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Neurotoxicity Research Feb 2021Recent marine and freshwater algal and cyanobacterial blooms in Florida have increased public concern and awareness of the risks posed by exposure to these organisms. In...
Recent marine and freshwater algal and cyanobacterial blooms in Florida have increased public concern and awareness of the risks posed by exposure to these organisms. In 2018, Lake Okeechobee and the Caloosahatchee river, on the west coast of Florida, experienced an extended bloom of Microcystis spp. and a bloom of Karenia brevis in the coastal waters of the Gulf of Mexico that coincided in the Fort Myers area. Samples from the Caloosahatchee at Fort Myers into Pine Island Sound and up to Boca Grande were collected by boat. High concentrations of microcystin-LR were detected in the cyanobacterial bloom along with brevetoxins in the marine samples. Furthermore, β-N-methylamino-L-alanine (BMAA) and isomers N-(2-aminoethyl)glycine (AEG) and 2,4-diaminobuytric acid (DAB) were detected in marine diatoms and dinoflagellates, and cyanobacteria of freshwater origin. High freshwater flows pushed the cyanobacterial bloom to barrier island beaches and Microcystis and microcystins could be detected into the marine environment at a salinity of 41 mS/cm. For comparison, in 2019 collections of Dapis (a new generic segregate from Lyngbya) mats from Sarasota showed high concentrations of BMAA, suggesting the possibility of long-term exposure of residents to BMAA. The findings highlight the potential for multiple, potentially toxic blooms to co-exist and the possible implications for human and animal health.
Topics: Cyanobacteria Toxins; Estuaries; Florida; Harmful Algal Bloom; Marine Toxins; Microcystins; Oxocins
PubMed: 32683648
DOI: 10.1007/s12640-020-00248-3 -
Marine Drugs Nov 2013Voltage-gated sodium channels (VGSCs) play a central role in the generation and propagation of action potentials in excitable neurons and other cells and are targeted by... (Review)
Review
Voltage-gated sodium channels (VGSCs) play a central role in the generation and propagation of action potentials in excitable neurons and other cells and are targeted by commonly used local anesthetics, antiarrhythmics, and anticonvulsants. They are also common targets of neurotoxins including shellfish toxins. Shellfish toxins are a variety of toxic secondary metabolites produced by prokaryotic cyanobacteria and eukaryotic dinoflagellates in both marine and fresh water systems, which can accumulate in marine animals via the food chain. Consumption of shellfish toxin-contaminated seafood may result in potentially fatal human shellfish poisoning. This article provides an overview of the structure, bioactivity, and pharmacology of shellfish toxins that act on VGSCs, along with a brief discussion on their pharmaceutical potential for pain management.
Topics: Animals; Crustacea; Humans; Marine Toxins; Pain; Pain Management; Voltage-Gated Sodium Channels
PubMed: 24287955
DOI: 10.3390/md11124698 -
Biosensors Dec 2022Phycotoxins or marine toxins cause massive harm to humans, livestock, and pets. Current strategies based on ordinary methods are long time-wise and require expert... (Review)
Review
Phycotoxins or marine toxins cause massive harm to humans, livestock, and pets. Current strategies based on ordinary methods are long time-wise and require expert operators, and are not reliable for on-site and real-time use. Therefore, it is urgent to exploit new detection methods for marine toxins with high sensitivity and specificity, low detection limits, convenience, and high efficiency. Conversely, biosensors can distinguish poisons with less response time and higher selectivity than the common strategies. Aptamer-based biosensors (aptasensors) are potent for environmental monitoring, especially for on-site and real-time determination of marine toxins and freshwater microorganisms, and with a degree of superiority over other biosensors, making them worth considering. This article reviews the designed aptasensors based on the different strategies for detecting the various phycotoxins.
