Search Results (25,493)

The hybrid approach remains a compelling strategy for designing molecules that combine enhanced biological activity with a favorable safety profile. Marine peptides, in particular, have attracted significant attention due to their well-documented broad spectrum of biological activities. Peptides derived from rays have been recognized for their diverse biological activities. Notably, physicochemical properties of these peptides support practical application without requiring further refinement of the mature molecule or specialized formulations. In this study, we present two new chimeric peptides, PK01# and PK02#, which incorporate an opioid pharmacophore linked to a short amino acid sequence derived from the skate Raja porosa. Those compounds interact with the opioidergic system, specifically targeting the mu-opioid receptor (MOR). Furthermore, the compounds were evaluated for their effects on cancer cell viability through in vitro MTT assays (as an exploratory endpoint) and for their binding compatibility with EGFR via in silico docking. Both compounds showed limited effects on cell viability in HeLa, SAS, and PANC-1 cells, while PK02# induced a minor reduction in metabolic activity in glioblastoma cells without reaching IC50 values or significant cytotoxic thresholds. Interestingly, the structures of these hybrid compounds offer valuable insights into the role of phenylalanine residues within their sequences, which appear to be critical for both biological activity and receptor interaction. Moreover, these findings may support future structural optimization of peptide hybrids focused on receptor modulation and biological profiling. Full article

Reliable species-level information on elasmobranchs (sharks, rays, and skates) in the Arabian Gulf remains limited, despite these fish being among the most threatened marine vertebrates. Taxonomic uncertainty, driven by morphological similarities and incomplete reference datasets, continues to hinder accurate biodiversity assessments in the region. In this study, NADH dehydrogenase subunit 2 (NADH2) gene sequences were analyzed to assess the taxonomic status of elasmobranchs in United Arab Emirates waters, based on 182 specimens representing 31 species (15 sharks and 16 batoids) across 12 families. Shark lineages were consistently recovered and matched closely with published references, indicating a stable taxonomy. Batoids (rays), however, showed greater complexity, including misidentification among morphologically similar taxa, gaps in available reference sequences, and signs of possible cryptic diversity, reflecting persistent challenges in species identification and the need for more comprehensive molecular resources. Our findings highlight the value of genetic approaches in improving taxonomic resolution and establishing robust biodiversity baselines. Expanding reference databases, applying multi-locus genomic approaches, and broadening regional sampling will be essential to refining taxonomic frameworks and informing conservation management for elasmobranchs in the Arabian Gulf. Full article

Marine macroalgae, microalgae, and associated microorganisms are increasingly recognised as valuable sources of bioactive compounds with applications across biotechnology and health. The environmental and ecological conditions they inhabit shape their metabolite diversity, leading to the production of high-value compounds such as sulphated polysaccharides, lipids, pigments, phenolics, and peptides. These compounds exhibit conserved biological activities that underpin potent antioxidant, anti-inflammatory, cytotoxic, and pro-regenerative effects with strong potential for translation. Although external factors drive rich metabolite diversity, continual variation can also lead to translational constraints including heavy-metal accumulation, inconsistency in extract composition, and regulatory complexity. This review examines the environmental drivers of metabolite diversity and the functional potential of bioactives derived from marine algae. We focus on their translational application within four areas of growing interest: nutraceuticals, cosmetics, regenerative medicine, and oncology, where emerging evidence suggests their promise as next-generation bioactive ingredients and therapeutic leads. In addition, insights from Irish and Welsh Small and Medium Enterprises (SMEs) are collated to identify key bottlenecks in commercialisation and the requirements for effective marine biodiscovery pipelines. We consider the importance of controlled cultivation, standardised analytics, preclinical testing platforms, and collaborative innovation ecosystems and highlight the need for coordinated scientific, technical, and regulatory advances to unlock the full translational potential of marine-derived compounds. Full article

