title: The comparison of beta-thymosin homologues among metazoa supports an arthropod-nematode clade.
abstract: The definition of an Ecdysozoa clade among the protostomians, including all phyla with a regularly molted alpha-chitin-rich cuticle, has been one of the most provocative hypotheses to arise from recent investigations on animal phylogeny. Here we present evidence in favor of an arthropod-nematode clade, from the comparison of beta-thymosin homologues among the Metazoa. Arthropods and nematodes share the absence of the highly conserved beta-thymosin form found in all other documented bilaterian phyla as well as sponges, and the possession of a very unusual, internally triplicated homologue of the beta-thymosin protein, unknown in other phyla. We argue that such discrete molecular character is phylogenetically very powerful and provides strong evidence for the monophyly of an arthropod-nematode clade.
authors.affiliation: Station Marine d'Endoume, Centre d'Océanologie de Marseille, Université de la Méditerranée, UMR CNRS 6540 DIMAR, rue de la Batterie des Lions, 13 007 Marseille, France. manuel@com.univ-mrs.fr
authors.forename: M
authors.initials: M
authors.lastname: Manuel
authors.forename: M
authors.initials: M
authors.lastname: Kruse
authors.forename: W E
authors.initials: WE
authors.lastname: Müller
authors.forename: Y
authors.initials: Y
authors.lastname: Le Parco
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001181:Arthropods / Q000235:genetics*; D017173:Caenorhabditis elegans / Q000235:genetics; D004331:Drosophila melanogaster / Q000235:genetics; D008969:Molecular Sequence Data; D009348:Nematoda / Q000235:genetics*; D010802:Phylogeny; D017386:Sequence Homology, Amino Acid; D013947:Thymosin / Q000235:genetics*
chemical_list: D013947:Thymosin