Search Results (565)

Cyanobacteria are prolific producers of specialized metabolites of growing interest for blue biotechnology, transversal to various sectors such as cosmetics, foods and pharmaceuticals. In this work, the marine cyanobacterial strain Salileptolyngbya sp. LEGE 181209, from Cabo Verde, was systematically characterized to resolve its taxonomy, pigments profile, and cytotoxicity assessment. A polyphasic workflow combining 16S rRNA gene phylogenies, 16S–23S ITS secondary structures, p-distance, morphology, and scanning electron microscopy (SEM) was used to establish the taxonomic placement of the strain as a new species of the genus. PCR assays targeting the toxin biosynthetic genes mcyA and anaC, and cytotoxicity assays in HaCaT keratinocytes showed low-to-absent cytotoxicity, supporting a safety-forward profile for downstream use. A sequential extraction with solvents of different polarities yielded complementary pigment fractions profiled by HPLC-PDA and spectrophotometry. Total carotenoids reached 72.7 µg mg⁻¹ of dry extract (DE), the profile being dominated by β-carotene and zeaxanthin (≈42 and 8 µg mg⁻¹ of DE, respectively); chlorophyll-a was also very representative, reaching 85.6 µg mg⁻¹ of DE. Phycobiliproteins dominated the polar fraction, with phycocyanin reaching 150 µg mg⁻¹, followed by sugars (19.7 µg of glucose equivalents mg⁻¹) and phenols (8.8 µg of gallic acid equivalents mg⁻¹). Full article

Saxitoxin (STX) is one of the most potent marine neurotoxins, produced by several species of freshwater cyanobacteria and marine dinoflagellates. Although omics-based approaches have advanced our understanding of STX biosynthesis in recent decades, the origin, regulation, and ecological drivers of STX in dinoflagellates remain poorly resolved. Specifically, dinoflagellate STX biosynthetic genes (sxt) are extremely fragmented, inconsistently expressed, and unevenly distributed between toxic and non-toxic taxa. Environmental studies further report inconsistent relationships between abiotic factors and STX production, suggesting regulation across multiple genomic, transcriptional, post-transcriptional, and epigenetic levels. These gaps prevent a comprehensive understanding of STX biosynthesis in dinoflagellates and limit the development of accurate predictive models for harmful algal blooms (HABs) and paralytic shellfish poisoning (PSP). Artificial intelligence (AI), including machine learning and deep learning, offers new opportunities in ecological pattern recognition, molecular annotation, and data-driven prediction. This review explores the current state of knowledge and persistent knowledge gaps in dinoflagellate STX research and proposes an AI-integrated multi-omics framework highlighting recommended models for sxt gene identification (e.g., DeepFRI, ProtTrans, ESM-2), evolutionary reconstruction (e.g., PhyloGAN, GNN, PhyloVAE, NeuralNJ), molecular regulation (e.g., MOFA+, LSTM, GRU, DeepMF), and toxin prediction (e.g., XGBoost, LightGBM, LSTM, ConvLSTM). By integrating AI with diverse biological datasets, this novel framework outlines how AI can advance fundamental understanding of STX biosynthesis and inform future applications in HAB monitoring, seafood safety, and PSP risk management in aquaculture and fisheries. Full article

Diarrheic shellfish toxins (DSTs), especially okadaic acid (OA) and its related compounds, are lipophilic marine biotoxins mainly synthesized by dinoflagellates of the genera Dinophysis and Prorocentrum. These compounds bioaccumulate in filter-feeding shellfish like mussels and clams, posing a considerable public health risk due to their strong gastrointestinal effects when contaminated seafood is consumed. This review offers a thorough overview of the current understanding of OA-group toxins with a focus on the molecular mechanisms of toxicity, including cytoskeletal disruption, apoptosis, inflammation, oxidative stress, and mitochondrial dysfunction. Additionally, their ecological impacts on aquatic organisms and patterns of bioaccumulation are explored. Recent advances in detection methods and regulatory frameworks are discussed, highlighting the necessity for robust monitoring systems to safeguard seafood safety. Enhanced knowledge of the toxicity, distribution, and fate of DSP (diarrheic shellfish poisoning) is essential for improving risk assessment and managing marine biotoxins. Despite methodological advances, gaps remain regarding chronic exposure and species-specific detoxification pathways. Full article

