title: Primitive duplicate Hox clusters in the European eel's genome.
abstract: The enigmatic life cycle and elongated body of the European eel (Anguilla anguilla L., 1758) have long motivated scientific enquiry. Recently, eel research has gained in urgency, as the population has dwindled to the point of critical endangerment. We have assembled a draft genome in order to facilitate advances in all provinces of eel biology. Here, we use the genome to investigate the eel's complement of the Hox developmental transcription factors. We show that unlike any other teleost fish, the eel retains fully populated, duplicate Hox clusters, which originated at the teleost-specific genome duplication. Using mRNA-sequencing and in situ hybridizations, we demonstrate that all copies are expressed in early embryos. Theories of vertebrate evolution predict that the retention of functional, duplicate Hox genes can give rise to additional developmental complexity, which is not immediately apparent in the adult. However, the key morphological innovation elsewhere in the eel's life history coincides with the evolutionary origin of its Hox repertoire.
authors.affiliation: ZF-screens BV, Leiden, The Netherlands. henkel@zfscreens.com
authors.forename: Christiaan V
authors.initials: CV
authors.lastname: Henkel
authors.forename: Erik
authors.initials: E
authors.lastname: Burgerhout
authors.forename: Daniëlle L
authors.initials: DL
authors.lastname: de Wijze
authors.forename: Ron P
authors.initials: RP
authors.lastname: Dirks
authors.forename: Yuki
authors.initials: Y
authors.lastname: Minegishi
authors.forename: Hans J
authors.initials: HJ
authors.lastname: Jansen
authors.forename: Herman P
authors.initials: HP
authors.lastname: Spaink
authors.forename: Sylvie
authors.initials: S
authors.lastname: Dufour
authors.forename: Finn-Arne
authors.initials: FA
authors.lastname: Weltzien
authors.forename: Katsumi
authors.initials: K
authors.lastname: Tsukamoto
authors.forename: Guido E E J M
authors.initials: GE
authors.lastname: van den Thillart
mesh_terms: D000818:Animals; D017124:Conserved Sequence; D004524:Eels / Q000235:genetics*; D004641:Emigration and Immigration; D005060:Europe; D005260:Female; D020131:Genes, Duplicate; D016678:Genome; D018398:Homeodomain Proteins / Q000235:genetics* / Q000502:physiology*; D008018:Life Cycle Stages; D008297:Male; D008969:Molecular Sequence Data; D005810:Multigene Family; D012333:RNA, Messenger / Q000378:metabolism; D017422:Sequence Analysis, DNA; D013997:Time Factors
chemical_list: D018398:Homeodomain Proteins; D012333:RNA, Messenger