ABSTRACT
Plasmonic Au-Ag nanostars are excellent surface-enhanced Raman scattering (SERS) probes due to bimetallic coupling and the tip effect. However, the existing preparation methods of AuAg nanostars cannot achieve controlled growth of the Ag layer on the branches of nanostars and so cannot display their SERS to the maximum extent, thus limiting its sensitivity in biosensing. Herein, a novel strategy "PEI (polyethylenimine)-guided Ag deposition method" is proposed for synthesizing AuAg core-shell nanostars (AuAg@Ag NS) with a tunable distribution of the Ag layer from the core to the tip, which offers an avenue for investigating the correlation between SERS efficiency and the extent of spread of the Ag layer. It is found that AuAg@Ag NS with a Ag layer coated the whole branch has the strongest SERS performance because the coupling between the tips and Ag layer is maximized. Meanwhile, as a completely closed core-shell structure, AuAg@Ag NS can confine and anchor 4-ATP inside the Ag layer to avoid an unstable SERS signal. By connecting the aptamer, a reliable internal standard nanoprobe with a SERS enhancement factor (EF) up to 1.86 × 108 is prepared. Okada acid is detected through competitive adsorption of this SERS probes, and the detection limit is 36.6 pM. The results gain fundamental insights into tailoring the nanoparticle morphologies and preparation of internal standard nanoprobes and also provide a promising avenue for marine toxin detection in food safety.
Subject(s)
Gold , Metal Nanoparticles , Okadaic Acid , Shellfish , Silver , Spectrum Analysis, Raman , Silver/chemistry , Spectrum Analysis, Raman/methods , Gold/chemistry , Okadaic Acid/analysis , Shellfish/analysis , Metal Nanoparticles/chemistry , Animals , Polyethyleneimine/chemistry , Limit of Detection , Aptamers, Nucleotide/chemistry , Food Contamination/analysisABSTRACT
Pomegranate polyphenol ellagic acid has medicinal potential in neurodegenerative disorders. The advantageous effect of this polyphenol in improving cognition in okadaic acid (OA)-instigated murine model with unraveling some modes of its action was assessed. Rats received ICV okadaic acid (OA) and post-treated with oral ellagic acid for 3 weeks (25 and 100 mg/kg/day). Cognition was analyzed in behavioral tasks besides assessment of oxidative, apoptotic, and inflammatory factors in addition to hippocampal histochemical analysis. Ellagic acid at a dose of 100 mg/kg properly attenuated cognitive abnormalities in novel object recognition (NOR), Y maze, and Barnes maze tests. Additionally, ellagic acid diminished hippocampal changes of malondialdehyde (MDA), protein carbonyl, reactive oxygen species (ROS), glutathione (GSH), glutathione peroxidase, superoxide dismutase (SOD), apoptotic factors caspases 1 and 3, tumor necrosis factor α (TNFα), and acetylcholinesterase (AChE) and beta secretase 1 (BACE 1) besides reversal of AMP-activated protein kinase (AMPK) and hyperphosphorylated tau (p-tau). Moreover, lower glial fibrillary acidic protein (GFAP) and less injury of hippocampal CA1 pyramidal neurons were observed upon ellagic acid. To conclude, neuroprotective potential of ellagic acid was shown which is somewhat attributable to its reversal of oxidative, apoptotic, and neuroinflammatory events in addition to proper regulation of AMPK and p-tau.