Topics: Humans; Aptamers, Nucleotide; Marine Toxins; Food Safety; Fresh Water; Biosensing Techniques
PubMed: 36671891
DOI: 10.3390/bios13010056 -
Toxins Jul 2020Diarrhetic shellfish toxins (DSTs) are among the most prevalent marine toxins in Europe's and in other temperate coastal regions. These toxins are produced by several... (Review)
Review
Diarrhetic shellfish toxins (DSTs) are among the most prevalent marine toxins in Europe's and in other temperate coastal regions. These toxins are produced by several dinoflagellate species; however, the contamination of the marine trophic chain is often attributed to species of the genus . This group of toxins, constituted by okadaic acid (OA) and analogous molecules (dinophysistoxins, DTXs), are highly harmful to humans, causing severe poisoning symptoms caused by the ingestion of contaminated seafood. Knowledge on the mode of action and toxicology of OA and the chemical characterization and accumulation of DSTs in seafood species (bivalves, gastropods and crustaceans) has significantly contributed to understand the impacts of these toxins in humans. Considerable information is however missing, particularly at the molecular and metabolic levels involving toxin uptake, distribution, compartmentalization and biotransformation and the interaction of DSTs with aquatic organisms. Recent contributions to the knowledge of DSTs arise from transcriptomics and proteomics research. Indeed, OMICs constitute a research field dedicated to the systematic analysis on the organisms' metabolisms. The methodologies used in OMICs are also highly effective to identify critical metabolic pathways affecting the physiology of the organisms. In this review, we analyze the main contributions provided so far by OMICs to DSTs research and discuss the prospects of OMICs with regard to the DSTs toxicology and the significance of these toxins to public health, food safety and aquaculture.
Topics: Animals; Biomarkers; Biotransformation; Food Safety; Genomics; Humans; Marine Toxins; Proteomics; Shellfish; Shellfish Poisoning
PubMed: 32752012
DOI: 10.3390/toxins12080493 -
Marine Drugs Oct 2013Okadaic acid (OA) is one of the most frequent and worldwide distributed marine toxins. It is easily accumulated by shellfish, mainly bivalve mollusks and fish, and,... (Review)
Review
Okadaic acid (OA) is one of the most frequent and worldwide distributed marine toxins. It is easily accumulated by shellfish, mainly bivalve mollusks and fish, and, subsequently, can be consumed by humans causing alimentary intoxications. OA is the main representative diarrheic shellfish poisoning (DSP) toxin and its ingestion induces gastrointestinal symptoms, although it is not considered lethal. At the molecular level, OA is a specific inhibitor of several types of serine/threonine protein phosphatases and a tumor promoter in animal carcinogenesis experiments. In the last few decades, the potential toxic effects of OA, beyond its role as a DSP toxin, have been investigated in a number of studies. Alterations in DNA and cellular components, as well as effects on immune and nervous system, and even on embryonic development, have been increasingly reported. In this manuscript, results from all these studies are compiled and reviewed to clarify the role of this toxin not only as a DSP inductor but also as cause of alterations at the cellular and molecular levels, and to highlight the relevance of biomonitoring its effects on human health. Despite further investigations are required to elucidate OA mechanisms of action, toxicokinetics, and harmful effects, there are enough evidences illustrating its toxicity, not related to DSP induction, and, consequently, supporting a revision of the current regulation on OA levels in food.
Topics: Animals; Environmental Monitoring; Humans; Marine Toxins; Okadaic Acid; Shellfish Poisoning
PubMed: 24184795
DOI: 10.3390/md11114328 -
Marine Drugs Mar 2022Marine phycotoxins are a multiplicity of bioactive compounds which are produced by microalgae and bioaccumulate in the marine food web. Phycotoxins affect the ecosystem,... (Review)
Review
Marine phycotoxins are a multiplicity of bioactive compounds which are produced by microalgae and bioaccumulate in the marine food web. Phycotoxins affect the ecosystem, pose a threat to human health, and have important economic effects on aquaculture and tourism worldwide. However, human health and food safety have been the primary concerns when considering the impacts of phycotoxins. Phycotoxins toxicity information, often used to set regulatory limits for these toxins in shellfish, lacks traceability of toxicity values highlighting the need for predefined toxicological criteria. Toxicity data together with adequate detection methods for monitoring procedures are crucial to protect human health. However, despite technological advances, there are still methodological uncertainties and high demand for universal phycotoxin detectors. This review focuses on these topics, including uncertainties of climate change, providing an overview of the current information as well as future perspectives.
