RESUMO
In the context of harmful algal blooms, fish can be exposed to the combined effects of more than one toxin. We studied the effects of consecutive exposure to Microcystin-LR (MCLR) in vivo and paralytic shellfish toxins (PST) ex vivo/in vitro (MCLR+PST) in the rainbow trout Oncorhynchus mykiss's middle intestine. We fed juvenile fish with MCLR incorporated in the feed every 12 h and euthanized them 48 h after the first feeding. Immediately, we removed the middle intestine to make ex vivo and in vitro preparations and exposed them to PST for one hour. We analyzed glutathione (GSH) and glutathione disulfide (GSSG) contents, glutathione S-transferase (GST), glutathione reductase (GR), catalase (CAT), and protein phosphatase 1 (PP1) activities in ex vivo intestinal strips; apical and basolateral ATP-biding cassette subfamily C (Abcc)-mediated transport in ex vivo everted and non- everted sacs; and reactive oxygen species (ROS) production in isolated enterocytes in vitro. MCLR+PST treatment decreased the GSH content, GSH/GSSG ratio, GST activity, and increased ROS production. GR activity remained unchanged, while CAT activity only increased in response to PST. MCLR inhibited PP1 activity and activated Abcc-mediated transport only at the basolateral side of the intestine. Our results show a combined effect of MCLR+PST on the oxidative balance in the O. mykiss middle intestine, which is not affected by the two toxins groups when applied individually. Basolateral Abcc transporters activation by MCLR treatment could lead to an increase in the absorption of toxicants (including MCLR) into the organism. Therefore, MCLR makes the O. mykiss middle intestine more sensitive to possibly co-occurring cyanotoxins like PST.
Assuntos
Mucosa Intestinal , Toxinas Marinhas , Microcistinas , Oncorhynchus mykiss , Estresse Oxidativo , Espécies Reativas de Oxigênio , Animais , Microcistinas/toxicidade , Toxinas Marinhas/toxicidade , Mucosa Intestinal/efeitos dos fármacos , Mucosa Intestinal/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Oncorhynchus mykiss/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Glutationa/metabolismo , Saxitoxina/toxicidadeRESUMO
This work highlights the significant potential of marine toxins, particularly saxitoxin (STX) and its derivatives, in the exploration of novel pharmaceuticals. These toxins, produced by aquatic microorganisms and collected by bivalve mollusks and other filter-feeding organisms, offer a vast reservoir of chemical and biological diversity. They interact with sodium channels in physiological processes, affecting various functions in organisms. Exposure to these toxins can lead to symptoms ranging from tingling sensations to respiratory failure and cardiovascular shock, with STX being one of the most potent. The structural diversity of STX derivatives, categorized into carbamate, N-sulfocarbamoyl, decarbamoyl, and deoxydecarbamoyl toxins, offers potential for drug development. The research described in this work aimed to computationally characterize 18 STX derivatives, exploring their reactivity properties within marine sponges using conceptual density functional theory (CDFT) techniques. Additionally, their pharmacokinetic properties, bioavailability, and drug-likeness scores were assessed. The outcomes of this research were the chemical reactivity parameters calculated via CDFT as well as the estimated pharmacokinetic and ADME properties derived using computational tools. While they may not align directly, the integration of these distinct datasets enriches our comprehensive understanding of the compound's properties and potential applications. Thus, this study holds promise for uncovering new pharmaceutical candidates from the considered marine toxins.