At present, there is still a lack of effective treatments to slow the progression of Parkinson’s disease. Naturally derived active substances, valued for their safety and multi-target potential, have become an important direction in anti-PD drug development, with marine organisms representing a valuable source of bioactive peptides. This study aimed to isolate and identify anti-PD peptides from Rapana venosa protein hydrolysates. Through bioactivity-guided screening combined with an MPTP-induced zebrafish PD model, three novel active peptides—KSTELLI, FLVKLPMFM, and SDSLSEILIS—were successfully identified. The study showed that these peptides significantly alleviated dopaminergic neuron loss, improved the cerebral vascular system, restored motor and sensory function, and alleviated oxidative stress. Molecular docking confirmed their stable binding to key PD targets (DDC, α-synuclein, and MAO-B). Further transcriptomic and gene expression analyses revealed that their neuroprotective effects involve the regulation of pathways related to metabolism, oxidative stress, inflammation, and apoptosis, with the three peptides exhibiting distinct mechanistic emphases. The research demonstrates that these marine-derived peptides exert neuroprotective effects through a synergistic multi-target mechanism, laying a foundation for the development of novel lead compounds against Parkinson’s disease. Full article

Quantifying the detection efficiency of buoy-based sonar and optimizing deployment strategies in complex marine environments remain significant challenges. This study proposes a transceiver depth optimization method based on the Bellhop ray model to enhance underwater remote sensing data quality. For the first time, we validated the applicability of acoustic reciprocity in deep-sea environments exceeding 5000 m, characterized by non-uniform sound speed profiles, horizontal inhomogeneity, and steep seamount terrain, with a maximum relative error of <1.2%. This extends the applicable boundaries of the acoustic reciprocity theorem from idealized simple waveguides to complex, realistic deep-sea environments. Building on this validation, we developed a novel, equivalent, superposition modeling framework for bidirectional transmission loss (TL), which converts the computationally intractable TL from target to receiver into the calculable TL from receiver to target, thus significantly reducing computational complexity. Systematic simulations uncovered a depth-layered dependency mechanism: shallow sources (23.14~69.42 m) and deep sources (≥347.10 m) show robustness to large depth differences exceeding 500 m, whereas mid-layer sources (161.98~231.40 m) exhibit a distinct critical threshold effect. Static simulations identify a performance degradation cliff with an onset at an approximate depth difference of 185 m, leading to a 50% reduction in detection range and fragmented near-field detection coverage. To accommodate environmental temporal variability (e.g., internal waves), a conservative safety margin was incorporated, establishing a robust engineering threshold of 150 m. Accordingly, we define 160~350 m as the optimal detection depth window and propose a layered deployment protocol that fills a critical industry gap in quantitative deployment design for deep-sea acoustic detection. Specifically, transceiver depth differences should be strictly constrained to <150 m for mid-layer operations, while more-flexible depth configurations are permissible for shallow and deep sources. These findings furnish quantitative engineering criteria for the design of reliable underwater remote sensing networks, while balancing long-range detection stability and near-field coverage integrity. Full article

Benthic foraminifera, single-cell marine organisms found worldwide, represent an important component of seabed ecosystems. Due to their sensitivity to environmental pollution, they are often used as bioindicators, providing an efficient tool in toxicity studies. Among the pollutants affecting marine coastal and estuarine environments, persistent flame retardants, such as polybrominated diphenyl ethers (PBDEs), are frequently found. Low-level exposure to BDE-47, a PBDE congener, is known to affect organismal development. In this framework, this study aims to assess the effects of BDE-47 exposure on benthic foraminifera from coastal marine environments. Foraminifera specimens belonging to the symbiont-bearing Peneroplidae family were sampled and exposed to two different BDE-47 concentrations for up to 48 h. Vitality indicators such as changes in pseudopodial activity, movement, reproduction, loss of symbiont algae, and occasional mortality events were monitored during the experiment. Exposure to BDE-47 induced alterations in pseudopodial activity, movement, reproduction, and symbiont retention, with the progressive loss of vitality and limited mortality at increasing exposure levels, highlighting the sensitivity of this species to BDE-47. These findings suggest the harmful repercussions of PBDE pollution on marine coastal ecosystems, affecting benthic organisms and potentially contributing to biomagnification processes within the food web, with possible implications for human health. Full article

