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 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 It might be outdated or ideologically biased.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

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

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 ?

Symptoms of pyogenic and amebic liver abscesses are similar and most commonly include fever and abdominal pain.

Hepatic Abscess in a Returning Traveler with Crohn's Disease: Differentiating Amebic from Pyogenic Liver Abscess

Hyun Jo et al., "Amebic Liver Abscess in HIV-infected Patients, Republic of Korea," Emerging Infectious Diseases, vol.

Amoebic Liver Abscess and Indigenous Alcoholic Beverages in the Tropics

Endoscopic features such as cryptitis and crypt abscesses, as well as erosions and ulceration of the rectum, which are commonly seen in ulcerative colitis, may also be present in amebic colitis [25, 44].

Entamoeba Histolytica: Updates in Clinical Manifestation, Pathogenesis, and Vaccine Development

In addition, the company said Impavido has received orphan drug designation in treating Primary Amebic Meningoencephalitis (PAM), the brain infection caused by the water-born amoeba Naegleria fowleri and Acanthamoeba Keratitis, and is the first Rx product launched in the US.

Profounda wins US FDA's orphan drug designation for miltefosine for Granulomatous Amebic Encephalitis

Pleuropulmonary complications (i.e., pleural effusion, lung abscess, and, rarely, pleural empyema) are the second most frequent extraintestinal complication; they occur in 720% of patients with amebic liver abscesses and in 2-3% of those with invasive disease [6].

Primary Pulmonary Amebiasis Complicated with Multicystic Empyema

Primary Amebic Meningoencephalitis caused by Naegleria fowleri, Karachi, Pakistan.

NAEGLERIA: PREVENTABLE BY WATER CHLORINATION

The pathogenesis of amebic liver abscess (ALA) has been studied both in animal models (Ventura et al, 2002; Tsutsumi & Shibayama, 2006) and in humans by anatomical characteristics (Perez-Tamayo, 1990).

Amebic Liver Abscess in Rat: Morphological Evidence of Innate Immune Modulation by the Sympathetic Nervous System/ Absceso Hepatico Amebiano en Rata: Evidencia Morfologica de la Modulacion de la Respuesta Inmune Innata por el Sistema Nervioso Simpatico

microbiological culture from blood and/or aspirate, stool examination, amebic serology), type of imaging study, abscesses characteristics (i.e., site, size and numbers of abscesses), type of interferences and duration of admission.

Epidemiology, clinical features and outcome of liver abscess: a single reference center experience in Qatar

Huston, "Parasite and host contributions to the pathogenesis of amebic colitis," Trends in Parasitology, vol.

Entamoeba histolytica: gene expression analysis of cells invading tissues

Acanthamoeba castellanii is one of the etiological agents of chronic granulomatous amebic encephalitis [10] and amoebic keratitis, a progressive and painful sightthreatening eye infection [11-13].

Morphological features and in vitro cytopathic effect of Acanthamoeba griffini trophozoites isolated from a clinical case

The Chutia, Sonowal Kachan, Tai Ahom and Ao Naga tribal groups of Disoi Valley Reserve Forest of Jorhat District, Assam, India, use floral parts of the plant against amebic dysentery [7].