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 It might be outdated or ideologically biased.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 ?
There are a limited number of publications on Peru and contiguous areas of testate amoebae. The data represent modern and palaeo wetlands, lake sediments and terrestrial habitats (Bonnet, 1966; Haman, 1994; Krashevska, Bonkowski, & Maraun, 2007; Krashevska, Maraun, & Scheu, 2012; Swindles et al., 2014; Swindles, Lamentowicz, Reczuga, & Galloway, 2016; Patterson, Huckerby, Kelly, Swindles, & Nasser, 2015; Reczuga, Swindles, Grewling, & Lamentowicz, 2015).
Increasing magnification to 10K and using available literature as specified in the text enabled genera determination of most of these as diatoms, testaceous amoebae, phacus and other undetermined organisms such as yeasts and spores, some to generic or specific level while others remain undetermined (Figures 1-11).
Posing a significant risk of deadly future outbreaks in the metropolitan, the presence of the Naegleria fowleri amoebae in domestic water systems of Karachi is alarming, which necessitates urgent measures to be taken by the local health authorities, concludes the study.
Thus, this study aimed to provide the first list of testate amoebae of the Paranoa Lake and develop a pictorial key to the taxa of Arcella recorded in this environment.
Molecular analyses performed in 2003 [15, 16] concluded that this amoeba belongs to the T3 genotype, which is clinically relevant since other pathogenic amoebae are also included in this cluster [17].
This was done by dividing the number of amoebae with adhered bacteria by the total number of amoebae with and without adhered bacteria and multiplying by 100.
Distribution of testate amoebae along a gradient hummocklawn-hollow in a Sphagnum bog: potential implications for palaeoecological reconstructions.
If amoebae occur in well-mixed cosmopolitan groups, then cheaters will always be able to thrive by freeloading on their cooperative neighbors.
as to study the difference in the growth of the amoebae. Heat killed bacterial cells were prepared by suspending a loopful of respective active bacterial culture in saline and heating the suspension at 60[degrees] C for 60 min (Neff et al., 1957).
The study, conducted by evolutionary biologists Joan Strassmann and David Queller of Rice University, has shown that long-studied social amoebae Dictyostellum discoideum (commonly known as slime molds) increase their odds of survival through a rudimentary form of agriculture.
Cultures of amoebae were grown to a concentration of 1 X [10.sup.6] cells/ml in PYG.
To hear Mark Mazzola describe his latest discovery in the weird, wild world of microorganisms, you'd think the amoebae he's been studying--and the bacteria they stalk in the soil--were lion and wildebeest locked in an epic battle for survival on the plains of the Serengeti in East Africa.