Search Results (70)

Sea cucumbers, important members of the phylum Echinodermata, play a crucial role in sediment mixing and nutrient cycling on the seafloor. They also hold significant economic value, particularly in Asian food and pharmaceutical markets. In the Mediterranean Sea, the harvesting of sea cucumbers has recently intensified, often without regulation, threatening both species populations and the health of benthic ecosystems. This study investigated the potential of using fatty acid (FA) profiles as ecological biomarkers to trace the different origin and feeding ecology of two sea cucumber species, Holothuria polii and H. tubulosa, collected from ten coastal sites in Italy. A total of 285 individuals were analyzed through lipid extraction and characterization from their body walls using gas chromatography (GC-FID and GC-MS). Key fatty acids identified included arachidonic acid, eicosapentaenoic acid, eicosenoic acid, palmitic acid, palmitoleic acid, stearic acid, and nervonic acid. Principal Component Analysis (PCA) revealed patterns consistent with geographic origin, suggesting that FA profiles can reflect site-specific trophic conditions. The analysis also indicated that sea cucumbers primarily feed on diatoms, bacteria, and blue-green algae, with notable regional variation. This study is the first to successfully apply FA-based trophic markers to differentiate Italian populations of these species, providing insights for ecological monitoring and fishery management. Full article

Accurate and rapid aquatic organism recognition is a core technology for fisheries automation and aquatic organism statistical research. However, due to absorption and scattering effects, images of aquatic organisms often suffer from poor contrast and color distortion. Additionally, the clustering behavior of aquatic organisms often leads to occlusion, further complicating the identification task. This study proposes a lightweight object detection model, Mobile-YOLO, for the recognition of four representative aquatic organisms, namely holothurian, echinus, scallop, and starfish. Our model first utilizes the Mobile-Nano backbone network we proposed, which enhances feature perception while maintaining a lightweight design. Then, we propose a lightweight detection head, LDtect, which achieves a balance between lightweight structure and high accuracy. Additionally, we introduce Dysample (dynamic sampling) and HWD (Haar wavelet downsampling) modules, aiming to optimize the feature fusion structure and achieve lightweight goals by improving the processes of upsampling and downsampling. These modules also help compensate for the accuracy loss caused by the lightweight design of LDtect. Compared to the baseline model, our model reduces Params (parameters) by 32.2%, FLOPs (floating point operations) by 28.4%, and weights (model storage size) by 30.8%, while improving FPS (frames per second) by 95.2%. The improvement in mAP (mean average precision) can also lead to better accuracy in practical applications, such as marine species monitoring, conservation efforts, and biodiversity assessment. Furthermore, the model’s accuracy is enhanced, with the mAP increased by 1.6%, demonstrating the advanced nature of our approach. Compared with YOLO (You Only Look Once) series (YOLOv5-12), SSD (Single Shot MultiBox Detector), EfficientDet (Efficient Detection), RetinaNet, and RT-DETR (Real-Time Detection Transformer), our model achieves leading comprehensive performance in terms of both accuracy and lightweight design. The results indicate that our research provides technological support for precise and rapid aquatic organism recognition. Full article

Holothurian fisheries have become a prominent métier in the Mediterranean due to increasing worldwide demand for sea cucumbers. In these newly explored grounds, their fisheries are poorly understood, especially considering the applied tactics and socioeconomics of the harvesting fleet. This study examines the small-scale holothurian (Holothuria) fishery métiers and associated socioeconomics in the Hellenic Seas—a main Mediterranean fishery ground. Holothuria fishing licenses increased in 2020 and stabilized (130) in the next years. Holothuria poli and H. tubulosa are the target species, caught by hand, using the surface air supply method or free diving. Most fishermen harvest holothurians close to the port of origin, and only the fleet from Kalymnos exploits remote grounds over the Greek territory. According to harvesting tactics, three economically viable métiers are practiced; however, shifting to alternative fishery resources is necessary to grant annual income. Sea cucumbers are sold fresh from fishermen to merchandisers who process the catch into final products (trepang) and export them. For most fishermen (64.7%), fishing for holothurians is the main occupation, gaining a highly variable monthly income (EUR 700 to 4000). The presented results refine the métiers and associated economics of an active holothurian fishery fleet, providing essential information for the viability of coastal fishery societies. Full article