This study investigated the bioaccumulation of ciguatoxins (CTXs) in dusky grouper (Epinephelus marginatus) following dietary exposure to toxic fish flesh. Two feeding groups were established: group A (amberjack (Seriola spp.) and dusky grouper flesh) and group B (moray eel (Muraena spp. and Gymnothorax spp.) flesh). CTX-like toxicity was detected in muscle and liver of group A. Flesh toxicity progressively increased from the first sampling. In contrast, CTX activity was only detected in livers in group B. Liquid chromatography–mass spectrometry analysis revealed the presence of C-CTX1 in both groups, and the 17-OH-C-CTX1 analogue was exclusively observed in group A. Toxicity in the liver peaked at 10 weeks in experimental group A, but it showed a decline by the end of the experiment while increasing the storage of the toxin in muscle tissue. These findings demonstrate the differential bioaccumulation of CTXs in grouper flesh and liver, highlighting the potential role of the liver in metabolizing and/or detoxifying ciguatoxins. The efficacy of a combination of different techniques, including the cell-based assay (CBA) and liquid chromatography—low- and high-resolution mass spectrometry (LC-MS/MS and LC-HRMS), was demonstrated to confirm the presence of CTX analogues at very low levels. The results provide insights into CTX transfer and accumulation in marine food webs, underlining the need for further studies on toxin metabolism in predatory fish species. Full article

The Isles of Scilly are an archipelago of islands in the far southwest of the UK which contain numerous beds of wild bivalve molluscs which are recreationally harvested for local consumption. However, the islands have never previously been assessed for the presence of harmful algae and their shellfish toxin metabolites which can cause serious human health impacts. This study sought to address these knowledge gaps through the analysis of seawater and shellfish tissues for microalgae and toxins utilizing portable and lab-based microscopy, nanopore sequencing, chemical analysis and immunoassay kits. The study design was affected by the national COVID-19 lockdown which enforced implementation of citizen-led sampling and in-field microscopy. Microscopy and sequencing approaches led to the confirmation of multiple HAB species of concern, including those potentially responsible for production of neurotoxic and diarrhetic shellfish toxins. A portable microscope was successfully utilized in the field for recognition of microalgae and for early warning of potential shellfish toxicity events. Chemical analysis of cockle, clam and mussel samples confirmed the detection of paralytic, diarrhetic and amnesic shellfish toxins, with an unusual okadaic acid group toxin profile reaching a maximum toxicity of approximately half the regulatory limit as defined by EU law. The Sensoreal Alert Lateral Flow Assay was used to screen and highlight samples containing higher concentrations of DSP toxins. Furthermore, Tetrodotoxin was detected for the first time in the UK in cockle and grooved carpet shells. Multiple saxitoxin analogues were also detected in two echinoderm species, with this providing the first ever report of paralytic shellfish toxins in the spiny starfish, Marthasterias glacialis. The toxin profiles in the two species varied significantly with a dominance of GTX4 in Luidia ciliaris as opposed to a dominance of STX in Marthasterias glacialis. Overall, the study showed that a multi-method assessment of a previously unexplored region within the UK territory contained microalgae and toxins of concern to human health, and that a citizen-led programme could be instigated using portable microscopy and rapid toxin testing to assess the early warning for potentially harmful microalgae and toxins in the region, with confirmatory analysis being conducted to establish actual levels of risk for local consumers of seafood. Full article

V. furnissii is a marine bacterium capable of infecting both invertebrates and humans. However, the mechanisms underlying its drug resistance and virulence remain largely elusive. In this study, we isolated a multidrug-resistant V. furnissii strain, MT14, from bivalve mollusks. Genomic analysis revealed that MT14 carries a novel pAQU-type plasmid, designated pMT14, which harbors six antibiotic resistance genes: qnrS2, qnrVC6, dfrA31, tetA; sul2, and bla_GMA-1. Notably, bla_GMA-1 and its variants confer resistance to penicillin-class antibiotics, including ampicillin, amoxicillin, and carbenicillin. Comparative genomic analysis further revealed that V. furnissii strains commonly encode T6SS1, T6SS2, and the hemolysin gene vfh, while only five sequenced strains carry zot toxin gene. To our knowledge, this is the first report of zot in V. furnissii. In addition, the absence of drug resistance genes in the majority of genomes (73.3%, 22/30) suggests that such traits are not intrinsic to the species but have been acquired by specific strains, likely through plasmid transfer or other mobile genetic elements. The emergence of bla_GMA-1 and zot in V. furnissii represents a potential public health concern, underscoring the need for enhanced surveillance of antimicrobial resistance in marine pathogens. Full article

