- polyether toxins
-
maitotoxin (MTX) is an activator
of voltage-gated Ca2+ channels
. - ciguatera toxin / ciguatoxin (CTX) => ciguatera disease. At present, 24 related ciguatoxins are known and these were found in different fishes from the Pacific.
- Ctenochaetus striatus
- Naso unicornis
- Naso brevirostris
- Caranx sexfasciatus
- Cheilinus undulatus
- Lethrinus miniatus
- Lutjanus bohar
- Lutjanus monostigma
- Lutjamus rivulatus
- Glabrilutjanus nematophorus
- Gymnothorax undulatus
- Plectorhynchus punctatissimus
- Scarus gibbus
- Epinephelus fuscoguttatus (flowery cod)
- Plectropomus leopardus (coral trout)
- Cephalopholis argus
- Sphyraena barracuda (barracuda)
- Scomberomorus tritor (West-African Spanish mackerel)
- Lycodotis (Moray eel)
- groupers
- snappers
- jacks
- triggerfish
- neurologic
- cardiovascular
- gastrointestinal
- general symptoms.
- Dinophysidae
- Dinophysis
- Dinophysis acuminata
- pectenotoxin-1 (PTX-1)
- pectenotoxin-2 (PTX-2)
- Gonyaulacales
- Gonyaulacaceae
- Alexandrium blooms generally do not involve large-cell accumulations that discolor the water and may instead be invisible below the water surface. Low-density populations can cause severe problems due to the high potency of the toxins produced. Furthermore, Alexandrium spp. can grow in relatively pristine waters, and it is difficult to argue that anthropogenic nutrient inputs are stimulating the blooms. These characteristics are important when considering mitigation and control strategies.
- Alexandrium catenella
- Alexandrium fundyense, the predominant red tide species in the Gulf of Maine
- Alexandrium minutum
- Alexandrium ostenfeldii
- Alexandrium tamarense
- Pyrodinium
- Pyrodinium bahamense
- single sulphated STXs
- gonyautoxins (GTX) 1-4 (produced by Moraxella spp. symbionts of Protogonyaulax spp. ?)
- B-toxins
- doubly sulphated STXs (C-toxins)
- decarbamyl STXs (dcSTX)
- Gymnodiniales
- Gymnodiniaceae
- Gymnodinium
- Gymnodinium catenatum
- Karenia
- Karenia brevis (formerly Gymnodinium breve). Karenia was chosen in honor of Dr. Karen Steidinger, a prominent red tide scientist from the Florida Marine Research Institute in St. Petersburg, FLref.
- type I : 11 rings (8 6-membered rings, 2 heptameric and 1 8-membered ring)
- type II : 10 rings, with variation in the size of the rings ranging from 5 bonds to 9 bonds
- < 1,000 cells/L : no effects
- 5,000 cells/L : shellfish harvesting closed
- 10,000 cells/L : respiratory irritation
- 50,000 cells /L : respiratory irritation and possible fish kills
- > 1 million cells/L : respiratory irritation, fish kills and water discoloration.
- Peridiniales; Ostreopsidaceae; Ostreopsis
- Ostreopsis ovata
Food chain : Gambierdiscus toxicus produces gambiertoxin-4A => microalgae => herbivorous fish and invertebrates make biotransformation and acid-catalysed spiroisomerisation of gambiertoxin-4A to create ciguatoxin => carnivorous warm-water fishesref :
Pathogenesis : ciguatoxins bind to site 5-6 on a-subunit of voltage-gated Na+ channels
and close them (except for an isoform which opens).
The term ciguatera originated in the Caribbean area to designate intoxication induced by the ingestion of the marine snail Turbo pica (called cigua). Today, the term is widely used to denote a particular type of fish poisoning that results from ingestion of primarily reef fishes encountered around islands in the Caribbean and the Pacific. The clinical symptoms
Symptoms & signs (ciguatera fish poisoning (CFP)) can be classified into 4 broad groups:
and diarrhea,
generalized weakness, a decreased sensation to pain or touch, unusual or
painful sensations produced by ordinary stimuli, a burning or tingling
of the hands and legs or around the mouth, muscle pain and temperature
reversal sensation (hot things feel cold and cold things feel hot). Other
less common symptoms include: chills, itching, dizziness,
sweating, headache
and taste disturbances (a metallic taste or fuzzy sensation). The nausea
and vomiting,
and other gastrointestinal symptoms last for approximately 1 to 2 days.
