to an aqueous extract of Holothuria parva body walls. Proliferative molecules were detected using gas chromatography-mass spectrometry (GC-MS) analysis in an aqueous extract of H. parva. The aqueous extract concentrations of 5, 10, 20, 40, and 80 µg/mL and 10 and 20 ng/mL of human epidermal growth factor (EGF) as positive controls were treated on hUC-MSCs. MTT, cell count, viability, and cell cycle assays were performed. Using Western blot analysis, the effects of extracts of H. parva and EGF on cell proliferation markers were detected. Computational modeling was done to detect effective proliferative compounds in the aqueous extract of H. parva. A MTT assay showed that the 10, 20, and 40 µg/mL aqueous extract of H. parva had a proliferative effect on hUC-MSCs. The cell count, which was treated with a 20 µg/mL concentration, increased faster and higher than the control group (p < 0.05). This concentration of the extract did not have a significant effect on hUC-MSCs' viability. The cell cycle assay of hUC-MSCs showed that the percentage of cells in the G2 stage of the extract was biologically higher than the control group. Expression of cyclin D1, cyclin D3, cyclin E, HIF-1α, and TERT was increased compared with the control group. Moreover, expression of p21 and PCNA decreased after treating hUC-MSCs with the extract. However, CDC-2/cdk-1 and ERK1/2 had almost the same expression as the control group. The expression of CDK-4 and CDK-6 decreased after treatment. Between the detected compounds, 1-methyl-4-(1-methyl phenyl)-benzene showed better affinity to CDK-4 and p21 than tetradecanoic acid. The H. parva aqueous extract showed proliferative potential on hUC-MSCs. [ABSTRACT FROM AUTHOR]

Sulfated glycans from marine organisms are excellent sources of naturally occurring glycosaminoglycan (GAG) mimetics that demonstrate therapeutic activities, such as antiviral/microbial infection, anticoagulant, anticancer, and anti-inflammation activities. Many viruses use the heparan sulfate (HS) GAG on the surface of host cells as co-receptors for attachment and initiating cell entry. Therefore, virion–HS interactions have been targeted to develop broad-spectrum antiviral therapeutics. Here we report the potential anti-monkeypox virus (MPXV) activities of eight defined marine sulfated glycans, three fucosylated chondroitin sulfates, and three sulfated fucans extracted from the sea cucumber species Isostichopus badionotus, Holothuria floridana, and Pentacta pygmaea, and the sea urchin Lytechinus variegatus, as well as two chemically desulfated derivatives. The inhibitions of these marine sulfated glycans on MPXV A29 and A35 protein–heparin interactions were evaluated using surface plasmon resonance (SPR). These results demonstrated that the viral surface proteins of MPXV A29 and A35 bound to heparin, which is a highly sulfated HS, and sulfated glycans from sea cucumbers showed strong inhibition of MPXV A29 and A35 interactions. The study of molecular interactions between viral proteins and host cell GAGs is important in developing therapeutics for the prevention and treatment of MPXV. [ABSTRACT FROM AUTHOR]