Topics: Animals; Climate Change; Humans; Marine Toxins; Microalgae; Water Pollutants
PubMed: 35323497
DOI: 10.3390/md20030198 -
Marine Drugs Feb 2022A variety of microalgal species produce lipophilic toxins (LT) that are accumulated by filter-feeding bivalves. Their negative impacts on human health and shellfish... (Review)
Review
A variety of microalgal species produce lipophilic toxins (LT) that are accumulated by filter-feeding bivalves. Their negative impacts on human health and shellfish exploitation are determined by toxic potential of the local strains and toxin biotransformations by exploited bivalve species. Chile has become, in a decade, the world's major exporter of mussels () and scallops () and has implemented toxin testing according to importing countries' demands. Species of the complex and are the most widespread and abundant LT producers in Chile. Dominant strains, notwithstanding, unlike most strains in Europe rich in okadaic acid (OA), produce only pectenotoxins, with no impact on human health. , suspected to be the main cause of diarrhetic shellfish poisoning outbreaks, is found in the two southernmost regions of Chile, and has apparently shifted poleward. Mouse bioassay (MBA) is the official method to control shellfish safety for the national market. Positive results from mouse tests to mixtures of toxins and other compounds only toxic by intraperitoneal injection, including already deregulated toxins (PTXs), force unnecessary harvesting bans, and hinder progress in the identification of emerging toxins. Here, 50 years of LST events in Chile, and current knowledge of their sources, accumulation and effects, are reviewed. Improvements of monitoring practices are suggested, and strategies to face new challenges and answer the main questions are proposed.
Topics: Animals; Biological Assay; Bivalvia; Chile; Humans; Marine Toxins; Mice; Microalgae; Shellfish Poisoning
PubMed: 35200651
DOI: 10.3390/md20020122 -
Environmental Health Perspectives Sep 2022The excitotoxic molecule, domoic acid (DA), is a marine algal toxin known to induce overt hippocampal neurotoxicity. Recent experimental and epidemiological studies...
BACKGROUND
The excitotoxic molecule, domoic acid (DA), is a marine algal toxin known to induce overt hippocampal neurotoxicity. Recent experimental and epidemiological studies suggest adverse neurological effects at exposure levels near the current regulatory limit (20 ppm, ). At these levels, cognitive effects occur in the absence of acute symptoms or evidence of neuronal death.
OBJECTIVES
This study aimed to identify adverse effects on the nervous system from prolonged, dietary DA exposure in adult, female monkeys.
METHODS
Monkeys were orally exposed to 0, 0.075, and for an average of 14 months. Clinical blood counts, chemistry, and cytokine levels were analyzed in the blood. In-life magnetic resonance (MR) imaging assessed volumetric and tractography differences in and between the hippocampus and thalamus. Histology of neurons and glia in the fornix, fimbria, internal capsule, thalamus, and hippocampus was evaluated. Hippocampal RNA sequencing was used to identify differentially expressed genes. Enrichment of gene networks for neuronal health, excitotoxicity, inflammation/glia, and myelin were assessed with Gene Set Enrichment Analysis.
RESULTS
Clinical blood counts, chemistry, and cytokine levels were not altered with DA exposure in nonhuman primates. Transcriptome analysis of the hippocampus yielded 748 differentially expressed genes (; ), reflecting differences in a broad molecular profile of intermediate early genes (e.g., ) and genes related to myelin networks in DA animals. Between exposed and control animals, MR imaging showed comparable connectivity of the hippocampus and thalamus and histology showed no evidence of hypomyelination. Histological examination of the thalamus showed a larger microglia soma size and an extension of cell processes, but suggestions of a response showed no indication of astrocyte hypertrophy.
