76-429: Echeneididae The remora ( / ˈ r ɛ m ə r ə / ), sometimes called suckerfish or sharksucker , is any of a family ( Echeneidae ) of ray-finned fish in the order Carangiformes . Depending on species, they grow to 30–110 cm (12–43 in) long. Their distinctive first dorsal fins take the form of a modified oval, sucker-like organ with slat-like structures that open and close to create suction and take
152-399: A coma . If the patient survives 24 hours, recovery without any aftereffects will usually occur over a few days. Therapy is supportive and based on symptoms, with aggressive early airway management. If consumed, treatment can consist of emptying the stomach, feeding the victim activated charcoal to bind the toxin, and taking standard life-support measures to keep the victim alive until
228-506: A host animal such as a whale , turtle , shark or ray . It is probably a mutualistic arrangement as the remora can move around on the host, removing ectoparasites and loose flakes of skin, while benefiting from the protection provided by the host and the constant flow of water across its gills. Although many believe that remoras feed off particulate matter from the host's meals, some posit alternative theories; they claim their diets to be composed primarily of host feces . Further research
304-583: A biochemical probe has elucidated two distinct types of voltage-gated sodium channels (VGSCs) present in mammals: tetrodotoxin-sensitive voltage-gated sodium channels (TTX-s Na channels) and tetrodotoxin-resistant voltage-gated sodium channels (TTX-r Na channels). Tetrodotoxin inhibits TTX-s Na channels at concentrations of around 1–10 nM, whereas micromolar concentrations of tetrodotoxin are required to inhibit TTX-r Na channels. Nerve cells containing TTX-r Na channels are located primarily in cardiac tissue, while nerve cells containing TTX-s Na channels dominate
380-585: A diagnosis of poisoning in hospitalized patients or to assist in the forensic investigation of a case of fatal overdosage. Most analytical techniques involve mass spectrometric detection following gas or liquid chromatographic separation. Tetrodotoxin has been investigated as a possible treatment for cancer-associated pain. Early clinical trials demonstrate significant pain relief in some patients. It has also been studied in relation to migraine headaches. Mutations in one particular TTX-sensitive Na channel are associated with some migraine headaches, although it
456-559: A firm hold against the skin of larger marine animals. The disk is made up of stout, flexible membranes that can be raised and lowered to generate suction. By sliding backward, the remora can increase the suction, or it can release itself by swimming forward. Remoras sometimes attach to small boats, and have been observed attaching to divers as well. They swim well on their own, with a sinuous, or curved, motion. Remora front dorsal fins have evolved to enable them to adhere by suction to smooth surfaces, and they spend most of their lives clinging to
532-459: A free-swimming larval stage. However other patterns of ontogeny exist, with one of the commonest being sequential hermaphroditism . In most cases this involves protogyny , fish starting life as females and converting to males at some stage, triggered by some internal or external factor. Protandry , where a fish converts from male to female, is much less common than protogyny. Most families use external rather than internal fertilization . Of
608-690: A plot device for characters to fake death, as in the films Hello Again (1987), The Serpent and the Rainbow (1988), The A-Team (2010) and Captain America: The Winter Soldier (2014), War (2019), and in episodes of " Jane the Virgin ", Miami Vice (1985), Nikita , MacGyver Season 7, Episode 6, where the antidote is Datura stramonium leaf, CSI: NY (Season 4, episode 9 "Boo") and Chuck . In Law Abiding Citizen (2009) and Alex Cross (2012), its paralysis
684-495: A resistance of 6.1–5.5 × 10 M. Some cultures use remoras to catch turtles. A cord or rope is fastened to the remora's tail, and when a turtle is sighted, the fish is released from the boat; it usually heads directly for the turtle and fastens itself to the turtle's shell, and then both remora and turtle are hauled in. Smaller turtles can be pulled completely into the boat by this method, while larger ones are hauled within harpooning range. This practice has been reported throughout
760-725: A restaurant, while the others all involved fishermen eating their catch. From 2006 through 2009 in Japan there were 119 incidents involving 183 people but only seven people died. Only a few cases have been reported in the United States, and outbreaks in countries outside the Indo-Pacific area are rare. In Haiti, tetrodotoxin was thought to have been used in voodoo preparations, in so-called zombie poisons. Subsequent careful analysis has however repeatedly called early studies into question on technical grounds, and failed to identify
