The comparison of beta-thymosin homologues among metazoa supports an arthropod-nematode clade

J Mol Evol. 2000 Oct;51(4):378-81. doi: 10.1007/s002390010100.


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.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Arthropods / genetics*
  • Caenorhabditis elegans / genetics
  • Drosophila melanogaster / genetics
  • Molecular Sequence Data
  • Nematoda / genetics*
  • Phylogeny*
  • Sequence Homology, Amino Acid
  • Thymosin / genetics*


  • Thymosin