ABSTRACT
Dinophysis, a mixotrophic dinoflagellate that is known to prey on the ciliate Mesodinium rubrum, and retain its chloroplasts, is responsible for diarrhetic shellfish poisoning (DSP) in humans and has been identified on all U.S. coasts. Monocultures of Dinophysis have been used to investigate the growth of Dinophysis species in response to variations in environmental conditions, however, little is known about the roles of system stability (turbulence) and mixotrophy in the growth and toxicity of Dinophysis species in the U.S.. To begin to address this gap in knowledge, culturing experiments were conducted with three species (four strains) of Dinophysis, that included predator-prey co-incubation (Dinophysis spp.+ M. rubrum) and prey-only (M. rubrum) flasks. Cultures were investigated for effects of low or high turbulence on Dinophysis spp. growth, feeding, and amounts of intra- and extracellular toxins: okadaic acid and derivatives (diarrhetic shellfish toxins, DSTs) and pectenotoxins (PTXs). Turbulence did not have a measurable effect on the rates of ingestion of M. rubrum prey by Dinophysis spp. for any of the four strains, however, effects on growth and particulate and dissolved toxins were observed. High turbulence (ε = 10-2 m2s-3) significantly slowed growth of both D. acuminata and D. ovum relative to still controls, but significantly stimulated growth of the D. caudata strain. Increasing turbulence also resulted in significantly higher intracellular toxin content in D. acuminata cultures (DSTs and PTXs), but significantly reduced intracellular toxin content (PTXs) in those of D. caudata. An increase in turbulence appeared to promote toxin leakage, as D. ovum had significantly more extracellular DSTs found in the medium under high turbulence when compared to the still control. Overall, significant responses to turbulence were observed, whereby the three strains from the "Dinophysis acuminata complex" displayed a stress response to turbulence, i.e., decreasing growth, increasing intracellular toxin content and/or increasing toxin leakage, while the D. caudata strain had an opposite response, appearing stimulated by, or more tolerant of, high turbulence.
Subject(s)
Dinoflagellida , Marine Toxins , Okadaic Acid , Dinoflagellida/physiology , Dinoflagellida/growth & development , Marine Toxins/metabolism , Okadaic Acid/metabolism , Ciliophora/physiology , Ciliophora/metabolismABSTRACT
Okadaic acid (OA), a prevalent marine biotoxin found in shellfish, is known for causing acute gastrointestinal symptoms. Despite its potential to reach the bloodstream and the liver, the hepatic effects of OA are not well understood, highlighting a significant research gap. This study aims to comprehensively elucidate the impact of OA on the liver by examining the transcriptome, proteome, and phosphoproteome alterations in human HepaRG liver cells exposed to non-cytotoxic OA concentrations. We employed an integrative multi-omics approach, encompassing RNA sequencing, shotgun proteomics, phosphoproteomics, and targeted DigiWest analysis. This enabled a detailed exploration of gene and protein expression changes, alongside phosphorylation patterns under OA treatment. The study reveals concentration- and time-dependent deregulation in gene and protein expression, with a significant down-regulation of xenobiotic and lipid metabolism pathways. Up-regulated pathways include actin crosslink formation and a deregulation of apoptotic pathways. Notably, our results revealed that OA, as a potent phosphatase inhibitor, induces alterations in actin filament organization. Phosphoproteomics data highlighted the importance of phosphorylation in enzyme activity regulation, particularly affecting proteins involved in the regulation of the cytoskeleton. OA's inhibition of PP2A further leads to various downstream effects, including alterations in protein translation and energy metabolism. This research expands the understanding of OA's systemic impact, emphasizing its role in modulating the phosphorylation landscape, which influences crucial cellular processes. The results underscore OA's multifaceted effects on the liver, particularly through PP2A inhibition, impacting xenobiotic metabolism, cytoskeletal dynamics, and energy homeostasis. These insights enhance our comprehension of OA's biological significance and potential health risks.
Subject(s)
Carcinoma, Hepatocellular , Liver Neoplasms , Okadaic Acid , Proteomics , Okadaic Acid/toxicity , Humans , Liver Neoplasms/metabolism , Liver Neoplasms/pathology , Cell Line, Tumor , Carcinoma, Hepatocellular/metabolism , Phosphorylation , Proteome/drug effects , Proteome/metabolism , Transcriptome/drug effects , Marine Toxins , Hepatocytes/drug effects , Hepatocytes/metabolism , Liver/drug effects , Liver/metabolism , MultiomicsABSTRACT
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-1, 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.
