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Courtney C Cocilova, Leanne J Flewelling, Gregory D Bossart, April A Granholm, Sarah L Milton
Harmful algal blooms (HABs) occur nearly annually off the west coast of Florida and can impact both humans and wildlife, resulting in morbidity and increased mortality of marine animals including sea turtles. The key organism in Florida red tides is the dinoflagellate Karenia brevis that produces a suite of potent neurotoxins referred to as the brevetoxins (PbTx). Despite recent mortality events and rehabilitation efforts, still little is known about how the toxin directly impacts sea turtles, as they are not amenable to experimentation and what is known about toxin levels and distribution comes primarily from post-mortem data...
March 7, 2017: Aquatic Toxicology
Rodrigo Gonzalez-Romero, Victoria Suarez-Ulloa, Javier Rodriguez-Casariego, Daniel Garcia-Souto, Gabriel Diaz, Abraham Smith, Juan Jose Pasantes, Gary Rand, Jose M Eirin-Lopez
Massive algal proliferations known as Harmful Algal Blooms (HABs) represent one of the most important threats to coastal areas. Among them, the so-called Florida Red Tides (FRTs, caused by blooms of the dinoflagellate Karenia brevis and associated brevetoxins) are particularly detrimental in the southeastern U.S., causing high mortality rates and annual losses in excess of $40 million. The ability of marine organisms to cope with environmental stressors (including those produced during HABs) is influenced by genetic and epigenetic mechanisms, the latter resulting in phenotypic changes caused by heritable modifications in gene expression, without involving changes in the genetic (DNA) sequence...
March 7, 2017: Aquatic Toxicology
J J Walsh, J M Lenes, R H Weisberg, L Zheng, C Hu, K A Fanning, R Snyder, J Smith
Reductions of zooplankton biomasses and grazing pressures were observed during overfishing-induced trophic cascades and concurrent oil spills at global scales. Recent phytoplankton increments followed, once Fe-, P-, and N-nutrient limitations of commensal diazotrophs and dinoflagellates were also eliminated by respective human desertification, deforestation, and eutrophication during climate changes. Si-limitation of diatoms instead ensued during these last anthropogenic perturbations of agricultural effluents and sewage loadings...
January 19, 2017: Marine Pollution Bulletin
Justin R Perrault, Katherine D Bauman, Taylor M Greenan, Patricia C Blum, Michael S Henry, Catherine J Walsh
Blooms of Karenia brevis (also called red tides) occur almost annually in the Gulf of Mexico. The health effects of the neurotoxins (i.e., brevetoxins) produced by this toxic dinoflagellate on marine turtles are poorly understood. Florida's Gulf Coast represents an important foraging and nesting area for a number of marine turtle species. Most studies investigating brevetoxin exposure in marine turtles thus far focus on dead and/or stranded individuals and rarely examine the effects in apparently "healthy" free-ranging individuals...
November 2016: Aquatic Toxicology
Courtney C Cocilova, Sarah L Milton
Harmful algal blooms are increasing in frequency and extent worldwide and occur nearly annually off the west coast of Florida where they affect both humans and wildlife. The dinoflagellate Karenia brevis is a key organism in Florida red tides that produces a suite of potent neurotoxins collectively referred to as the brevetoxins (PbTx). Brevetoxins bind to and open voltage gated sodium channels (VGSC), increasing cell permeability in excitable cells and depolarizing nerve and muscle tissue. Exposed animals may thus show muscular and neurological symptoms including head bobbing, muscle twitching, paralysis, and coma; large HABs can result in significant morbidity and mortality of marine life, including fish, birds, marine mammals, and sea turtles...
November 2016: Aquatic Toxicology
D Ransom Hardison, William C Holland, Jennifer R McCall, Andrea J Bourdelais, Daniel G Baden, H Taiana Darius, Mireille Chinain, Patricia A Tester, Damian Shea, Harold A Flores Quintana, James A Morris, R Wayne Litaker
Ciguatera fish poisoning is an illness suffered by > 50,000 people yearly after consumption of fish containing ciguatoxins (CTXs). One of the current methodologies to detect ciguatoxins in fish is a radiolabeled receptor binding assay (RBA(R)). However, the license requirements and regulations pertaining to radioisotope utilization can limit the applicability of the RBA(R) in certain labs. A fluorescence based receptor binding assay (RBA(F)) was developed to provide an alternative method of screening fish samples for CTXs in facilities not certified to use radioisotopes...
