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Tetrodotoxin
Tetrodotoxin (TTX) is a potent neurotoxin. Its name derives from Tetraodontiformes, an Order (biology), order that includes Tetraodontidae, pufferfish, porcupinefish, ocean sunfish, and triggerfish; several of these species carry the toxin. Although tetrodotoxin was discovered in these fish, it is found in several other animals (e.g., in blue-ringed octopus, blue-ringed octopuses, Taricha, rough-skinned newts, and Naticidae, moon snails). It is also produced by certain infectious or symbiotic bacteria like ''Pseudoalteromonas tetraodonis, Pseudoalteromonas'', ''Pseudomonas'', and ''Vibrio'' as well as other species found in symbiotic relationships with animals and plants. Although it produces thousands of intoxications annually and several deaths, it has shown efficacy for the treatment of cancer-related pain in phase II and III clinical trials. Tetrodotoxin is a sodium channel blocker. It inhibits the firing of action potentials in neurons by binding to the voltage-gated sodiu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neurotoxin
Neurotoxins are toxins that are destructive to nervous tissue, nerve tissue (causing neurotoxicity). Neurotoxins are an extensive class of exogenous chemical neurological insult (medical), insultsSpencer 2000 that can adversely affect function in both developing and mature nervous tissue.Olney 2002 The term can also be used to classify endogenous compounds, which, when abnormally contacted, can prove neurologically toxic. Though neurotoxins are often neurologically destructive, their ability to specifically target neural components is important in the study of nervous systems. Common examples of neurotoxins include lead, ethanol (drinking alcohol), glutamate,Choi 1987 nitric oxide, botulinum toxin (e.g. Botox), tetanus toxin,Simpson 1986 and tetrodotoxin. Some substances such as nitric oxide and glutamate are in fact essential for proper function of the body and only exert neurotoxic effects at excessive concentrations. Neurotoxins inhibit neuron control over ion concentrations ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blue-ringed Octopus
Blue-ringed octopuses, comprising the genus ''Hapalochlaena'', are four extremely venomous species of octopus that are found in tide pools and coral reefs in the Pacific and Indian Oceans, from Japan to Australia. They can be identified by their yellowish skin and characteristic blue and black rings that can change color dramatically when the animals are threatened. They eat small crustaceans, including crabs, hermit crabs, shrimp, and other small sea animals. They are some of the world's most venomous marine animals. Despite their small size——and relatively docile nature, they are very dangerous if provoked when handled because their venom contains a powerful neurotoxin called tetrodotoxin. The species tends to have a lifespan around two to three years, which may vary depending on factors such as nutrition, temperature, and the intensity of light within its environment. Classification The genus was described by British zoologist Guy Coburn Robson in 1929. Four specie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Action Potential
An action potential (also known as a nerve impulse or "spike" when in a neuron) is a series of quick changes in voltage across a cell membrane. An action potential occurs when the membrane potential of a specific Cell (biology), cell rapidly rises and falls. This depolarization then causes adjacent locations to similarly depolarize. Action potentials occur in several types of Membrane potential#Cell excitability, excitable cells, which include animal cells like neurons and myocyte, muscle cells, as well as some plant cells. Certain endocrine cells such as pancreatic beta cells, and certain cells of the anterior pituitary gland are also excitable cells. In neurons, action potentials play a central role in cell–cell interaction, cell–cell communication by providing for—or with regard to saltatory conduction, assisting—the propagation of signals along the neuron's axon toward axon terminal, synaptic boutons situated at the ends of an axon; these signals can then connect wit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Wilson Moore
John Wilson Moore (November 1, 1920 – March 30, 2019) was an American biophysicist who pioneered the emergent power of computers, beginning in the 1950s, to reveal how signals are generated, integrated, and then travel in neurons. He is well known for his discovery (with Toshio Narahashi), that the puffer fish toxin tetrodotoxin causes death by blocking the sodium ion channels that are responsible for nerve activity. Moore was emeritus professor of Neurobiology at Duke University Medical School where he had been a member of the faculty since 1961. Moore's NEURON simulator software, begun with and now carried forward by Michael Hines, is used worldwide. Moore received the Cole Award of the Biophysical Society in 1981. Early life and education Moore was born in November 1920 in Winston-Salem, North Carolina, where his father was superintendent of the Winston-Salem public schools. He studied physics at Davidson College and entered a graduate program in physics at the University ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Toshio Narahashi
Toshio Narahashi (January 30, 1927 – April 21, 2013) was an internationally known pharmacologist. He was the John Evans Professor of Pharmacology and former chair of the Department of Pharmacology at Northwestern University Feinberg School of Medicine, where he served on the faculty from 1977 to 2013. Prior, he was vice chairman of the Department of Physiology and Pharmacology at Duke University, where he served on the faculty from 1962 to 1977. He is considered by many to be the "founding father of neurotoxicology" and is credited with discovering how tetrodotoxin, the poison in puffer fish, immobilizes parts of the nervous system. Born in Tokyo, Japan, Narahashi received an undergraduate degree in agriculture from the University of Tokyo in 1948. According to the Chicago Tribune, "He began his career studying insecticides in an entomology lab. His findings in the lab helped form the basis of 26 published papers and a doctorate in neurotoxicology that he would earn in 1960 f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sodium Channel Blocker