Six experimental diets (crude protein 12.58%, crude fat 1.93%, and total energy 10.72 kJ/kg) containing 0.24%, 0.37%, 0.51%, 0.62%, 0.77%, and 0.89% phosphorus were formulated to evaluate dietary phosphorus requirement for sea cucumber Apostichopus japonicus. The feeding trial was conducted in 18 fiberglass tanks (220 L) for 63 days. Each diet was randomly assigned to triplicate tanks of 50 sea cucumbers (9.99 g) and fed once daily. With the increase of dietary phosphorus level, weight gain (WG), specific growth rate (SGR), daily feed intake (DFI), feces production ratio, the activities of amylase, alkaline phosphatase, phosphofructokinase, succinate dehydrogenase, and glutathione peroxidase as well as the contents of glutathione and glutathione oxidized significantly increased and then decreased afterwards (P < 0.05). A. japonicus fed diet with 0.63%, 0.63%, and 0.55% dietary phosphorus was estimated to yield the highest WG (11.39 g), SGR (1.09%/d), and DFI (2.55%/d) according to the quadratic regression analysis of WG, SGR, and DFI against dietary phosphorus level, respectively. The apparent digestibility of dry material and energy followed an opposite tendency. Feed efficiency, the contents of whole-body phosphorus, initially increased and then plateaued, fitting piecewise-linear models with breakpoint at 0.57% and 0.55% dietary phosphorus. Daily phosphorus intake, pyruvate kinase activity, and the ratio of glutathione and glutathione oxidized increased (P < 0.05) but the apparent digestibility of phosphorus, the activities of alkaline protease, aspartate transaminase, and phosphoenolpyruvate carboxykinase decreased (P < 0.05), responding to the increasing dietary phosphorus. Considering the present results, the optimal dietary phosphorus for A. japonicus is 0.57–0.63%. [ABSTRACT FROM AUTHOR]

Some tropical sea cucumbers of the family Holothuriidae can efficiently repel or even fatally ensnare predators by sacrificially ejecting a bioadhesive matrix termed the Cuvierian organ (CO), so named by the French zoologist Georges Cuvier who first described it in 1831. Still, the precise mechanisms for how adhesiveness genetically arose in CO and how sea cucumbers perceive and transduce danger signals for CO expulsion during defense have remained unclear. Here, we report the first high-quality, chromosome-level genome assembly of Holothuria leucospilota, an ecologically significant sea cucumber with prototypical CO. The H. leucospilota genome reveals characteristic long-repeat signatures in CO-specific outer-layer proteins, analogous to fibrous proteins of disparate species origins, including spider spidroin and silkworm fibroin. Intriguingly, several CO-specific proteins occur with amyloid-like patterns featuring extensive intramolecular cross-β structures readily stainable by amyloid indicator dyes. Distinct proteins within the CO connective tissue and outer surface cooperate to give the expelled matrix its apparent tenacity and adhesiveness, respectively. Genomic evidence offers further hints that H. leucospilota directly transduces predator-induced mechanical pressure onto the CO surface through mediation by transient receptor potential channels, which culminates in acetylcholine-triggered CO expulsion in part or in entirety. Evolutionarily, innovative events in two distinct regions of the H. leucospilota genome have apparently spurred CO’s differentiation from the respiratory tree to a lethal defensive organ against predators. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the effect of sea cucumber hydrolysate (SCH) on immunosuppressed mice induced by cyclophosphamide (Cy). Our findings demonstrated that SCH could increase the thymus index and spleen index, decrease the serum alanine transaminase (ALT) and aspartate aminotransferase (AST) levels, increase the serum IgG and small intestinal sIgA levels, reduce small intestinal and colon tissue damage, and activate the nuclear factor-κB (NF-κB) pathway by increasing TRAF6 and IRAK1 protein levels, as well as the phosphorylation levels of IκBα and p65, thereby enhancing immunity. In addition, SCH alleviated the imbalance of the gut microbiota by altering the composition of the gut microbiota in immunosuppressed mice. At the genus level, when compared with the model group, the relative abundance of Dubosiella, Lachnospiraceae, and Ligilactobacillus increased, while that of Lactobacillus, Bacteroides, and Turicibacter decreased in the SCH groups. Moreover, 26 potential bioactive peptides were identified by oligopeptide sequencing and bioactivity prediction. This study's findings thus provide an experimental basis for further development of SCH as a nutritional supplement to alleviate immunosuppression induced by Cy as well as provides a new idea for alleviating intestinal damage induced by Cy. [ABSTRACT FROM AUTHOR]

