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Saxitoxin

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https://www.readbyqxmd.com/read/28927993/voltage-gated-sodium-channel-%C3%AE-subunits-the-power-outside-the-pore-in-brain-development-and-disease
#1
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 16, 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
#2
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
#3
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
#4
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 concentrations. Next, we tested the RBA assay on 295 naturally contaminated mussel tissue samples, ranging in concentrations from 320 µg STX equiv...
August 18, 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
#5
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...
August 7, 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
#6
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
#7
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
#8
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
#9
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
#10
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
#11
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
#12
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
https://www.readbyqxmd.com/read/28585115/cyanobacterial-neurotoxins-their-occurrence-and-mechanisms-of-toxicity
#13
Kenneth J Rodgers, Brendan J Main, Kate Samardzic
Cyanobacteria are some of the oldest organisms on earth, and have evolved to produce a battery of toxic metabolites, including hepatotoxins, dermatoxins, and neurotoxins. In this review, we focus on the occurrence and mechanisms of toxicity of a number of neurotoxins synthesised by these ancient photosynthetic prokaryotes. We discuss the evidence linking β-methylamino-L-alanine (BMAA), a non-protein amino acid, to an unusual neurological disease complex reported on the island of Guam in the 1950s, and how 60 years later, the role that BMAA plays in human disease is still unclear...
June 5, 2017: Neurotoxicity Research
https://www.readbyqxmd.com/read/28526117/the-efficiency-of-combined-coagulant-and-ballast-to-remove-harmful-cyanobacterial-blooms-in-a-tropical-shallow-system
#14
Marcela Miranda, Natália Noyma, Felipe S Pacheco, Leonardo de Magalhães, Ernani Pinto, Suzan Santos, Maria Fernanda A Soares, Vera L Huszar, Miquel Lürling, Marcelo M Marinho
We tested the hypothesis that a combination of coagulant and ballast could be efficient for removal of positively buoyant harmful cyanobacteria in shallow tropical waterbodies, and will not promote the release of cyanotoxins. This laboratory study examined the efficacy of coagulants [polyaluminium chloride (PAC) and chitosan (made of shrimp shells)] alone, and combined with ballast (lanthanum modified bentonite, red soil or gravel) to remove the natural populations of cyanobacteria collected from a shallow eutrophic urban reservoir with alternating blooms of Cylindrospermopsis and Microcystis...
May 2017: Harmful Algae
https://www.readbyqxmd.com/read/28495477/quantification-of-saxitoxin-in-human-blood-by-elisa
#15
Rebekah E Wharton, Melanie C Feyereisen, Andrea L Gonzalez, Nicole L Abbott, Elizabeth I Hamelin, Rudolph C Johnson
Saxitoxin (STX) is a potent marine toxin that causes paralytic shellfish poisoning (PSP) which can result in significant morbidity and mortality in humans. Low lethal doses, rapid onset of PSP symptoms, and brief STX half-life in vivo require sensitive and rapid diagnostic techniques to monitor human exposures. Our laboratory has validated an enzyme-linked immunosorbent assay (ELISA) for quantitative detection of STX from 0.020 to 0.80 ng/mL in human whole blood and from 0.06 to 2.0 ng/mL in dried human blood which is simple, sensitive, rapid, and cost-effective...
July 2017: Toxicon: Official Journal of the International Society on Toxinology
https://www.readbyqxmd.com/read/28433693/cyanotoxins-which-detection-technique-for-an-optimum-risk-assessment
#16
Virginie Gaget, Melody Lau, Barbara Sendall, Suzanne Froscio, Andrew R Humpage
The presence of toxigenic cyanobacteria (blue-green algae) in drinking water reservoirs poses a risk to human and animal health worldwide. Guidelines and health alert levels have been issued in the Australian Drinking Water Guidelines for three major toxins, which are therefore the subject of routine monitoring: microcystin, cylindrospermopsin and saxitoxin. While it is agreed that these toxic compounds should be monitored closely, the routine surveillance of these bioactive chemicals can be done in various ways and deciding which technique to use can therefore be challenging...
