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Saxitoxin

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https://www.readbyqxmd.com/read/29128272/cytoprotection-of-lipoic-acid-against-toxicity-induced-by-saxitoxin-in-hippocampal-cell-line-ht-22-through-in-silico-modeling-and-in-vitro-assays
#1
Patrícia Ramos, Marcos Schmitz, Sibele Gama, Aline Portantiolo, Michael Gonzalez Durruthy, Ana Paula de Souza Votto, Luisa Rodrigues Cornetet, Karina Dos Santos Machado, Adriano Wehrli, Mariana Zancan Tonel, Solange Binotto Fagan, João Sarkis Yunes, José Maria Monserrat
Saxitoxins (STXs) are potent neurotoxins that block voltage-gated channels in neurons and induce cytotoxicity. These toxins not only can generate reactive oxygen species but also can alter antioxidant levels, promoting oxidative stress. Under this pro-oxidant situation, the use of the antioxidant lipoic acid (LA) can represent a chemoprotective alternative to minimize the deleterious effects induced by neurotoxins as STXs. P-glycoprotein (P-gp) is a well-known ATP-binding cassette (ABC) transporter that plays a crucial role in the extrusion of toxic substances, decreasing their accumulation and potential intracellular effects in virtue of its broad substrate specificity, its expression in many excretory tissues and its large efflux capacity...
November 8, 2017: Toxicology
https://www.readbyqxmd.com/read/29100123/comparative-studies-of-saxitoxin-stx-induced-cytotoxicity-in-neuro-2a-and-rtg-2%C3%A2-cell-lines-an-explanation-with-respect-to-changes-in-ros
#2
Zhongyuan Zhou, Xuexi Tang, Hongmei Chen, You Wang
Saxitoxin (STX), a paralytic shellfish toxin (PST) produced from toxic bloom-forming dinoflagellates, was selected to comparatively investigate the induction of cytotoxicity and apoptosis and a possible mechanism based on changes in the antioxidant defence system of two cellular strains: the mouse neuroblastoma cell line Neuro-2a and the rainbow trout fish cell line RTG-2. Increasing concentrations of STX (0-256 nM) presented little cytotoxic or apoptotic effects on the two cell lines. Measurements of cellular viability, lethal ratio and LDH leakage showed slight changes in Neuro-2a and RTG-2 cells (p > 0...
October 14, 2017: Chemosphere
https://www.readbyqxmd.com/read/29079725/complementary-mechanisms-for-neurotoxin-resistance-in-a-copepod
#3
Vittoria Roncalli, Petra H Lenz, Matthew C Cieslak, Daniel K Hartline
Toxin resistance is a recurring evolutionary response by predators feeding on toxic prey. These adaptations impact physiological interaction and community ecology. Mechanisms for resistance vary depending on the predator and the nature of the toxin. Potent neurotoxins like tetrodotoxin (TTX) and saxitoxin (STX) that are highly toxic to humans and other vertebrates, target conserved voltage-gated sodium channels (NaV) of nerve and muscle, causing paralysis. The copepod Calanus finmarchicus consumes the STX-producing dinoflagellate, Alexandrium fundyense with no effect on survival...
October 27, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29074674/draft-genome-sequences-of-two-brazilian-cyanobacterial-strains-of-cylindrospermopsis-raciborskii-differences-in-membrane-transporters-saxitoxin-production-and-antioxidant-activities
#4
Luísa Hoffmann, Ravi José Tristão Ramos, Iame Alves Guedes, Pamela Fernandes Costa, Catarina Rufino Diniz Miguel, Sandra Maria Feliciano de Oliveira E Azevedo, Rosane Silva
We report here the draft genome sequences of two Brazilian strains of Cylindrospermopsis raciborskii, a saxitoxin-producer (CYRF) and a non-saxitoxin producer (CYLP), with each strain comprising one assembled scaffold. We revealed differences in the compositions of gene members coding for membrane transporters and antioxidant activities between the strains.