Mass mortality and low growth highly decrease the production efficiency and sustainable aquaculture development of the sea cucumber Apostichopus japonicus in summer. Sea urchin feces was proposed to address the summer problems. A laboratory study was conducted for ~ 5 weeks to investigate survival, food consumption, growth and resistance ability of A. japonicus cultured with the feces of sea urchins fed kelp (KF feces, group KF), the feces of sea urchins fed prepared feed (FF feces, group FF), and the prepared sea cucumber feed (group S) at high temperature (25 °C). The sea cucumbers of group KF had better survival (100%) than those of the group FF (~ 84%), higher CTmax (35.9 °C) than those of the group S (34.5 °C), and the lowest skin ulceration proportion (0%) when they were exposed to an infectious solution among the three groups. These results suggest that the feces of sea urchins fed kelp is a promising diet for improving the survival and enhancing the resistance in A. japonicus aquaculture in summer. Sea cucumbers fed significantly less FF feces after 24 h of ageing than the fresh FF feces, suggesting this kind of feces became unsuitable for A. japonicus in a short time (within 48 h). However, the 24 h of ageing at 25 °C for the high fiber feces of sea urchins fed kelp had no significant effects on the fecal consumption of sea cucumbers. In the present study, both fecal diets provide better individual growth to sea cucumbers than the prepared feed. Yet, the feces of sea urchins fed kelp provided the highest weight gain rate (WGR) to sea cucumbers. Therefore, the feces of sea urchins fed kelp is a promising food to reduce the mortality, to address the problems of summer, and to achieve higher efficiency in A. japonicus aquaculture in summer. [ABSTRACT FROM AUTHOR]

Fatty acids and carotenoids are known to have roles in embryonic and larval development of sea cucumbers, but their changes in gonads during gametogenesis have not yet been studied. To improve our knowledge of the reproductive cycle of sea cucumbers in an aquaculture perspective, we collected 6–11 individuals of the species Holothuria (Panningothuria) forskali Delle Chiaje, 1823 approximately every 2 months from December 2019 to July 2021 east of the Glenan Islands (Brittany – France; 47.710°N, 3.948°W) at a depth of 8–12 m. Our results show that soon after spawning, sea cucumbers take advantage of an increased food availability in spring to rapidly and opportunistically accumulate nutrients in the form of lipids in their gonads (from May to July) and then slowly elongate, desaturate and probably rearrange fatty acids within lipid classes for the next reproductive season according to the specific requirements of both sexes. In contrast, acquisition of carotenoids occurs synchronously with gonads filling and/or through the reabsorption of spent tubules (T5), thus revealing little seasonal variations at the scale of the entire gonad in terms of relative abundance in both sexes. All results suggest that gonads are fully replenished with nutrients by October and that broodstock for induced reproduction could be captured at this moment and kept until the production of larvae is required. Maintaining broodstock for consecutive years would probably be a higher level challenge as the dynamics of tubule recruitment are not fully understood and seem to last for several years. [ABSTRACT FROM AUTHOR]

Summary: In this study, sea cucumber (Holothuria scabra; Jaegar 1833) extracts and collagens were evaluated for inhibitory properties of protein‐bound advanced glycation end products (AGEs). Processed dried sea cucumber with salt extract showed a significant lower IC50 value for fluorescent AGEs (9.19 ± 7.68 μg mL−1, P < 0.05) and fructosamine (503.47 ± 46.37 μg mL−1, P < 0.05), respectively. Processed dried with and without salt extracts significantly reduced the Nε‐carboxymethyllysine (CML) and methylglyoxal‐derived hydroimidazolone‐1 (MG‐H1) levels tested at 250 μg mL−1. Smoked dried and fresh‐dried extracts significantly reduced the Nε‐carboxyethyllysine (CEL) levels tested at 250 μg mL−1. Pepsin‐solubilised collagen and the crude collagen fibrils significantly reduced CML and MG‐H1 levels whereas CEL levels were unchanged. Pearson's correlation analysis showed that protein‐bound AGE and CML inhibition significantly correlated with the total phenolic and antioxidant activities, respectively. This study provides a strong rationale for further investigation aimed at identifying the active compounds responsible for the observed effects on biomarkers relevant to diabetes. [ABSTRACT FROM AUTHOR]

