title: Hox gene survey in the chaetognath Spadella cephaloptera: evolutionary implications.
abstract: We present the isolation of six Hox genes in the chaetognath Spadella cephaloptera. We identified one member of the paralogy group 3, four median genes and a mosaic gene that shares features of both median and posterior classes ( SceMedPost). Several hypotheses may account for the presence of a mosaic Hox gene in this animal. Here we propose that SceMedPost may represent an ancestral gene, which has not diverged totally into a posterior or a median one. This hypothesis has interesting implications for the reconstruction of the evolutionary history of Hox genes and suggests that Chaetognatha lineage divergence could predate the deuterostome/protostome split. Such a phylogenetic position is considered in the light of their embryological and morphological characters.
authors.affiliation: Centre d'Océanologie de Marseille, UMR 6540 CNRS DIMAR, Rue batterie des lions, 13007, Marseille, France. papillon@com.univ-mrs.fr
authors.forename: Daniel
authors.initials: D
authors.lastname: Papillon
authors.forename: Yvan
authors.initials: Y
authors.lastname: Perez
authors.forename: Laurent
authors.initials: L
authors.lastname: Fasano
authors.forename: Yannick
authors.initials: Y
authors.lastname: Le Parco
authors.forename: Xavier
authors.initials: X
authors.lastname: Caubit
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017931:DNA Primers; D019143:Evolution, Molecular; D005602:France; D005801:Genes, Homeobox / Q000235:genetics*; D007448:Invertebrates / Q000235:genetics*; D008957:Models, Genetic; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics*; D010802:Phylogeny; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
chemical_list: D017931:DNA Primers