In recent years, there has been an increase in the consumption of seafood such as shellfish and crustaceans due to their pleasant taste and nutritional value. Fish are also a crucial part of a healthy, balanced diet. However, the consumption of these products may cause food poisoning through marine biotoxins. In recent years, several legal acts have been published by the European Commission to regulate toxin limits and describe their reference analysis methods. Commission Regulation (EC) No. 853/2004 established the maximum contents of marine biotoxins only in bivalve mollusks. Although other groups of marine organisms such as crustaceans (crabs, shrimps, and lobsters) and fish are not included in the EU rules for toxin monitoring, they may still be vectors of marine biotoxins for humans. Due to this, there is an urgent need for studies regarding the occurrence of marine biotoxins in non-bivalve seafood organisms and their potential influence on public health. In this review, the most important cases of accumulation of marine biotoxins in crustaceans and fish in recent years are described. Full article

Tetrodotoxin (TTX) is an extremely potent neurotoxin, a selective blocker of voltage-gated sodium (NaV) channels, produced by bacteria and accumulated across a wide range of taxa. Several TTX-bearing animals have developed molecular adaptations in their NaV channels that provide TTX resistance, making this toxin one of the factors of molecular evolution. However, the molecular basis of TTX resistance in NaV channels of a significant proportion of tetrodotoxic species remains poorly studied. Nemertea is a phylum of marine worms, comprising both TTX-bearing and non-TTX-bearing species. Here, we analyzed the amino acid sequences of the NaV1 channel regions responsible for TTX binding from 22 species of nemerteans. Substitutions previously characterized as conferring TTX resistance in other taxa were detected in sixteen nemerteans; local clustering was observed within several families. These findings suggest that TTX resistance in nemerteans evolved multiple times independently and may serve as either as an adaptation facilitating TTX accumulation for subsequent use for defense and predation, or as a mechanism allowing consumption of tetrodotoxic prey without toxin accumulation. Full article

Advances in neuroscience, immunology, and neuroimmunology have revealed that the nervous and immune systems form a bidirectional integrated network, ranging from regulating inflammation to directing stress responses, pivotal for the maintenance of the brain–body physiology. Like peripheral inflammation, neuroinflammation is a conserved process aimed at activating innate/adaptive immune and non-immune cells to effectively deal with bacteria, viruses, toxins, and injuries, and eventually at removing the microbial pathogens and supporting tissue repair and recovery. A failure of this process or the permanent release of pro-inflammatory mediators causes a condition called “chronic low-grade neuroinflammation” resulting in tissue damage and an increased risk of developing neurodegenerative diseases (NDD), such as Alzheimer’s disease (AD), Parkinson’s disease (PD), multiple sclerosis (MS), and amyotrophic lateral sclerosis (ALS). Marine-derived bioactive components are able to modulate lipid and glucose metabolism as well as inflammation and oxidative stress. In this review, we describe the neuroinflammatory process and its involvement in the pathogenesis and progression of AD, PD, MS, and ALS. Then, we discuss the potential therapeutic efficacy of select marine-derived bioactive components. Full article

A growing body of evidence indicates that freshwater bodies, particularly eutrophic systems, are significant sources of the greenhouse gases (GHGs) carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O). Unlike marine environments, freshwater systems are generally shallower and more directly influenced by terrestrial inputs, including nutrient enrichment, organic matter deposition, and steep redox gradients in both the water column and sediments. These conditions promote intense phytoplankton growth, including massive harmful cyanobacterial blooms (HCBs), and stimulate microbial processes that drive GHG production and release. This opinion article examines the biogeochemical mechanisms underlying these emissions and evaluates the potential of mitigation treatments to both enhance carbon sequestration and reduce CH₄ and N₂O emissions. We argue that effective control of HCBs, whether through nutrient load reduction or direct mitigation protocols, would not only provide communities with toxin-free water but also significantly lower GHG emissions from eutrophic waterbodies. As this is an opinion paper rather than a comprehensive review, we intentionally avoided citing widely accepted concepts, since doing full justice to the many excellent contributions across all relevant subfields would not be possible within the scope of this work. Full article

Historically, saxitoxin (STX) and its analogs, like neosaxitoxin (NeoSTX), have been restricted to scientific research due to their potent toxicity, despite their potential as therapeutic agents. This study aimed to evaluate the pharmacological versatility of STX and NeoSTX through molecular docking. Using the SwissTargetPrediction server, 18 potential human therapeutic targets were identified, with the 5-HT6 receptor being the primary target. Molecular docking assays were performed with AutoDock Vina version 1.1.2, and the lowest-energy pose for NeoSTX (−5.7 kcal/mol) suggested a stronger binding affinity compared to STX (−5.5 kcal/mol). The analysis of the binding mode revealed key interactions, including hydrogen bonds with Thr199 and hydrophobic contacts with Phe285. These findings provide robust hypotheses regarding the therapeutic potential of NeoSTX as a 5-HT6 receptor antagonist, supporting the development of novel bioactive agents derived from these marine toxins. Full article

