-
BMJ Open Jun 2024Cyanobacterial blooms are increasingly common in freshwater sources used for swimming and other recreational water contact activities in Canada. Many species of...
INTRODUCTION
Cyanobacterial blooms are increasingly common in freshwater sources used for swimming and other recreational water contact activities in Canada. Many species of cyanobacteria can produce toxins that affect human and animal health, but there are limited data on the risk of illness associated with water contact at impacted beaches.
METHODS AND ANALYSIS
This study will investigate the incidence of recreational water illness due to exposure to cyanobacterial blooms and their toxins in four targeted and popular freshwater beaches in Ontario, Manitoba and Nova Scotia, Canada. A prospective cohort design and One Health approach will be used. On-site recruitment of recreational water users will be conducted at two beaches per year during the summers of 2024 and 2025. The population of interest includes recreational water users of any age and their pet dogs. After enrolment, an in-person survey will determine beach exposures and confounding factors, and a 3-day follow-up survey will ascertain any acute illness outcomes experienced by participants or their dogs. The target sample size is 2500 recreational water users. Water samples will be taken each recruitment day and analysed for cyanobacterial indicators (pigments), cell counts and toxin levels. Bayesian regression analysis will be conducted to estimate the association with water contact, cyanobacterial levels and risks of different acute illness outcomes.
ETHICS AND DISSEMINATION
This study has been approved by the Toronto Metropolitan University Research Ethics Board (REB 2023-461). Study results will be published in a peer-reviewed journal and as infographics on a project website.
Topics: Prospective Studies; Humans; Cyanobacteria; Bathing Beaches; Animals; Fresh Water; Dogs; Cyanobacteria Toxins; Ontario; Recreation; Water Microbiology; Bacterial Toxins; Bayes Theorem; Nova Scotia; Harmful Algal Bloom; Manitoba; Environmental Exposure; Marine Toxins; Research Design; Canada
PubMed: 38866574
DOI: 10.1136/bmjopen-2024-085406 -
PloS One 2024A large body of evidence has shown that treatments that interfere with memory consolidation become ineffective when animals are subjected to an intense learning...
A large body of evidence has shown that treatments that interfere with memory consolidation become ineffective when animals are subjected to an intense learning experience; this effect has been observed after systemic and local administration of amnestic drugs into several brain areas, including the striatum. However, the effects of amnestic treatments on the process of extinction after intense training have not been studied. Previous research demonstrated increased spinogenesis in the dorsomedial striatum, but not in the dorsolateral striatum after intense training, indicating that the dorsomedial striatum is involved in the protective effect of intense training. To investigate this issue, male Wistar rats, previously trained with low, moderate, or high levels of foot shock, were used to study the effect of tetrodotoxin inactivation of dorsomedial striatum on memory consolidation and subsequent extinction of inhibitory avoidance. Performance of the task was evaluated during seven extinction sessions. Tetrodotoxin produced a marked deficit of memory consolidation of inhibitory avoidance trained with low and moderate intensities of foot shock, but normal consolidation occurred when a relatively high foot shock was used. The protective effect of intense training was long-lasting, as evidenced by the high resistance to extinction exhibited throughout the extinction sessions. We discuss the possibility that increased dendritic spinogenesis in dorsomedial striatum may underly this protective effect, and how this mechanism may be related to the resilient memory typical of post-traumatic stress disorder (PTSD).
Topics: Animals; Male; Rats, Wistar; Extinction, Psychological; Rats; Avoidance Learning; Corpus Striatum; Tetrodotoxin; Memory Consolidation; Amnesia; Electroshock
PubMed: 38843228
DOI: 10.1371/journal.pone.0305066 -
Harmful Algae May 2024This article presents the first results on shellfish toxicity in the Slovenian sea (Gulf of Trieste, Adriatic Sea) since the analytical methods for the detection of...
Okadaic acid as a major problem for the seafood safety (Mytilus galloprovincialis) and the dynamics of toxic phytoplankton in the Slovenian coastal sea (Gulf of Trieste, Adriatic Sea).
