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Brevetoxin
Brevetoxin (PbTx), or brevetoxins, are a suite of cyclic polyether compounds produced naturally by a species of dinoflagellate known as '' Karenia brevis''. Brevetoxins are neurotoxins that bind to voltage-gated sodium channels in nerve cells, leading to disruption of normal neurological processes and causing the illness clinically described as neurotoxic shellfish poisoning (NSP). Although brevetoxins are most well-studied in ''K. brevis'', they are also found in other species of '' Karenia'' and at least one large fish kill has been traced to brevetoxins in ''Chattonella''. Other Brevetoxins: *Brevetoxin-5 (PbTx-5): like PbTx-2, but acetylated hydroxyl group in position 38. *Brevetoxin-6 (PbTx-6): like PbTx-2, but double bond 27-28 is epoxidated. Brevetoxin-B was synthesized in 1995 by K. C. Nicolaou and coworkers in 123 steps with 91% average yield (final yield ~9·10−6) and in 2004 in a total of 90 steps with an average 93% yield for each step (0.14% overall). K. C. Nic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brevetoxin A
Brevetoxin (PbTx), or brevetoxins, are a suite of cyclic polyether compounds produced naturally by a species of dinoflagellate known as ''Karenia brevis''. Brevetoxins are neurotoxins that bind to voltage-gated sodium channels in nerve cells, leading to disruption of normal neurological processes and causing the illness clinically described as neurotoxic shellfish poisoning (NSP). Although brevetoxins are most well-studied in ''K. brevis'', they are also found in other species of '' Karenia'' and at least one large fish kill has been traced to brevetoxins in ''Chattonella''. Other Brevetoxins: *Brevetoxin-5 (PbTx-5): like PbTx-2, but acetylated hydroxyl group in position 38. *Brevetoxin-6 (PbTx-6): like PbTx-2, but double bond 27-28 is epoxidated. Brevetoxin-B was synthesized in 1995 by K. C. Nicolaou and coworkers in 123 steps with 91% average yield (final yield ~9·10−6) and in 2004 in a total of 90 steps with an average 93% yield for each step (0.14% overall). K. C. Nico ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brevetoxin B
Brevetoxin (PbTx), or brevetoxins, are a suite of cyclic polyether compounds produced naturally by a species of dinoflagellate known as ''Karenia brevis''. Brevetoxins are neurotoxins that bind to voltage-gated sodium channels in nerve cells, leading to disruption of normal neurological processes and causing the illness clinically described as neurotoxic shellfish poisoning (NSP). Although brevetoxins are most well-studied in ''K. brevis'', they are also found in other species of '' Karenia'' and at least one large fish kill has been traced to brevetoxins in ''Chattonella''. Other Brevetoxins: *Brevetoxin-5 (PbTx-5): like PbTx-2, but acetylated hydroxyl group in position 38. *Brevetoxin-6 (PbTx-6): like PbTx-2, but double bond 27-28 is epoxidated. Brevetoxin-B was synthesized in 1995 by K. C. Nicolaou and coworkers in 123 steps with 91% average yield (final yield ~9·10−6) and in 2004 in a total of 90 steps with an average 93% yield for each step (0.14% overall). K. C. Nico ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neurotoxic Shellfish Poisoning
Neurotoxic shellfish poisoning (NSP) is caused by the consumption of brevetoxins, which are marine toxins produced by the dinoflagellate ''Karenia brevis'' (among several others). These toxins can produce a series of gastrointestinal and neurological effects. Outbreaks of NSP commonly take place following harmful algal bloom (HAB) events, commonly referred to as "Florida red tide" (given that blooms are more commonplace along the coasts of Florida and Texas, especially during late summer and early fall). Algal blooms are a naturally-occurring phenomenon, however their frequency has been increasing in recent decades at least in-part due to human activities, climate changes, and the eutrophication (over-abundance of plant nutrients as a result of agricultural runoff, deforestation, river bed erosion, etc.) of marine waters. HABs have been occurring for all of documented history, evidenced by the Native Americans' understanding of the dangers of shellfish consumption during periods of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phycotoxins