Toxin-antitoxin (TA) systems, ubiquitous in bacterial and archaeal genomes, play pivotal roles in responding to environmental stresses, forming biofilms, defending against phages, and influencing pathogen virulence. The marine environment harbors Earth’s most diverse and abundant microbial communities, where microorganisms have evolved unique genetic adaptations and specialized metabolic processes to thrive amid distinct environmental challenges. Research on the presence and function of TA systems in marine bacteria lags significantly behind that in model bacteria and pathogens. Here, we explored the diversity of the TA system in marine bacteria, including species from the Global Ocean Microbiome Catalogue (GOMC) and the Mariana Trench Environment and Ecology Research (MEER) databases. Our findings revealed that types I to VII (featuring protein toxins) of eight types of TA systems are prevalent in these microorganisms, with unidentified TA combinations diverging from previously characterized systems. Interestingly, some toxins or antitoxins lack canonical counterparts, indicating evolutionary divergence. Additionally, previously uncharacterized potential TA systems have been identified in extremophilic bacteria from the deep-sea Mariana Trench. These results highlight the adaptive importance of marine TA systems, which are likely operating through unconventional mechanisms. Full article

Background: The Kingdom of Saudi Arabia is adjacent to two vital marine ecosystems; the semi-enclosed Arabian Gulf and the largely landlocked Red Sea. Dinoflagellates are repeatedly found in these bodies of marine water, which serve as significant routes for cargo ships. Through these ships and ballast water, invasive dinoflagellate species and their cysts are introduced. They compete with indigenous species for nutrients and space, cause massive fish kill-off and disturb the ecological balance and biodiversity. To address these threats, the International Convention for the Control and Management of Ships’ Ballast Water and Sediments (BWM Convention) set forth guidelines intended to curtail the dissemination of such detrimental organisms. The Kingdom of Saudi Arabia was one of the co-signatory countries to this Convention. Methods of detection and monitoring include microscopy, molecular characterization and remote sensing, which are employed for the detection and monitoring of these harmful algae, in order to avert disasters such as fish die-offs. The results of several reports confirmed the presence of number of dinoflagellates in both the Arabian Gulf and the Red Sea, some of which are toxin producers, with certain species being highlighted as invasive species whose presence requires a high level of alert. Discussion: The monitoring, the change in engineering of cargo ships and the introduction of advanced surveillance methods, together with the proper treatments of ballast water, are all important security elements that ensure the safe disposal of ballast water without introducing harmful species. Full article

Domoic acid (DA), produced by Pseudo-nitzschia diatoms, is the one of the major toxin threats from harmful algal blooms (HABs) on the west coast of the United States. DA events vary in magnitude, timing, and duration, and elucidating drivers for individual events is a persistent challenge. Monterey Bay experiences near-annual DA events and hosts long-term HAB monitoring at the Santa Cruz Municipal Wharf (SCW). Here we characterize two toxin events, occurring in May 2023 and March 2024. The events were similar in magnitude and duration, but an exploration of physical, biological, and chemical dynamics revealed distinct environmental drivers. These differences resulted in a significant deviation in cellular DA (cDA) within the same species of Pseudo-nitzschia. In addition, opportunistic solid-phase adsorption toxin tracking (SPATT) was used for environmental metabolomics. The novel application of SPATT revealed 159 metabolites that were strongly correlated with DA in both events and produced a spectral match to a new marine natural product using Global Natural Products Social Molecular Networking (GNPS). This work takes a multivariable approach to understanding toxin drivers and lends proof of concept for the integration of environmental metabolomics in HAB monitoring. Full article

Accurate detection of residual jellyfish venom is crucial for species identification and clinical management post-envenomation. We developed a highly specific immunoassay for Nemopilema nomurai venom using polyclonal antibodies (titer: 1:256,000). The established i-ELISA exhibited linear detection (0–20 ng/mL) with low variability (intra-plate CV: 0.77–2.78%; inter-plate CV: 2.25–5.17%). The kit demonstrated remarkable thermal stability (<15% signal decay after 6 days at 37 °C; detectable positivity through Day 9), suggesting >1-year shelf life at 4 °C. It showed significantly higher sensitivity for N. nomurai venom than venoms from Rhopilema esculentum, Chrysaora quinquecirrha, Cyanea melanaster, scorpions, or bees (p < 0.01). Validation in murine/human skin envenomation models and serum from systemically intoxicated mice confirmed the reproducibility and stability of residual toxins. This study developed a highly sensitive, specific, reproducible, and stable i-ELISA for Nemopilema nomurai venom, providing a methodological basis for creating diagnostic kits for marine envenomation. Full article