October 26, 2017: Genome Announcements
https://www.readbyqxmd.com/read/29027918/temperature-influences-the-production-and-transport-of-saxitoxin-and-the-expression-of-sxt-genes-in-the-cyanobacterium-aphanizomenon-gracile
#5
Samuel Cirés, Adrián Delgado, Miguel González-Pleiter, Antonio Quesada
The cyanobacterium Aphanizomenon gracile is the most widely distributed producer of the potent neurotoxin saxitoxin in freshwaters. In this work, total and extracellular saxitoxin and the transcriptional response of three genes linked to saxitoxin biosynthesis (sxtA) and transport (sxtM, sxtPer) were assessed in Aphanizomenon gracile UAM529 cultures under temperatures covering its annual cycle (12 °C, 23 °C, and 30 °C). Temperature influenced saxitoxin production being maximum at high temperatures (30 °C) above the growth optimum (23 °C), concurring with a 4...
October 13, 2017: Toxins
https://www.readbyqxmd.com/read/29027912/guanidinium-toxins-and-their-interactions-with-voltage-gated-sodium-ion-channels
#6
REVIEW
Lorena M Durán-Riveroll, Allan D Cembella
Guanidinium toxins, such as saxitoxin (STX), tetrodotoxin (TTX) and their analogs, are naturally occurring alkaloids with divergent evolutionary origins and biogeographical distribution, but which share the common chemical feature of guanidinium moieties. These guanidinium groups confer high biological activity with high affinity and ion flux blockage capacity for voltage-gated sodium channels (NaV). Members of the STX group, known collectively as paralytic shellfish toxins (PSTs), are produced among three genera of marine dinoflagellates and about a dozen genera of primarily freshwater or brackish water cyanobacteria...
October 13, 2017: Marine Drugs
https://www.readbyqxmd.com/read/29016314/case-report-paralytic-shellfish-poisoning-in-sabah-malaysia
#7
Maria Suleiman, Jenarun Jelip, Christina Rundi, Tock H Chua
During the months of January-February and May-June 2013 coinciding with the red tide occurrence in Kota Kinabalu, Sabah, Malaysia, six episodes involving 58 cases of paralytic shellfish poisoning (PSP) or saxitoxin (STX) poisoning and resulting in four deaths were reported. Many of them were intoxicated from consuming shellfish purchased from the markets, whereas others were intoxicated from eating shellfish collected from the beach. Levels of STX in shellfish collected from the affected areas were high (mean 2,920 ± 780 and 360 ± 140 µg STX equivalents/100 g shellfish meat respectively for the two periods)...
October 9, 2017: American Journal of Tropical Medicine and Hygiene
https://www.readbyqxmd.com/read/28977469/rapid-and-sensitive-elisa-screening-assay-for-several-paralytic-shellfish-toxins-in-human-urine
#8
P Eangoor, A S Indapurkar, M Vakkalanka, J S Yeh, J S Knaack
Paralytic shellfish poisoning is caused by a group of paralytic shellfish toxins that are produced by dinoflagellates. Toxins in this group include saxitoxin, neosaxitoxin and gonyautoxins. A rapid diagnostic test to identify poisoning by these toxins can be helpful in guiding the appropriate treatment of victims. Additionally, quick receipt of diagnostic results can provide timely proof that shellfish harvesting should be stopped in a given area, thereby preventing additional exposures. We have developed and validated a rapid urinary enzyme-linked immunosorbent assay-based screening test to diagnose exposure to several major paralytic shellfish toxins...
August 30, 2017: Journal of Analytical Toxicology
https://www.readbyqxmd.com/read/28927993/voltage-gated-sodium-channel-%C3%AE-subunits-the-power-outside-the-pore-in-brain-development-and-disease
#9
REVIEW
Jacob M Hull, Lori L Isom
Voltage gated sodium channels (VGSCs) were first identified in terms of their role in the upstroke of the action potential. The underlying proteins were later identified as saxitoxin and scorpion toxin receptors consisting of α and β subunits. We now know that VGSCs are heterotrimeric complexes consisting of a single pore forming α subunit joined by two β subunits; a noncovalently linked β1 or β3 and a covalently linked β2 or β4 subunit. VGSC α subunits contain all the machinery necessary for channel cell surface expression, ion conduction, voltage sensing, gating, and inactivation, in one central, polytopic, transmembrane protein...