Marine invertebrates, particularly Holothurians, have emerged as valuable sources of bioactive compounds with potential anticancer properties. In this study, we investigated the effects of two acidic polysaccharide-enriched (APs) fractions (Ht1 and Ht2) from the sea cucumber species Holothuria tubulosa on the highly invasive cell line MDA-MB-231. Functional assays were performed to assess cell viability, migratory potential, adhesion on collagen I, and cell morphology, alongside gene expression analysis. Additionally, a preliminary evaluation of their effects on three-dimensional breast cancer cell-derived spheroids was conducted. Both AP fractions exerted anticancer effects by decreasing cell viability. Ht1 showed a significant inhibitory effect on cell migration, increased adhesion on collagen I, and exhibited a trend to transform the mesenchymal MDA-MB-231 cells to a more epithelial phenotype. Treatment with the AP fractions modulated the expression of genes, such as the epithelial marker E-cadherin (for the Ht1), a key cell adhesion molecule, and the matrix metalloproteinases 7 and 9 (for the Ht2), enzymes involved in extracellular matrix remodeling, which hold critical roles in cancer progression and metastasis. No significant effects were observed on spheroids, possibly due to the high charge and hydrophilicity of the APs, leading to poor penetration into the inner spheroid layers. Although preliminary, these findings highlight the potential of H. tubulosa-derived APs as promising antineoplastic agents, warranting further investigation into their mechanisms of action and structural characterization. Full article

Biological data, such as length–weight relationships, are essential for the management and stewardship of harvested individuals. Sea cucumbers are a lucrative industry globally but many of the associated fisheries lack species-level biological data, which reduces the effectiveness of any management strategy. The Queensland Sea Cucumber Fishery (QSCF) on the Great Barrier Reef is managed through various controls: primarily catch limits, effort limits, zoning, and size restrictions. Over 20 species may be harvested but there is a lack of comprehensive biological data for many of these species, particularly important life history characteristics. This study addresses this knowledge gap by assessing 2621 individual length–weight relationships of key-target sea cucumber species associated with the fishery across the range of the distribution of the species and covering a variety of habitats, depths, sampling times, and management zones. Linear models with log transformations were used to analyse the relationships between length and weight. Results revealed significant positive relationships for all assessed species, with Holothuria atra having the clearest relationship between length and weight (R² = 0.45). Only negative allometric relationships were observed, as is the case for many species of holothurians. Despite challenges associated with measuring and weighing these soft and elastic animals, results will be useful for understanding length–weight dynamics across species. This research underscores the importance of robust biological data for the effective management of sea cucumber fisheries and ultimately reef health. Full article

Oxidosqualene cyclases (OSCs) are enzymes responsible for converting linear triterpenes into tetracyclic ones, which are known as precursors of other important and bioactive metabolites. Two OSCs genes encoding parkeol synthase and lanostadienol synthase have been found in representatives of the genera Apostichopus and Stichopus (family Stichopodidae, order Synallactida). As a limited number of sea cucumber OSCs have been studied thus far, OSCs encoding gene(s) of the sea cucumber Eupentacta fraudatrix (family Sclerodactylidae, order Dendrochirotida) were investigated to fill this gap. Here, we employed RACEs, molecular cloning, and Oxford Nanopore Technologies to identify candidate OSC mRNAs and genes. The assembled cDNAs were 2409 bp (OSC1) and 3263 bp (OSC2), which shared the same CDS size of 2163 bp encoding a 721-amino-acid protein. The E. fraudatrix OSC1 and OSC2 had higher sequence identity similarity to each other (77.5%) than to other holothurian OSCs (64.7–71.0%). According to the sequence and molecular docking analyses, OSC1 with L436 is predicted to be parkeol synthase, while OSC2 with Q439 is predicted to be lanostadienol synthase. Based on the phylogenetic analysis, E. fraudatrix OSCs cDNAs clustered with other holothurian OSCs, forming the isolated branch. As a result of gene analysis, the high polymorphism and larger size of the OSC1 gene suggest that this gene may be an ancestor of the OSC2 gene. These results imply that the E. fraudatrix genome contains two OSC genes whose evolutionary pathways are different from those of the OSC genes in Stichopodidae. Full article

