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A
rather famous amoeba as it was one of the first to become known to be
without mitochondria and instead to rely upon a symbiotic relationship
with methanogenic bacteria (van
Bruggen et al, 1988;
Whatley, 1976). Some confusion possibly still results from the fact
that the name "Pelomyxa" was used to describe quite a
different amoeba Chaos. Pelomyxa is a huge
club-shaped amoeba often green as a result of it playing host to
algae. Pelomyxa is a microaeophilic amoeba living amongst
the detritus in ponds and other freshwater. Pelomyxa is
always monopodal, the only projections appear at the rear as colosomes.
Many have mineral grains and/or cytoplasmic crystals.
Classification According
to Walker et
al, 2001
and Griffin,
1988, Pelomyxa
is related to Mastigamoeba being included
in the pelobiont group together with Mastigella and Mastigina.
The pelobionts being a sister group to eumcetozoan slime moulds
including Physarum, Protosporangium and Hyperamoeba.
These relationships has support from both ultra-structural (Walker
et al, 2001)
and partial SSUrDNA data (). A more recent and complete
SSUrDNA study has confirmed the close relationship between Pelomyxa
and Phreatamoeba but that Mastigamoeba does not cluster
with these (Milyutina
et al, 2001).
This study also concludes that Pelomyxa is related to
Entamoeba, Endamoeba (the Archamoebae), and not to Physarum
as previously suggested. The analysis of other genes is required
to settle these relationship as the SSUrDNA analysis is complicated in
this case by the very long SSUrDNA of Pelomyxa palustris (Milyutina
et al, 2001). |
| References:-
Chapman-Andersen, C, & Hamburger,
K. (1981), "Respiratory studies on the giant amoeba Pelomyxa
palustris." J. Protozool. 28, 433-440.
Daniels, E.W. & Breyer, E.P. (1967). "Ultrastructure
of a giant amoeba Pelomyxa palustris." J.Protozool.
14, 167-179.
Greef, R.
(1874). "Pelomyxa palustris (Pelobius), ein amobenartiger
organismus des sussen wasser. Arch.Mikrosk.Anat. 10,
51-73.
Griffin, R
(1988). "Fine structure and taxonomic position of the giant
amoeboid flagellate Pelomyxa palustris." J. Protozool. 35,
300-315.
Milyutina, I. A., Aleshin, V. V.,
Mikrjukov, K. A., Kedrova, O. S. & Petrov, N. B. (2001) The
unusually long small subunit ribosomal RNA gene found in amitochondriate
amoeboflagellate Pelomyxa palustris: its rRNA predicted secondary
structure and phylogenetic implication., Gene. 272, 131-139.
van Bruggen,
J.J.A., van Rens, G.L.M., Geertman, E.J.M., Zwart, K.B., Stumm, C.K.
Vogels, G.D. (1988). "Isolation of a methanogenic endosymbiont of
the sapropelic amoeba Pelomyxa palustris Greef. J. Protozool.
35, 20-23.
Whatley, J.M.
(1976). "Bacteria and nuclei in Pelomyxa palustris: comments
on the theory of serial endosymbiosis." New Phytol. 76,
111-120.
Walker, G.,
Simpson, A. G. B., Edgcomb, V., Sogin, M. L. & Patterson, D. J.
(2001) Ultrastructural identies of Mastigamoeba punctachora, Mastigamoeba
simplex and Mastigella commutans and assessment of hypotheses
of relatedness of the pelobionts (Protista)., Eur.J.Protistol. 37,
25-49.
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