Diabetes is a chronic metabolic disorder characterized by elevated blood glucose levels. Major limitations of synthetic drugs, including high cost, efficacy, and adverse side effects, have prompted researchers to seek more effective and low‐cost alternative therapies with fewer adverse effects. Marine life forms are considered the most important sources of biologically active natural products due to their secondary metabolites. In this research, sea cucumber Holothuria parva was collected from coastal areas of Bandar Lengeh, Hormozgan, Iran, and was then subjected to extraction. The results showed that compounds extracted from Holothuria parva had a stimulatory effect on enzyme activity, and in the presence of these compounds, the Vmax value of the enzyme was increased about two times, while the Km value was reduced. The phosphate buffer form of extracts had the greatest impact on enzyme activity. Upon an increase in the concentration of silver nanoparticles (AgNPs), the α‐amylase activity was inhibited in parallel. Silver nanoparticles exhibited the highest enzyme inhibition with an IC50 of 0.86 mg/ml. Silver nanoparticles showed anti‐α‐amylase activity and had the ability to decrease intestinal glucose uptake in diabetic individuals when prescribed as a novel supplementary medicine. [ABSTRACT FROM AUTHOR]

The aim of this study is to investigate the effects of probiotic products composed of different Bacillus spp on the survival and metamorphosis of sea cucumber larvae and tracks their impact on juvenile development, survival ratio and water quality. In addition to the control, three types of commercial probiotics, PLUS10, SKB01 and SKB0, were used. The experiment was conducted in three replications, each with 500 liter tanks containing 50,000 larvae (100 larvae/liter), over 40 days and in a completely randomized design. The experiment was conducted in three replicates, each with 500 liter tanks containing 50,000 larvae (100 larvae/liter), over 40 days and in a completely randomized design. The results showed that the larval metamorphosis and settlement are varied insignificantly with probiotics and significantly with days of application whereas no noticeable changes occur with SKB01 and SKB02. Furthermore, the survival rate decreased slightly with the PLUS10 (11.1 ± 4.2) compared to the control and falling dramatically with SKB01 and SKB02. Additionally, there was a marked improvement in larvae growth with PLUS 10. Finally, Finally, probiotics such as SKB01, SKB02, and PLUS10 enhance water quality, but they have a little negative impact on survival rates at this stage. As a result, it is recommended they can be utilized in the juvenile stage rather than the Auricularia stage. Consequently, further research on the impact of probiotics on the growth rates of Auricularia are urgently required. [ABSTRACT FROM AUTHOR]

BACKGROUND: This study sought to investigate the inhibitory effect of pre‐gelatinized dialdehyde starch (P‐DAS) on the deterioration of sea cucumber during high‐temperature sterilization. RESULTS: It was found that pre‐gelatinization reduced crystallinity and average molecular weight of dialdehyde starch (DAS), exposed free aldehyde groups, improved the solubility, and unified the particle sizes. According to the texture profiles of sea cucumber, the crosslinking power of P‐DAS was higher than that of DAS. The results of free amino content, total soluble substance, water retention, water distribution, relaxation time and scanning electron microscopy all showed that the crosslinking effect was dose‐dependent on crosslinking agent. CONCLUSION: These results have proved that large molecules such as P‐DAS, when properly handled, could also efficiently enter collagen hydrogels and perform crosslinking, providing reference for the development of new protein food stabilizing agents. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