Sodium channel blockers are drugs which impair the conduction of sodium ions (Na+) through sodium channels. Extracellular The following naturally-produced substances block sodium channels by binding to and occluding the extracellular pore opening of the channel: * Alkaloids: ** Saxitoxin (STX) ** Neosaxitoxin (NSTX) ** Tetrodotoxin (TTX) Intracellular Drugs which block sodium channels by blocking from the intracellular side of the channel include: * Local anesthetics: ''lidocaine'' * Class I antiarrhythmic agents * Various anticonvulsants: ''phenytoin, oxcarbazepine (derivative of carbamazepine)'' Unknown mechanism * Calcium has been shown to block sodium channels which explains the effects of hypercalcemia and hypocalcemia. * Lamotrigine is known to block sodium channels but it is not known whether it is extracellular or intracellular. * Cannabidiol (CBD) has been shown to cause inhibitory effects on sodium currents. This voltage-dependent inhibition is non-selective in natu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astropecten
''Astropecten'' is a genus of sea stars of the family Astropectinidae. Identification These sea stars are similar one to each other and it can be difficult to determine with certainty the species only from a photograph. To have a certain determination, in some cases, animals should be analyzed in the laboratory or using genetic testing, but often it isn’t possible. In order to determine the species, with a reasonable margin of error, it’s necessary to observe the appearance of the animal, in particular, based on some typical features described by principal authors that have analyzed over the years a large number of specimens in the laboratory. The main elements, to determine the various species from photo, are: the appearance of the dorsal marginal plates and spines, the size, the shape of disc and arms. For a good identification by sea photo it is important to take a complete picture of all the subject, a picture of the detail of the marginal plates and to measure as pre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Starfish
Starfish or sea stars are Star polygon, star-shaped echinoderms belonging to the class (biology), class Asteroidea (). Common usage frequently finds these names being also applied to brittle star, ophiuroids, which are correctly referred to as brittle stars or basket stars. Starfish are also known as asteroids due to being in the class Asteroidea. About 1,900 species of starfish live on the seabed in all the world's oceans, from warm, tropics, tropical zones to frigid, polar regions of Earth, polar regions. They are found from the intertidal zone down to abyssal zone, abyssal depths, at below the surface. Starfish are marine invertebrates. They typically have a central disc and usually five arms, though some species have a larger number of arms. The aboral or upper surface may be smooth, granular or spiny, and is covered with overlapping plates. Many species are brightly coloured in various shades of red or orange, while others are blue, grey or brown. Starfish have tube fe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nassarius
''Nassarius'', common name nassa mud snails (USA) or dog whelks (UK), is a genus of minute to medium-sized sea snails, marine gastropod molluscs in the family Nassariidae.Bouchet, P.; Gofas, S. (2010). Nassarius Duméril, 1806. In: Bouchet, P.; Gofas, S.; Rosenberg, G. (2010) World Marine Mollusca database. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=138235 on 2010-11-30 They are scavengers. Etymology The name is derived from the Latin word "nassa", meaning a wickerbasket with a narrow neck, for catching fish. ''Nassarius'' would then mean "someone who uses such a wickerbasket for catching fish". Ecology Distribution and habitat Species within this genus are found worldwide. These snails usually live on mud flats or sand flats, intertidally or subtidally. Life habits Most ''Nassarius'' species are very active scavengers, feeding on crabs and carrion as dead fish, etc. They often burrow into marine substrates a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pomacanthidae
Marine angelfish are perciform fish of the family Pomacanthidae. They are found on shallow reefs in the tropical Atlantic, Indian, and mostly western Pacific Oceans. The family contains seven genera and about 86 species. They should not be confused with the freshwater angelfish, tropical cichlids of the Amazon Basin. Description With their bright colours and deep, laterally compressed bodies, marine angelfishes are some of the more conspicuous residents of the reef. They most closely resemble the butterflyfishes, a related family of similarly showy reef fish. Marine angelfish are distinguished from butterflyfish by the presence of strong preopercle spines (part of the gill covers) in the former. This feature also explains the family name Pomacanthidae; from the Greek πομα, ''poma'' meaning "cover" and ακάνθα, ''akantha'' meaning "thorn". Many species of marine angelfishes have streamer-like extensions of the soft dorsal and anal fins. The fish have small mouths ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pufferfish
Tetraodontidae is a family of marine and freshwater fish in the order Tetraodontiformes. The family includes many familiar species variously called pufferfish, puffers, balloonfish, blowfish, blowers, blowies, bubblefish, globefish, swellfish, toadfish, toadies, toadle, honey toads, sugar toads, and sea squab. They are morphologically similar to the closely related porcupinefish, which have large external spines (unlike the thinner, hidden spines of the Tetraodontidae, which are only visible when the fish have puffed up). The majority of pufferfish species are toxic, with some among the most poisonous vertebrates in the world. In certain species, the internal organs, such as the liver, and sometimes the skin, contain mucus tetrodotoxin, and are highly toxic to most animals when eaten; nevertheless, the meat of some species is considered a delicacy in Japan (as 河豚, pronounced ''fugu''), Korea (as 복, ''bok'', or 복어, ''bogeo''), and China (as 河豚, ''hétún'') w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Voltage Clamp
The voltage clamp is an experimental method used by electrophysiologists to measure the ion currents through the membranes of excitable cells, such as neurons, while holding the membrane voltage at a set level. A basic voltage clamp will iteratively measure the membrane potential, and then change the membrane potential (voltage) to a desired value by adding the necessary current. This "clamps" the cell membrane at a desired constant voltage, allowing the voltage clamp to record what currents are delivered. Because the currents applied to the cell must be equal to (and opposite in charge to) the current going across the cell membrane at the set voltage, the recorded currents indicate how the cell reacts to changes in membrane potential. Cell membranes of excitable cells contain many different kinds of ion channels, some of which are voltage-gated. The voltage clamp allows the membrane voltage to be manipulated independently of the ionic currents, allowing the current–voltag ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