July 1, 2017: Water Research
https://www.readbyqxmd.com/read/28409869/single-and-combined-effects-of-microcystin-and-saxitoxin-producing-cyanobacteria-on-the-fitness-and-antioxidant-defenses-of-cladocerans
#17
Aloysio da S Ferrão-Filho, Daniel de Abreu S Silva, Taissa A de Oliveira, Valéria Freitas de Magalhães, Stephan Pflugmacher, Eduardo Mendes da Silva
Cyanobacteria produce different toxic compounds that affect animal life, among them hepatotoxins and neurotoxins. Because cyanobacteria are able to produce a variety of toxic compounds at the same time, organisms may be, generally, subjected to their combined action. In the present study, we demonstrate the single and combined effects on cladocerans of cyanobacteria that produce microcystins (hepatotoxins) and saxitoxins (neurotoxins). Animals were exposed (either singly or combined) to 2 strains of cyanobacteria isolated from the same environment (Funil Reservoir, Rio de Janeiro, Brazil)...
April 14, 2017: Environmental Toxicology and Chemistry
https://www.readbyqxmd.com/read/28370934/synthesis-and-identification-of-key-biosynthetic-intermediates-for-the-formation-of-the-tricyclic-skeleton-of-saxitoxin
#18
Shigeki Tsuchiya, Yuko Cho, Renpei Yoshioka, Keiichi Konoki, Kazuo Nagasawa, Yasukatsu Oshima, Mari Yotsu-Yamashita
Saxitoxin (STX) and its analogues are potent voltage-gated sodium channel blockers biosynthesized by freshwater cyanobacteria and marine dinoflagellates. We previously identified genetically predicted biosynthetic intermediates of STX at early stages, Int-A' and Int-C'2, in these microorganisms. However, the mechanism to form the tricyclic skeleton of STX was unknown. To solve this problem, we screened for unidentified intermediates by analyzing the results from previous incorporation experiments with (15) N-labeled Int-C'2...
May 2, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28366387/the-physiological-adaptations-and-toxin-profiles-of-the-toxic-alexandrium-fundyense-on-the-eastern-bering-sea-and-chukchi-sea-shelves
#19
Masafumi Natsuike, Hiroshi Oikawa, Kohei Matsuno, Atsushi Yamaguchi, Ichiro Imai
Abundant cyst distributions of the toxic dinoflagellate Alexandrium fundyense (previous A. tamarense north American clade) were recently observed on the north Chukchi Sea shelf and on the eastern Bering Sea shelf, suggesting that A. fundyense is both highly adapted to the local environments in the high latitude areas and might cause toxin contamination of plankton feeders. However, little is known about the physiological characteristics and toxin profiles of A. fundyense in these areas, which are characterized by low water temperatures, weak sunlight, and more or less permanent ice cover during winter...
March 2017: Harmful Algae
https://www.readbyqxmd.com/read/28364328/use-of-three-monitoring-approaches-to-manage-a-major-chrysosporum-ovalisporum-bloom-in-the-murray-river-australia-2016
#20
Adam Crawford, Jon Holliday, Chester Merrick, John Brayan, Mark van Asten, Lee Bowling
An unusual bloom of Chrysosporum ovalisporum (basionym Aphanizomenon ovalisporum) occurred for the first time in the Murray River and distributary rivers in New South Wales, Australia, from mid-February to early June 2016. At its greatest extent, it contaminated a combined river length of ca. 2360 km. Chrysosporum ovalisporum usually comprised >99% of the total bloom biovolume at most locations sampled, which at times exceeded 40 mm(3) l(-1). The origins of the bloom were most likely reservoirs on the upper Murray River, with cyanobacterial-infested water released from them contaminating the river systems downstream...
April 2017: Environmental Monitoring and Assessment
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