This article presents the first results on shellfish toxicity in the Slovenian sea (Gulf of Trieste, Adriatic Sea) since the analytical methods for the detection of biotoxins (PSP, ASP, DSP and other lipophilic toxins) in bivalve molluscs were included in the national monitoring program in 2013. In addition to toxins, the composition and abundance of toxic phytoplankton and general environmental characteristics of the seawater (surface temperature and salinity) were also monitored. During the 2014-2019 study period, only lipophilic toxins were detected (78 positive tests out of 446 runs), of which okadaic acid (OA) predominated in 97 % of cases, while dinophysistoxin-2 and yessotoxins only gave a positive result in one sampling event each. The number of samples that did not comply with the EC Regulation for the OA group was 17 or 3.8 % of all tests performed, all of which took place from September to November, while a few positive OA tests were also recorded in December, April, and May. This toxicity pattern was consistent with the occurrence pattern of the five most common DSP-producing dinoflagellates, which was supported by the development of warm and thermohaline stratified waters: Dinophysis caudata, D. fortii, D. sacculus, D. tripos and Phalacroma rotundatum. The strong correlation (r = 0.611, p < 0.001) between D. fortii, reaching abundances of up to 950 cells L, and OA suggests that D. fortii is the main cause of OA production in Slovenian waters. Strong interannual variations in OA and phytoplankton dynamics, exacerbated by the effects of anthropogenic impacts in this coastal ecosystem, reduce the predictability of toxicity events and require continuous and efficient monitoring. Our results also show that the introduction of the LC-MS/MS method for lipophilic toxins has improved the management of aquaculture activities, which was not as accurate based on mouse bioassays.
Topics: Okadaic Acid; Animals; Phytoplankton; Marine Toxins; Slovenia; Mytilus; Seafood; Seawater; Dinoflagellida
PubMed: 38830710
DOI: 10.1016/j.hal.2024.102632 -
Harmful Algae May 2024Cyanobacterial harmful algal blooms (CyanoHABs) threaten public health and freshwater ecosystems worldwide. In this study, our main goal was to explore the dynamics of...
Cyanobacterial harmful algal blooms (CyanoHABs) threaten public health and freshwater ecosystems worldwide. In this study, our main goal was to explore the dynamics of cyanobacterial blooms and how microcystins (MCs) move from the Lalla Takerkoust reservoir to the nearby farms. We used Landsat imagery, molecular analysis, collecting and analyzing physicochemical data, and assessing toxins using HPLC. Our investigation identified two cyanobacterial species responsible for the blooms: Microcystis sp. and Synechococcus sp. Our Microcystis strain produced three MC variants (MC-RR, MC-YR, and MC-LR), with MC-RR exhibiting the highest concentrations in dissolved and intracellular toxins. In contrast, our Synechococcus strain did not produce any detectable toxins. To validate our Normalized Difference Vegetation Index (NDVI) results, we utilized limnological data, including algal cell counts, and quantified MCs in freeze-dried Microcystis bloom samples collected from the reservoir. Our study revealed patterns and trends in cyanobacterial proliferation in the reservoir over 30 years and presented a historical map of the area of cyanobacterial infestation using the NDVI method. The study found that MC-LR accumulates near the water surface due to the buoyancy of Microcystis. The maximum concentration of MC-LR in the reservoir water was 160 µg L. In contrast, 4 km downstream of the reservoir, the concentration decreased by a factor of 5.39 to 29.63 µgL, indicating a decrease in MC-LR concentration with increasing distance from the bloom source. Similarly, the MC-YR concentration decreased by a factor of 2.98 for the same distance. Interestingly, the MC distribution varied with depth, with MC-LR dominating at the water surface and MC-YR at the reservoir outlet at a water depth of 10 m. Our findings highlight the impact of nutrient concentrations, environmental factors, and transfer processes on bloom dynamics and MC distribution. We emphasize the need for effective management strategies to minimize toxin transfer and ensure public health and safety.
Topics: Microcystins; Harmful Algal Bloom; Microcystis; Satellite Imagery; Environmental Monitoring; Cyanobacteria; Indonesia; Synechococcus; Lakes
PubMed: 38830709
DOI: 10.1016/j.hal.2024.102631 -
Journal of Molecular Evolution Jun 2024Snakes in the family Elapidae largely produce venoms rich in three-finger toxins (3FTx) that bind to the subunit of nicotinic acetylcholine receptors (nAChRs), impeding...
Snakes in the family Elapidae largely produce venoms rich in three-finger toxins (3FTx) that bind to the subunit of nicotinic acetylcholine receptors (nAChRs), impeding ion channel activity. These neurotoxins immobilize the prey by disrupting muscle contraction. Coral snakes of the genus Micrurus are specialist predators who produce many 3FTx, making them an interesting system for examining the coevolution of these toxins and their targets in prey animals. We used a bio-layer interferometry technique to measure the binding interaction between 15 Micrurus venoms and 12 taxon-specific mimotopes designed to resemble the orthosteric binding region of the muscular nAChR subunit. We found that Micrurus venoms vary greatly in their potency on this assay and that this variation follows phylogenetic patterns rather than previously reported patterns of venom composition. The long-tailed Micrurus tend to have greater binding to nAChR orthosteric sites than their short-tailed relatives and we conclude this is the likely ancestral state. The repeated loss of this activity may be due to the evolution of 3FTx that bind to other regions of the nAChR. We also observed variations in the potency of the venoms depending on the taxon of the target mimotope. Rather than a pattern of prey-specificity, we found that mimotopes modeled after snake nAChRs are less susceptible to Micrurus venoms and that this resistance is partly due to a characteristic tryptophan serine mutation within the orthosteric site in all snake mimotopes. This resistance may be part of a Red Queen arms race between coral snakes and their prey.