836-453: A role in TTX biosynthesis" – although the correlation has been extended to most but not all animals in which the toxin has been identified. To the contrary, there has been a failure in a single case, that of newts ( Taricha granulosa ), to detect TTX-producing bacteria in the tissues with highest toxin levels ( skin , ovaries , muscle ), using PCR methods, although technical concerns about
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#1732801379760912-517: A strong case is made for ingestion of TTX and/or TTX-producing bacteria, with accumulation and possible subsequent colonization and production. Nevertheless, without clear biosynthetic pathways (not yet found in animals, but shown for bacteria), it remains uncertain whether it is simply via bacteria that each animal accumulates TTX; the question remains as to whether the quantities can be sufficiently explained by ingestion, ingestion plus colonization, or some other mechanism. Tetrodotoxin binds to what
988-610: A tetrodotoxin derivative. There have been several reported poisonings from mislabelled pufferfish, and at least one report of a fatal episode in Oregon when an individual swallowed a rough-skinned newt Taricha granulosa on a dare. In 2009, a major scare in the Auckland Region of New Zealand was sparked after several dogs died eating Pleurobranchaea maculata (grey side-gilled seaslug) on beaches. Children and pet owners were asked to avoid beaches, and recreational fishing
1064-544: A tonic effect when used at the correct dose. The principal use was "to arrest convulsive diseases". In the Pen-T’so Kang Mu (Index Herbacea or The Great Herbal by Li Shih-Chen, 1596) some types of the fish Ho-Tun (the current Chinese name for tetraodon ) were also recognized as both toxic yet, at the right dose, useful as part of a tonic. Increased toxicity in Ho-Tun was noted in fish caught at sea (rather than river) after
1140-742: A trait still present in Holostei ( bowfins and gars ). In some fish like the arapaima , the swim bladder has been modified for breathing air again, and in other lineages it have been completely lost. The teleosts have urinary and reproductive tracts that are fully separated, while the Chondrostei have common urogenital ducts, and partially connected ducts are found in Cladistia and Holostei. Ray-finned fishes have many different types of scales ; but all teleosts have leptoid scales . The outer part of these scales fan out with bony ridges, while
1216-587: Is a class of bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fins made of webbings of skin supported by radially extended thin bony spines called lepidotrichia , as opposed to the bulkier, fleshy lobed fins of the sister class Sarcopterygii (lobe-finned fish). Resembling folding fans , the actinopterygian fins can easily change shape and wetted area , providing superior thrust-to-weight ratios per movement compared to sarcopterygian and chondrichthyian fins. The fin rays attach directly to
1292-685: 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, it is found in several other animals (e.g., in blue-ringed octopi , rough-skinned newts , and moon snails ). It is also produced by certain infectious or symbiotic bacteria like 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
1368-483: Is believed that dolphins with remoras attached do not benefit from the relationship. The attachment of the remora increases the dolphin's drag , which increases the energy needed for swimming. The remora is also thought to irritate the skin of the dolphin. Research into the physiology of the remora has been of significant benefit to the understanding of ventilation costs in fish. Remoras, like many other fishes, have two different modes of ventilation. Ram ventilation
1444-545: Is divided into the infraclasses Holostei and Teleostei . During the Mesozoic ( Triassic , Jurassic , Cretaceous ) and Cenozoic the teleosts in particular diversified widely. As a result, 96% of living fish species are teleosts (40% of all fish species belong to the teleost subgroup Acanthomorpha ), while all other groups of actinopterygians represent depauperate lineages. The classification of ray-finned fishes can be summarized as follows: The cladogram below shows
1520-530: Is in development by USAMRIID that was effective, in the one study, for reducing toxin lethality in tests on mice. Poisonings from tetrodotoxin have been almost exclusively associated with the consumption of pufferfish from waters of the Indo-Pacific Ocean regions, primarily because equally toxic pufferfishes from other regions are much less commonly eaten. Several reported cases of poisonings, including fatalities, nonetheless involved pufferfish from
1596-507: Is increasing respiratory distress , speech is affected, and the victim usually exhibits shortness of breath , excess pupil dilation , and abnormally low blood pressure . Paralysis increases, and convulsions , mental impairment, and irregular heartbeats may occur. The victim, although completely paralysed, may be conscious and in some cases completely understandable until shortly before death, which generally occurs within 4 to 6 hours (range ~20 minutes to ~8 hours). However, some victims enter