2016: PloS One
Silas Anselm Rasmussen, Aaron John Christian Andersen, Nikolaj Gedsted Andersen, Kristian Fog Nielsen, Per Juel Hansen, Thomas Ostenfeld Larsen
Microalgae, particularly those from the lineage Dinoflagellata, are very well-known for their ability to produce phycotoxins that may accumulate in the marine food chain and eventually cause poisoning in humans. This includes toxins accumulating in shellfish, such as saxitoxin, okadaic acid, yessotoxins, azaspiracids, brevetoxins, and pinnatoxins. Other toxins, such as ciguatoxins and maitotoxins, accumulate in fish, where, as is the case for the latter compounds, they can be metabolized to even more toxic metabolites...
March 25, 2016: Journal of Natural Products
Fang Zhao, Xichun Li, Liang Jin, Fan Zhang, Masayuki Inoue, Boyang Yu, Zhengyu Cao
Voltage-gated sodium channels (VGSCs) are responsible for the generation of the action potential. Among nine classified VGSC subtypes (Nav1.1-Nav1.9), Nav1.7 is primarily expressed in the sensory neurons, contributing to the nociception transmission. Therefore Nav1.7 becomes a promising target for analgesic drug development. In this study, we compared the influence of an array of VGSC agonists including veratridine, BmK NT1, brevetoxin-2, deltamethrin and antillatoxin (ATX) on membrane depolarization which was detected by Fluorescence Imaging Plate Reader (FLIPR) membrane potential (FMP) blue dye...
February 16, 2016: Marine Drugs
Wenqiang Lai, Qiaohua Wei, Junyang Zhuang, Minghua Lu, Dianping Tang
We designed a new colorimetric immunoassay for sensitive monitoring of brevetoxin B (BTB) using enzyme-controlled Fenton reaction with a high-resolution 3,3',5,5'-tetramethylbenzidine (TMB)-based visual colored system. Upon addition of hydrogen peroxide (H2O2), the equivalent iron(II) could be first converted into iron(III) and free hydroxyl radical (•OH) via the classical Fenton reaction. Then the as-produced iron(III) and •OH could cause a perceptible change from colorless to blue with the increasing H2O2 concentration in the presence of TMB...
June 15, 2016: Biosensors & Bioelectronics
Pengfei Sun, Cristian Leeson, Xiaoduo Zhi, Fenfei Leng, Richard H Pierce, Michael S Henry, Kathleen S Rein
Epoxide hydrolases (EH, EC have been proposed to be key enzymes in the biosynthesis of polyether (PE) ladder compounds such as the brevetoxins which are produced by the dinoflagellate Karenia brevis. These enzymes have the potential to catalyze kinetically disfavored endo-tet cyclization reactions. Data mining of K. brevis transcriptome libraries revealed two classes of epoxide hydrolases: microsomal and leukotriene A4 (LTA4) hydrolases. A microsomal EH was cloned and expressed for characterization...
February 2016: Phytochemistry
Tadeusz Płusa
The criteria for recognizing a chemical compound for the toxin are vague and gave it the possibility of inclusion in this group a number of biological agents. Toxins list is extensive, but the interest is focused on bacterial toxins, poisons derived from snake venoms, algae and plant proteins, and small molecules. Particular attention is focused on the so-called "sea" toxins, which include tetrodotoxin, brevetoxin and saxitoxin. This indicates the search for a new hitherto unknown potential bioterrorist threats...
September 2015: Polski Merkuriusz Lekarski: Organ Polskiego Towarzystwa Lekarskiego
Youxiu Lin, Qian Zhou, Yuping Lin, Minghua Lu, Dianping Tang
A new signal amplification strategy based on mesoporous carbon-enriched palladium nanostructure (MSC-PdNS) was designed for enzyme-free electrochemical immunoassay of brevetoxin B (BTB) in marine toxins. The assay was carried out on a BTB-bovine serum albumin-functionalized electrode by using monoclonal mouse anti-BTB-labeling MSC-PdNS as the signal-transduction tag. A competitive-type assay protocol was successfully introduced to develop a high-efficiency enzyme-free immunoassay accompanying the doped palladium nanostructure into MSC-PdNS toward reduction of H2O2...
August 5, 2015: Analytica Chimica Acta
Kristina M Cammen, Thomas F Schultz, Patricia E Rosel, Randall S Wells, Andrew J Read
Harmful algal blooms (HABs), which can be lethal in marine species and cause illness in humans, are increasing worldwide. In the Gulf of Mexico, HABs of Karenia brevis produce neurotoxic brevetoxins that cause large-scale marine mortality events. The long history of such blooms, combined with the potentially severe effects of exposure, may have produced a strong selective pressure for evolved resistance. Advances in next-generation sequencing, in particular genotyping-by-sequencing, greatly enable the genomic study of such adaptation in natural populations...