Subject(s)
Marine Toxins , Mytilus , Okadaic Acid , Phytoplankton , Okadaic Acid/analysis , Okadaic Acid/toxicity , Animals , Marine Toxins/analysis , Slovenia , Seafood/analysis , Seawater/chemistry , DinoflagellidaABSTRACT
Dinophysistoxin 1 (DTX1, 1) and okadaic acid (OA, 2), produced by the dinoflagellates Dinophysis spp. and Prorocentrum spp., are primary diarrhetic shellfish toxins (DSTs), which may cause gastric illness in people consuming such as bivalves. Both compounds convert to dinophysistoxin 3 (DTX3, 3; generic name for 1 and 2 with fatty acids conjugated at 7-OH) in bivalves. The enzyme okadaic acid O-acyl transferase (OOAT) is a membrane protein found in the microsomes of the digestive glands of bivalves. In this study, we established an in vitro enzymatic conversion reaction using 4-nitro-2,1,3-benzoxadiazole (NBD)-OA (4), an OA derivative conjugated with (R)-(-)-4-nitro-7-(3-aminopyrrolidin-1-yl)-2,1,3-benzoxadiazole (NBD-APy) on 1-CO2H, as a substrate. We detected the enzymatically produced 3, NBD-7-O-palmitoyl-OA (NBD-Pal-OA), using high-performance liquid chromatography-fluorescence detection. We believe that an OOAT assay using 4 will facilitate the fractionation and isolation of OOAT in the future.
Subject(s)
Acyltransferases , Okadaic Acid , Chromatography, High Pressure Liquid/methods , Acyltransferases/metabolism , Acyltransferases/chemistry , Animals , Oxadiazoles/chemistry , Enzyme Assays/methodsABSTRACT
BACKGROUND: Okadaic acid (OA), as a diarrhetic shellfish poisoning, can increase the risk of acute carcinogenic or teratogenic effects for the ingestion of OA contaminated shellfish. At present, much effort has been made to graft immunoassay onto a paper substrate to make paper-based sensors for rapid and simple detection of shellfish toxin. However, the complicated washing steps and low protein fixation efficiency on the paper substrate need to be further addressed. RESULTS: A novel paper-tip immunosensor for detecting OA was developed combined with smartphone and naked eye readout. The trapezoid paper tip was consisted of quantitative and qualitative detection zones. To improve the OA antigen immobilization efficiency on the paper substrate, graphene oxide (GO)-assisted protein immobilization method was introduced. Meanwhile, Au nanoparticles composite probe combined with the lateral flow washing was developed to simplify the washing step. The OA antigen-immobilized zone, as the detection zone â , was used for quantitative assay by smartphone imaging. The paper-tip front, as the detection zone â ¡, which could qualitatively differentiate OA pollution level within 45 min using the naked eye. The competitive immunoassay on the paper tip exhibited a wide linear range for detecting OA (0.02-50 ngâmL-1) with low detection limit of 0.02 ngâmL-1. The recovery of OA in spiked shellfish samples was in the range of 90.3 %-113.%. SIGNIFICANCE: These results demonstrated that the proposed paper-tip immunosensor could provide a simple, low-cost and high-sensitivity test for OA detection without the need for additional large-scale equipment or expertise. We anticipate that this paper-tip immunosensor will be a flexible and versatile tool for on-site detecting the pollution of marine products.
Subject(s)
Biosensing Techniques , Gold , Graphite , Okadaic Acid , Paper , Smartphone , Graphite/chemistry , Okadaic Acid/analysis , Immunoassay/methods , Gold/chemistry , Metal Nanoparticles/chemistry , Immobilized Proteins/chemistry , Limit of Detection , Animals , Antibodies, Immobilized/immunology , Antibodies, Immobilized/chemistryABSTRACT
In this study, a sensitive dual-signal electrochemiluminescence (ECL) immunosensor was developed for okadaic acid (OA) detection utilizing copper nanoclusters (CuNCs) and Ru(bpy)32+-doped silica nanoparticles (RuSiNPs). Interestingly, the CuNCs could simultaneously enhance both cathodic (-0.95 V) and anodic (+1.15 V) ECL signals of RuSiNPs, forming a dual-signal ECL sensing platform. Further, RuSiNPs@CuNCs were used as immunomarkers by covalently conjugating them with an anti-OA monoclonal antibody (mAb) to form probes. Finally, dual ECL signals of the immunosensor were fabricated and showed good linear relationships with OA concentrations in the range of 0.05-70 ng mL-1, having a median inhibitory concentration (IC50) of 1.972 ng mL-1 and a limit of detection of 0.039 ng mL-1. Moreover, the constant ratio of the cathodic and anodic ECL peaks achieved self-calibration of the detection signal and improved the reliability of the results. Finally, we successfully applied the ECL sensor to detect OA in spiked oyster samples.