DISCUSSION
In the absence of overt hippocampal excitotoxicity, chronic exposure of monkeys to environmentally relevant levels of DA suggested a subtle shift in the molecular profile of the hippocampus and the microglia phenotype in the thalamus that was possibly reflective of an adaptive response due to prolonged DA exposure. https://doi.org/10.1289/EHP10923.
Topics: Animals; Cytokines; Female; Kainic Acid; Macaca fascicularis; Marine Toxins; Neurotoxicity Syndromes
PubMed: 36102641
DOI: 10.1289/EHP10923 -
Toxins Apr 2020Eutrophication has played a major role in the worldwide increase of harmful algal blooms (HABs). Higher input of key nutrients, such as nitrogen (N) and phosphorus (P),... (Meta-Analysis)
Meta-Analysis Review
Eutrophication has played a major role in the worldwide increase of harmful algal blooms (HABs). Higher input of key nutrients, such as nitrogen (N) and phosphorus (P), can stimulate the growth of harmful algal species in freshwater, estuarine, and coastal marine ecosystems. Some HAB-forming taxa, particularly several cyanobacteria and dinoflagellate species, are harmful through the production of N-rich toxins that have detrimental effects on the environment and human health. Here, we test how changes in nutrient availability affect N-rich toxin synthesis in cyanobacteria and dinoflagellates using a meta-analysis approach. Overall, N-rich toxin content showed an increase with P limitation, while it tended to decrease with N limitation, but we also observed substantial variation in responses both within and across genera and toxin groups. For instance, in response to N limitation, microcystin content varied from a 297% decrease up to a 273% increase, and paralytic shellfish poisoning (PSP) toxin content varied from a 204% decrease to an 82% increase. Cylindrospermopsin, produced by N-fixing cyanobacteria, showed no clear direction in response to nutrient limitation, and cellular contents of this compound may thus vary independently of nutrient fluctuations. Our results confirm earlier reported stoichiometric regulation of N-rich phytoplankton toxins, showing increased toxin content with an increase in cellular N:P ratios, and vice versa. Thus, changes in N-rich toxin content largely follow the changes in relative cellular N content. Consequently, although nutrient limitation may limit bloom biomass and thereby bloom toxicity, our results warn that P limitation can cause accumulation of cellular toxins and thus lead to unexpected increases in bloom toxicity.
Topics: Bacteria; Bacterial Toxins; Harmful Algal Bloom; Marine Toxins; Nitrogen; Phosphorus; Phytoplankton
PubMed: 32244741
DOI: 10.3390/toxins12040221 -
Journal of Natural Products Mar 2016Microalgae, particularly those from the lineage Dinoflagellata, are very well-known for their ability to produce phycotoxins that may accumulate in the marine food chain... (Review)
Review
Microalgae, particularly those from the lineage Dinoflagellata, are very well-known for their ability to produce phycotoxins that may accumulate in the marine food chain and eventually cause poisoning in humans. This includes toxins accumulating in shellfish, such as saxitoxin, okadaic acid, yessotoxins, azaspiracids, brevetoxins, and pinnatoxins. Other toxins, such as ciguatoxins and maitotoxins, accumulate in fish, where, as is the case for the latter compounds, they can be metabolized to even more toxic metabolites. On the other hand, much less is known about the chemical nature of compounds that are toxic to fish, the so-called ichthyotoxins. Despite numerous reports of algal blooms causing massive fish kills worldwide, only a few types of compounds, such as the karlotoxins, have been proven to be true ichthyotoxins. This review will highlight marine microalgae as the source of some of the most complex natural compounds known to mankind, with chemical structures that show no resemblance to what has been characterized from plants, fungi, or bacteria. In addition, it will summarize algal species known to be related to fish-killing blooms, but from which ichthyotoxins are yet to be characterized.
Topics: Animals; Ciguatoxins; Dinoflagellida; Food Contamination; Humans; Marine Toxins; Molecular Structure; Mollusk Venoms; Oxocins; Spiro Compounds
PubMed: 26901085
DOI: 10.1021/acs.jnatprod.5b01066