300px, class=skin-invert-image, Chemical structure of the ciguatoxin CTX1B Ciguatoxins are a class of

toxic Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a subst ...

polycyclic

polyether In organic chemistry, ethers are a class of compounds that contain an ether group, a single oxygen atom bonded to two separate carbon atoms, each part of an organyl group (e.g., alkyl or aryl). They have the general formula , where R and R� ...

s found in fish that cause

ciguatera Ciguatera fish poisoning (CFP), also known as ciguatera, is a foodborne illness caused by eating tropical reef fish contaminated with ciguatoxins. Such individual fish are said to be ciguatoxic. Symptoms may include diarrhea, vomiting, numbness ...

. 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 seem to 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 channel Sodium channels are integral membrane proteins that form ion channels, conducting sodium ions (Na+) through a cell (biology), cell's cell membrane, membrane. They belong to the Cation channel superfamily, superfamily of cation channels. Classific ...

s in the

nervous system In biology, the nervous system is the complex system, highly complex part of an animal that coordinates its behavior, actions and sense, sensory information by transmitting action potential, signals to and from different parts of its body. Th ...

. Opening a sodium channel causes

depolarization In biology, depolarization or hypopolarization is a change within a cell (biology), cell, during which the cell undergoes a shift in electric charge distribution, resulting in less negative charge inside the cell compared to the outside. Depolar ...

, which could sequentially cause paralysis, heart arrhythmia, and changing the senses of heat and cold. Such poisoning from ciguatoxins is known as ciguatera. Ciguatoxins are

lipophilic Lipophilicity (from Greek language, Greek λίπος "fat" and :wikt:φίλος, φίλος "friendly") is the ability of a chemical compound to dissolve in fats, oils, lipids, and non-polar solvents such as hexane or toluene. Such compounds are c ...

, able to cross the

blood–brain barrier The blood–brain barrier (BBB) is a highly selective semipermeable membrane, semipermeable border of endothelium, endothelial cells that regulates the transfer of solutes and chemicals between the circulatory system and the central nervous system ...

, and can cause both central and peripheral neurologic symptoms. The major symptoms will develop within 1–3 hours of toxin ingestion: vomiting, diarrhea, numbness of extremities, mouth and lips, reversal of hot and cold sensation, muscle and joint aches. The symptoms may last from days to weeks or even months depending on each individual situation. There is no known antidote, though several therapeutic targets have been identified. The LD₅₀ of ciguatoxin in mice is around 200 to 300 ng/kg.

Bioaccumulation

Ciguatoxin is produced by ''

Gambierdiscus toxicus ''Gambierdiscus toxicus'' is a species of photosynthetic unicellular eukaryote belonging to the Alveolata, part of the SAR supergroup. It is a dinoflagellate which can cause the foodborne illness ciguatera, and is known to produce several natura ...

'', a type of

dinoflagellate The Dinoflagellates (), also called Dinophytes, are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered protists. Dinoflagellates are mostly marine plankton, but they are also commo ...

. The phenomenon occurs in the Caribbean Sea, Hawaii, and coastal Central America. The toxin usually accumulates in the skin, head, viscera, and

roe Roe, ( ) or hard roe, is the fully ripe internal egg masses in the ovaries, or the released external egg masses, of fish and certain marine animals such as shrimp, scallop, sea urchins and squid. As a seafood, roe is used both as a cooking, c ...

of big reef fish like

grouper Groupers are a diverse group of marine ray-finned fish in the family Epinephelidae, in the order Perciformes. Groupers were long considered a subfamily of the seabasses in Serranidae, but are now treated as distinct. Not all members of this f ...

wrasse The wrasses are a family, Labridae, of marine ray-finned fish, many of which are brightly colored. The family is large and diverse, with over 600 species in 81 genera, which are divided into nine subgroups or tribes. They are typically small, ...

triggerfish Triggerfish are about 40 species of often brightly colored marine ray-finned fishes belonging to the family Balistidae. Often marked by lines and spots, they inhabit tropical and subtropical oceans throughout the world, with the greatest speci ...

lionfish ''Pterois'' is a genus of venomous fish, venomous marine fish, commonly known as the lionfish, native to the Indo-Pacific. It is characterized by conspicuous aposematism, warning coloration with red or black bands and ostentatious dorsal fins tip ...

, and

amberjack Amberjacks are Atlantic and Pacific Ocean, Pacific fish in the genus ''Seriola'' of the family Carangidae. They are widely consumed across the world in various cultures, most notably for Pacific amberjacks in Japanese cuisine; they are most oft ...

. It also affects

barracuda A barracuda is a large, predatory, ray-finned, saltwater fish of the genus ''Sphyraena'', the only genus in the family Sphyraenidae, which was named by Constantine Samuel Rafinesque in 1815. It is found in tropical and subtropical oceans worldw ...

, snapper,

hogfish The hogfish (''Lachnolaimus maximus''), also known as boquinete, doncella de pluma or pez perro in Mexico is a species of wrasse native to the Western Atlantic Ocean, living in a range from Nova Scotia, Canada, to northern South America, includ ...

king mackerel The king mackerel (''Scomberomorus cavalla'') surmayi or kingfish, is a migratory species of mackerel of the western Atlantic Ocean and Gulf of Mexico. It is an important species to both the commercial and recreational fishing industries. Descri ...

, and sea bass.

References

External links

* {{Toxins Ion channel toxins Marine neurotoxins Phycotoxins Polyether toxins Sodium channel openers Spiro compounds Non-protein ion channel toxins

Toxic effect on humans

Bioaccumulation

See also

References

External links