Topics: Elapid Venoms; Animals; Receptors, Nicotinic; Phylogeny; Coral Snakes; Interferometry; Predatory Behavior; Elapidae
PubMed: 38814340
DOI: 10.1007/s00239-024-10176-x -
Environment International Jun 2024Microcystins (MCs) and nitrites are coexisted in the environment and have reproductive toxicity. The combined toxic effect and mechanism of MCs and nitrite on...
Microcystins (MCs) and nitrites are coexisted in the environment and have reproductive toxicity. The combined toxic effect and mechanism of MCs and nitrite on spermatogenesis remain largely unclear. In the present study, co-exposure to microcystin-leucine arginine (MC-LR) and sodium nitrite (NaNO) aggravated testicular damage of Balb/c mice and mitochondrial impairment of spermatogonia, Sertoli cells, and sperm. Furthermore, MC-LR and NaNO reduced sperm density with a synergistic effect. In addition, MC-LR and NaNO synergistically induced oxidative stress in the reproductive system by decreasing superoxide dismutase (SOD) activity and glutathione (GSH) levels and increasing levels of mitochondrial reactive oxygen species (mtROS) and reactive oxygen species (ROS). More importantly, mitoquidone mesylate (MitoQ), an inhibitor of mtROS, blocked MC-LR and NaNO-induced spermatogonia and Sertoli cell apoptosis by inhibiting high expression of Bax, Fadd, Caspase-8, and cleaved-Caspase-3. On the other hand, MitoQ suppressed pyroptosis of Sertoli cells by inhibiting the expression of NLRP3, N-GSDMD, and cleaved-Caspase-1. Additionally, MitoQ alleviated co-exposure-induced sperm density reduction and organ index disorders in F1 generation mice. Together, co-exposure of MC-LR and NaNO can enhance spermatogenic disorders by mitochondrial oxidative impairment-mediated germ cell death. This study emphasizes the potential risks of MC-LR and NaNO on reproduction in realistic environments and highlights new insights into the cause and treatment of spermatogenic disorders.
Topics: Microcystins; Animals; Male; Mice; Apoptosis; Spermatogenesis; Mice, Inbred BALB C; Reactive Oxygen Species; Pyroptosis; Oxidative Stress; Mitochondria; Testis; Spermatozoa; Sertoli Cells; Sodium Nitrite; Marine Toxins; Spermatogonia
PubMed: 38805914
DOI: 10.1016/j.envint.2024.108771 -
Journal, Genetic Engineering &... Jun 2024Venomous marine cone snails produce unique neurotoxins called conopeptides or conotoxins, which are valuable for research and drug discovery. Characterizing Conus venom...
BACKGROUND
Venomous marine cone snails produce unique neurotoxins called conopeptides or conotoxins, which are valuable for research and drug discovery. Characterizing Conus venom is important, especially for poorly studied species, as these tiny and steady molecules have considerable potential as research tools for detecting new pharmacological applications. In this study, a worm-hunting cone snail, Conus flavidus inhabiting the Red Sea coast were collected, dissected and the venom gland extraction was subjected to proteomic analysis to define the venom composition, and confirm the functional structure of conopeptides.
RESULTS
Analysis of C. flavidus venom identified 117 peptide fragments and assorted them to conotoxin precursors and non-conotoxin proteins. In this procedure, 65 conotoxin precursors were classified and identified to 16 conotoxin precursors and hormone superfamilies. In the venom of C. flavidus, the four conotoxin superfamilies T, A, O2, and M were the most abundant peptides, accounting for 75.8% of the total conotoxin diversity. Additionally, 19 non-conotoxin proteins were specified in the venom, as well as several potentially biologically active peptides with putative applications.
CONCLUSION
Our research displayed that the structure of the C. flavidus-derived proteome is similar to other Conus species and includes toxins, ionic channel inhibitors, insulin-like peptides, and hyaluronidase. This study provides a foundation for discovering new conopeptides from C. flavidus venom for pharmaceutical use.
