Dinotoxin
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Dinotoxins are a group of
toxins A toxin is a naturally occurring organic poison produced by metabolic activities of living cells or organisms. Toxins occur especially as a protein or conjugated protein. The term toxin was first used by organic chemist Ludwig Brieger (1849–1 ...
which are produced by
flagellate A flagellate is a cell or organism with one or more whip-like appendages called flagella. The word ''flagellate'' also describes a particular construction (or level of organization) characteristic of many prokaryotes and eukaryotes and their ...
, aquatic, unicellular protists called
dinoflagellates The dinoflagellates (Greek δῖνος ''dinos'' "whirling" and Latin ''flagellum'' "whip, scourge") are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered algae. Dinoflagellates a ...
. Dinotoxin was coined by Hardy and Wallace in 2012 as a general term for the variety of toxins produced by dinoflagellates. Dinoflagellates are an enormous group of marine life, with much diversity. With great diversity comes many different toxins, however, there are a few toxins (or derivatives) that multiple species have in common. Dinoflagellates normally have a low toxin production rate, therefore in small concentrations their toxins are not potent. However their toxins are highly poisonous in large concentrations. They are capable of poisoning various species of marine life such as many fish and shellfish, and affecting the nervous system of any wildlife or humans that consume the infected marine life, or drink the contaminated water. Under bloom conditions, commonly referred to as
red tides A harmful algal bloom (HAB) (or excessive algae growth) is an algal bloom that causes negative impacts to other organisms by production of natural algae-produced toxins, mechanical damage to other organisms, or by other means. HABs are sometimes ...
or harmful algal blooms, dinoflagellates are capable of producing immense dinotoxin concentrations causing large fish die-offs, and contamination of shellfish. This contamination of shellfish leads to multiple severe human related illnesses. These illnesses include
paralytic shellfish poisoning Paralytic shellfish poisoning (PSP) is one of the four recognized syndromes of shellfish poisoning, which share some common features and are primarily associated with bivalve mollusks (such as mussels, clams, oysters and scallops). These shellfi ...
,
diarrhetic shellfish poisoning Diarrhetic shellfish poisoning (DSP) is one of the four recognized symptom types of shellfish poisoning, the others being paralytic shellfish poisoning, neurotoxic shellfish poisoning and amnesic shellfish poisoning. As the name suggests, this sy ...
,
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 neurolog ...
, and
ciguatera Ciguatera fish poisoning (CFP), also known simply as ciguatera, is a foodborne illness caused by eating reef fish whose flesh is contaminated with certain toxins. Such individual fish are said to be ciguatoxic. Symptoms may include diarrhea, vomi ...
fish poisoning. Dinotoxins are impacting not only the marine ecosystem, but the economy as well. The economic impact is increasing compared to past years, due to the increase in seafood consumption, and coastal tourism.


Common toxins

Below are three of the most common dinotoxins, these toxins are produced by a large variety of dinoflagellates. There is thought to be more than a few hundred different toxins produced by dinoflagellates.
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 paralyt ...
s and
Gonyautoxin Gonyautoxins (GTX) are a few similar toxic molecules that are naturally produced by algae. They are part of the group of saxitoxins, a large group of neurotoxins along with a molecule that is also referred to as saxitoxin (STX), neosaxitoxin (NSTX ...
s are deadly
neurotoxins Neurotoxins are toxins that are destructive to nerve tissue (causing neurotoxicity). Neurotoxins are an extensive class of exogenous chemical neurological insultsSpencer 2000 that can adversely affect function in both developing and mature nerv ...
which cause paralytic shellfish poisoning. Saxitoxin B1 has a lethal concentration of 86 to 788 micrograms per kilogram of body weight, while Gonyautoxins C1 and C2 are lethal in concentrations of 411 micrograms per kilogram of body weight.
Yessotoxin Yessotoxins are a group of lipophilic, sulfur bearing polyether toxins that are related to ciguatoxins. They are produced by a variety of dinoflagellates, most notably ''Lingulodinium polyedrum'' and '' Gonyaulax spinifera''. When the environm ...
s (YTXs) are potent cytotoxins which are made of disulfated polyether compounds. This toxins compromises the tumor suppressive functions of the E-cadherin–catenin system in epithelial cells.


Function

Dinotoxins are produced for one of two intentional reasons; either to aid in predation or to act as a defense against predation. Toxins may also be produced as an unintentional byproduct due to metabolic processes that takes place within the organism.


Genetics

The molecular genetics of dinotoxin synthesis is not widely understood, but the polyketide pathway involving
polyketide synthase Polyketides are a class of natural products derived from a precursor molecule consisting of a chain of alternating ketone (or reduced forms of a ketone) and methylene groups: (-CO-CH2-). First studied in the early 20th century, discovery, biosynth ...
(PKS) is known to be associated with the production of dinotoxins. The toxins released by dinoflagellates commonly include sulfated polysaccharides. One common toxin, saxitoxin, blocks sodium ions from moving through sodium channels on cell membranes.


Applications

Dinotoxins are high-value toxins in multiple fields of work such as chemical research, toxicological, and biomedical. An economic increase in the seafood industry has made these toxins of higher interest to scientists. Studying dinotoxins allows scientists to create toxin assays can be used to analyze fish and seafood for safe levels of toxicity before consumption. Antibodies can also be developed against dinotoxins, which can be effective in potentially harmful outbreak or field situations. Some dinotoxins are useful in pain management. These toxins may have potential therapeutic effects along with other medical applications, including antiviral, antibacterial, and antioxidant activity. Free-radical scavenging, inflammation control, and tumor destruction are also applications of dinotoxins. They can act as anticoagulants, biolubricants, and can prevent pathogenic microorganisms from binding to cell membranes with an anti-adhesive property.


See also

*
Cyanotoxin Cyanotoxins are toxins produced by cyanobacteria (also known as blue-green algae). Cyanobacteria are found almost everywhere, but particularly in lakes and in the ocean where, under high concentration of phosphorus conditions, they exponential gr ...


References

{{reflist Toxins