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Pelomyxa

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 ChaosPelomyxa 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).

 

Described species:-

Pelomyxa palustris (100mm-3mm! in length).  (Greef, 1874). Feeds on bacteria, diatoms, algae.
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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