September 18, 2017: Neuropharmacology
https://www.readbyqxmd.com/read/28851479/detection-of-paralytic-shellfish-toxins-in-mussels-and-oysters-using-the-qualitative-neogen-lateral-flow-immunoassay-an-interlaboratory-study
#10
Juan José Dorantes-Aranda, Jessica Y C Tan, Gustaaf M Hallegraeff, Katrina Campbell, Sarah C Ugalde, D Tim Harwood, Jill K Bartlett, Mònica Campàs, Steven Crooks, Arjen Gerssen, Keith Harrison, Anne-Catherine Huet, Timothy B Jordan, Martina Koeberl, Tim Monaghan, Sam Murray, Rama Nimmagadda, Corinne Ooms, Rae K Quinlan, Feng Shi, Andrew D Turner, Betsy Jean Yakes, Alison R Turnbull
Paralytic shellfish toxins (PSTs) in bivalve molluscs represent a public health risk and are controlled via compliance with a regulatory limit of 0.8 mg saxitoxin (STX)⋅2HCl equivalents per kilogram of shellfish meat (eq/kg). Shellfish industries would benefit from the use of rapid immunological screening tests for PSTs to be used for regulation, but to date none have been fully validated. An interlaboratory study involving 16 laboratories was performed to determine the suitability of the Neogen test to detect PSTs in mussels and oysters...
August 30, 2017: Journal of AOAC International
https://www.readbyqxmd.com/read/28836116/mechanisms-and-effects-posed-by-neurotoxic-products-of-cyanobacteria-microbial-eukaryotes-dinoflagellates-in-algae-blooms-a-review
#11
Fiona D Mello, Nady Braidy, Helder Marçal, Gilles Guillemin, Seyed Mohammad Nabavi, Brett A Neilan
Environmental toxins produced by cyanobacteria and dinoflagellates have increasingly become a public health concern due to their ability to damage several tissues in humans. In particular, emerging evidence has called attention to the neurodegenerative effects of the cyanobacterial toxin β-N-methylamino-L-alanine (BMAA). Furthermore, other toxins such as anatoxin, saxitoxin, microcystin, nodularin and ciguatoxin also have a different range of effects on human tissues, including hepatotoxicity, neurotoxicity and gastrointestinal irritation...
August 23, 2017: Neurotoxicity Research
https://www.readbyqxmd.com/read/28820049/receptor-binding-assay-for-the-detection-of-paralytic-shellfish-poisoning-toxins-comparison-to-the-mouse-bioassay-and-applicability-under-regulatory-use
#12
Shiyamalie R Ruberu, Gregg W Langlois, Melisa Masuda, Clive Kittredge, S Kusum Perera, Raphael M Kudela
The receptor-binding assay (RBA) method for the detection of paralytic shellfish poisoning (PSP) toxins was evaluated for its overall performance in comparison with the mouse bioassay (MBA). An initial study to evaluate the effects of filtering shellfish extracts prior to running the RBA indicated no significant difference between filtered and unfiltered extracts on the determined saxitoxin (STX) concentrations. Next, we tested the RBA assay on 295 naturally contaminated mussel tissue samples, ranging in concentrations from 320 µg STX equiv...
