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This
genera is in some state of confusion! It has been assumed that Mastigamoeba
and Phreatamoeba are synonymous but this has been
challenged (Milyutina et al, 2001).
Mastigamoeba
balamuthi (old name Phreatamoeba balamuthi) was isolated
from a well in Gambia, West Africa (Chávez
et al, 1986). It is unusual in having
only one flagella in that stage, but the ability to transform into a
flagellate suggests a kinship with Vahlkampfiidae, however, SSUrDNA
analysis places Mastigamoeba balamuthi far from the
Vahlkampfiidae and its nearest relative (of those analysed) seems to be
Dictyostelium (Sogin et al, 1996;
Hinkle et al, 1994).
However a more recent detailed morphological analysis
(Walker
et al, 2001)
concludes that Mastigamoeba together with other amoeboid genera Mastigella,
Mastigina and Peloxyma represent a group "the
pelobionts" which is a sister group to Eumycetozoa (which includes
amoeboid "Physarum" and "Hyperamoeba"
). Another analysis (Milyutina
et al, 2001)
suggests that this is not the case. Instead Mastigamoeba is
differentiated from Phreatamoeba, and Pelomyxa is included
with Entamoeba and Endamoeba in the Archamoebae (Milyutina
et al, 2001).
The flagellate stage does not reproduce and is without a cyclostome,
rostrum or collar. Mastigamoeba balamuthi is multinucleate with
a length of between 11 and 160mm, in addition
to having a flagellate phase it also produces cysts 9-18mm
in diameter without pores. The nuclear divisions are synchronous
and then flagella has a cone-like microtubular complex associated with
the nucleus similar to that found in Physarum polycephalum (a
true slime mould) (Wright et al, 1979).
Taken together is seems that Mastigamoeba may be related to
the slime moulds (Wright et al, 1979).
The situation has more recently been the subject of a very detailed
molecular study (Baptiste et al,
2002) in which 100 genes from Dictyostelium,
Entamoeba and Mastigamoeba balamuthi ATCC 30984
were compared. The conclusion of this study was to support the
existence of the subphylum "Conosa" erected earlier by
Cavalier-Smith (Cavalier-Smith, 1998),
to include the three genera (amongst others). Entamoeba
however, is strongly suspected of harbouring a large number of genes
from bacteria! (). This would greatly complicate matters if for example Mastigamoeba
also has significant numbers of bacterial genes. It is already
clear that Mastigamoeba contains an inorganic
pyrophosphate-dependent phosphofructosokinase that is more closely
related to eubacterial genes that fellow eukaryotes (Muller
et al, 2001).
The status of the mitochondria in Mastigamoeba
too is confusing, although some place the group in the order Pelobiontida (
a group lacking mitochondria) (Stiller et
al, 1998), the original description of Phreatamoeba
balamuthi, clearly stated that this amoeba "contains
cytoplasmic organelles (Fig.11) ultra-structurally similar to the type
of mitochondria characteristic of organisms living in low-oxygen
environments". A complication is that Stiller and coworkers (Stiller
et al, 1998) studied Mastigamoeba
invertens, and the it seems likely that it and M. balamuthi are not closely related (Milyutina
et al, 2001). A further
complication is that a pathogenic amoebic genera called Balamuthia
exists! (see Balamuthia)
A
thorough analysis (Walker
et al, 2001)
of the ultra-structure of the flagella, basal body and mitochondria in M.
punctachora, M. simplex, and Mastigella commutans suggested
a relationship between Mastigamoeba and the pelobionts. Mastigamoeba
may be related to Mastigina and/or Mastigella.
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References:-
Bapteste, E., Brinkmann, H., Lee, J.
A., Moore, D. V., Sensen, C. W., Gordon, P., Durufle, L., Gaasterland,
T., Lopez, P., Muller, M. & Philippe, H. (2002) The analysis of 100
genes supports the grouping of three highly devergent amoebae: Dictyostelium,
Entamoeba, and Mastigamoeba. PNAS. 99, 1414-1419.
Bernard, C.,
Simpson, A. G. B. & Patterson, D. J. (2000) Some free-living
flagellates (Protista) from anoxic habitats. Ophelia. 52,
113-142.
Chávez, L. A., Balamuth, W., & Gong, T.
(1986). "A light and electron microscopic study of a new
polymorphic free-living amoeba. Phreatamoeba balamuthi n.g, n.sp."
J.Protozool. 33(3): 397-404.
Goldschmidt, R.
(1907). "Uber die lebensgeschichte der Mastigella vitrea
n.sp. und Mastigina setosa n sp. Arch.Protistenkd.Suppl.
1, 83-168.
Hinkle, G., Leipe, D.D., Nerad, T.A. &
Sogin, M.L. (1994). "The unusually long small subunit ribosomal RNA
of Phreatamoeba balamuthi." Nuc.Acids Res. 22:
465-469.
Kudo, R.R.
(1966). "Protozoology." 5th Edition, Charles C Thomas
Publisher.
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.
Simpson, A. G.
B., Bernard, C., Fenchel, T. & Patterson, D. J. (1997) The
organisation of Mastigamoeba schizophrenia n. sp.: more evidence
of ultrastructural idiosyncrasy and simplicity in pelobiont protists., Eur.
J. Protistol. 33, 87-98.
Sogin, M. L., Silberman, J.D, Hinkle, G. &
Morrison, H.G. (1996). "Problems with molecular diversity in the
eukarya.".Society of General Microbiology Symposium: Evolution of
microbial Life ed.Roberts, D.M., Sharp, P., Alderson, G. & Collins,
M.A. Cambridge University Press. pp167-184.
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.
Wright, M., Moisand, A., & Mir, L. (1979).
"The structure of the flagellar apparatus of the swarm cells of Physarum
polycephalum." Protoplasma 100:
231-250.
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