Background/Objectives: Inflammation is a critical contributor to the development of diabetic retinopathy (DR). In the early stages of DR, the compromised permeability of the blood–retina barrier facilitates the infiltration of macrophages and the activation of microglia. These specific retinal immune cells can adopt morphologies M1 or M2, linked to pro- or anti-inflammatory responses, respectively. This dual response represents a new therapeutic target against DR progression. This study aimed to investigate the modulation of the response M1/M2 and the molecular mechanism of two algal diterpenoids, rugukadiol A (RK) and ruguloptone A (RL), in the early inflammatory events associated with DR. Methods: LPS-stimulated microglial (Bv.2) and macrophage (RAW264.7) cells and an ex vivo physiological model of DR were used to analyze the effects of RK and RL on M1 and M2 inflammatory markers. Results: Compounds RK and RL, besides decreasing the expression of the M1 pro-inflammatory factors iNOS, Il6 mRNA, and NLRP3 in LPS-stimulated Bv.2 cells, caused enhancements in Arg-1 mRNA and Il10 mRNA expression consistent with the induction of an M2 anti-inflammatory response. RK promoted p38α-MAPK phosphorylation, suggesting a non-classical activation of p38α related to the induction of anti-inflammatory responses. Consistently, treatment of retinal explants of BB rats in the early stages of DR with RL decreased M1 pro-inflammatory mediators and induced M2 anti-inflammatory markers, with a reduction in gliosis and a phenotype switch from activated to resting microglia. Conclusions: This study provides the first evidence of algal diterpenoids attenuating pro-inflammatory mediators and promoting the resolution of inflammation in a diabetic retinopathy context, thus opening the way to further explore this class of marine natural products and analogs for early DR management. Full article

Forward-looking sonar (FLS) is an important sensing modality for autonomous underwater vehicles and other marine robotic systems operating in turbid, low-visibility, and acoustically cluttered environments. Reliable target detection in FLS imagery remains challenging because target echoes are often weak, compact targets can be obscured by background clutter, and embedded processors impose strict limits on model size, latency, and computation. To address these issues, this study presents a lightweight FLS sensing framework for embedded target detection in resource-constrained underwater systems. The framework combines a compact detection architecture, difficulty-aware supervision, and teacher–student knowledge transfer. Specifically, FPN-Mix is developed as a lightweight backbone with a Conv-Mix module to improve contextual aggregation under limited computational budgets. A target-aware dynamic weighting loss is introduced to increase the supervision weight of difficult acoustic samples associated with weak echoes, ambiguous boundaries, and clutter interference. A multi-level knowledge distillation strategy is then adopted to transfer feature-level and prediction-level knowledge from an enhanced teacher model to the compact student detector. Experiments on the public UATD benchmark and the independently collected Zhanjiang Bay No.1 field dataset show that the proposed method achieves a favorable balance between detection accuracy and efficiency and remains competitive in a real marine aquaculture environment. The proposed model contains only 2.83 M parameters and requires 6.68 GFLOPs. After ONNX export and TensorRT FP16 acceleration, the model reaches 72.23 frames per second (FPS) on an NVIDIA Jetson Orin NX platform, supporting its practical use in embedded FLS sensing systems. Full article

This study investigates the reuse of mussel shell waste as a secondary raw material in bio-cement mortars designed for the additive manufacturing of artificial reefs for marine habitat restoration. The novelty of the research lies in combining a high recycled shell content (60 wt.%), low-clinker cement, and two 3D-printing techniques: Extruded Material Systems (EMS) and Powder-Based Systems (PBS). Mechanical performance was evaluated through flexural and compressive tests after 7, 28, and 91 days under both air and freshwater curing conditions, while environmental impacts were assessed through Life Cycle Assessment (LCA). The LCA evaluated both the environmental performance of shell-based mixtures compared with conventional materials and the impacts associated with the investigated fabrication techniques. The best-performing bio-mixtures achieved compressive strengths up to 46.01 MPa and flexural strengths up to 9.91 MPa after freshwater curing, demonstrating the suitability of shell-based mortars for submerged applications. LCA results showed reduced impacts in land use and mineral resource depletion compared with conventional mixtures, despite slightly higher energy and water demands associated with shell pre-treatment. The results demonstrate the technical and environmental feasibility of integrating aquaculture waste into sustainable 3D-printed marine restoration solutions. Full article

