Alexandrium tamarense
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Classification
Picture courtesy of USGS Woods Hole Science Center
Higher order taxa
Domain: Eukaryota
Phylum: Alveolata
Class: Dinophyceae
Order: Gonyaulacales
Family: Gonyaulacaceae
Species
Alexandrium tamarense
Synonyms: Gonyaulax tamarensis Lebour 1925 , G. excavata (Braarud) Balech 1971 Protogonyaulax tamarensis (Lebour) F. J. R. Taylor 1979
Description and significance
Describe the appearance, habitat, etc. of the organism, and why it is important enough to have its genome sequenced. Describe how and where it was isolated.
Alexandrium tamarense is a single-celled dinoflagellate found in coastal marine environments throughout the world and is the cause of algal blooms that result in the phenomenon known as red tides.
At only 25-46 micrometers in length per cell A. tamarense is microscopic in size and is brown and somewhat spherical in appearance. Blooms of millions of these cells in every liter of seawater create red tides (pictured below).
A. tamarense can be highly toxic to humans as well as other organisms such as marine mammals, birds, and fish. This has led scientists to....
Genome structure
Describe the size and content of the genome. How many chromosomes? Circular or linear? Other interesting features?Does it have any plasmids? Are they important to the organism's lifestyle?
Like other dinoflagellates, Alexandrium tamarense consists of large amounts of DNA compared to other eukaryotic organisms. It also lacks nucleosomes. It consists of 144 chromosomes which are condensed in the nucleus until DNA replication. A total of 11,103 nucleotides [218 nucleotide core and 10,885 expressed sequence tags (ESTs)] have been sequenced.
It is still not clear which genes play a role in toxin production.
Cell structure and metabolism
Describe any interesting features and/or cell structures; how it gains energy; what important molecules it produces.
Like some other dinoflagellate species, A. tamarense is photoautotrophic and obtains it manufactures its own food by using energy is obtains from sunlight. It is considered a primary producer and is a source of food for many othe organisms.
A. tamarense is also motile, having two flagella which it uses to propel itself through water.
It is also considered "armored" because it is surrounded by a layer of cellulose that form plates known as thecae.
Ecology
Describe any interactions with other organisms (included eukaryotes), contributions to the environment, effect on environment, etc.
Different strains of Alexandrium tamarense are found in the same algal blooms but not all are toxic. Some provide a food source for many organisms such as fish and shellfish that feed on primary producers. Many are toxic, however, and have devastating effects on the environment and its inhabitants.
While some organisms are unaffected by the toxins produced by A. tamarense, these toxins can accumulate to extremely high levels in these organisms and can be very dangerous to higher organisms that consume them. Consumption of infected organisms can lead to many different illnesses. Paralytic Shellfish Poisoning (PSP) is the primary illness caused by A. tamarense.
Fish that affected by this illness and also attack the central nervous system, fish are no longer able to breathe in these environments and this often leads to fish kills.
Pathology
How does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.
Not all strains of Alexandrium tamarense are toxic. Different strains are often found in the same algal blooms caused by this species.
However, some strains of Alexandrium tamarense produce very potent neurotoxins known as paralytic shellfish toxins (PSTs). These toxins, which include gonyautoxins, neosaxitoxin and saxitoxin, affect fish, marine mammals, birds, and humans.
Many deaths have been reported from the consumption of shellfish infected with these toxins.
Resting cysts can harbour PSP toxins, it was been demonstrated that cysts were more toxic than their motile stage. Humans, other mammals, fish and birds can be affected. Please consult original reference for further details. Harmful species http://www.algaebase.org/search/species/detail/?species_id=40299
http://www.nmnh.si.edu/botany/projects/dinoflag/Taxa/Atamarense.htm
Application to Biotechnology
Does this organism produce any useful compounds or enzymes? What are they and how are they used?
Current Research
Enter summaries of the most recent research here--at least three required
A recent increase in harmful algal blooms produced by A. tamarense and similar species have caused concern for fisheries around the world.
Areas along the coast of Maine have had outbreaks year after year prompting a five year project which is currently underway at Woods Hole Institute's Anderson Laboratory. This project is focused on the abundance, distribution, and motility of A. tamarense in the region. (http://www.whoi.edu/redtide/labweb/projects.html)
At the Hong Kong University of Science and Technology, (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V7H-44PWXYG-2&_user=699469&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000039278&_version=1&_urlVersion=0&_userid=699469&md5=e22cc9ea0a95b7c463337a6ff596c71e)
http://en.wikipedia.org/wiki/Paralytic_shellfish_poisoning
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1173104
http://www.nmnh.si.edu/botany/projects/dinoflag/Taxa/Atamarense.htm
http://www.assurecontrols.com/info-dinoflagellates.htm
http://microbewiki.kenyon.edu/index.php/Alexandrium