Subject(s)
Copper , Electrochemical Techniques , Luminescent Measurements , Okadaic Acid , Silicon Dioxide , Copper/chemistry , Silicon Dioxide/chemistry , Luminescent Measurements/methods , Luminescent Measurements/instrumentation , Okadaic Acid/analysis , Nanoparticles/chemistry , Animals , Biosensing Techniques , Limit of Detection , Immunoassay/methods , Immunoassay/instrumentation , Metal Nanoparticles/chemistryABSTRACT
Microplastics (MPs) and okadaic acid (OA) are known to coexist in marine organisms, potentially impacting humans through food chain. However, the combined toxicity of OA and MPs remains unknown. In this study, mice were orally administered OA at 200⯵g/kg bw and MPs at 2â¯mg/kg bw. The co-exposure group showed a significant increase in malondialdehyde (MDA) content and significant decreases in superoxide dismutase (SOD) activity and glutathione (GSH) level compared to the control, MPs and OA groups (p < 0.05). Additionally, the co-exposure group exhibited significantly higher levels of IL-1ß and IL-18 compared to other groups (p < 0.05). These results demonstrated that co-exposure to MPs and OA induces oxidative stress and exacerbates inflammation. Histological and cellular ultrastructure analyses suggested that this combined exposure may enhance gut damage and compromise barrier integrity. Consequently, the concentration of OA in the small intestine of the co-exposure group was significantly higher than that in the OA group. Furthermore, MPs were observed in the lamina propria of the gut in the co-exposure group. Transcriptomic analysis revealed that the co-exposure led to increased expression of certain genes related to the NF-κB/NLRP3 pathway compared to the OA and MPs groups. Overall, this combined exposure may disrupt the intestinal barrier, and promote inflammation through the NF-κB/NLRP3 pathway. These findings provide precious information for the understanding of health risks associated with MPs and phycotoxins.
Subject(s)
Intestine, Small , Microplastics , Okadaic Acid , Oxidative Stress , Polystyrenes , Animals , Microplastics/toxicity , Mice , Okadaic Acid/toxicity , Intestine, Small/drug effects , Intestine, Small/pathology , Intestine, Small/ultrastructure , Polystyrenes/toxicity , Oxidative Stress/drug effects , Malondialdehyde/metabolism , Male , NLR Family, Pyrin Domain-Containing 3 Protein/metabolism , NLR Family, Pyrin Domain-Containing 3 Protein/genetics , Glutathione/metabolism , Superoxide Dismutase/metabolism , Water Pollutants, Chemical/toxicityABSTRACT
Background: Royal jelly is an anti-inflammatory, antioxidant, and neuroprotective bee product. There are several sources for royal jelly and one of them is Indian Royal Jelly (IRJ). However, the neuroprotective actions of IRJ and the underlying molecular mechanisms involved are not well known. Objective: To evaluate the neuroprotective effect of IRJ in the okadaic acid (OKA)-induced Alzheimer's disease (AD) model in rats. Methods: In male Wistar rats, OKA was intracerebroventricularly (ICV) administered, and from day 7, they were treated orally with IRJ or memantine for 21 days. Spatial and recognition learning and memory were evaluated from days 27-34; employing the Morris water maze (MWM) and the novel object recognition tests (NORT), respectively. In vitro biochemical measurements were taken of the cholinergic system and oxidative stress markers. In silico docking was used to find the role of tau protein kinase and phosphatase in the pharmacological action. Results: In OKA-induced rats, IRJ decreased the escape latency and path length in MWM and increased the exploration time for novel objects and the discrimination index in NORT. ICV-OKA rats had higher free radicals and cytokines that caused inflammation and their level of free radical scavengers was back to normal with IRJ treatment. IRJ increased the level of acetylcholine and inhibited acetylcholinesterase. Moreover, the in silico docking study revealed the strong binding affinity of 10-hydroxy-2-decenoic acid (10-HDA), a bioactive constituent of IR, to the tau protein kinases and phosphatases. Conclusion: IRJ may serve as a nootropic agent in the treatment of dementia, and owing to its capacity to prevent oxidative stress and neuroinflammation, and increase cholinergic tone; it has the potential to be explored as a novel strategy for the treatment of dementia and AD. More studies may be needed to develop 10-HDA as a novel drug entity for AD.