September 8, 2017: Food Additives & Contaminants. Part A, Chemistry, Analysis, Control, Exposure & Risk Assessment
https://www.readbyqxmd.com/read/28797629/molecular-and-morphological-survey-of-saxitoxin-producing-cyanobacterium-dolichospermum-circinale-anabaena-circinalis-isolated-from-geographically-distinct-regions-of-australia
#13
Joao P A Pereyra, Paul M D'Agostino, Rabia Mazmouz, Jason N Woodhouse, Russell Pickford, Ian Jameson, Brett A Neilan
The cyanobacterium Dolichospermum circinale (formerly Anabaena circinalis) is responsible for neurotoxic saxitoxin-producing blooms in Australia. Previous studies have reported distinct isolates of toxic D. circinale producing different saxitoxin analogues at varying amounts, but the mechanisms responsible remain poorly understood. To assess the characteristics that may be responsible for this variance, a morphological, molecular and chemical survey of 28 Anabaena isolates was conducted. Morphological characteristics, presence or absence of saxitoxin biosynthetic genes and toxin amount and profile were assessed...
November 2017: Toxicon: Official Journal of the International Society on Toxinology
https://www.readbyqxmd.com/read/28797318/single-laboratory-validation-of-the-neogen-qualitative-lateral-flow-immunoassay-for-the-detection-of-paralytic-shellfish-toxins-in-mussels-and-oysters
#14
Alison R Turnbull, Jessica Y C Tan, Sarah C Ugalde, Gustaaf M Hallegraeff, Katrina Campbell, D Tim Harwood, Juan José Dorantes-Aranda
Detection of paralytic shellfish toxins (PSTs) in bivalve shellfish by analytical methods is complicated and costly, requiring specific expertise and equipment. Following extensive blooms of Alexandrium tamarense Group 1 in Tasmania, Australia, an investigation was made into commercially available screening test kits suitable for use with the toxin profiles found in affected bivalves. The qualitative Neogen rapid test kit, with a modified protocol to convert gonyautoxins GTX1&4 and GTX2&3 into neosaxitoxin and saxitoxin (STX), respectively, with higher cross-reactivities, was the best fit-for-purpose...
August 10, 2017: Journal of AOAC International
https://www.readbyqxmd.com/read/28771148/influence-of-environmental-variables-on-saxitoxin-yields-by-cylindrospermopsis-raciborskii-in-a-mesotrophic-subtropical-reservoir
#15
Simone Pereira Casali, André Cordeiro Alves Dos Santos, Patrícia Bortoletto de Falco, Maria do Carmo Calijuri
Saxitoxins are a class of toxins produced by at least two groups of evolutionarily distant organisms (cyanobacteria and dinoflagellates). While the toxicity of these toxins is relatively well characterized, to date little is known about their drivers and ecological functions, especially in lower latitude tropical and subtropical freshwater ecosystems. In the present study, we aimed to obtain a better understanding of the main drivers of saxitoxin concentrations in aquatic environments. We investigated the relationships among saxitoxin concentrations in a mesotrophic subtropical reservoir dominated by the cyanobacteria Cylindrospermopsis raciborskii with physical, chemical and biological water variables...
August 2017: Journal of Water and Health
https://www.readbyqxmd.com/read/28711010/the-paralytic-shellfish-toxin-saxitoxin-enters-the-cytoplasm-and-induces-apoptosis-of-oyster-immune-cells-through-a-caspase-dependent-pathway
#16
Celina Abi-Khalil, Darren S Finkelstein, Genevieve Conejero, Justin Du Bois, Delphine Destoumieux-Garzon, Jean Luc Rolland
Exposure of the toxin-producing dinoflagellate Alexandrium catenella (A. catenella) was previously demonstrated to cause apoptosis of hemocytes in the oyster species Crassostrea gigas. In this work, a coumarin-labeled saxitoxin appeared to spread throughout the cytoplasm of the hemocytes. PSTs, including saxitoxin, were also shown to be directly responsible for inducing apoptosis in hemocytes, a process dependent on caspase activation and independent of reactive oxygen species (ROS) production. A series of in vitro labelling and microscopy experiments revealed that STX and analogs there of induced nuclear condensation, phosphatidylserine exposure, membrane permeability, and DNA fragmentation of hemocytes...