Assuntos
Toxinas Marinhas , Saxitoxina , Biodiversidade , Disponibilidade Biológica , Preparações FarmacêuticasRESUMO
The proliferation of Raphidiopsis raciborskii blooms has sparked concerns regarding potential human exposure to heightened saxitoxins (STXs) levels. Thus, comprehending how environmental elements drive the proliferation of this STXs-producing species can aid in predicting human exposure risks. This study aimed to explore the link between cyanobacteria R. raciborskii, STXs cyanotoxins, and environmental factors in 37 public supply reservoirs in the tropical region and assess potential health hazards these toxins pose in the reservoir waters. A Structural Equation Model was used to assess the impact of environmental factors (water volume and physical and chemical variables) on R. raciborskii biomass and STXs levels. Furthermore, the potential risk of STXs exposure from consuming untreated reservoir water was evaluated. Lastly, the cumulative distribution function (CDF) of STXs across the reservoirs was computed. Our findings revealed a correlation between R. raciborskii biomass and STXs concentrations. Total phosphorus emerged as a critical environmental factor positively influencing species biomass and indirectly affecting STXs levels. pH significantly influenced STXs concentrations, indicating different factors influencing R. raciborskii biomass and STXs. Significantly, for the first time, the risk of STXs exposure was gauged using the risk quotient (HQ) for untreated water consumption from public supply reservoirs in Brazil's semi-arid region. Although the exposure risks were generally low to moderate, the CDF underscored the risk of chronic exposure due to low toxin concentrations in over 90% of samples. These outcomes emphasize the potential expansion of R. raciborskii in tropical settings due to increased phosphorus, amplifying waterborne STXs levels and associated intoxication risks. Thus, this study reinforces the importance of nutrient control, particularly phosphorus regulation, as a mitigation strategy against R. raciborskii blooms and reducing STXs intoxication hazards.
Assuntos
Cylindrospermopsis , Saxitoxina , Qualidade da Água , Humanos , Brasil , FósforoRESUMO
Alexandrium tamiyavanichii is a marine dinoflagellate known to produce Paralytic Shellfish Poisoning (PSP) toxin. Thus, a strain was isolated from La Paz Bay, Baja California Sur, Mexico and used to explore whether stress conditions, such as phosphorus limitation (PL) and nitrogen enrichment (NE) modulate population growth and PSP toxin production in the GSe medium. Growth kinetics showed that the PL treatment produced a 3.4-fold increase in cell density versus control at day 30 of the culture cycle. The highest PSP concentration was found in the control culture (309 fmol cell-1) on day 21. Saxitoxin (STX) was the main analog in all the treatments (> 40 % mol). In conclusion, PL and NE treatments promoted growth kinetics in the species studied but did not affect the PSP toxin production. For the first time, the present research describes A. tamiyavanichii high toxicity strain isolated from Mexican coasts relative to the South-Atlantic strains.
Assuntos
Dinoflagellida , Intoxicação por Frutos do Mar , Humanos , México , Dinoflagellida/metabolismo , SaxitoxinaRESUMO
Harmful algal blooms (HABs) can produce a variety of noxious effects and, in some cases, the massive mortality of wild and farmed marine organisms. Some HAB species produce toxins that are released into seawater or transferred via food webs (particulate toxin fraction). The objective of the present study was to identify the toxicological effects of subacute exposure to saxitoxin (STX) during embryonic and early larval stages in Seriola rivoliana. Eggs were exposed to dissolved 19 STX (100 µg L-1). The toxic effects of STX were evaluated via the hatching percentage, the activity of three enzymes (protein and alkaline phosphatases and peroxidase), and the expression of four genes (HSF2, Nav1.4b, PPRC1, and DUSP8). A low hatching percentage (less than 5%) was observed in 44 hpf (hours post fertilization) embryos exposed to STX compared to 71% in the unexposed control. At this STX concentration, no oxidative stress in the embryos was evident. However, STX induced the expression of the NaV1.4 channel α-subunit (NaV1.4b), which is the primary target of this toxin. Our results revealed the overexpression of all four candidate genes in STX-intoxicated lecithotrophic larvae, reflecting the activation of diverse cellular processes involved in stress responses (HSF2), lipid metabolism (PPRC1), and MAP kinase signaling pathways associated with cell proliferation and differentiation (DUSP8). The effects of STX were more pronounced in young larvae than in embryos, indicating a stage-specific sensitivity to the toxin.
