Entamoeba

related topics
{specie, animal, plant}
{disease, patient, cell}
{acid, form, water}
{math, energy, light}
{woman, child, man}
{son, year, death}
{line, north, south}
{area, part, region}

E. coli
E. dispar
E. gingivalis
E. histolytica
E. invadens
E. moshkovskii
etc.

Entamoeba is a genus of Amoebozoa found as internal parasites or commensals of animals.

In 1875, Fedor Lösch described the first proven case of amoebic dysentery in St Petersburg, Russia. He referred to the amoeba he observed microscopically as 'Amoeba coli'; however it is not clear whether he was using this as a descriptive term or intended it as a formal taxonomic name.[1] The genus Entamoeba was defined by Casagrandi and Barbagallo for the species Entamoeba coli, which is known to be a commensal organism.[2] Lösch's organism was renamed Entamoeba histolytica by Fritz Schaudinn in 1903; he later died, in 1906, from a self inflicted infection when studying this amoeba. For a time during the first half of the 20th century the entire genus Entamoeba was transferred to Endamoeba, a genus of amoebas infecting invertebrates about which little is known. This move was reversed by the International Commission on Zoological Nomenclature in the late 1950s, and Entamoeba has stayed 'stable' ever since.

Contents

Species

Several species are found in humans. Entamoeba histolytica is the pathogen responsible for 'amoebiasis' (which includes amoebic dysentery and amoebic liver abscesses), while others such as Entamoeba coli (Not to be confused with Escherichia coli) and E. dispar [3] are harmless. With the exception of Entamoeba gingivalis, which lives in the mouth, and E. moshkovskii, which is frequently isolated from river and lake sediments, all Entamoeba species are found in the intestines of the animals they infect.

Structure

Entamoeba cells are small, with a single nucleus and typically a single lobose pseudopod taking the form of a clear anterior bulge. They have a simple life cycle. The trophozoite (feeding-dividing form) is approximately 10-20 μm in diameter and feeds primarily on bacteria. It divides by simple binary fission to form two smaller daughter cells. Almost all species form cysts, the stage involved in transmission (the exception is E. gingivalis). Depending on the species, these can have one, four or eight nuclei and are variable in size; these characteristics help in species identification.

Full article ▸

related documents
Rotifer
Toothwort
Orthoptera
Aster (genus)
Cotyledon
Common Kestrel
Milkweed butterfly
Medicago
Trees of Britain and Ireland
Acouchi
Crab
Gigantopithecus blacki
Geranium
Asparagales
Nightingale
Dicotyledon
Protura
Azalea
Sloughi
Toad
Scaevola
Santalales
Sculpin
Goeldi's Marmoset
Commensalism
Parakeet
Poales
Vernation
Pudú
Anemone