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#17328013797601672-412: Is known as site 1 of the fast voltage-gated sodium channel . Site 1 is located at the extracellular pore opening of the ion channel. Any molecule bound to this site will block sodium ions from going into the nerve cell through this channel (which is ultimately necessary for nerve conduction). Saxitoxin , neosaxitoxin , and several of the conotoxins also bind the same site. The use of this toxin as
1748-597: Is needed to validate the extent of this alternative feeding mechanism. Remoras are tropical open-ocean dwellers, but are occasionally found in temperate or coastal waters if they have attached to large fish that have wandered into these areas. In the mid- Atlantic Ocean , spawning usually takes place in June and July; in the Mediterranean Sea , it occurs in August and September. The sucking disc begins to show when
1824-460: Is not a factor in susceptibility to tetrodotoxin poisoning. This toxicosis may be avoided by not consuming animal species known to contain tetrodotoxin, principally pufferfish; other tetrodotoxic species are not usually consumed by humans. Poisoning from tetrodotoxin is of particular public health concern in Japan, where fugu is a traditional delicacy. It is prepared and sold in special restaurants where trained and licensed chefs carefully remove
1900-403: Is only partially understood. It is long known that the molecule is related to saxitoxin , and as of 2011 it is believed that there are separate routes for aquatic (bacterial) and terrestrial (newt) TTX. In 2020, new intermediates found in newts suggest that the synthesis starts with geranyl guanidine in the amphibian; these intermediates were not found in aquatic TTX-containing animals, supporting
1976-668: Is presented as a method of assisting torture. The toxin was also referenced in "synthetic form" in the S1E2 of the series " FBI ". The toxin is used as a weapon in both the second season of Archer , in Covert Affairs and in the Inside No. 9 episode " The Riddle of the Sphinx ". In Columbo, Episode 2 of Season 7, fugu is used to kill the antagonists victim. Columbo (season 7) In The Apothecary Diaries light novel, as well as
2052-432: Is relatively rare and is found in about 6% of living teleost species; male care is far more common than female care. Male territoriality "preadapts" a species for evolving male parental care. There are a few examples of fish that self-fertilise. The mangrove rivulus is an amphibious, simultaneous hermaphrodite, producing both eggs and spawn and having internal fertilisation. This mode of reproduction may be related to
2128-418: Is the process in which at higher speeds, the remora uses the force of the water moving past it to create movement of fluid in the gills. At lower speeds, the remora will use a form of active ventilation, in which the fish actively moves fluid through its gills. In order to use active ventilation, a fish must actively use energy to move the fluid; however, determining this energy cost is normally complicated due to
2204-557: Is unclear as to whether this has any therapeutic relevance for most people with migraine. Tetrodotoxin has been used clinically to relieve negative affects associated with heroin withdrawal . In the U.S., tetrodotoxin appears on the select agents list of the Department of Health and Human Services , and scientists must register with HHS to use tetrodotoxin in their research. However, investigators possessing less than 500 mg are exempt from regulation. Tetrodotoxin serves as
2280-506: The Cyprinidae (in goldfish and common carp as recently as 14 million years ago). Ray-finned fish vary in size and shape, in their feeding specializations, and in the number and arrangement of their ray-fins. In nearly all ray-finned fish, the sexes are separate, and in most species the females spawn eggs that are fertilized externally, typically with the male inseminating the eggs after they are laid. Development then proceeds with
2356-658: The Indian Ocean , especially from eastern Africa near Zanzibar and Mozambique , and from northern Australia near Cape York and Torres Strait . Similar reports come from Japan and from the Americas. Some of the first records of the "fishing fish" in the Western literature come from the accounts of the second voyage of Christopher Columbus . However, Leo Wiener considers the Columbus accounts to be apocryphal : what
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2432-592: The deep sea to subterranean waters to the highest mountain streams . Extant species can range in size from Paedocypris , at 8 mm (0.3 in); to the massive ocean sunfish , at 2,300 kg (5,070 lb); and to the giant oarfish , at 11 m (36 ft). The largest ever known ray-finned fish, the extinct Leedsichthys from the Jurassic , has been estimated to have grown to 16.5 m (54 ft). Ray-finned fishes occur in many variant forms. The main features of typical ray-finned fish are shown in