Sea cucumbers are benthic marine invertebrate members of the phylum Echinodermata. Due to the absence of a rigid skeleton, these species have developed chemical defenses based on the production of saponins (triterpene glycosides). These secondary metabolites are bioactive molecules with a broad biological, ecological, and pharmaceutical spectrum. However, the saponin profiles of several species of sea cucumbers are not known yet. The present study aims to highlight the mixture of saponins in two sea cucumber species from the Algerian coast, namely Holothuria (Holothuria) algeriensis, which has been recently described in central and western Algerian waters, and Holothuria (Roweothuria) arguinensis, originating from the Atlantic Ocean and reported in Algeria for the first time in 2014. Saponin extracts from three individuals of H. (H.) algeriensis and two individuals of H. (R.) arguinensis were analyzed using mass spectrometry, i.e., Matrix-assisted Laser Desorption/Ionization mass spectrometry (MALDI-MS), MALDI-High Resolution MS (MALDI-HRMS), Liquid Chromatography MS (LC-MS) and tandem MS (LC-MS/MS). These analyses allow us to detect 11 and 18 elemental compositions for H. (H.) algeriensis and H. (R.) arguinensis, respectively, each presenting several isomers. In total, 13 new saponin structures are proposed, of which four are common between the two species, six are specific to H. (H.) algeriensis and three to H. (R.) arguinensis. The saponin profiles of the two species were compared to those of other species of the same genus existing on the Algerian coast and the results showed that they share non-sulfated saponins with Holothuria (Panningothuria) forskali and Holothuria (Platyperona) sanctori and sulfated saponins with Holothuria (Holothuria) tubulosa and Holothuria (Roweothuria) poli. Full article

The Salento peninsula in southern Italy (Mediterranean Sea) is a strip of land between the Adriatic and the Ionian Seas, both characterized by local regimes of currents, different geological and physical backgrounds, and quite diversified fauna. In this area, specimens of the sea cucumber Holothuria tubulosa (Brünnich, 1768) (Echinodermata) were collected at four stations in the spring and autumn of 2020 to investigate a possible symbiotic association with the inquiline fish Carapus acus (Brünnich, 1768). Among the collected holothurians, five pearlfish specimens were found in the body cavity of four H. tubulosa collected at 10 m of depth, in autumn, at “Grotta Verde” in Marina di Andrano, Lecce (Ionian Sea). More than half of the sea cucumbers from the latter station hosted the symbiont, suggesting the presence of a shallow population of C. acus inhabiting this coastal area. Furthermore, morphometric analysis carried out on the collected fish helped to shed light on the population dynamics characterizing this neglected species. This is the first report of C. acus from Apulian waters, allowing us to unite previously disjoined areas and providing essential baseline knowledge for planning future in-depth analysis of this difficult-to-study fish in a geographical area that is strategic in terms of the conservation of Mediterranean biodiversity. Furthermore, the range of preferred host species is extended, as C. acus was previously known to prefer other sea cucumber species such as Parastichopus regalis (Cuvier, 1817) instead of H. tubulosa. Finally, the finding of C. acus in a single station and in only one season is not trivial and delivers baseline useful information for future conservation purposes. Full article

Thromboembolic conditions are the most common cause of death in developed countries. Anticoagulant therapy is the treatment of choice, and heparinoids and warfarin are the most adopted drugs. Sulphated polysaccharides extracted from marine organisms have been demonstrated to be effective alternatives, blocking thrombus formation by inhibiting some factors involved in the coagulation cascade. In this study, four acidic glycan fractions from the marine sponge Sarcotragus spinosulus were purified by anion-exchange chromatography, and their anticoagulant properties were investigated through APTT and PT assays and compared with both standard glycosaminoglycans and holothurian sulphated polysaccharides. Moreover, their topographic localization was assessed through histological analysis, and their cytocompatibility was tested on a human fibroblast cell line. A positive correlation between the amount of acid glycans and the inhibitory effect towards both the intrinsic and extrinsic coagulation pathways was observed. The most effective anticoagulant activity was shown by a highly charged fraction, which accounted for almost half (about 40%) of the total hexuronate-containing polysaccharides. Its preliminary structural characterization, performed through infrared spectroscopy and nuclear magnetic resonance, suggested that it may consist of a fucosylated chondroitin sulphate, whose unique structure may be responsible for the anticoagulant activity reported herein for the first time. Full article