September 2015: Molecular Ecology
Juan José Dorantes-Aranda, Andreas Seger, Jorge I Mardones, Peter D Nichols, Gustaaf M Hallegraeff
Quantification of the role of reactive oxygen species, phycotoxins and fatty acids in fish toxicity by harmful marine microalgae remains inconclusive. An in vitro fish gill (from rainbow trout Oncorhynchus mykiss) assay was used to simultaneously assess the effect in superoxide dismutase, catalase and lactate dehydrogenase enzymatic activities caused by seven species of ichthyotoxic microalgae (Chattonella marina, Fibrocapsa japonica, Heterosigma akashiwo, Karenia mikimotoi, Alexandrium catenella, Karlodinium veneficum, Prymnesium parvum)...
2015: PloS One
Nicholas Fowler, Carmelo Tomas, Daniel Baden, Lisa Campbell, Andrea Bourdelais
One of the most widely studied organisms responsible for Harmful Algal Blooms (HABs) is the marine dinoflagellate Karenia brevis. This organism produces neurotoxic compounds known as brevetoxins. A related dinoflagellate, Karenia papilionacea, has been reported to occasionally co-bloom with K. brevis but has received little attention as a possible toxin producing species. Therefore, our aim was to investigate the toxin profile for K. papilionacea. A toxic fraction was identified using a cell based cytotoxicity assay and the toxin was isolated and identified as the ladder frame polyether brevetoxin-2 (PbTx-2) using mass spectrometry (MS) and nuclear magnetic resonance (NMR)...
July 2015: Toxicon: Official Journal of the International Society on Toxinology
Qin Wang, Jiaru Fang, Duanxi Cao, Hongbo Li, Kaiqi Su, Ning Hu, Ping Wang
Saxitoxin (STX) and brevetoxin (PbTX-2), which are produced by marine dinoflagellates, are highly-toxic marine toxins targeting separate sites of the α subunit of voltage-dependent sodium channels (VDSCs). In this work, a portable cardiomyocyte-based potential biosensor is designed for rapid detection of STX and PbTX-2. This potential biosensor is constructed by cardiomyocyte and microelectrode array (MEA) with a label-free and real-time wireless 8-channel recording system which can dynamically monitor the multisite electrical activity of cardiomyocyte network...
October 15, 2015: Biosensors & Bioelectronics
Ryan T Cassell, Wei Chen, Serge Thomas, Li Liu, Kathleen S Rein
The brevetoxins are neurotoxins that are produced by the "Florida red tide" dinoflagellate Karenia brevis. They bind to and activate the voltage-gated sodium channels in higher organisms, specifically the Nav 1.4 and Nav 1.5 channel subtypes. However, the native physiological function that the brevetoxins perform for K. brevis is unknown. By using fluorescent and photoactivatable derivatives, brevetoxin was shown to localize to the chloroplast of K. brevis where it binds to the light-harvesting complex II (LHCII) and thioredoxin...
May 4, 2015: Chembiochem: a European Journal of Chemical Biology
Andrew D Turner, Cowan Higgins, Keith Davidson, Andrea Veszelovszki, Daniel Payne, James Hungerford, Wendy Higman
Regular occurrence of brevetoxin-producing toxic phytoplankton in commercial shellfishery areas poses a significant risk to shellfish consumer health. Brevetoxins and their causative toxic phytoplankton are more limited in their global distribution than most marine toxins impacting commercial shellfisheries. On the other hand, trends in climate change could conceivably lead to increased risk posed by these toxins in UK waters. A request was made by UK food safety authorities to examine these toxins more closely to aid possible management strategies, should they pose a threat in the future...
March 12, 2015: Marine Drugs
Anne Rolton, Philippe Soudant, Julien Vignier, Richard Pierce, Michael Henry, Sandra E Shumway, V Monica Bricelj, Aswani K Volety
The bivalve mollusc, Crassostrea virginica, is frequently exposed to blooms of Karenia brevis along the west coast of Florida during periods of spawning and early larval development. A continuous 4-day exposure of gametes and 2-4 cell stage embryos of C. virginica to whole-cell and culture filtrate of K. brevis at 500 and 5000 cells mL(-1), was followed by a 4-day 'recovery' period. Larval growth, percent of normal, abnormal and dead larvae, and the presence of food in the larval gut were measured throughout the exposure period...
June 1, 2015: Toxicon: Official Journal of the International Society on Toxinology
Shimaa Eissa, Mohamed Siaj, Mohammed Zourob
Brevetoxins (BTXs) are very potent marine neurotoxins that increased in geographical distribution in the past decade causing the illness clinically described as neurological shellfish poisoning (NSP). The ethical problems as well as the technical difficulties associated with the currently employed analysis methods for marine toxins are encouraging the research for suitable alternatives to be applied in a regulatory monitoring regime. Here, we report an electrochemical biosensor platform for BTX-2 detection utilising aptamer as specific receptor...
July 15, 2015: Biosensors & Bioelectronics
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