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Amoeba proteus CCAP 1503/9.

Inverted NikonDiaphot, phase contrast.
Locomotive forms, nucleus and uroidal structures.

Photo: A.Smirnov

Amoeba proteus (Pallas, 1766) Leidy, 1878
CCAP 1503/9

  • Lentgh in locomotion 220-740 mkm (average about 425 mkm). Majority of amoebae are polypodial (polytactic) under favourable conditions, with small minority orthotactic. Most of crystals truncate bipyramids. Floating form of radial type; several thick pseudopodia of unequal lenght radiate from irregular central mass of the granuloplasm.

  • Nucleus of granular type, discoid, often concave, 22-62 mkm in diameter (average 40 mkm).

  • Surface coat consists of crinkly filaments up to 230 nm above plasma membrane; mitochondrial heteromorphism is known (Flickinger, 1974); honeycomb-like nuclear lamina (Page, 1986).

  • Identification of this species is often questionable. Nearly any large uninucleate amoebae with granular nucleus appears to be an A. proteus, but not nesessarily is. There are many species, resembling A. proteus (see Page, 1988, p. 59); species distinction and sinonimity are still under discussion. I would advice to assign an isolate to the species A. proteus only after careful consideration of all arguments "for and against". TEM of the cell coat (obligate for correct identification) shows some variability in length and shape of the filaments even between different recognised strains of this species.

  • Keep in mind that in many laboratories and in some of culture collections there are local isolates named "A. proteus" without proper investigation. For important studies, like biochemical and molecular comparison of species and phylogeny I would strongly advice to use only the isolates with known history of identification (like these available from the Culture Collection of Algae and Protozoa, CEH Windermere, UK), but not a local ones of unknown origin.

  • Freshwater, Europe, North America (but perhaps, worldwide).
    Cultivation: PJ medium + Tetrahymena. Can be maintained for some time in PJ + wheat (rise) grain, in presence of Tetrahymena.

  • Basic references for identification:
    • Flickinger C.J. 1974. The fine structure of four "species" of Amoeba. J. Protozool. 21: 59-68.
    • Page F.C. 1986. The genera and possible relationships of the family Amoebidae, with special attention to comparative ultrastructure. Protistologica. 22: 301-316.
    • Page F.C. 1988. A new key to freshwater and soil gymnamoebae. FBA, Ambleside. 122p.
    • Page F.C. 1991. Nackte Rhizopoda. in: Protozoenfauna, b.2. Gustav Fisher, Stuttgart. 3-172.
    Note that the keys by Page from 1988 and 1991 harbour slightly different sets of illustrations for this species.

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