2508-488: The oviparous teleosts, most (79%) do not provide parental care. Viviparity , ovoviviparity , or some form of parental care for eggs, whether by the male, the female, or both parents is seen in a significant fraction (21%) of the 422 teleost families; no care is likely the ancestral condition. The oldest case of viviparity in ray-finned fish is found in Middle Triassic species of † Saurichthys . Viviparity
2584-663: The sister lineage of all other actinopterygians, the Acipenseriformes (sturgeons and paddlefishes) are the sister lineage of Neopterygii, and Holostei (bowfin and gars) are the sister lineage of teleosts. The Elopomorpha ( eels and tarpons ) appear to be the most basal teleosts. The earliest known fossil actinopterygian is Andreolepis hedei , dating back 420 million years ( Late Silurian ), remains of which have been found in Russia , Sweden , and Estonia . Crown group actinopterygians most likely originated near
2660-664: The viscera to reduce the danger of poisoning. There is potential for misidentification and mislabelling, particularly of prepared, frozen fish products. The mouse bioassay developed for paralytic shellfish poisoning (PSP) can be used to monitor tetrodotoxin in pufferfish and is the current method of choice. An HPLC method with post-column reaction with alkali and fluorescence has been developed to determine tetrodotoxin and its associated toxins. The alkali degradation products can be confirmed as their trimethylsilyl derivatives by gas chromatography/mass spectrometry. Tetrodotoxin may be quantified in serum, whole blood or urine to confirm
2736-665: The 1938 non-fiction book Tell My Horse by Zora Neale Hurston in which there were multiple accounts of purported tetrodotoxin poisoning in Haiti by a voodoo sorcerer called the bokor . These stories were later popularized by Harvard -trained ethnobotanist Wade Davis in his 1985 book and Wes Craven 's 1988 film, both titled The Serpent and the Rainbow . James Ellroy includes "blowfish toxin" as an ingredient in Haitian Vodou preparations to produce zombieism and poisoning deaths in his dark, disturbing, violent novel Blood's
2812-709: The Atlantic Ocean, Gulf of Mexico , and Gulf of California . There have been no confirmed cases of tetrodotoxicity from the Atlantic pufferfish, Sphoeroides maculatus , but three studies found extracts from fish of this species highly toxic in mice. Several recent intoxications from these fishes in Florida were due to saxitoxin , which causes paralytic shellfish poisoning with very similar symptoms and signs. The trumpet shell Charonia sauliae has been implicated in food poisonings, and evidence suggests it contains
2888-1013: The Devonian-Carboniferous boundary. The earliest fossil relatives of modern teleosts are from the Triassic period ( Prohalecites , Pholidophorus ), although it is suspected that teleosts originated already during the Paleozoic Era . The listing below is a summary of all extinct (indicated by a dagger , †) and living groups of Actinopterygii with their respective taxonomic rank . The taxonomy follows Phylogenetic Classification of Bony Fishes with notes when this differs from Nelson, ITIS and FishBase and extinct groups from Van der Laan 2016 and Xu 2021. [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] Tetrodotoxin Tetrodotoxin ( TTX )
2964-402: The adjacent diagram. The swim bladder is a more derived structure and used for buoyancy . Except from the bichirs , which just like the lungs of lobe-finned fish have retained the ancestral condition of ventral budding from the foregut , the swim bladder in ray-finned fishes derives from a dorsal bud above the foregut. In early forms the swim bladder could still be used for breathing,
3040-412: The amount needed to reach a lethal dose by injection is 8 μg per kg in mice. The toxin can enter the body of a victim by ingestion , injection, or inhalation , or through abraded skin. Poisoning occurring as a consequence of consumption of fish from the order Tetraodontiformes is extremely serious. The organs (e.g., liver) of the pufferfish can contain levels of tetrodotoxin sufficient to produce
3116-423: The approach have been raised. Critically for the general argument, Takifugu rubripes puffers captured and raised in laboratory on controlled, TTX-free diets "lose toxicity over time", while cultured, TTX-free Takifugu niphobles puffers fed on TTX-containing diets saw TTX in the livers of the fishes increase to toxic levels. Hence, as bacterial species that produce TTX are broadly present in aquatic sediments,
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3192-463: The bichirs and holosteans (bowfin and gars) in having gone through a whole-genome duplication ( paleopolyploidy ). The WGD is estimated to have happened about 320 million years ago in the teleosts, which on average has retained about 17% of the gene duplicates, and around 180 (124–225) million years ago in the chondrosteans. It has since happened again in some teleost lineages, like Salmonidae (80–100 million years ago) and several times independently within
