Hox and ParaHox genes in Nemertodermatida, a basal bilaterian clade

Eva Jiménez-Guri*, Jordi Paps, Jordi García-Fernàndez, Emili Saló

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

35 Citations (Scopus)


Molecular evidence suggests that Acoelomorpha, a proposed phylum composed of acoel and Nemertodermatida flatworms, are the most basal bilaterian animals. Hox and ParaHox gene complements characterised so far in acoels consist of a small set of genes, comprising representatives of anterior, central and posterior genes, altogether Hox and ParaHox, but no PG3-Xlox representatives have been reported. It has been proposed that this might be the ancestral Hox repertoire in basal bilaterians. However, no studies of the other members of the group, the Nemertodermatida, have been done. In order to get a more complete picture of the basal bilaterian Hox and ParaHox complement, we have analysed the Hox/ParaHox complement of the nemertodermatid Nemertoderma westbladi. We have found representatives of two central and one posterior Hox genes, as well as an Xlox and a CaudalParaHox gene. From our data we conclude that a PG3-Xlox gene was present in the ancestor of bilaterians. These findings support the speculation that basal bilaterians already had the beginnings of the extended central Hox set, driving back gene duplications in the central part of the Hox cluster deeper in phylogeny than previously suggested.

Original languageEnglish
Pages (from-to)675-679
Number of pages5
JournalInternational Journal of Developmental Biology
Issue number8
Publication statusPublished - 1 Dec 2006


  • Basal bilateria
  • Evolution
  • Hox
  • Nemertodermatida
  • ParaHox


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