Fishery stock assessments are often based on morphometric data from underwater diver surveys and landing surveys. Measurements of body length are usually converted to estimates of body weight, yet length–weight equations might differ among localities. We evaluated morphometric models for the sea cucumber, Pearsonothuria graeffei, collected at Lizard Island on the northern Great Barrier Reef, Australia, and explored differences in relative condition factor (Kn) across animal sizes. The estimation of body weight was compared among relationships with four different body size metrics: observed body length, SLW (square root of the body length–width product), recalculated body length (Le) from SLW, and body basal area. The basal area of the animals, the SLW index and Le provided more reliable estimations for body weight than using body length alone yet accounted for half of the variation in body weight. The length–weight relationship from animals at Lizard Island differed considerably from relationships published for the same species in New Caledonia and Philippines. Body condition was variable, and our model predicted a peak at 35 cm body length. Body metrics such as basal area, SLW index, and Le could offer more precise models for estimating the body weight of sea cucumbers for fishery purposes. Equations for estimating body weight from length and width of the sea cucumbers should be based on locality-specific data because morphometric relationships are spatially variable. Full article

Biological activity and bioactive compound content in sea cucumbers was assessed, considering Parastichopus regalis, Holothuria mammata, Holothuria forskali, and Holothuria arguinensis as species and intestine, muscle band, respiratory tree, body wall, and gonads as tissues. P. regalis had the lowest content in phenolic compounds and antioxidant activity in contrast to Holothuria species. In the respiratory tree, the highest phenolic concentration was recorded in H. arguinensis, 76.4 ± 1.2 mg GAE/100 g dw vs. 21.0–49.0 mg GAE/100 g dw in the other species. H. arguinensis had the highest DPPH and FRAP results in the gonads, 13.6 ± 0.7 mg AAE/100 g dw vs. 2.6–3.5 mg AAE/100 g dw and 27.1 ± 0.3 μmol Fe²⁺/g dw vs. 8.0–15.9 μmol Fe²⁺/g dw, respectively. Overall, P. regalis biomass presented the highest anti-inflammatory activity levels and H. arguinensis the lowest anti-inflammatory levels. The respiratory tree was the most anti-inflammatory (measured by the inhibition of cyclooxygenase-2, COX-2) tissue in H. mammata and H. forskali (also the muscle band in this case), 76.3 ± 6.3% and 59.5 ± 3.6% COX-2 inhibition in 1 mg/mL aqueous extracts, respectively. The results demonstrated a variable bioactive potential and advantage in targeting antioxidant properties in the muscle band and anti-inflammatory activity in the respiratory tree, which may constitute a starting point for a biorefinery approach envisaging multiple applications. Full article

Size limitations are commonly applied as regulatory measures for the sustainable management of marine invertebrate fishery resources. However, the setting of biologically meaningful size limits in holothurians is puzzling, due to the limited knowledge of their biology and the great plasticity in size and weight, owing to the increased contractibility of their body, and the large quantity and variability of their coelomic fluid. To evaluate the efficiency of official size limits in Hellenic fishery regulation, the biometry of the exploited species, i.e., H. tubulosa, H. poli, H. mammata, and H. sanctori, was assessed in the main fishery grounds of the Hellenic Seas. Specimens of all four species were haphazardly collected and measured for total length and drained body weight at 46 sampling sites dispersed in the north Aegean, the Sporades, the Cyclades, the Dodecanese, and the Ionian fishery grounds. According to presented results, the official size limit of 180 g for drained weight appeared to be adequate for H. tubulosa and H. mammata. Adjustment of the relevant regulations for H. poli and H. sanctori are suggested by reduction to 140 g for the former and increment to 200 g for the latter species, to better fit their biological traits. Full article