ABSTRACT
In Western Europe, the incidence of DST is likely the highest globally, posing a significant threat with prolonged bans on shellfish harvesting, mainly caused by species of the dinoflagellate genus Dinophysis. Using a time series from 2014 to 2020, our study aimed (i) to determine the concentration of D. acuminata in water at which shellfish toxin levels could surpass the regulatory limit (160 µg OA equiv kg-1) and (ii) to assess the predictability of toxic events for timely mitigation actions, especially concerning potential harvesting bans. The analysis considered factors such as (i) overdispersion in the data, (ii) distinct periods of presence and absence, (iii) the persistence of cells, and (iv) the temporal lag between cells in the water and toxins in shellfish. Four generalized additive models were tested, with the Tweedie (TW-GAM) model showing superior performance (>85%) and lower complexity. The results suggest existing thresholds currently employed (200 and 500 cells L-1) are well-suited for the Portuguese coast, supported by empirical evidence (54-79% accuracy). The developed algorithm allows for thresholds to be tailored on a case-by-case basis, offering flexibility for regional variations.
Subject(s)
Dinoflagellida , Marine Toxins , Shellfish Poisoning , Shellfish , Marine Toxins/analysis , Marine Toxins/toxicity , Shellfish Poisoning/prevention & control , Animals , Portugal , Environmental Monitoring/methods , Food Contamination/analysisABSTRACT
BACKGROUND: Reliability and robustness have been recognized as key challenges for Surface-enhanced Raman scattering (SERS) analytical techniques. Quantifying the concentration of an analyte using a single characteristic peak from SERS has been a controversial topic because the Raman signal is susceptible to highly concentrated electromagnetic hotspots, inhomogeneity of SERS substrate, or non-standardization of measurement conditions. Ratiometric SERS strategies have been demonstrated as a promising solution to effectively balance and compensate for signal fluctuations caused by matrix heterogeneity. However, it is not easy to construct ratiometric SERS sensors with monitoring the ratio of two different signal intensities for target analysis. RESULTS: An attempt has been made to develop a novel ratiometric biosensor that can be applied to detect okadaic acid (OA). Aptamer-anchored magnetic particles were first combined with gold-tagged short complementary DNA (Au-cDNA) to create heterogeneous nanostructures. When the target was present, the Au-cDNA was dissociated from nanostructures, and 4-nitrothiophenol (4-NTP) was initiated to reduce to 4-aminothiophenol (4-ATP) in the presence of hydrogen sources. The SERS ratio change of 4-NTP and 4-ATP was finally detected by AuNPs-coated film. OA was successfully quantified, and the detection limit was as low as 2.4524 ng/mL. The constructed biosensor had good stability and reproducibility with a relative standard deviation of less than 4.47%. The proposed method used gold nanoparticles as an intermediate to achieve catalytic signal amplification and subsequently increased the sensitivity of the biosensor. SIGNIFICANCE AND NOVELTY: Catalytic reaction-based ratiometric SERS biosensors combine the multiple advantages of catalytic signal amplification and signal self-calibration and provide new insights into the development of stable, reproducible, and reliable SERS detection techniques. This ratiometric SERS technique offered a universal method that is anticipated to be applicable for the detection of other targets by substituting the aptamer.
Subject(s)
Biosensing Techniques , Gold , Metal Nanoparticles , Okadaic Acid , Spectrum Analysis, Raman , Spectrum Analysis, Raman/methods , Gold/chemistry , Biosensing Techniques/methods , Okadaic Acid/analysis , Metal Nanoparticles/chemistry , Aptamers, Nucleotide/chemistry , Food Contamination/analysis , Limit of Detection , Food Analysis/methods , Surface PropertiesABSTRACT
Halomonas pacifica CARE-V15 was isolated from the southeastern coast of India to determine its genome sequence. Secondary metabolite gene clusters were identified using an anti-SMASH server. The concentrated crude ethyl acetate extract was evaluated by GC-MS. The bioactive compound from the crude ethyl acetate extract was fractionated by gel column chromatography. HPLC was used to purify the 3,6-diisobutyl-2,5-piperazinedione (DIP), and the structure was determined using FTIR and NMR spectroscopy. Purified DIP was used in an in silico molecular docking analysis. Purified DIP exhibits a stronger affinity for antioxidant genes like glutathione peroxidase (GPx), glutathione-S-transferase (GST), and glutathione reductase (GSR). Using in silco molecular docking analysis, the protein-ligand binding affinities of GSR (-4.70 kcal/mol), GST (-5.27 kcal/mol), and GPx (-5.37 kcal/mol) were measured. The expression of antioxidant genes were investigated by qRT-PCR. The in vivo reactive oxygen species production, lipid peroxidation, and cell death levels were significantly (p ≤ 0.05) increased in OA-induced group, but all these levels were significantly (p ≤ 0.05) decreased in the purified DIP pretreated group. Purified DIP from halophilic bacteria could thus be a useful treatment for neurological disorders associated with oxidative stress.
