title: The phylogenetic position of enteromonads: a challenge for the present models of diplomonad evolution.
abstract: Unikaryotic enteromonads and diplokaryotic diplomonads have been regarded as closely related protozoan groups. It has been proposed that diplomonads originated within enteromonads in a single event of karyomastigont duplication. This paper presents the first study to address these questions using molecular phylogenetics. The sequences of the small-subunit rRNA genes for three isolates of enteromonads were determined and a tree constructed with available diplomonad, retortamonad and Carpediemonas sequences. The diplomonad sequences formed two main groups, with the genus Giardia on one side and the genera Spironucleus, Hexamita and Trepomonas on the other. The three enteromonad sequences formed a clade robustly situated within the diplomonads, a position inconsistent with the original evolutionary proposal. The topology of the tree indicates either that the diplokaryotic cell of diplomonads arose several times independently, or that the monokaryotic cell of enteromonads originated by secondary reduction from the diplokaryotic state.
authors: Department of Parasitology, Faculty of Science, Charles University, Prague, Czech Republic.
authors: Martin
authors: M
authors: Kolisko
authors: Department of Parasitology, Faculty of Science, Charles University, Prague, Czech Republic.
authors: Ivan
authors: I
authors: Cepicka
authors: Department of Parasitology, Faculty of Science, Charles University, Prague, Czech Republic.
authors: Vladimír
authors: V
authors: Hampl
authors: Department of Parasitology, Faculty of Science, Charles University, Prague, Czech Republic.
authors: Jaroslav
authors: J
authors: Kulda
authors: Department of Parasitology, Faculty of Science, Charles University, Prague, Czech Republic.
authors: Jaroslav
authors: J
authors: Flegr
mesh_terms: D000818:Animals; D016054:DNA, Protozoan / Q000032:analysis; D004275:DNA, Ribosomal / Q000032:analysis; D016828:Diplomonadida / Q000145:classification* / Q000235:genetics*; D019143:Evolution, Molecular; D008969:Molecular Sequence Data; D010802:Phylogeny; D012335:RNA, Ribosomal / Q000235:genetics; D014426:Turtles / Q000469:parasitology
chemical_list: D016054:DNA, Protozoan; D004275:DNA, Ribosomal; D012335:RNA, Ribosomal