The analysis of 100 genes supports the grouping of three highly divergent amoebae: Dictyostelium, Entamoeba, and Mastigamoeba.
The phylogenetic relationships of amoebae are poorly resolved. To address this difficult question, we have sequenced 1,280 expressed sequence tags from Mastigamoeba balamuthi and assembled a large data set containing 123 genes for representatives of three phenotypically highly divergent major amoeboid lineages: Pelobionta, Entamoebidae, and Mycetozoa. Phylogenetic reconstruction was performed on approximately 25,000 aa positions for 30 species by using maximum-likelihood approaches. All well-established eukaryotic groups were recovered with high statistical support, validating our approach. Interestingly, the three amoeboid lineages strongly clustered together in agreement with the Conosa hypothesis [as defined by T. Cavalier-Smith (1998) Biol. Rev. Cambridge Philos. Soc. 73, 203-266]. Two amitochondriate amoebae, the free-living Mastigamoeba and the human parasite Entamoeba, formed a significant sister group to the exclusion of the mycetozoan Dictyostelium. This result suggested that a part of the reductive process in the evolution of Entamoeba (e.g., loss of typical mitochondria) occurred in its free-living ancestors. Applying this inexpensive expressed sequence tag approach to many other lineages will surely improve our understanding of eukaryotic evolution.
Bapteste
Eric
E
Unité Mixte de Recherche 7622 Centre National de la Recherche Scientifique, Université Paris 6, 9 Quai Saint Bernard, Bât C, 75005 Paris, France.
Brinkmann
Henner
H
Lee
Jennifer A
JA
Moore
Dorothy V
DV
Sensen
Christoph W
CW
Gordon
Paul
P
Duruflé
Laure
L
Gaasterland
Terry
T
Lopez
Philippe
P
Müller
Miklós
M
Philippe
Hervé
H
D000656:Amoeba / Q000145:classification* / Q000235:genetics; D000818:Animals; D005075:Biological Evolution; D004023:Dictyostelium / Q000145:classification* / Q000235:genetics; D004747:Entamoeba / Q000145:classification* / Q000235:genetics; D005796:Genes; D006801:Humans; D008969:Molecular Sequence Data; D010802:Phylogeny