3268-459: The body and brain. As a result, TTX causes loss of sensation, and paralysis of voluntary muscles including the diaphragm and intercostal muscles, stopping breathing. The therapeutic uses of puffer fish ( tetraodon ) eggs were mentioned in the first Chinese pharmacopoeia Pen-T’so Ching (The Book of Herbs, allegedly 2838–2698 BC by Shennong ; but a later date is more likely ), where they were classified as having "medium" toxicity, but could have
3344-423: The common names "sharksucker" and "whalesucker". Smaller remoras also fasten onto fish such as tuna and swordfish , and some of the smallest remoras travel in the mouths or gills of large manta rays, ocean sunfish , swordfish and sailfish . The relationship between a remora and its host is most often taken to be one of commensalism , specifically phoresy . While some of the relationships are mutualistic, it
3420-404: The described paralysis of the diaphragm and corresponding death due to respiratory failure . Toxicity varies between species and at different seasons and geographic localities, and the flesh of many pufferfish may not be dangerously toxic. The mechanism of toxicity is through the blockage of fast voltage-gated sodium channels, which are required for the normal transmission of signals between
3496-706: The different actinopterygian clades (in millions of years , mya) are from Near et al., 2012. Jaw-less fishes ( hagfish , lampreys ) [REDACTED] Cartilaginous fishes ( sharks , rays , ratfish ) [REDACTED] Coelacanths [REDACTED] Lungfish [REDACTED] Amphibians [REDACTED] Mammals [REDACTED] Sauropsids ( reptiles , birds ) [REDACTED] Polypteriformes ( bichirs , reedfishes ) [REDACTED] Acipenseriformes ( sturgeons , paddlefishes ) [REDACTED] Teleostei [REDACTED] Amiiformes ( bowfins ) [REDACTED] Lepisosteiformes ( gars ) [REDACTED] The polypterids (bichirs and reedfish) are
3572-436: The effect of the poison has worn off. Alpha adrenergic agonists are recommended in addition to intravenous fluids to increase the blood pressure; anticholinesterase agents "have been proposed as a treatment option but have not been tested adequately". No antidote has been developed and approved for human use, but a primary research report (preliminary result) indicates that a monoclonal antibody specific to tetrodotoxin
3648-495: The effects of TTX. Mutations in the VGSC genes, especially the genes for Na v 1.4 (skeletal muscle VGSC, "TTX-s" ), are found in many such animals. These mutations have independently arisen several times, even multiple times in different populations of the same species as seen in the garter snake. They consist of different amino acid substitutions in similar positions, a weak example of convergent evolution caused by how TTX binds to
3724-614: The fish were, to the extent that it would be used for suicide and that the Emperor specifically decreed that soldiers were not permitted to eat it. There is also evidence from other sources that knowledge of such toxicity was widespread throughout southeast Asia and India. The first recorded cases of TTX poisoning affecting Westerners are from the logs of Captain James Cook from 7 September 1774. On that date Cook recorded his crew eating some local tropic fish (pufferfish), then feeding
3800-432: The fish's habit of spending long periods out of water in the mangrove forests it inhabits. Males are occasionally produced at temperatures below 19 °C (66 °F) and can fertilise eggs that are then spawned by the female. This maintains genetic variability in a species that is otherwise highly inbred. Actinopterygii is divided into the subclasses Cladistia , Chondrostei and Neopterygii . The Neopterygii , in turn,
3876-408: The fish's movement when using either method. As a result, the remora has proved invaluable in finding this cost difference (since they will stick to a shark or tube, and hence remain stationary despite the movement, or lack thereof, of water). Experimental data from studies on remora found that the associated cost for active ventilation created a 3.7–5.1% increased energy consumption in order to maintain
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#17328013797603952-472: The following animals, specific bacterial species have been implicated: The association of bacterial species with the production of the toxin is unequivocal – Lago and coworkers state, "[e]ndocellular symbiotic bacteria have been proposed as a possible source of eukaryotic TTX by means of an exogenous pathway", and Chau and coworkers note that the "widespread occurrence of TTX in phylogenetically distinct organisms... strongly suggests that symbiotic bacteria play