A rapidly warming Arctic Ocean and associated sea‐ice decline is resulting in changing sea‐ice protist communities, affecting productivity of under‐ice, pelagic, and benthic fauna. Quantifying such effects is hampered by a lack of biomarkers suitable for tracing specific basal resources (primary producers and microorganisms) through food webs. We investigate the potential of δ13C values of essential amino acids (EAAs) (δ13CEAA values) to estimate the proportional use of diverse basal resources by organisms from the under‐ice (Apherusa glacialis), pelagic (Calanus hyperboreus) and benthic habitats (sponges, sea cucumber), and the cryo‐pelagic fish Boreogadus saida. Two approaches were used: baseline δ13CEAA values, that is, the basal resource specific δ13CEAA values, and δ13CEAA fingerprints, or mean‐centred baseline δ13CEAA values. Substantial use of sub‐ice algae Melosira arctica by all studied organisms suggests that its role within Arctic food webs is greater than previously recognized. In addition, δ13CEAA fingerprints from algae‐associated bacteria were clearly traced to the sponges, with an individually variable kelp use by sea cucumbers. Although mean‐centred δ13CEAA values in A. glacialis, C. hyperboreus, and B. saida tissues were aligned with microalgae resources, they were not fully represented by the filtered pelagic‐ and sea‐ice particulate organic matter constituting the spring diatom‐dominated algal community. Under‐ice and pelagic microalgae use could only be differentiated with baseline δ13CEAA values as similar microalgae clades occur in both habitats. We suggest that δ13CEAA fingerprints combined with microalgae baseline δ13CEAA values are an insightful tool to assess the effect of ongoing changes in Arctic basal resources on their use by organisms. [ABSTRACT FROM AUTHOR]

Copyright of Asian Journals of Ecotoxicology is the property of Gai Kan Bian Wei Hui and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Environmental Science & Technology (10036504) is the property of Editorial Board of Environmental Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Inspired by the stimuli-responsive ability of biological, a variety of hydrogel have been prepared by stimulus, showing great application value in actuators, soft robots, etc. However, it is still challenging to prepare a toughness hydrogel by the way of stimuli-responsive. Herein, we constructed a novel dual-network structure PNIPAM/PVA hydrogel using reversible molecular configuration conversion of PNIPAM chains. Under the stimulus of ethanol, the elastic modulus of PNIPAM/PVA hydrogel can be increased by 47 times (5 times the change of the modulus of sea cucumbers' tissue) and the stress can be six times of the original. The dynamic borate ester bond formed by the cross-linking of PVA and borax in the hydrogel enables rapid self-healing (η > 99%) within three minutes without external stimulus in the natural environment. In addition, PNIPAM/PVA hydrogels also showed outstanding underwater reversible thermokinetic properties (>25°) based on the hydrophilic/hydrophobic conversion of PNIPAM under thermal stimulation. The successful preparation of ethanol stimulus-enhancing self-healing PNIPAM/PVA hydrogel actuators, provides a new idea for the development of the soft underwater robots. [ABSTRACT FROM AUTHOR]

Great interest exists towards the discovery and development of broad-spectrum antivirals. This occurs due to the frequent emergence of new viruses which can also eventually lead to pandemics. A reasonable and efficient strategy to develop new broad-spectrum antivirals relies on targeting a common molecular player of various viruses. Heparan sulfate is a sulfated glycosaminoglycan present on the surface of cells which plays a key role as co-receptor in many virus infections. In previous work, marine sulfated glycans (MSGs) were identified as having antiviral activities. Their mechanism of action relies primarily on competitive inhibition of virion binding to heparan sulfate, preventing virus attachment to the cell surface prior to entry. In the current work we used pseudotyped lentivirus particles to investigate in a comparative fashion the inhibitory properties of five structurally defined MSGs against SARS-CoV-1, SARS-CoV-2, MERS-CoV, and influenza A virus (IAV). MSGs include the disaccharide-repeating sulfated galactan from the red alga Botryocladia occidentalis, the tetrasaccharide-repeating sulfated fucans from the sea urchin Lytechinus variegatus and from the sea cucumber Isostichopus badionotus, and the two marine fucosylated chondroitin sulfates from the sea cucumbers I. badionotus and Pentacta pygmaea. Results indicate specificity of action against SARS-CoV-1 and SARS-CoV-2. Curiously, the MSGs showed decreased inhibitory potencies against MERS-CoV and negligible action against IAV. Among the five MSGs, the two sulfated fucans here studied deserve further attention since they have the lowest anticoagulant effects but still present potent and selective antiviral properties. [ABSTRACT FROM AUTHOR]

