title: EST sequencing of Onychophora and phylogenomic analysis of Metazoa.
abstract: Onychophora (velvet worms) represent a small animal taxon considered to be related to Euarthropoda. We have obtained 1873 5' cDNA sequences (expressed sequence tags, ESTs) from the velvet worm Epiperipatus sp., which were assembled into 833 contigs. BLAST similarity searches revealed that 51.9% of the contigs had matches in the protein databases with expectation values lower than 10(-4). Most ESTs had the best hit with proteins from either Chordata or Arthropoda (approximately 40% respectively). The ESTs included sequences of 27 ribosomal proteins. The orthologous sequences from 28 other species of a broad range of phyla were obtained from the databases, including other EST projects. A concatenated amino acid alignment comprising 5021 positions was constructed, which covers 4259 positions when problematic regions were removed. Bayesian and maximum likelihood methods place Epiperipatus within the monophyletic Ecdysozoa (Onychophora, Arthropoda, Tardigrada and Nematoda), but its exact relation to the Euarthropoda remained unresolved. The "Articulata" concept was not supported. Tardigrada and Nematoda formed a well-supported monophylum, suggesting that Tardigrada are actually Cycloneuralia. In agreement with previous studies, we have demonstrated that random sequencing of cDNAs results in sequence information suitable for phylogenomic approaches to resolve metazoan relationships.
authors.affiliation: Institute of Zoology and Zoological Museum, University of Hamburg, D-20146 Hamburg, Germany.
authors.forename: Falko
authors.initials: F
authors.lastname: Roeding
authors.forename: Silke
authors.initials: S
authors.lastname: Hagner-Holler
authors.forename: Hilke
authors.initials: H
authors.lastname: Ruhberg
authors.forename: Ingo
authors.initials: I
authors.lastname: Ebersberger
authors.forename: Arndt
authors.initials: A
authors.lastname: von Haeseler
authors.forename: Michael
authors.initials: M
authors.lastname: Kube
authors.forename: Richard
authors.initials: R
authors.lastname: Reinhardt
authors.forename: Thorsten
authors.initials: T
authors.lastname: Burmester
mesh_terms: D000818:Animals; D001483:Base Sequence; D005057:Eukaryotic Cells / Q000378:metabolism*; D020224:Expressed Sequence Tags; D016678:Genome / Q000235:genetics*; D010802:Phylogeny; D012269:Ribosomal Proteins / Q000235:genetics; D016415:Sequence Alignment
chemical_list: D012269:Ribosomal Proteins