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Vannella
vs Platyamoeba |
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Page
updated 28/1/03 |
| These
flabellate amoebae are among the most numerous genera found in water be
it freshwater, brackish or marine. These genera have been very difficult
to distinguish morphologically at the light microscope level and can be
differentiated by the glycostyles, large glycoprotein complexes that
project from the cell surface (Figure 1). However, recent SSUrDNA
analysis (Sims et
al, 2002)
reveals that Vannella and Platyamoeba are closely related
and in fact sort out on the basis of the environment from which they
have been isolated so that Vannella and Platyamoeba from
seawater group together and are distinct from the group of amoebae
previously identified as either Vannella and Platyamoeba
on morphological basis. |
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Figure 1. |
| There
is a wider debate concerning the relative merits of morphological versus
SSUrDNA as suitable markers of phylogeny, and it should be remembered
that this analysis involved only a ~380bp fragment of the SSUrDNA gene (Sims
et al, 2002).
Perhaps what is required is an additional data set on a second,
unrelated gene such as (perhaps EF-1a,
used successfully for a number of other groups). |
| This
finding leaves the question of Clydonella
even more uncertain (Sawyer
et al, 1975),
as this genera has feature reported to be intermediate between Vannella
and Platyamoeba. |
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References:-
Sawyer, T.K.
(1975c). "Clydonella n.g. (Amoebida: Thecamoebidae) proposed
to provide an appropriate generic home for Schaeffer's marine species of
Rugipes, C. viva (Schaeffer, 1926) n. comb. Trans
Am.Microscop.Soc. 94:395-400.
Sims, G. P., Aitken, R. & Rogerson,
A. (2002) Identification and phylogenetic analysis of morphologically
similar naked amoebae using small subunits ribosomal RNA. J.Eukaryot.Microbiol.
49, 478-484. |
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