With the continuous development of complex marine hydrocarbon reservoirs, broadband seismic data have shown growing advantages in revealing abundant stratigraphic information. Affected by acquisition conditions and stratigraphic attenuation, the acquired seismic data commonly suffer from narrow bandwidth, and conventional broadband processing techniques are incapable of optimizing the overall frequency band. This study proposes a coordinated high- and low-frequency broadband compensation method based on adaptive weight fusion to effectively extend the frequency bandwidth of seismic data. Firstly, wavefield separation is used to suppress ghost reflections, compensate low-frequency effective signals, and restore the continuity of the low-frequency spectrum. Then, based on the spectrum extrapolation method of maximum entropy spectrum estimation, a spectrum prediction model is established to achieve the continuation of high-frequency effective signals. Finally, in combination with the signal-to-noise ratio of each frequency band, the adaptive weight fusion algorithm is applied for weighted summation. The acquired broadband seismic data feature a continuous spectrum and balanced energy, greatly improving seismic imaging quality. Comparative results obtained using conventional processing methods verify that the proposed method can significantly improve stratigraphic continuity and wave group characteristics. Full article

Background/Objectives: Obesity is a multifactorial metabolic disorder characterized by excessive adipose accumulation and dysregulated lipid and glucose homeostasis. Marine brown algae contain diverse bioactive compounds with potential metabolic benefits; however, the in vivo anti-obesity effects of Padina minor remain insufficiently characterized. Methods: This study evaluated the effects of P. minor ethanolic extract on adipose metabolism and metabolic parameters in obese rats induced by a high-fat diet (HFD). Male Wistar rats (n = 36) were rendered obese via HFD and treated with P. minor extract (25, 50, or 100 mg/kg BW) for 4 weeks, with orlistat (30 mg/kg BW) serving as a reference control. Body weight, food intake, Lee index, visceral fat mass, serum lipid profile, and glucose levels were assessed, alongside protein expression of PPARγ, CNR1, and ESR1 (ELISA) and gene expression of Pparγ and Adipor1 (qPCR). Phytochemical constituents were analyzed using GC–MS and LC–MS/MS. Results: P. minor extract significantly attenuated body weight gain, adiposity indices, and visceral fat accumulation compared with HFD controls (p < 0.05), and improved metabolic profiles by reducing total cholesterol, triglycerides, and glucose levels while increasing HDL-cholesterol. At the molecular level, treatment was associated with decreased PPARγ and CNR1 expression and increased Adipor1 and ESR1 expression. The highest dose (100 mg/kg BW) produced effects comparable to orlistat. Phytochemical analysis identified flavonoids and phenolic acids, including quercetin, catechin, chlorogenic acid, and p-coumaric acid. Conclusions: Padina minor ethanolic extract improves metabolic parameters and adipose tissue characteristics in HFD-induced obese rats, potentially through modulation of pathways related to adipogenesis and lipid metabolism, supporting its potential as a marine-derived nutraceutical candidate for obesity management; however, further studies are required to confirm its mechanisms and clinical relevance. Full article

The present study provides a comprehensive investigation into the hydrodynamic performance of grooved rubber journal bearings (GRJBs) employed as shaft supports in various rotating systems, with particular emphasis on marine applications. These bearings are lubricated with non-Newtonian fluids such as modern oil containing additives and viscoelastic water-based lubricant, which—owing to its complex composition including hydrocarbon chains, metal oxides, and impurity particles and contaminants such as salts, organic substances, microalgae, biopolymers, and microorganisms—deviates from the ideal Newtonian fluid model and demonstrates non-Newtonian rheological behavior. By examining various theories used in the analysis of non-Newtonian fluid behavior, the power-law model, which has a high degree of generality, has been employed in the present study. Also, to improve modeling accuracy, the elastic deformation of the rubber bush in this study is characterized using the Winkler foundation approach and analyzed via the finite element method (FEM). This advanced mechanical formulation, integrated with non-Newtonian lubrication modeling of lubricant using the power-law fluid model, and the parametric assessment of groove number and dimensions on steady-state bearing performance parameters, constitutes the core of this research. The investigation focuses on groove configurations of 4, 6, 8, and 10 channels. The findings indicate that increasing the groove count partitions the convergent pressure film zone into discrete segments, thereby reducing the maximum hydrodynamic pressure while intensifying the overall energy dissipation within the bearing. Additionally, the influences of rheological properties of the fluid—namely the power-law index (n) and the consistency index (m)—on key performance characteristics are thoroughly examined. An increase in both parameters enhances the effective viscosity and load carrying capacity; however, the exponential amplification due to the power-law index exhibits a more pronounced effect on load capacity and peak pressure compared to the consistency index. Full article

