Parallel Expansions of Sox Transcription Factor Group B Predating the Diversifications of the Arthropods and Jawed Vertebrates

Group B of the Sox transcription factor family is crucial in embryo development in the insects and vertebrates. Sox group B, unlike the other Sox groups, has an unusually enlarged functional repertoire in insects, but the timing and mechanism of the expansion of this group were unclear. We collected and analyzed data for Sox group B from 36 species of 12 phyla representing the major metazoan clades, with an emphasis on arthropods, to reconstruct the evolutionary history of SoxB in bilaterians and to date the expansion of Sox group B in insects. We found that the genome of the bilaterian last common ancestor probably contained one SoxB1 and one SoxB2 gene only and that tandem duplications of SoxB2 occurred before the arthropod diversification but after the arthropod-nematode divergence, resulting in the basal repertoire of Sox group B in diverse arthropod lineages. The arthropod Sox group B repertoire expanded differently from the vertebrate repertoire, which resulted from genome duplications. The parallel increases in the Sox group B repertoires of the arthropods and vertebrates are consistent with the parallel increases in the complexity and diversification of these two important organismal groups

Comparative cytogenetic mapping of Sox2 and Sox14 in cichlid fishes and inferences on the genomic organization of both genes in vertebrates

To better understand the genomic organization and evolution of Sox genes in vertebrates, we cytogenetically mapped Sox2 and Sox14 genes in cichlid fishes and performed comparative analyses of their orthologs in several vertebrate species. The genomic regions neighboring Sox2 and Sox14 have been conserved during vertebrate diversification. Although cichlids seem to have undergone high rates of genomic rearrangements, Sox2 and Sox14 are linked in the same chromosome in the Etroplinae Etroplus maculatus that represents the sister group of all remaining cichlids. However, these genes are located on different chromosomes in several species of the sister group Pseudocrenilabrinae. Similarly, the ancestral synteny of Sox2 and Sox14 has been maintained in several vertebrates, but this synteny has been broken independently in all major groups as a consequence of karyotype rearrangements that took place during the vertebrate evolution.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)São Paulo State Univ, Dept Morphol, Biosci Inst, UNESP, BR-18618970 São Paulo, BrazilSão Paulo State Univ, Dept Morphol, Biosci Inst, UNESP, BR-18618000 São Paulo, BrazilWellcome Trust Sanger Inst, Cambridge CB10 1SA, EnglandUniv Maryland, Dept Biol, College Pk, MD 20742 USASão Paulo State Univ, Dept Morphol, Biosci Inst, UNESP, BR-18618970 São Paulo, BrazilSão Paulo State Univ, Dept Morphol, Biosci Inst, UNESP, BR-18618000 São Paulo, Brazi