The rapid development of convolutional neural networks has significant implications for automated underwater fishing operations. Among these, object detection algorithms based on underwater robots have become a hot topic in both academic and applied research. Due to the complexity of underwater imaging environments, many studies have employed large network structures to enhance the model’s detection accuracy. However, such models contain many parameters and consume substantial memory, making them less suitable for small devices with limited memory and computing capabilities. To address these issues, a YOLOv6-based lightweight underwater object detection model, YOLOv6-ESG, is proposed to detect seafood, such as echinus, holothurian, starfish, and scallop. First, a more lightweight backbone network is designed by rebuilding the EfficientNetv2 with a lightweight ODConv module to reduce the number of parameters and floating-point operations. Then, this study improves the neck layer using lightweight GSConv and VoVGSCSP modules to enhance the network’s ability to detect small objects. Meanwhile, to improve the detection accuracy of small underwater objects with poor image quality and low resolution, the SPD-Conv module is also integrated into the two parts of the model. Finally, the Adan optimizer is utilized to speed up model convergence and further improve detection accuracy. To address the issue of interference objects in the URPC2022 dataset, data cleaning has been conducted, followed by experiments on the cleaned dataset. The proposed model achieves 86.6% mAP while the detection speed (batch size = 1) reaches 50.66 FPS. Compared to YOLOv6, the proposed model not only maintains almost the same level of detection accuracy but also achieves faster detection speed. Moreover, the number of parameters and floating-point operations reaches the minimum levels, with reductions of 75.44% and 79.64%, respectively. These results indicate the feasibility of the proposed model in the application of underwater detection tasks. Full article

Extracellular vesicles (EVs), carriers of molecular signals, are considered a critical link in maintaining homeostasis in mammals. Currently, there is growing interest in studying the role of EVs, including exosomes (subpopulation of EVs), in animals of other evolutionary levels, including marine invertebrates. We have studied the possibility of obtaining appropriate preparations of EVs from whole-body extract of holothuria Eupentacta fraudatrix using a standard combination of centrifugation and ultracentrifugation. However, the preparations were heavily polluted, which did not allow us to conclude that they contained vesicles. Subsequent purification by FLX gel filtration significantly reduced the pollution but did not increase vesicle concentration to a necessary level. To detect EVs presence in the body of holothurians, we used transmission electron microscopy of ultrathin sections. Late endosomes, producing the exosomes, were found in the cells of the coelom epithelium covering the gonad, digestive tube and respiratory tree, as well as in the parenchyma cells of these organs. The study of purified homogenates of these organs revealed vesicles (30–100 nm) morphologically corresponding to exosomes. Thus, we can say for sure that holothurian cells produce EVs including exosomes, which can be isolated from homogenates of visceral organs. Full article

Some biologically active compounds isolated from sea cucumbers stimulate the body’s immune response by activating immune cells. Immune function is closely related to the integrity intestinal barrier and balanced gut microbiota. However, it is unknown whether the daily administration of holothurian wall hydrolysate (HWH) ameliorated intestinal dysbiosis and barrier injury induced by immunodeficiency. This study aimed to investigate the immunomodulatory effect and the underlying mechanism of HWH in cyclophosphamide (CTX)-induced immunocompromised mice. BALB/c mice received CTX (80 mg/kg, intraperitoneally) once a day for 3 days to induce immunodeficiency, and then they received the oral administration of HWH (80 or 240 mg/kg) or levamisole hydrochloride (LH, 40 mg/kg, positive control), respectively, once a day for 7 days. We utilized 16S rRNA sequencing for microbial composition alterations, histopathological analysis for splenic and colonic morphology, Western blotting for expressions of tight junction proteins (TJs), and quantitative real-time (qRT)-PCR for measurements of pro-inflammatory cytokines. HWH attenuated the immune organ damage induced by CTX, increased the secretions of interleukin (IL)-6, IL-1β, and tumor necrosis factor (TNF)-α, and promoted the recovery of goblet cells and the production of TJs (claudin-1, occludin, and ZO-1) in the colon of the immunocompromised mice. Moreover, HWH promoted the growth of beneficial microorganisms such as Lactobacillus, Lachnospiraceae, Christensenellaceae, and Bifidobacterium, while it suppressed the populations of Ruminococcus, Staphylococcus, and Streptococcus. These results demonstrate that HWH elicits intestinal mucosal immunity, repairs the damage to intestinal mucosal integrity, and normalizes the imbalanced intestinal microbial profiles in immunocompromised mice. It may be helpful to identify the biological activities of HWH to support its potential use in new prebiotics, immunomodulatory agents, and medical additives for intestinal repair. Full article