A growing body of evidence suggests that spatial population structure can develop in marine species despite large population sizes and high gene flow. Characterizing population structure is important for the effective management of exploited species, as it can be used to identify appropriate scales of management in fishery and aquaculture contexts. The California sea cucumber, Apostichopus californicus, is one such exploited species whose management could benefit from further characterization of population structure. Using restriction site-associated DNA (RAD) sequencing, we developed 2075 single nucleotide polymorphisms (SNPs) to quantify genetic structure over a broad section of the species' range along the North American west coast and within the Salish Sea, a region supporting the Washington State A. californicus fishery and developing aquaculture production of the species. We found evidence for population structure (global fixation index (FST) = 0.0068) with limited dispersal driving two patterns of differentiation: isolation-by-distance and a latitudinal gradient of differentiation. Notably, we found detectable population differences among collection sites within the Salish Sea (pairwise FST = 0.001–0.006). Using FST outlier detection and gene-environment association, we identified 10.2% of total SNPs as putatively adaptive. Environmental variables (e.g., temperature, salinity) from the sea surface were more correlated with genetic variation than those same variables measured near the benthos, suggesting that selection on pelagic larvae may drive adaptive differentiation to a greater degree than selection on adults. Our results were consistent with previous estimates of and patterns in population structure for this species in other extents of the range. Additionally, we found that patterns of neutral and adaptive differentiation co-varied, suggesting that adaptive barriers may limit dispersal. Our study provides guidance to decision-makers regarding the designation of management units for A. californicus and adds to the growing body of literature identifying genetic population differentiation in marine species despite large, nominally connected populations. [ABSTRACT FROM AUTHOR]

In the sea cucumber, Holothuria scabra, the competent larvae require main settlement organs (SOs), including the ciliary bands (CiBs), tentacles (Ts), podia (PDs), and cues from neurotransmitters, including gamma-aminobutyric acid (GABA) and dopamine (DA), for successful settlement. In the present study, we investigated the spatial distribution of GABA and DA in the developmental stages of H. scabra, with special emphasis on SOs by detecting immunoreactivity (-ir) against these two neurotransmitters. Strong GABA-ir and DA-ir cells and fibers were specifically detected in several SO structures, including CiBs, CiB cells (CiBCs), and long cilia (LCi), of H. scabra larvae. Additionally, we found intense GABA-ir and DA-ir cells in the epithelial lining of bud-papillae (BP) and mesothelium (Me) in the stem (S) region of Ts in larvae and juveniles. Intense GABA-ir and DA-ir were observed in the epineural nerve plexus (ENP) and hyponeural nerve plexus (HNP) of Ts in H. scabra pentactula and juvenile stages. Staining for these two neurotransmitters was particularly intense in the PDs and their nerve fibers. We also found significant changes in the numbers of GABA-ir and DA-ir-positive cells and intensities in the CiBs, Ts, and PDs during the developmental stages. Taken together, we are the first to report on the existence and distribution of GABAergic and dopaminergic systems in structures associated with the settlement. Our findings provide new and important insights into the possible functions of these two neurotransmitters in regulating the settlement of this sea cucumber species. [ABSTRACT FROM AUTHOR]