Assuntos
Perciformes , Saxitoxina , Animais , Saxitoxina/toxicidade , Toxicogenética , Proliferação Nociva de Algas , Organismos Aquáticos , LarvaRESUMO
Two Raphidiopsis (=Cylindrospermopsis) raciborskii metagenome-assembled genomes (MAGs) were recovered from two freshwater metagenomic datasets sampled in 2011 and 2012 in Pampulha Lake, a hypereutrophic, artificial, shallow reservoir, located in the city of Belo Horizonte (MG), Brazil. Since the late 1970s, the lake has undergone increasing eutrophication pressure, due to wastewater input, leading to the occurrence of frequent cyanobacterial blooms. The major difference observed between PAMP2011 and PAMP2012 MAGs was the lack of the saxitoxin gene cluster in PAMP2012, which also presented a smaller genome, while PAMP2011 presented the complete sxt cluster and all essential proteins and clusters. The pangenome analysis was performed with all Raphidiopsis/Cylindrospermopsis genomes available at NCBI to date, with the addition of PAMP2011 and PAMP2012 MAGs (All33 subset), but also without the South American strains (noSA subset), and only among the South American strains (SA10 and SA8 subsets). We observed a substantial increase in the core genome size for the 'noSA' subset, in comparison to 'All33' subset, and since the core genome reflects the closeness among the pangenome members, the results strongly suggest that the conservation level of the essential gene repertoire seems to be affected by the geographic origin of the strains being analyzed, supporting the existence of a distinct SA clade. The Raphidiopsis pangenome comprised a total of 7943 orthologous protein clusters, and the two new MAGs increased the pangenome size by 11%. The pangenome based phylogenetic relationships among the 33 analyzed genomes showed that the SA genomes clustered together with 99% bootstrap support, reinforcing the metabolic particularity of the Raphidiopsis South American clade, related to its saxitoxin producing unique ability, while also indicating a different evolutionary history due to its geographic isolation.
Assuntos
Cianobactérias , Cylindrospermopsis , Cylindrospermopsis/genética , Saxitoxina/genética , Saxitoxina/metabolismo , Filogenia , Metagenoma , Cianobactérias/genética , Lagos , BrasilRESUMO
Harmful algal blooms of toxin-producing microalgae are recurrent in southern Chile. Paralytic shellfish poisoning (PSP) outbreaks pose the main threat to public health and the fishing industry in the Patagonian fjords. This study aims to increase understanding of the individual and spatial variability of PSP toxicity in the foot of Concholepas concholepas, Chile's most valuable commercial benthic invertebrate species, extracted from the Guaitecas Archipelago in Chilean Patagonia. The objective is to determine the effect of pigment removal and freezing during the detoxification process. A total of 150 specimens (≥90 mm length) were collected from this area. The live specimens were transferred to a processing plant, where they were measured and gutted, the foot was divided into two equal parts, and pigment was manually removed from one of these parts. The PSP toxicity of each foot (edible tissue) was determined by mouse bioassay (MBA) and high-performance liquid chromatography with fluorescence detection and postcolumn oxidation (HPLC-FLD PCOX). The individual toxicity per loco, as the species is known locally, varied from <30 to 146 µg STX diHCL eq 100 g−1 (CV = 43.83%) and from 5.96 to 216.3 µg STX diHCL eq 100 g−1 (CV = 34.63%), using MBA and HPLC, respectively. A generalized linear model showed a negative relation between individual weight and toxicity. The toxicological profile showed a dominance of STX (>95%), neoSTX and GTX2. The removal of pigment produced a reduction in PSP toxicity of up to 90% and could represent a good detoxification tool moving forward. The freezing process in the muscle with pigment did not produce a clear pattern. There is a significant reduction (p < 0.05) of PSP toxicity via PCOX but not MBA. Furthermore, the study discusses possible management and commercialization implications of the findings regarding small-scale fisheries.