Weakness may last for 1 to 7 days. Neurologic symptoms such as tingling
or temperature reversal generally persist for up to 1 week, but it is not
unusual for these symptoms to periodically re-occur for a month or more.
The poisoned victim may note an increased or decreased heart rate. Medical
personnel may also note systemic
arterial hypotension,
mydriasis,
and cardiac arrhythmia.
These symptoms resolve in 2 to 3 days
Therapy : the best treatment for ciguatera poisoning during the early phase of poisoning (1-3 days after eating a toxic fish) has been mannitol
infusion, which relieves many of the severe symptoms of poisoning, except
for diarrhea
in some patients. The long term chronic symptoms such as muscle ache, joint
pains and a weak, tired feeling in some patients have been successfully
treated with tocainide
and amitriptyline.
Currently gabapentin
was used as effective therapeutics of ciguatera intoxication.
Prognosis : if consumed in sufficient dose, can cause symptoms persisting for weeks, months or years. In some patients, long term symptoms occur or reoccur after generally eating fatty foods, seafood products and alcohol.
Prevention : ciguatoxins are not destroyed by cooking
=> okadaic acid
=> dinophysistoxins => pectenotoxins
Routes of intoxication : Mytilus spp. and other marine mollusks bioaccumulate STXs by filter feeding upon the microalgae during red tides (an explosive growth of dinoflagellate phytoplanktons whose red pigments color the water). Although mussels themselves are apparently unafffected by saxitoxin, mussel predators quickly develop NSP. Normally, shellfish beds are closed if there are > 80 mg of toxin per 100 grams of shellfish meat.
Epidemiology : Texas' 1st recorded red tide occurred in 1935 and affected waters from Port Aransas to Mexico. It was 20 years before the next episode at Galveston and nearly another 2 decades before a bloom was reported off Brownsville. In 1986, a red tide bloom killed an estimated 22 million fish from Galveston to the Rio Grande, and then a series of blooms occurred in 1987, 1990-91, 1993-97 and 2000.
They all bind to site 1 (or 5-6 ?) on voltage-gated Na+ channels
and block Na+ flux. They can be detected by using crown ethers,
which become fluorescent under UV light when bound to saxitoxins.=> saxitoxins
=> brevetoxins (BVX). The algae proliferate during red tide incidents (in high
concentration can make the water look red). BVX and related toxins are believed to have been responsible for massive fish kills from red tides in several regions. There are 2 types of brevetoxins
in cell walls, changing the voltage at which this opening occurs nearer
to the voltage threshold that triggers this process essentially making
the Na+ channel, and consequently, the affected nervous and
muscular cells hyperexcitable. Brevetoxins are unusually stable materials
in the dry state. They are stable as well as in different solvents (acetone,
acetonitrile, alcohol, ethyl acetate or DMSO), including water, where half-lives
for active material range from 4-6 months. Solutions with pH < 2 or
> 10 degrade the toxins.
Routes of intoxication : Mytilus spp. feed on them
Web resources : The Red Tide Alliance
Environmental experts have closed a stretch of beach near the northern Italian city of Genoa after toxic algae poisoned around 80 people needed hospital attention Sun Jul 17 and Mon Jul 18 2005 because of the microscopic algae, which is usually found in the tropics. No one was reported to be seriously ill, but experts said the 6-km (3.7-mile) stretch of Ligurian coastline would remain closed until Wed Jun 20 to allow time for further tests. It has been very hot recently and the sea has been very calm, which probably encouraged this phenomenon. People who come into contact with the algae can suffer fever, nausea and coughing fits.