Phycotoxins (from Greek, ''phykos'', "seaweed"; and ''toxikon'', "toxin") are complex allelopathic chemicals produced by eukaryotic and prokaryotic algal secondary metabolic pathways. More simply, these are toxic chemicals synthesized by photosynthetic organisms. These metabolites are (in most cases) not harmful to the producer but may be toxic to either one or many members of the marine food web. This page focuses on phycotoxins produced by marine microalgae; however, freshwater algae and macroalgae are known phycotoxin producers and may exhibit analogous ecological dynamics. In the pelagic marine food web, phytoplankton are subjected to grazing by macro- and micro-zooplankton as well as competition for nutrients with other phytoplankton species. Marine bacteria try to obtain a share of organic carbon by maintaining symbiotic, parasitic, commensal, or predatory interactions with phytoplankton. Other bacteria will degrade dead phytoplankton or consume organic carbon released by vir ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Red Tide
A harmful algal bloom (HAB) (or excessive algae growth) is an algal bloom that causes negative impacts to other organisms by production of natural phycotoxin, algae-produced toxins, mechanical damage to other organisms, or by other means. HABs are sometimes defined as only those algal blooms that produce toxins, and sometimes as any algal bloom that can result in severely lower oxygen saturation, oxygen levels in natural waters, killing organisms in marine habitats, marine or fresh waters. Blooms can last from a few days to many months. After the bloom dies, the microorganism, microbes that decompose the dead algae use up more of the oxygen, generating a "dead zone (ecology), dead zone" which can cause fish kill, fish die-offs. When these zones cover a large area for an extended period of time, neither fish nor plants are able to survive. Harmful algal blooms in marine environments are often called "red tides". It is sometimes unclear what causes specific HABs as their occurrence ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Karenia Brevis
''Karenia brevis'' is a microscopic, single-celled, photosynthetic organism in the genus '' Karenia''. It is a marine dinoflagellate commonly found in the waters of the Gulf of Mexico. It is the organism responsible for the "Florida red tides" that affect the Gulf coasts of Florida and Texas in the U.S., and nearby coasts of Mexico. ''K. brevis'' has been known to travel great lengths around the Florida peninsula and as far north as the Carolinas. Each cell has two flagella that allow it to move through the water in a spinning motion. ''K. brevis'' is unarmored, and does not contain peridinin. Cells are between 20 and 40 μm in diameter. ''K. brevis'' naturally produces a suite of potent neurotoxins collectively called brevetoxins, which cause gastrointestinal and neurological problems in other organisms and are responsible for large die-offs of marine organisms and seabirds. History ''Karenia brevis'' was named for Dr. Karen A. Steidinger in 2001, and was previously known ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Karenia (dinoflagellate)
''Karenia'' is a genus that consists of unicellular, photosynthetic, planktonic organisms found in marine environments. The genus currently consists of 12 described species. They are best known for their dense toxic algal blooms and red tides that cause considerable ecological and economical damage; some ''Karenia'' species cause severe animal mortality. One species, ''Karenia brevis'', is known to cause respiratory distress and neurotoxic shellfish poisoning (NSP) in humans. Taxonomy The genus ''Karenia'' is named for Dr. Karen Steidinger for her exceptional contributions to dinoflagellate research. She has spent many decades researching ''Karenia brevis''. 12 species have been described in the genus ''Karenia'' thus far: * ''Karenia asterichroma'' * ''Karenia bicuneiformis'' * ''Karenia brevis'' * ''Karenia brevisulcata'' * ''Karenia concordia'' * ''Karenia cristata'' * ''Karenia digitata'' * ''Karenia longicanalis'' * ''Karenia mikimotoi'' * ''Karenia papilionacea'' * ''Kare ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Domoic Acid
Domoic acid (DA) is a kainic acid-type neurotoxin that causes amnesic shellfish poisoning (ASP). It is produced by algae and accumulates in shellfish, sardines, and anchovies. When sea lions, otters, cetaceans, humans, and other predators eat contaminated animals, poisoning may result. Exposure to this compound affects the brain, causing seizures, and possibly death. History There has been little use of domoic acid throughout history except for in Japan, where it has been used as an anthelmintic for centuries. Domoic acid was first isolated in 1959 from a species of red algae, '' Chondria armata'', in Japan, which is commonly referred to as ''dōmoi'' (ドウモイ) in the Tokunoshima dialect, or ''hanayanagi''. Poisonings in history have been rare, or undocumented; however, it is thought that the increase in human activities is resulting in an increasing frequency of harmful algal blooms along coastlines in recent years. In 2015, the North American Pacific coast was heavily impac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Okadaic Acid