PubMed: 38797555
DOI: 10.1016/j.jgeb.2024.100375 -
Sensors (Basel, Switzerland) May 2024is the term used to describe an abnormal and rapid growth of cyanobacteria in aquatic ecosystems such as lakes, rivers, and oceans as a consequence of anthropic...
is the term used to describe an abnormal and rapid growth of cyanobacteria in aquatic ecosystems such as lakes, rivers, and oceans as a consequence of anthropic factors, ecosystem degradation, or climate change. Cyanobacteria belonging to the genera , , , and produce and release toxins called microcystins (MCs) into the water. MCs can have severe effects on human and animal health following their ingestion and inhalation. The MC structure is composed of a constant region (composed of five amino acid residues) and a variable region (composed of two amino acid residues). When the MC variable region is composed of arginine and leucine, it is named MC-LR. The most-common methods used to detect the presence of MC-LR in water are chromatographic-based methods (HPLC, LC/MS, GC/MS) and immunological-based methods (ELISA). In this work, we developed a new competitive Förster resonance energy transfer (FRET) assay to detect the presence of traces of MC-LR in water. Monoclonal antibody anti-MC-LR and MC-LR conjugated with bovine serum albumin (BSA) were labeled with the near-infrared fluorophores CF568 and CF647, respectively. Steady-state fluorescence measurements were performed to investigate the energy transfer process between anti-MC-LR 568 and MC-LR BSA 647 upon their interaction. Since the presence of unlabeled MC-LR competes with the labeled one, a lower efficiency of FRET process can be observed in the presence of an increasing amount of unlabeled MC-LR. The limit of detection (LoD) of the FRET assay is found to be 0.245 nM (0.245 µg/L). This value is lower than the provisional limit established by the World Health Organization (WHO) for quantifying the presence of MC-LR in drinking water.
Topics: Microcystins; Fluorescence Resonance Energy Transfer; Drinking Water; Marine Toxins; Cyanobacteria; Humans; Animals; Antibodies, Monoclonal
PubMed: 38794058
DOI: 10.3390/s24103204 -
Microorganisms May 2024Plasmids are mobile genetic elements known to carry secondary metabolic genes that affect the fitness and survival of microbes in the environment. Well-studied cases of...
Plasmids are mobile genetic elements known to carry secondary metabolic genes that affect the fitness and survival of microbes in the environment. Well-studied cases of plasmid-encoded secondary metabolic genes in marine habitats include toxin/antitoxin and antibiotic biosynthesis/resistance genes. Here, we examine metagenome-assembled genomes (MAGs) from the permanently-stratified water column of the Cariaco Basin for integrated plasmids that encode biosynthetic gene clusters of secondary metabolites (smBGCs). We identify 16 plasmid-borne smBGCs in MAGs associated primarily with Planctomycetota and Pseudomonadota that encode terpene-synthesizing genes, and genes for production of ribosomal and non-ribosomal peptides. These identified genes encode for secondary metabolites that are mainly antimicrobial agents, and hence, their uptake via plasmids may increase the competitive advantage of those host taxa that acquire them. The ecological and evolutionary significance of smBGCs carried by prokaryotes in oxygen-depleted water columns is yet to be fully elucidated.
PubMed: 38792759
DOI: 10.3390/microorganisms12050929 -
Toxins May 2024Paralytic shellfish poisoning is an important concern for mollusk fisheries, aquaculture, and public health. In Galicia, NW Iberian Peninsula, such toxicity has been...
Paralytic Shellfish Toxins in Mollusks from Galicia Analyzed by a Fast Refined AOAC 2005.06 Method: Toxicity, Toxin Profile, and Inter-Specific, Spatial, and Seasonal Variations.
Paralytic shellfish poisoning is an important concern for mollusk fisheries, aquaculture, and public health. In Galicia, NW Iberian Peninsula, such toxicity has been monitored for a long time using mouse bioassay. Therefore, little information exists about the precise toxin analogues and their possible transformations in diverse mollusk species and environments. After the change in the European PSP reference method, a refinement of the Lawrence method was developed, achieving a 75% reduction in chromatogram run time. Since the beginning of 2021, when this refinement Lawrence method was accredited under the norm UNE-EN ISO/IEC 17025, it has been used in the area to determine the toxin profiles and to estimate PSP toxicity in more than 4500 samples. In this study, we have summarized three years of monitoring results, including interspecific, seasonal, and geographical variability of PSP toxicity and toxin profile. PSP was detected in more than half of the samples analyzed (55%), but only 4.4% of the determinations were above the EU regulatory limit. GTX1,4 was the pair of STX analogs that produced the highest toxicities, but GTX2,3 was found in most samples, mainly due to the reduction of GTX1,4 but also by the higher sensitivity of the method for this pair of analogs. STX seems to be mainly a product of biotransformation from GTX2,3. The studied species (twelve bivalves and one gastropod) accumulated and transformed PSP toxins to a different extent, with most of them showing similar profiles except for and . Two seasonal peaks of toxicity were found: one in spring-early summer and another in autumn, with slightly different toxin profiles during outbreaks in relation to the toxicity during valleys. In general, both the total toxicity and toxin profiles of the southernmost locations were different from those in the northern part of the Atlantic coast and the Cantabrian Sea, but this general pattern is modified by the PSP history of some specific locations.
Topics: Animals; Seasons; Shellfish Poisoning; Marine Toxins; Mollusca; Spain; Saxitoxin
PubMed: 38787082
DOI: 10.3390/toxins16050230