Subject(s)
Acetates , Antioxidants , Halomonas , Neuroprotective Agents , Animals , Antioxidants/pharmacology , Antioxidants/metabolism , Zebrafish/metabolism , Neuroprotective Agents/pharmacology , Okadaic Acid/metabolism , Okadaic Acid/pharmacology , Molecular Docking Simulation , Oxidative Stress , Glutathione Peroxidase/metabolism , Glutathione Reductase/metabolism , Diketopiperazines/metabolism , Diketopiperazines/pharmacology , Glutathione Transferase/metabolismABSTRACT
Okadaic acid (OA) is one of the most potent marine biotoxins, causing diarrheal shellfish poisoning (DSP). The proliferation of microalgae that produce OA and its analogues is frequent, threatening human health and socioeconomic development. Several methods have been tested to remove this biotoxin from aquatic systems, yet none has proven enough efficacy to solve the problem. In this work, we synthesized and characterized low-cost composites and tested their efficacy for OA adsorption in saltwater. For the synthesis of the composites, the following starting materials were considered: chitosan of low and medium molecular weight (CH-LW and CH-MW, respectively), activated carbon (AC), and montmorillonite (MMT). Characterization by vibrational spectroscopy (FTIR), X-ray diffraction (XRD), and microscopy revealed differences in the mode of interaction of CH-LW and CH-MW with AC and MMT, suggesting that the interaction of CH-MW with MMT has mainly occurred on the surface of the clay particles and no sufficient intercalation of CH-MW into the MMT interlayers took place. Among the composites tested (CH-LW/AC, CH-MW/AC, CH-MW/AC/MMT, and CH-MW/MMT), CH-MW/MMT was the one that revealed lower OA adsorption efficiency, given the findings evidenced by the structural characterization. On the contrary, the CH-MW/AC composite revealed the highest average percentage of OA adsorption (53 ± 11%). Although preliminary, the results obtained in this work open up good perspectives for the use of this type of composite material as an adsorbent in the removal of OA from marine environments.
Subject(s)
Bentonite , Chitosan , Okadaic Acid , Adsorption , Chitosan/chemistry , Okadaic Acid/chemistry , Bentonite/chemistry , Charcoal/chemistry , Marine Toxins/chemistry , Shellfish Poisoning/prevention & controlABSTRACT
This study was designed to investigate the potential neuronal damage mechanism of the okadaic acid (OA) in the brain tissues of zebrafish embryos by evaluating in terms of immunofluorescence of Nf KB, TLR-4, caspase 3, ERK ½, c-FOS and 8-OHdG signaling pathways. We also evaluated body malformations. For this purpose, zebrafish embryos were exposed to 0.5 µg/ml, 1 µg/ml and 2.5 µg/ml of OA for 5 days. After application, FITC/GFP labeled protein-specific antibodies were used in immunofluorescence assay for NfKB, TLR-4, caspase 3, ERK ½, c-FOS and 8-OHdG respectively. The results indicated that OA caused immunofluorescence positivity of NfKB, TLR-4, caspase 3, ERK ½, c-FOS and 8-OHdG in a dose-dependent manner in the brain tissues of zebrafish embryos. Pericardial edema (PE), nutrient sac edema (YSE) and body malformations, tail malformation, short tail and head malformation (BM) were detected in zebrafish embryos. These results suggest that OA induces neuronal damage by affecting the modulation of DNA damage, apoptotic, and inflammatory activities in the brain tissues of zebrafish embryos. The increase in signaling pathways shows that OA can cause damage in the structure and function of brain nerve cells. Our results provide a new basis for the comprehensive assessment of the neural damage of OA and will offer enable us to better understand molecular the mechanisms underlying the pathophysiology of OA toxicity.
