title: Evolutionary analyses of hedgehog and Hoxd-10 genes in fish species closely related to the zebrafish.
abstract: The study of development has relied primarily on the isolation of mutations in genes with specific functions in development and on the comparison of their expression patterns in normal and mutant phenotypes. Comparative evolutionary analyses can complement these approaches. Phylogenetic analyses of Sonic hedgehog (Shh) and Hoxd-10 genes from 18 cyprinid fish species closely related to the zebrafish provide novel insights into the functional constraints acting on Shh. Our results confirm and extend those gained from expression and crystalline structure analyses of this gene. Unexpectedly, exon 1 of Shh is found to be almost invariant even in third codon positions among these morphologically divergent species suggesting that this exon encodes for a functionally important domain of the hedgehog protein. This is surprising because the main functional domain of Shh had been thought to be that encoded by exon 2. Comparisons of Shh and Hoxd-10 gene sequences and of resulting gene trees document higher evolutionary constraints on the former than on the latter. This might be indicative of more general evolutionary patterns in networks of developmental regulatory genes interacting in a hierarchical fashion. The presence of four members of the hedgehog gene family in cyprinid fishes was documented and their homologies to known hedgehog genes in other vertebrates were established.
authors.affiliation: Department of Ecology and Evolution, State University of New York, Stony Brook 11794-5245, USA.
authors.forename: R
authors.initials: R
authors.lastname: Zardoya
authors.forename: E
authors.initials: E
authors.lastname: Abouheif
authors.forename: A
authors.initials: A
authors.lastname: Meyer
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002645:Chickens; D003001:Cloning, Molecular; D004247:DNA / Q000302:isolation & purification; D005091:Exons; D005399:Fishes / Q000145:classification* / Q000235:genetics*; D005801:Genes, Homeobox; D053823:Hedgehog Proteins; D018398:Homeodomain Proteins / Q000235:genetics*; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal; D009154:Mutation; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D011506:Proteins / Q000737:chemistry / Q000235:genetics*; D051381:Rats; D017386:Sequence Homology, Amino Acid; D015534:Trans-Activators; D014157:Transcription Factors / Q000235:genetics*; D014982:Xenopus laevis; D015027:Zebrafish / Q000145:classification* / Q000235:genetics*; D029961:Zebrafish Proteins
chemical_list: D053823:Hedgehog Proteins; D018398:Homeodomain Proteins; C490944:Hoxd10 protein, mouse; C489520:Hoxd4 protein, mouse; D011506:Proteins; C509239:SHH protein, human; D015534:Trans-Activators; D014157:Transcription Factors; D029961:Zebrafish Proteins; C099223:hoxd10a protein, zebrafish; C072064:HOXD10 protein, human; D004247:DNA