amoeba

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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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The Columbia Electronic Encyclopedia™ Copyright © 2013, Columbia University Press. Licensed from Columbia University Press. All rights reserved. www.cc.columbia.edu/cu/cup/
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

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

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

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.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

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
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005

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.
This article is provided by FOLDOC - Free Online Dictionary of Computing (foldoc.org)
References in periodicals archive ?
Then, evolution stopped again because the amount of membrane an amoeba can contain also has a size limitation.
The amoeba made different amounts of proteins in each stage, suggesting that it was responding to new demands.
Diagnosis depends on clinical features positive history of contact with lake water and negative culture of bacteria viruses and fungi CSF detection of free living amoebas observation of amoeba in rhinopharyngeal cavity wash and testing with monoclonal antibodies2.
The first description of Acanthamoeba griffini was done by Sawyer [14], but reports on this amoeba on the scientific literature are very limited.
Two Louisiana residents died in 2011 from an infection caused by an amoeba that was likely delivered directly to their brains via a neti pot, a device that some people use to flush out their sinuses.
Like Mimivirus, Megavirus has hair-like structures, or fibrils, on the exterior of its shell, or capsid, that probably attract unsuspecting amoebas looking to prey on bacteria displaying similar features.
Education was initially centered on understanding what the infectious organism was, as well as how the patient came in contact with the amoeba. In the State of Florida, the community is becoming more aware of this diagnosis because of the local news stories and the health departments erecting signage in areas of freshwater where the amoebas have been found.
When there are plenty of edible bacteria around, the amoebas ooze around and dine by themselves.
Brad, a criminology graduate from the University of Teesside, said: "It was a physically and mentally tough challenge, not helped by the fact that I suffered from altitude sickness as well as catching an amoeba.
A PAPER IN the January/February Journal of Eukaryotic Microbiology dispels "the myths of intelligent design" by examining the evolution of amoebas and other unicellular organisms.