Underwater image enhancement is critical for marine robotic perception, yet existing methods often face a persistent trade-off between restoration quality, structural reliability, and deployment efficiency. Although lightweight enhancement networks are attractive for resource-constrained underwater platforms, many of them mainly rely on empirical architectural simplification and appearance-oriented objectives, with limited mathematical analysis of complexity reduction, semantic regularization, and optimization coordination. To address this issue, this paper proposes MobileGAN, a lightweight underwater image enhancement framework equipped with dual-reference regularization and a theoretical analysis module. The proposed generator adopts a compact encoder–bottleneck–decoder architecture based on depthwise separable convolutions, which substantially reduces convolutional redundancy while preserving effective restoration capability. A dual-reference feature consistency formulation is introduced to simultaneously constrain the enhanced image toward the high-quality target representation and the degraded-input semantic anchor. In addition, an edge-aware regularization term and a stage-wise dynamic weighting mechanism are incorporated to improve local structure recovery and multi-objective optimization behavior. Beyond architectural design, we provide a mathematical analysis of the proposed framework from three aspects: computational complexity reduction, geometric interpretation of dual-reference regularization, and piecewise optimization properties of stage-wise weighted training. Extensive experiments on the UIEB benchmark demonstrate that MobileGAN achieves a favorable trade-off between enhancement quality and computational efficiency. The proposed method maintains real-time inference with a compact model size while providing competitive structural consistency and detail restoration. These results indicate that MobileGAN is not only a practical deployment-oriented enhancement framework but also an interpretable optimization model with analyzable structural properties. Full article

Benthic foraminifera are effective indicators of heavy metal contamination in marine ecosystems. Traditional methods for benthic foraminiferal identification and biodiversity assessment rely predominantly on stereomicroscopic analysis. However, this approach is time-consuming, labor-intensive, and cannot effectively identify small or morphologically similar species. In this study, we aimed to enhance the utility of benthic foraminifera as bioindicators. To this end, we investigated the responses of benthic foraminiferal communities to varying concentrations of Cd under controlled laboratory conditions using both morphological assessments and metabarcoding analyses. Cd exposure reduced the abundance of benthic foraminifera. High Cd concentrations led to Cd enrichment in foraminiferal tests and altered the contents of other elements. Quinqueloculina, Ammonia, and Miliammina exhibited tolerance to Cd, whereas Parasorites and Ovammina were more sensitive. This study provides an effective approach for evaluating the short-term effects of heavy metal pollution on benthic foraminiferal communities. Full article

The marine benthic invertebrate Urechis unicinctus exhibits extraordinary tolerance to hypoxic environments, making its coelomic fluid a unique and promising biological source for discovering novel stress-adapting macromolecules. Polysaccharides derived from the coelomic fluid of U. unicinctus were systematically extracted, fractionated, and characterized to investigate their structural features and associated biological activities. Gradient ethanol precipitation (30–80%) combined with DEAE-52 ion exchange chromatography yielded twelve fractions with distinct physicochemical properties. Significant variations were observed in molecular weight (10³–10⁵ Da), sulfate content (3.77–24.26%), and monosaccharide composition. High-ethanol fractions, particularly U68P and U18P (extracted at 60 °C and 100 °C, respectively, and both precipitated with 80% ethanol), were enriched in low-molecular-weight, highly sulfated heteropolysaccharides composed of galactose, fucose, glucosamine, and ribose. These fractions exhibited superior antioxidant activities, including strong scavenging effects against DPPH, ABTS, and hydroxyl radicals. Moreover, they demonstrated pronounced neuroprotective effects in the oxygen–glucose deprivation/reoxygenation (OGD/R) model using SH-SY5Y cells, significantly improving cell viability. Structure–activity relationship analysis revealed that reduced molecular weight, increased sulfation degree, and more diverse monosaccharide composition (e.g., more diverse monosaccharide composition) synergistically contribute to improved bioactivity by facilitating cellular uptake and exposing functional groups. In contrast, high-molecular-weight homoglucan fractions showed relatively weak effects. Overall, this study identifies U. unicinctus coelomic fluid as a promising source of bioactive polysaccharides and provides a theoretical basis for the development of marine-derived anti-hypoxic and antioxidant agents. Full article