No more than 14: the end of the amphioxus Hox cluster

Carolina Minguillón, Josep Gardenyes, Elisa Serra, L. Filipe C. Castro, Alicia Hill-Force, Peter W.H. Holland, Chris T. Amemiya, Jordi Garcia-Fernàndez
2005 International Journal of Biological Sciences  
A Ab bs st tr ra ac ct t The Hox gene cluster has been a key paradigm for a generation of developmental and evolutionary biologists. Since its discovery in the mid-1980's, the identification, genomic organization, expression, colinearity, and regulation of Hox genes have been immediate targets for study in any new model organism, and metazoan genome projects always refer to the structure of the particular Hox cluster(s). Since the early 1990's, it has been dogma that vertebrate Hox clusters are
more » ... composed of thirteen paralogous groups. Nonetheless, we showed that in the otherwise prototypical cephalochordate amphioxus (Branchiostoma floridae), the Hox cluster contains a fourteenth Hox gene, and very recently, a 14 th Hox paralogous group has been found in the coelacanth and the horn shark, suggesting that the amphioxus cluster was anticipating the finding of Hox 14 in some vertebrate lineages. In view of the pivotal place that amphioxus occupies in vertebrate evolution, we thought it of considerable interest to establish the limits of its Hox gene cluster, namely resolution of whether more Hox genes are present in the amphioxus cluster (e.g., Hox 15). Using two strategies, here we report the completion and characterization of the Hox gene content of the single amphioxus Hox cluster, which encompasses 650 kb from Hox1 to Evx. Our data have important implications for the primordial Hox gene cluster of chordates: the prototypical nature of the single amphioxus Hox cluster makes it unlikely that additional paralogous groups will be found in any chordate lineage. We suggest that 14 is the end. K Ke ey y w wo or rd ds s gene clusters, Evx, gene duplication, vertebrate evolution A Au ut th ho or r b bi io og gr ra ap ph hy y Carolina Minguillón obtained her Ph. D. from the University in Barcelona in 2002. Her main achievements involved the partial characterisation of the Hox and Evx genomic regions and the study of somitogenesis (by virtue of the analyses of Mox and hairy genes) in the cephalochordate amphioxus. Currently, she is an EMBO postdoctoral
doi:10.7150/ijbs.1.19 pmid:15951846 pmcid:PMC1140354 fatcat:5z5faswg7rer3ejw7rin4pve44