September 2017: Aquatic Toxicology
https://www.readbyqxmd.com/read/28661471/development-and-validation-of-a-liquid-chromatography-tandem-mass-spectrometry-method-coupled-with-dispersive-solid-phase-extraction-for-simultaneous-quantification-of-eight-paralytic-shellfish-poisoning-toxins-in-shellfish
#17
Xianli Yang, Lei Zhou, Yanglan Tan, Xizhi Shi, Zhiyong Zhao, Dongxia Nie, Changyan Zhou, Hong Liu
In this study, a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed for simultaneous determination of eight paralytic shellfish poisoning (PSP) toxins, including saxitoxin (STX), neosaxitoxin (NEO), gonyautoxins (GTX1-4) and the N-sulfo carbamoyl toxins C1 and C2, in sea shellfish. The samples were extracted by acetonitrile/water (80:20, v/v) with 0.1% formic and purified by dispersive solid-phase extraction (dSPE) with C18 silica and acidic alumina. Qualitative and quantitative detection for the target toxins were conducted under the multiple reaction monitoring (MRM) mode by using the positive electrospray ionization (ESI) mode after chromatographic separation on a TSK-gel Amide-80 HILIC column with water and acetonitrile...
June 29, 2017: Toxins
https://www.readbyqxmd.com/read/28606423/unraveling-the-presence-of-multi-class-toxins-from-trichodesmium-bloom-in-the-gulf-of-mannar-region-of-the-bay-of-bengal
#18
Sumathy Shunmugam, Manickam Gayathri, Nainangu Prasannabalaji, Nooruddin Thajuddin, Gangatharan Muralitharan
Trichodesmium is an enigmatic bloom forming, non-heterocystous cyanobacterium reported most frequently in the coastal waters of India. However, the toxigenic potential of this globally significant N2 fixing cyanobacterium has not been characterized. In this study, we report for the first time the presence of potent multi-class neurotoxins such as Anatoxin-a, Saxitoxins, Gonyautoxin and hepatotoxins like MC-LR, MC-YA from a bloom material of Trichodesmium sp. MBDU 524 collected at the Gulf of Mannar region. Toxins were determined using liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS) analysis of HPLC purified aqueous and solvent fractions...
June 9, 2017: Toxicon: Official Journal of the International Society on Toxinology
https://www.readbyqxmd.com/read/28604648/prevalence-variability-and-bioconcentration-of-saxitoxin-group-in-different-marine-species-present-in-the-food-chain
#19
Javiera Oyaneder Terrazas, Héctor R Contreras, Carlos García
The saxitoxin-group (STX-group) corresponds to toxic metabolites produced by cyanobacteria and dinoflagellates of the genera Alexandrium, Gymnodinium, and Pyrodinium. Over the last decade, it has been possible to extrapolate the areas contaminated with the STX-group worldwide, including Chile, a phenomenon that has affected ≈35% of the Southern Pacific coast territory, generating a high economic impact. The objective of this research was to study the toxicity of the STX-group in all aquatic organisms (bivalves, algae, echinoderms, crustaceans, tunicates, cephalopods, gastropods, and fish) present in areas with a variable presence of harmful algal blooms (HABs)...
June 12, 2017: Toxins
https://www.readbyqxmd.com/read/28587138/toxin-variability-estimations-of-68-alexandrium-ostenfeldii-dinophyceae-strains-from-the-netherlands-reveal-a-novel-abundant-gymnodimine
#20
Helge Martens, Urban Tillmann, Kirsi Harju, Carmela Dell'Aversano, Luciana Tartaglione, Bernd Krock
Alexandrium ostenfeldii is a toxic dinoflagellate that has recently bloomed in Ouwerkerkse Kreek, The Netherlands, and which is able to cause a serious threat to shellfish consumers and aquacultures. We used a large set of 68 strains to the aim of fully characterizing the toxin profiles of the Dutch A. ostenfeldii in consideration of recent reports of novel toxins. Alexandrium ostenfeldii is known as a causative species of paralytic shellfish poisoning, and consistently in the Dutch population we determined the presence of several paralytic shellfish toxins (PST) including saxitoxin (STX), GTX2/3 (gonyautoxins), B1 and C1/C2...
May 26, 2017: Microorganisms
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