title: The phylogenetic position of the pelobiont Mastigamoeba balamuthi based on sequences of rDNA and translation elongation factors EF-1alpha and EF-2.
abstract: The taxonomic position and phylogenetic relationships of the Pelobionta, an amitochondriate amoeboflagellate group, are not yet completely settled. To provide more information, we obtained sequences for the large subunit rDNA gene, the gene for translation elongation factor 1alpha, and for a large part of the gene encoding translation elongation factor 2 from a representative of this group, Mastigamoeba balamuthi (formerly Phreatamoeba balamuthi). The gene for the large subunit rDNA was unusually large compared to those of other protists, a phenomenon that had previously been observed for the gene encoding the small subunit rDNA. Phylogenetic reconstruction using a maximum likelihood method was performed with these sequences, as well as the gene encoding the small subunit rDNA. When evaluated individually, the M. balamuthi genes for the small and large subunit rDNAs and elongation factor 1alpha had a most recent common ancestor with either the Mycetozoa (slime molds) or with Entamoeba histolytica. A clade formed by M. balamuthi, E. histolytica, and Mycetozoa was not rejected statistically for any of the sequences. A combined maximum likelihood analysis using 3,935 positions from all molecules suggested that these three taxonomic units form a robust clade. We were unable to resolve the closest group to this clade using the combined analysis. These findings support the notion, which had previously been proposed primarily on cytological evidence, that both M. balamuthi and E. histolytica are closely related to the Mycetozoa and that these three together represent a major eukaryotic lineage.
authors.affiliation: Department of Biosystems Science, Graduate University for Advanced Studies (Sokendai), Hayama, Kanagawa, Japan.
authors.forename: Nobuko
authors.initials: N
authors.lastname: Arisue
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Hashimot
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Lee
authors.forename: Dorothy V
authors.initials: DV
authors.lastname: Moore
authors.forename: Paul
authors.initials: P
authors.lastname: Gordon
authors.forename: Christoph W
authors.initials: CW
authors.lastname: Sensen
authors.forename: Terry
authors.initials: T
authors.lastname: Gaasterland
authors.forename: Masami
authors.initials: M
authors.lastname: Hasegawa
authors.forename: Miklós
authors.initials: M
authors.lastname: Müller
mesh_terms: D000818:Animals; D016054:DNA, Protozoan / Q000032:analysis; D004275:DNA, Ribosomal / Q000032:analysis*; D056890:Eukaryota / Q000145:classification* / Q000235:genetics; D019143:Evolution, Molecular; D020459:Genes, rRNA; D014644:Genetic Variation; D008969:Molecular Sequence Data; D020648:Peptide Elongation Factor 1 / Q000235:genetics*; D020652:Peptide Elongation Factor 2 / Q000235:genetics*; D010802:Phylogeny; D014176:Protein Biosynthesis; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
chemical_list: D016054:DNA, Protozoan; D004275:DNA, Ribosomal; D020648:Peptide Elongation Factor 1; D020652:Peptide Elongation Factor 2