The purpose of this study was to assess the effects of a low temperature-resistant probiotic strain, Bacillus baekryungensis MS1, on the growth, nutritional quality, digestion and immunity of the sea cucumber Apostichopus japonicus under low temperature conditions. A feeding experiment was designed in which low (106 cfu/g) and high (108 cfu/g) doses of B. baekryungensis MS1 were added to the feed of sea cucumbers for 60 days; sea cucumbers not fed B. baekryungensis MS1 were used as controls. At the end of the experiment, the growth performance (including weight gain ratio, specific growth ratio and feed conversion ratio) of sea cucumbers fed the B. baekryungensis MS1-supplemented feed was significantly improved, in a dose-dependent manner. Also, the amino acid composition of the body wall had changed, and the total amino acid content had increased significantly. In addition, the content of polyunsaturated fatty acids, especially docosahexaenoic acid, had increased significantly, but no significant difference between the high- and low-dose groups was observed. The gut protease and α-amylase activities of sea cucumbers fed the B. baekryungensis MS1-supplemented diet were significantly increased. The activities of nitric oxide synthase, lysozyme, catalase, acid phosphatase and alkaline phosphatase were significantly higher in the high-dose group than in the low-dose group and the control group. In the challenge test with Vibrio splendidum, the mortality of sea cucumbers fed B. baekryungensis MS1 was significantly lower than that of the control group. Based on these results, we conclude that providing A. japonicus with B. baekryungensis MS1-supplemented feed (especially at the dose of 108 cfu/g) resulted in improved growth, changes in the nutrients in the body wall and enhanced digestibility and immunity at low temperatures; it also provided effective support for the healthy overwintering aquaculture of A. japonicus. [ABSTRACT FROM AUTHOR]

In this study, a sustainable and eco-friendly method was used to prepare zinc oxide nanoparticles (ZnO-NPs) using a sea cucumber aqueous extract. Then, ZnO-NPs were characterized by instrumental analysis (UV-vis, HR-TEM, XRD, FT-IR, and DLS) and evaluated for their possible antibacterial, antifungal, and insecticidal activities. Additionally, the toxicity of ZnO-NPs was evaluated in vivo against Nile Tilapia (Oreochromis niloticus). The sea cucumber was collected from the Gulf of Suez (Red Sea) at Al-Ain Al-Sokhna coast in Egypt and identified as Holothuria impatiens. The prepared Hi-ZnO-NPs peaked at 350 nm in UV–Vis spectral analysis. They showed quasi-spherical shaped particles with sizes ranging from 13 nm to 47 nm and a predominate size of 26 nm as indicated by HR-TEM. The XRD pattern of Hi-ZnO-NPs revealed a crystalline phase with an average size of 17.2 nm as calculated by Debye–Scherrer equation. FTIR analysis revealed the possible role of H. impatiens biological molecules in the biosynthesis process of ZnO-NPs. Hi-ZnO-NPs showed a negative zeta potential of −19.6 mV, demonstrating moderate stability. Biosynthesized Hi-ZnO-NPs revealed broad antimicrobial activity against Gram-positive bacteria (S. aureus ATCC 25923 and E. feacalis), Gram-negative bacteria (S. typhi, K. pneumonia and E. coli), and filamentous fungi (Aspergillus niger). Hi-ZnO-NPs demonstrated larvicidal activity against the mosquito, Culex pipiens (LC50 = 2.756 ppm and LC90 = 9.294 ppm), and adulticidal action against the housefly, Musca domestica (LD50 = 4.285 ppm and LD90 = 22.847 ppm). Interestingly, Hi-ZnO-NPs did not show mortality effects against Nile tilapia fish (Oreochromis niloticus), highlighting the potential safety of Hi-ZnO-NPs to highly exposed, non-target organisms. However, histopathological and hematological investigations provided dose-dependent impacts of Hi-ZnO-NPs to Nile tilapia. Overall, data provide an eco-friendly approach for synthesizing novel Hi-ZnO-NPs with multiple biomedical properties and potentially low toxicity to Nile tilapia fish. [ABSTRACT FROM AUTHOR]