Subject(s)
Brain , NF-kappa B , Okadaic Acid , Signal Transduction , Toll-Like Receptor 4 , Zebrafish , Animals , Zebrafish/immunology , Brain/drug effects , Toll-Like Receptor 4/genetics , Toll-Like Receptor 4/metabolism , Signal Transduction/drug effects , Okadaic Acid/toxicity , NF-kappa B/metabolism , NF-kappa B/immunology , 8-Hydroxy-2'-Deoxyguanosine , Caspase 3/metabolism , Caspase 3/genetics , Larva/drug effects , Proto-Oncogene Proteins c-fos/metabolism , Proto-Oncogene Proteins c-fos/genetics , Deoxyguanosine/analogs & derivatives , Deoxyguanosine/metabolismABSTRACT
An accurate and efficient method was developed for the determination of azaspiracid shellfish toxins (azaspiracids-1, -2, and -3), neurotoxic shellfish toxins (brevetoxins-2 and -3), diarrhetic shellfish toxins (okadaic acid and dinophysistoxins-1 and -2), and the amnesic shellfish toxin (domoic acid) in mussels (Mytilus galloprovincialis). Lipophilic marine biotoxins (azaspiracids, brevetoxins, and okadaic acid group) were extracted with 0.5 % acetic acid in methanol under heating at 60°C to improve the extraction efficiency of okadaic acid group toxins and then cleaned up with a C18 solid-phase extraction cartridge. Domoic acid was extracted with 50 % aqueous methanol and then cleaned up with a graphitized carbon solid-phase extraction cartridge. Lipophilic marine biotoxins and domoic acid were quantified by reversed-phase liquid chromatography coupled to electrospray ionization tandem mass spectrometry. The developed method had insignificant matrix effects for the nine analytes and good recoveries in the range of 79.0 % to 97.6 % at three spiking levels for all analytes except brevetoxin-2 (43.8-49.8 %). The developed method was further validated by analyzing mussel tissue certified reference materials, and good agreement was observed between certified and determined values.
Subject(s)
Bivalvia , Kainic Acid/analogs & derivatives , Oxocins , Polyether Toxins , Spiro Compounds , Tandem Mass Spectrometry , Animals , Okadaic Acid/analysis , Tandem Mass Spectrometry/methods , Chromatography, Reverse-Phase , Methanol , Chromatography, Liquid/methods , Shellfish/analysis , Marine Toxins/analysis , Bivalvia/chemistry , Solid Phase ExtractionABSTRACT
Marine biotoxins are a heterogenous group of natural toxins, which are able to trigger different types of toxicological responses in animals and humans. Health effects arising from exposure to marine biotoxins are ranging, for example, from gastrointestinal symptoms to neurological effects, depending on the individual toxin(s) ingested. Recent research has shown that the marine biotoxin okadaic acid (OA) can strongly diminish the expression of drug-metabolizing cytochrome P450 (CYP) enzymes in human liver cells by a mechanism involving proinflammatory signaling. By doing so, OA may interfere with the metabolic barrier function of liver and intestine, and thus alter the toxico- or pharmacokinetic properties of other compounds. Such effects of marine biotoxins on drug and xenobiotic metabolism have, however, not been much in the focus of research yet. In this review, we present the current knowledge on the effects of marine biotoxins on CYP enzymes in mammalian cells. In addition, the role of CYP-regulating nuclear receptors as well as inflammatory signaling in the regulation of CYPs by marine biotoxins is discussed. Strong evidence is available for effects of OA on CYP enzymes, along with information about possible molecular mechanisms. For other marine biotoxins, knowledge on effects on drug metabolism, however, is scarce.
Subject(s)
Cytochrome P-450 Enzyme System , Marine Toxins , Animals , Humans , Marine Toxins/toxicity , Cytochrome P-450 Enzyme System/metabolism , Okadaic Acid , Liver , Receptors, Cytoplasmic and Nuclear , Mammals/metabolismABSTRACT
Okadaic Acid, a type of diarrhetic shellfish poison, is widely distributed and harmful, causing symptoms such as diarrhea, vomiting, and more in humans. Recent studies have demonstrated that OA can lead to various toxicities such as cytotoxicity, neurotoxicity, embryotoxicity, and hepatotoxicity. In order to investigate the immunotoxicity of OA on intestinal cells, a transcriptome analysis was conducted to compare the differences in the Caco-2â cell transcriptional group before and after administration. The CCK-8 experiment demonstrated that OA had a detrimental effect on the activity of Caco-2 cells, with an IC50 value of 33.98â nM. Transcriptome data revealed changes in immune-related genes between the experimental and control groups, including inflammatory factors, heat shock proteins, and zinc finger proteins. The analysis of the results suggests that OA can induce the production of inflammatory factors and apoptosis in cells, and may also affect cell ferroptosis. These findings indicate that OA has a significant impact on intestinal immunity, providing valuable insights for the study of immune toxicity associated with OA.