Okadaic acid, C44H68O13, is a toxin produced by several species of dinoflagellates, and is known to accumulate in both marine sponges and shellfish. One of the primary causes of diarrhetic shellfish poisoning, okadaic acid is a potent inhibitor of specific protein phosphatases and is known to have a variety of negative effects on cells. A polyketide, polyether derivative of a C38 fatty acid, okadaic acid and other members of its family have shined light upon many biological processes both with respect to dinoflagellete polyketide synthesis as well as the role of protein phosphatases in cell growth. History As early as 1961, reports of gastrointestinal disorders following the consumption of cooked mussels appeared in both the Netherlands and Los Lagos. Attempts were made to determine the source of the symptoms, however they failed to elucidate the true culprit, instead implicating a species of microplanctonic dinoflagellates. In the summers of the late 1970s, a series of food po ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saxitoxin
Saxitoxin (STX) is a potent neurotoxin and the best-known paralytic shellfish toxin (PST). Ingestion of saxitoxin by humans, usually by consumption of shellfish contaminated by toxic algal blooms, is responsible for the illness known as paralytic shellfish poisoning (PSP). The term saxitoxin originates from the genus name of the butter clam (''Saxidomus'') from which it was first isolated. But the term saxitoxin can also refer to the entire suite of more than 50 structurally related neurotoxins (known collectively as "saxitoxins") produced by protists, algae and cyanobacteria which includes saxitoxin itself (STX), neosaxitoxin (NSTX), gonyautoxins (GTX) and decarbamoylsaxitoxin (dcSTX). Saxitoxin has a large environmental and economic impact, as its presence in bivalve shellfish such as mussels, clams, oysters and scallops frequently leads to bans on commercial and recreational shellfish harvesting in many temperate coastal waters around the world including the Northeastern and W ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetrodotoxin
Tetrodotoxin (TTX) is a potent neurotoxin. Its name derives from Tetraodontiformes, an order that includes pufferfish, porcupinefish, ocean sunfish, and triggerfish; several of these species carry the toxin. Although tetrodotoxin was discovered in these fish and found in several other animals (e.g., in blue-ringed octopuses, rough-skinned newts, and moon snails), it is actually produced by certain infecting or symbiotic bacteria like ''Pseudoalteromonas'', ''Pseudomonas'', and ''Vibrio'' as well as other species found in animals. Tetrodotoxin is a sodium channel blocker. It inhibits the firing of action potentials in neurons by binding to the voltage-gated sodium channels in nerve cell membranes and blocking the passage of sodium ions (responsible for the rising phase of an action potential) into the neuron. This prevents the nervous system from carrying messages and thus muscles from contracting in response to nervous stimulation. Its mechanism of action, selective blocking o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ciguatoxin
image:ciguatoxin.svg, 300px, Chemical structure of the ciguatoxin CTX1B Ciguatoxins are a class of toxic Polycyclic compound, polycyclic polyethers found in fish that cause ciguatera. There are several different chemicals in this class. "CTX" is often used as an abbreviation. * - Ciguatoxin 1 * - Ciguatoxin 2 * - Ciguatoxin 3 * - Ciguatoxin 4B (Gambiertoxin 4b) Toxic effect on humans Ciguatoxins do not harm the fish that carry them, but they are poisonous to humans. They cannot be smelled or tasted and cannot be destroyed by cooking. Rapid testing for this toxin in food is not standard. Some ciguatoxins lower the threshold for opening excitatory voltage-gated sodium channels in the nervous system. Opening a sodium channel causes depolarization, which could sequentially cause paralysis, heart contraction, and changing the senses of heat and cold. Such poisoning from ciguatoxins is known as ciguatera. Ciguatoxins are lipophillic, able to cross the blood brain barrier, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
