title: T-box and homeobox genes from the ctenophore Pleurobrachia pileus: comparison of Brachyury, Tbx2/3 and Tlx in basal metazoans and bilaterians.
abstract: Most animals are classified as Bilateria and only four phyla are still extant as outgroups, namely Porifera, Placozoa, Cnidaria and Ctenophora. These non-bilaterians were not considered to have a mesoderm and hence mesoderm-specific genes. However, the T-box gene Brachyury could be isolated from sponges, placozoans and cnidarians. Here, we describe the first Brachyury and a Tbx2/3 homologue from a ctenophore. In addition, analysing T-box and homeobox genes under comparable conditions in all four basal phyla lead to the discovery of novel T-box genes in sponges and cnidarians and a Tlx homeobox gene in the ctenophore Pleurobrachia pileus. The conservation of the T-box and the homeobox genes suggest that distinct subfamilies with different roles in bilaterians were already split in non-bilaterians.
authors.affiliation: Institute of Zoology, University of Basel, Biocenter/Pharmacenter, Klingelbergstrasse 50, CH-4056 Basel, Switzerland.
authors.forename: Cosimo
authors.initials: C
authors.lastname: Martinelli
authors.forename: Jürg
authors.initials: J
authors.lastname: Spring
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D037302:Ctenophora / Q000235:genetics*; D019143:Evolution, Molecular; D005326:Fetal Proteins / Q000235:genetics*; D005801:Genes, Homeobox; D006801:Humans; D008969:Molecular Sequence Data; D005810:Multigene Family; D010802:Phylogeny; D016415:Sequence Alignment; D020825:T-Box Domain Proteins / Q000145:classification / Q000235:genetics*; D000098908:Brachyury Protein
chemical_list: D005326:Fetal Proteins; D020825:T-Box Domain Proteins; D000098908:Brachyury Protein; C097348:T-Box Domain Protein 2