title: Secondary absence of mitochondria in Giardia lamblia and Trichomonas vaginalis revealed by valyl-tRNA synthetase phylogeny.
abstract: Nuclear-coded valyl-tRNA synthetase (ValRS) of eukaryotes is regarded of mitochondrial origin. Complete ValRS sequences obtained by us from two amitochondriate protists, the diplomonad, Giardia lamblia and the parabasalid, Trichomonas vaginalis were of the eukaryotic type, strongly suggesting an identical history of ValRS in all eukaryotes studied so far. The findings indicate that diplomonads are secondarily amitochondriate and give further evidence for such conclusion reached recently concerning parabasalids. Together with similar findings on other amitochondriate groups (microsporidia and entamoebids), this work provides critical support for the emerging notion that no representatives of the premitochondrial stage of eukaryotic phylogenesis exist among the species living today.
authors.affiliation: The Institute of Statistical Mathematics, 4-6-7 Minami-Azabu, Minato-ku, Tokyo 106, Japan. hasimoto@ism.ac.jp
authors.forename: T
authors.initials: T
authors.lastname: Hashimoto
authors.forename: L B
authors.initials: LB
authors.lastname: Sánchez
authors.forename: T
authors.initials: T
authors.lastname: Shirakura
authors.forename: M
authors.initials: M
authors.lastname: Müller
authors.forename: M
authors.initials: M
authors.lastname: Hasegawa
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D016829:Giardia lamblia / Q000235:genetics* / Q000648:ultrastructure*; D008928:Mitochondria / Q000235:genetics*; D008969:Molecular Sequence Data; D010802:Phylogeny; D016415:Sequence Alignment; D014246:Trichomonas vaginalis / Q000235:genetics* / Q000648:ultrastructure*; D014637:Valine-tRNA Ligase / Q000235:genetics*
chemical_list: D014637:Valine-tRNA Ligase