Subject(s)
Apoptosis , Intestines , Humans , Okadaic Acid/toxicity , Caco-2 Cells , Gene Expression ProfilingABSTRACT
AIM: The objective of this study is to explore the impact and underlying mechanism of Scutellaria baicalensis Georgi stem and leaf flavonoids (SSFs) on cognitive impairment caused by intracerebroventricular injection of okadaic acid (OA) in rats. METHODS: An experimental model of Alzheimer's disease (AD) was induced in rats by intracerebroventricular injection of OA, resulting in memory impairment. The Morris water maze test was employed to confirm the successful establishment of the memory impairment model. The rats that exhibited significant memory impairment were randomly divided into different groups, including a model group, three SSFs dose groups (25, 50, and 100 mg/kg), and a positive control group treated with Ginkgo biloba tablets (GLT) at a dose of 200 mg/kg. To evaluate the learning and memory abilities of the rats, the Morris water maze test was conducted. Hematoxylin-eosin (HE) staining was used to observe any morphological changes in neurons. Immunohistochemistry (IHC) was performed to measure the expression of choline acetyltransferase (ChAT) protein. Western blotting (WB) was utilized to assess the phosphorylation levels of tau protein at Ser262 and Ser396. The activities of inducible nitric oxide synthase (iNOS) and constitutive nitric oxide synthase (cNOS) were quantified using ultraviolet spectrophotometry. The levels of inflammatory factors, including interleukin-1ß (IL-1ß), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6), were measured using ELISA. RESULTS: In rats, the administration of OA via intracerebroventricular injection resulted in cognitive impairment, neuropathological changes, and alterations in protein expression and activity levels. Specifically, the protein expression of ChAT was significantly reduced (P<0.01), while the phosphorylation levels of tau protein at Ser262 and Ser396 were significantly increased (P<0.01). Moreover, iNOS activity in the hippocampus and cerebral cortex exhibited a significant increase (P<0.01), whereas cNOS activity showed a decrease (P<0.05). Furthermore, the levels of IL-1ß and TNF-α in the cerebral cortex were elevated (P<0.01), while the level of IL-6 was decreased (P<0.05). The administration of three doses of SSFs and GLT to rats exhibited varying degrees of improvement in the aforementioned pathological alterations induced by OA. CONCLUSION: SSFs demonstrated the ability to enhance cognitive function and mitigate memory deficits in rats following intracerebroventricular injection of OA. This beneficial effect may be attributed to the modulation of ChAT protein expression, tau hyperphosphorylation, NOS activity, and inflammatory cytokine levels by SSFs.
ABSTRACT
It is still limited that how the microalgal toxin okadaic acid (OA) affects the intestinal microbiota in marine fishes. In the present study, adult marine medaka Oryzias melastigma was exposed to the environmentally relevant concentration of OA (5 µg/L) for 10 days, and then recovered in fresh seawater for 10-days depuration. Analysis of taxonomic composition and diversity of the intestinal microbiota, as well as function prediction analysis and histology observation were carried out in this study. Functional prediction analysis indicated that OA potentially affected the development of colorectal cancer, protein and carbohydrate digestion and absorption functions, and development of neurodegenerative diseases like Parkinson's disease, which may be associated with changes in Proteobacteria and Firmicutes in marine medaka. Significant increases of C-reactive protein (CRP) and inducible nitric oxide synthase (iNOS) levels, as well as the changes of histology of intestinal tissue demonstrated that an intestinal inflammation was induced by OA exposure in marine medaka. This study showed that the environmental concentrations of OA could harm to the intestinal microbiota thus threatening the health of marine medaka, which hints that the chemical ecology of microalgal toxins should be paid attention to in future studies.