amoeba

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Related to amebic: amebic abscess

amoeba:

see amebaameba
or amoeba
, common name for certain one-celled organisms belonging to the phylum Sarcodina of the kingdom Protista. Amebas were previously classified as members of the animal kingdom.
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Amoeba

 

the order of the simplest organized protozoa of the class Sarcodina. Most live in fresh waters, a few in the soil; there are parasitic forms. They are usually of microscopic dimensions up to 50 μm, but there are also “giants” such as Pelomyxa, which grows to 2–3 mm. Amoebas have no constant body shape; their cytoplasmic body forms extrusions or pseudopodia which aid in motion and food gathering. They feed on bacteria, minute algae, and protozoa. The amoeba engulfs the food particle and from its cytoplasm the amoeba secretes digestive juices and forms a food vacuole within which the food is dissolved and is incorporated into the cytoplasm. The excretion of water (osmoregulation) and metabolic products occurs through the contractory vacuoles, which gradually accumulate waste matter and discharge it at the surface.

Amoebas ordinarily have one nucleus, but Pelomyxa is multinucleate. The majority of amoebas multiply asexually, dividing in two. The division of the body is preceded by mitosis in the nucleus. A sexual process is known only in very rare cases.

Upon subjection to unfavorable conditions—for instance, insufficient food, cold, or drying of the water body—the amoeba’s body becomes round and the surface of its cytoplasm becomes a dense protective layer; a cyst forms that is resistant to unfavorable effects of the dormant stage. Freshwater amoebas can serve as a water pollution index. Parasitic amoebas live in the intestines of various animals and man. Among these the most harmful is the dysentery amoeba (Entamoeba histolytica), which produces a severe form of amoebic dysentery in man. Infection occurs via cysts, which remain viable outside the human body.

REFERENCES

Dogel’, V. A., Iu. I. Polianskii, and E. M. Kheisin. Obshchaia protozoologiia. Moscow-Leningrad, 1962.
Seravin, L. N. Dvigatel’nye sistemy prosteishikh. Leningrad, 1967.

A. A. STRELKOV

Amoeba

[ə′mē·bə]
(invertebrate zoology)
A genus of naked, rhizopod protozoans in the order Amoebida characterized by a thin pellicle and thick, irregular pseudopodia.

amoeba

(US), ameba
any protozoan of the phylum Rhizopoda, esp any of the genus Amoeba, able to change shape because of the movements of cell processes (pseudopodia). They live in fresh water or soil or as parasites in man and animals

Amoeba

(operating system)
A distributed operating system developed by Andrew S. Tanenbaum and others of Vrije Universiteit, Amsterdam. Amoeba is only available under licence from the VUA, but is free of charge and includes all source, binaries and documentation.

http://am.cs.vu.nl/.

Amoeba

(computer, abuse)
A derogatory term for Commodore's Amiga personal computer.
References in periodicals archive ?
Assessing the risk of primary amebic meningoencephalitis from swimming in the presence of environmental Naegleria fowleri.
In a mouse model of amebic colitis and a hamster model of amebic liver abscess, the drug markedly decreased the number of parasites, damage from inflammation, and size of liver abscesses.
Although amebic colitis is frequently seen among older infants, symptomatic infection is rarely seen in the neonate.
The main focus of the survey was the facultative human parasite Naegleria fowleri, which is the etiological agent of primary amebic meningoencephalitis.
Flies are known to become contaminated with many species of pathogenic organisms, including the causative organisms of amebic and bacillary dysentery, typhoid fever, cholera, salmonellosis, anthrax, leprosy, yaws, trachoma, poliomyelitis, infectious hepatitis and many more others.
Association between amebic liver abscess and human immunodeficiency virus infection in Taiwanese subjects.
If I drop dead from amebic dysentery, salmonella or caffeine toxicity before finishing this column, it's all Mom's fault.
However, crypt abscess, crypt distortion, granulomas and amebic organisms were not seen.
In Egypt, 38 percent of individuals that went to an outpatient clinic with acute diarrhea were found to have amebic colitis.
The differential diagnosis of a solitary hepatic cystic mass is broad and includes simple (bile duct) cyst, benign adenoma, focal nodular hyperplasia, metastatic lesion, biliary cystadenoma or cystadenocarcinoma, primary hepatoma, pyogenic or amebic abscess, and echinococcal cyst.
The amebic pericarditis is an example of rare complication of amebic infection.