title: Hox cluster genomics in the horn shark, Heterodontus francisci.
abstract: Reconstructing the evolutionary history of Hox cluster origins will lead to insights into the developmental and evolutionary significance of Hox gene clusters in vertebrate phylogeny and to their role in the origins of various vertebrate body plans. We have isolated two Hox clusters from the horn shark, Heterodontus francisci. These have been sequenced and compared with one another and with other chordate Hox clusters. The results show that one of the horn shark clusters (HoxM) is orthologous to the mammalian HoxA cluster and shows a structural similarity to the amphioxus cluster, whereas the other shark cluster (HoxN) is orthologous to the mammalian HoxD cluster based on cluster organization and a comparison with noncoding and Hox gene-coding sequences. The persistence of an identifiable HoxA cluster over an 800-million-year divergence time demonstrates that the Hox gene clusters are highly integrated and structured genetic entities. The data presented herein identify many noncoding sequence motifs conserved over 800 million years that may function as genetic control motifs essential to the developmental process.
authors.affiliation: Department of Molecular Biology, Yale University, New Haven, CT 06520, USA.
authors.forename: C B
authors.initials: CB
authors.lastname: Kim
authors.forename: C
authors.initials: C
authors.lastname: Amemiya
authors.forename: W
authors.initials: W
authors.lastname: Bailey
authors.forename: K
authors.initials: K
authors.lastname: Kawasaki
authors.forename: J
authors.initials: J
authors.lastname: Mezey
authors.forename: W
authors.initials: W
authors.lastname: Miller
authors.forename: S
authors.initials: S
authors.lastname: Minoshima
authors.forename: N
authors.initials: N
authors.lastname: Shimizu
authors.forename: G
authors.initials: G
authors.lastname: Wagner
authors.forename: F
authors.initials: F
authors.lastname: Ruddle
mesh_terms: D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D017124:Conserved Sequence; D019143:Evolution, Molecular; D005801:Genes, Homeobox / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D010802:Phylogeny; D012045:Regulatory Sequences, Nucleic Acid; D016415:Sequence Alignment; D012754:Sharks / Q000235:genetics*; D014212:Tretinoin / Q000494:pharmacology
chemical_list: D014212:Tretinoin