4028-525: The identity of maculotoxin and TTX was reported in Science in 1978, and the synonymity of these two toxins is supported in modern reports (e.g., at Pubchem and in modern toxicology textbooks ) though historic monographs questioning this continue in reprint. The toxin is variously used by animals as a defensive biotoxin to ward off predation , or as both a defensive and predatory venom (e.g., in octopuses, chaetognaths , and ribbon worms ). Even though
4104-438: The inner part is crossed with fibrous connective tissue. Leptoid scales are thinner and more transparent than other types of scales, and lack the hardened enamel - or dentine -like layers found in the scales of many other fish. Unlike ganoid scales , which are found in non-teleost actinopterygians, new scales are added in concentric layers as the fish grows. Teleosts and chondrosteans (sturgeons and paddlefish) also differ from
4180-418: The lips and tongue is followed by developing it in the extremities, hypersalivation , sweating , headache, weakness, lethargy, incoordination , tremor , paralysis, bluish skin , loss of voice , difficulty swallowing , and seizures . The gastrointestinal symptoms are often severe and include nausea , vomiting , diarrhoea , and abdominal pain ; death is usually secondary to respiratory failure . There
4256-466: The main clades of living actinopterygians and their evolutionary relationships to other extant groups of fishes and the four-limbed vertebrates ( tetrapods ). The latter include mostly terrestrial species but also groups that became secondarily aquatic (e.g. whales and dolphins ). Tetrapods evolved from a group of bony fish during the Devonian period . Approximate divergence dates for
4332-471: The month of March. It was recognized that the most poisonous parts were the liver and eggs, but that toxicity could be reduced by soaking the eggs. (Tetrodotoxin is slightly water-soluble, and soluble at 1 mg/ml in slightly acidic solutions.) The German physician Engelbert Kaempfer , in his "A History of Japan" (translated and published in English in 1727), described how well known the toxic effects of
4408-477: The presence of the toxin by chemical analysis, and the association of the bacteria with TTX production by toxicity assay of media in which suspected bacteria are grown. As Lago et al. note, "there is good evidence that uptake of bacteria producing TTX is an important element of TTX toxicity in marine animals that present this toxin." TTX-producing bacteria include Actinomyces , Aeromonas , Alteromonas , Bacillus , Pseudomonas , and Vibrio species; in
4484-494: The proximal or basal skeletal elements, the radials, which represent the articulation between these fins and the internal skeleton (e.g., pelvic and pectoral girdles). The vast majority of actinopterygians are teleosts . By species count, they dominate the subphylum Vertebrata , and constitute nearly 99% of the over 30,000 extant species of fish . They are the most abundant nektonic aquatic animals and are ubiquitous throughout freshwater and marine environments from
4560-429: The remains to the pigs kept on board. The crew experienced numbness and shortness of breath, while the pigs were all found dead the next morning. In hindsight, it is clear that the crew survived a mild dose of tetrodotoxin, while the pigs ate the pufferfish body parts that contain most of the toxin, thus being fatally poisoned. The toxin was first isolated and named in 1909 by Japanese scientist Dr. Yoshizumi Tahara. It
4636-625: The remora is blamed for the defeat of Mark Antony at the Battle of Actium and, indirectly, for the death of Caligula . A modern version of the story is given by Jorge Luis Borges in Book of Imaginary Beings (1957). Actinopterygii Actinopterygii ( / ˌ æ k t ɪ n ɒ p t ə ˈ r ɪ dʒ i aɪ / ; from actino- 'having rays' and Ancient Greek πτέρυξ (ptérux) 'wing, fins'), members of which are known as ray-finned fish or actinopterygians ,
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#17328013797604712-426: The respective manga and anime adaptations, fugu toxin is encountered across multiple mystery arcs. Based on the presumption that tetrodotoxin is not always fatal, but at near-lethal doses can leave a person extremely unwell with the person remaining conscious, tetrodotoxin has been alleged to result in zombieism , and has been suggested as an ingredient in Haitian Vodou preparations. This idea first appeared in
4788-406: The rest of the body. TTX and its analogs have historically been important agents for use as chemical tool compounds, for use in channel characterization and in fundamental studies of channel function. The prevalence of TTX-s Na channels in the central nervous system makes tetrodotoxin a valuable agent for the silencing of neural activity within a cell culture . The biosynthetic route to TTX
4864-456: The same quantity of fluid flow the fish obtained by using ram ventilation. Other research into the remora's physiology came about as a result of studies across multiple taxa, or using the remora as an out-group for certain evolutionary studies. Concerning the latter case, remoras were used as an outgroup when investigating tetrodotoxin resistance in remoras, pufferfish, and related species, finding remoras (specifically Echeneis naucrates ) had
