Karenia brevis

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A Microbial Biorealm page on the genus Karenia brevis

Classification

Higher order taxa

cellular organisms; Eukaryota; Alveolata; Dinophyceae; Gymnodiniales; Gymnodiniaceae; Karenia

Species

NCBI: Taxonomy

Karenia brevis

Description and significance

Karenia brevis is an aquatic marine dinoflagellate in the phylum Protozoa and super group Alveolates. This Protist is of microscopic proportion usually between 20 and 40 μm in size. These unicellular, flagellated, photosynthetic organisms have cellulose plates (theca) that surround the cell. The plates are secreted by Alveoli (membrane bound vesicles just below the cell membrane) hence their super group name and create the outer boundary for the cell. Located on the cellulose plates are two grooves called the transverse and longitudinal groove. K. brevis has two flagella and these grooves are where the flagellum are attached. One flagellum raps around the body of the cell in the transverse groove, while the other extends from the body of the cell on the longitudinal groove. Using their flagella for locomotion they are able to have some source of propelling movement in the water column.

These dinoflagellates are usually found in abundant masses near coastal waters in warmer conditions. Though they are found in several other places in the vast ocean water, this area is of particular concern. K. brevis has an active involvement in harmful algal or “red tides” off the coasts of Florida and California. This is a problem due to the potent neurotoxins called brevetoxin’s that these cells create, and when there is an abundance or bloom of these organisms’ resources become limited. There is more competition for space and sunlight, as these organisms die from lack of resources they release their neurotoxins. The neutoxin’s cause all sorts of environmental and economic problems such as massive fish kills, fisheries crashing, paralytic shellfish poisoning, etc. This is a dangerous time for humans to eat seafood and can cause some major health problems and diseases.

Genome structure

K. brevis has a large haploid genore consisting of about 1 x 10 ^11 bp. It consists of permanently condensed chromatin which lacks nucleosomes. The condensed chromosomes have a characteristic banding pattern with stacked disks that form a continuous left-handed twist along the longitudinal axis. The disks end in less tightly packed loops of DNA that contain actively transcribed DNA. The K. brevis genome has not yet been sequenced due to its large size.

Cell structure and metabolism

Interesting features of cell structure; how it gains energy; what important molecules it produces.

Ecology

Habitat; symbiosis; contributions to the environment.

Pathology

How does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.

Current Research

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Cool Factor

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References

http://zipcodezoo.com/Protozoa/K/Karenia_brevis/

Edited by student of Iris Keren