Assuntos
Gastrópodes , Intoxicação por Frutos do Mar , Animais , Camundongos , Toxinas Marinhas/análise , Saxitoxina/análise , Cromatografia Líquida de Alta Pressão , Frutos do Mar/análiseRESUMO
In freshwater, saxitoxins (STX) are produced by different cyanobacteria genera, including Raphidiopsis. Data regarding cytogenotoxicity effects of STX on human cells are scarse, this merit further studies of its toxicology. This study assessed the cytotoxicity and the chromosome instability of STX on SHSY-5Y human cell line. The CBMN assay allows the detection of chromosome breaks and abnormal chromosomal segregation. Additionally, in silico systems biology approach, used to search for known and predicted interaction networks, was applied to study the interactions between STX and SHSY-5Y cellular components. The results of the CBMN assay demonstrated that STX concentrations of 2.5 - 10 µg/L induced cytostasis and chromosome instability in a dose-response relationship. Apoptosis was detected after exposure of SHSY-5Y cultured cells to STX concentration of 10 µg/L. The results of the systems biology analysis revealed the interaction of STX with proteins related with acetylcoline pathway, cell cycle regulation and apoptosis. Furthermore, combining the in vitro and in silico approachs, it was possible to suggest a mechanism of action of STX in SHSY-5Y cells. Overall, the data demonstrated the cytotoxicity and mutagenicity of environmentally relevant concentrations of STX. These results should be considered when setting up guidelines for monitoring STX in water supply.
Assuntos
Saxitoxina , Biologia de Sistemas , Humanos , Saxitoxina/toxicidade , Instabilidade Cromossômica , Linhagem CelularRESUMO
In September and November 2016, eight marine sampling sites along the coast of the southeastern Gulf of Mexico were monitored for the presence of lipophilic and hydrophilic toxins. Water temperature, salinity, hydrogen potential, dissolved oxygen saturation, inorganic nutrients and phytoplankton abundance were also determined. Two samples filtered through glass fiber filters were used for the extraction and analysis of paralytic shellfish toxins (PSTs) by lateral flow immunochromatography (IFL), HPLC with post-column oxidation and fluorescent detection (FLD) and UHPLC coupled to tandem mass spectrometry (UHPLC-MS/MS). Elevated nutrient contents were associated with the sites of rainwater discharge or those near anthropogenic activities. A predominance of the dinoflagellate Pyrodinium bahamense was found with abundances of up to 104 cells L-1. Identification of the dinoflagellate was corroborated by light and scanning electron microscopy. Samples for toxins were positive by IFL, and the analogs NeoSTX and STX were identified and quantified by HPLC-FLD and UHPLC-MS/MS, with a total PST concentration of 6.5 pg cell-1. This study is the first report that confirms the presence of PSTs in P. bahamense in Mexican waters of the Gulf of Mexico.
Assuntos
Dinoflagellida , Intoxicação por Frutos do Mar , Humanos , Toxinas Marinhas/análise , Espectrometria de Massas em Tandem/métodos , Golfo do México , Dinoflagellida/química , Frutos do Mar/análise , SaxitoxinaRESUMO
Harmful algal blooms are an increasing worldwide threat to the seafood industry and human health as a consequence of the natural production of biotoxins that can accumulate in shellfish. In the Argentine Sea, this has been identified as an issue for the offshore fisheries of Patagonian scallops (Zygochlamys patagonica), leading to potentially harmful effects on consumers. Here we assess spatial and temporal patterns in marine biotoxin concentrations in Patagonian scallops harvested in Argentinian waters between 2012-2017, based on analyses for paralytic shellfish toxins, lipophilic toxins, and amnesic shellfish toxins. There was no evidence for concentrations of lipophilic or amnesic toxins above regulatory acceptance thresholds, with trace concentrations of pectenotoxin 2, azaspiracid 2 and okadaic acid group toxins confirmed. Conversely, paralytic shellfish toxins were quantified in some scallops. Gonyautoxins 1 and 2 dominated the unusual toxin profiles (91%) in terms of saxitoxin equivalents with maximum concentrations reaching 3985 µg STX eq/kg and with changes in profiles linked in part to seasonal changes. Total toxin concentrations were compared between samples of the adductor muscle and whole tissue, with results showing the absence of toxins in the adductor muscle confirming toxin accumulation in the digestive tracts of the scallops and the absence of a human health threat following the processing of scallop adductor meat. These findings highlight that paralytic shellfish toxins with an unusual toxin profile can occur in relatively high concentrations in whole Patagonian scallops in specific regions and during particular time periods, also showing that the processing of scallops on board factory ships to obtain frozen adductor muscle is an effective management process that minimizes the risk of poisonings from final products destined for human consumption.