4940-424: The separate-route theory. In 2021, the first genome of a TTX-producing bacterium was produced. This " Bacillus sp. 1839" was identified as Cytobacillus gottheilii using its rRNA sequence. The researcher responsible for this study has not yet identified a coherent pathway but hopes to do so in the future. Animals that accumulate TTX as a defense mechanism as well as their predators must evolve to be resistant to
5016-439: The sodium channel – was shown definitively in 1964 by Toshio Narahashi and John W. Moore at Duke University , using the sucrose gap voltage clamp technique. Apart from their bacterial species of most likely ultimate biosynthetic origin (see below), tetrodotoxin has been isolated from widely differing animal species, including: Tarichatoxin was shown to be identical to TTX in 1964 by Mosher et al., and
5092-540: The structure of tetrodotoxin. The structure was confirmed by X-ray crystallography in 1970. Yoshito Kishi and coworkers reported the first total synthesis of racemic tetrodotoxin in 1972. M. Isobe and coworkers and J. Du Bois reported the asymmetric total synthesis of tetrodotoxin in 2003. The two 2003 syntheses used very different strategies, with Isobe's route based on a Diels-Alder approach and Du Bois's work using C–H bond activation . Since then, methods have rapidly advanced, with several new strategies for
5168-425: The synthesis of tetrodotoxin having been developed. TTX is extremely toxic. The material safety data sheet for TTX lists the oral median lethal dose ( LD 50 ) for mice as 334 μg per kg. For comparison, the oral LD 50 of potassium cyanide for mice is 8,500 μg per kg, demonstrating that even orally, TTX is more poisonous than cyanide . TTX is even more dangerous if administered intravenously;
5244-432: The toxin acts as a defense mechanism, some predators such as the common garter snake have developed insensitivity to TTX, which allows them to prey upon toxic newts . The association of TTX with consumed, infecting, or symbiotic bacterial populations within the animal species from which it is isolated is relatively clear; presence of TTX-producing bacteria within an animal's microbiome is determined by culture methods,
5320-401: The toxin in any preparation. Discussion of the matter has therefore all but disappeared from the primary literature since the early 1990s. Kao and Yasumoto concluded in the first of their papers in 1986 that "the widely circulated claim in the lay press to the effect that tetrodotoxin is the causal agent in the initial zombification process is without factual foundation." Genetic background
5396-562: 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 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 of
5472-407: The unmutated VGSC. Another path to TTX resistance is toxin-binding proteins that hold onto TTX tightly enough to prevent it reaching the vulnerable VGSCs. Various proteins that bind TTX have been found in pufferfish, crabs, and gastropods. There are also proteins that bind saxitoxin (STX), a toxin with a similar mode of action. In 1964, a team of scientists led by Robert B. Woodward elucidated
5548-421: The young fish are about 1 cm (0.4 in) long. When the remora reaches about 3 cm (1.2 in), the disc is fully formed and the remora can then attach to other animals. The remora's lower jaw projects beyond the upper, and the animal lacks a swim bladder . Some remoras associate with specific host species. They are commonly found attached to sharks, manta rays , whales, turtles, and dugongs , hence
5624-594: Was also interrupted for a time. After exhaustive analysis, it was found that the sea slugs must have ingested tetrodotoxin. Statistics from the Tokyo Bureau of Social Welfare and Public Health indicate 20–44 incidents of fugu poisoning per year between 1996 and 2006 in the entire country, leading to 34–64 hospitalizations and 0–6 deaths per year, for an average fatality rate of 6.8%. Of the 23 incidents recorded within Tokyo between 1993 and 2006, only one took place in
5700-452: Was one of the agents studied by Japan's Unit 731 , which evaluated biological weapons on human subjects in the 1930s. The diagnosis of pufferfish poisoning is based on the observed symptomatology and recent dietary history. Symptoms typically develop within 30 minutes of ingestion, but may be delayed by up to four hours; however, if the dose is fatal, symptoms are usually present within 17 minutes of ingestion. Having pins and needles of
5776-512: Was taken for accounts of the Americas may have been, in fact, notes Columbus derived from accounts of the East Indies, his desired destination. In ancient times, the remora was believed to stop a ship from sailing. In Latin, remora means "delay", while the genus name Echeneis comes from Greek ἔχειν, echein ("to hold") and ναῦς, naus ("a ship"). In a notable account by Pliny the Elder ,
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