Made available in DSpace on 2014-12-17T15:18:12Z (GMT). No. of bitstreams: 1 LorenaCBL.pdf: 1131500 bytes, checksum: f844b916fb8784c601514bd7da1743b9 (MD5) Previous issue date: 2007-02-26 / The Tetraodontiformes order is composed for about 400 species of fish, distributed in ten families, with circuntropical distribution. The morphologic diversity of each family reflects in, part, the different levels of specialization. This group represents an ancestry after-Perciformes and constitutes the last branch of the diffusion of the Tele?steos, occupying a position of prominence. The phylogenetics relationships of the Tetraodontiformes exist diverse works examining and, in all, these families are recognized as groups brothers, being Diodontidae next to Tetraodontidae and Balistidae next to Monacanthidae. Although it possesss a representative number of species, the works involving of the families Balistidae and Monacanthidae are few exemplary, especially species of oceanic islands. In this work cytogenetic studies in five species had been analyzed Cantherhines macrocerus, Cantherhines pullus (Monacanthidae), Melichthys niger (Balistidae), Sphoeroides testud?neus (Tetraodontidae) and Chilomycterus antennatus (Diodontidae); through conventional coloration, Ag-NORs and C banding. Ahead of the different karyological trends of evolution presented by the Tetraodontiformes, the present work also searched to verify the relation existence enters the total size of the chromosomes with the amount of DNA in these groups of Tetraodontiformes. For such, they had been correlated the total size of the chromosomes of these species, with values of content of available DNA in literature. The cytogenetics analyses for the species C.macrocerusJ C.pullus (Monacanthidae) and M.niger (Balistidae), had disclosed 40 chromosomes, all acrocentrics. All possess only one pair of NORs and pericentromeric heterochromatin. For S.testud?neus the found dyploid number was equal 2n=46, with NF=78 (16m+18sm+8st+4a), while that for C.antennatus it possesss 2n=50, with NF=76 (4m+22st+24a). Both species possess simple NORs and pericentromeric heterochromatin blocks. In M.niger, the presence of positive marking (heterochromatin and NOR) in the secondary constriction in the second chromosomic pair suggesting the occurrence of a rearrangement, possibly a fusing involving these homologous ones, indicating that these events had been important for the establishment of the karyological history of this group. A maintenance of the chromosomic constancy found in the populations of C.macrocerus (Monacanthidae) and S.testudineus (Tetraodontidae) perhaps if must for the aiding of the gene flow through oceanic chains. These data contrast with the differentiated kinds of chromosomes of C.antennatus between the Northeast coast and Southeastern, suggesting that the ecological standards of each species, added to the conditions of the marine environment, can be responsible for the karyological delineation of each species. The found characteristics for the species C.macrocerus, C.pullus, M.niger, S.testudineus and C.antennatus add it the available data for other species of Tetraodontiformes. From the data gotten in the present study, it can be inferred that the DNA content possesss direct relation with the total length of the chromosomes / RESUMO A ordem Tetraodontiformes ? composta por cerca de 400 esp?cies de peixes, distribu?das em dez fam?lias, com distribui??o circuntropical. A diversidade morfol?gica de cada fam?lia reflete em, parte, os diferentes n?veis de especializa??o. Este grupo representa uma linhagem p?s-Perciformes e constitui o ?ltimo ramo da difus?o dos Tele?steos, ocupando uma posi??o filogen?tica de destaque. Nesta ordem encontram-se algumas das esp?cies de peixes mais conhecidas popularmente, os baiacus, fam?lias Diodontidae e Tetraodontidae; e os cangulos, fam?lias Balistidae e Monacanthidae. Existem diversos trabalhos examinando as rela??es filogen?ticas dos Tetraodontiformes e, em todos, estas fam?lias s?o reconhecidas como grupos irm?os, sendo Diodontidae mais pr?ximo de Tetraodontidae e Balistidae mais pr?ximo de Monacanthidae. Embora possua um n?mero representativo de esp?cies, s?o poucos os trabalhos citogen?ticos envolvendo exemplares das fam?lias Balistidae e Monacanthidae, especialmente esp?cies insulares. Neste trabalho foram analisadas citogeneticamente as esp?cies Cantherhines macrocerus, Cantherhines pullus (Monacanthidae), Melichthys niger (Balistidae), Sphoeroides testudineus (Tetraodontidae) e Chilomycterus antennatus (Diodontidae); atrav?s de colora??o convencional, Ag-RONs e bandamento C. Diante das diferentes tend?ncias de evolu??o cariot?picas apresentadas pelos Tetraodontiformes, o presente trabalho tamb?m buscou verificar a exist?ncia de rela??o entre o tamanho total dos cromossomos com a quantidade de DNA nestes grupos de Tetraodontiformes. Para tal, foram correlacionados o tamanho total do complemento hapl?ide destas esp?cies, com valores de conte?do de DNA dispon?veis na literatura. As an?lises citogen?ticas para as esp?cies C.macrocerus, C.pullus (Monacanthidae) e M.niger (Balistidae), revelaram um cari?tipo composto de 40 cromossomos, todos acroc?ntricos. Todas possuem apenas um par de RONs e heterocromatina pericentrom?rica. Para S.testudineus o n?mero dipl?ide encontrado foi igual a 2n=46, com NF=78 (16m+18sm+8st+4a), enquanto que para C.antennatus possui 2n=50, com NF=76 (4m+22st+24a). Ambas esp?cies possuem RONs simples e blocos heterocrom?ticos centrom?ricos. Em M. niger, a presen?a de marca??o positiva (heterocromatina e RON) na constri??o secund?ria no 2?par cromoss?mico em M. niger sugerindo a ocorr?ncia de um rearranjo, possivelmente uma fus?o envolvendo estes hom?logos, indicando que estes eventos foram importantes para o estabelecimento dos cari?tipos deste grupo.A manuten??o da const?ncia cariot?pica encontrada nas popula??es de C. macrocerus (Monacanthidae) e Sphoeroides testudineus (Tetraodontidae) talvez se deva pelo favorecimento do fluxo g?nico atrav?s das correntes oce?nicas. Estes dados contrastam com os cit?tipos diferenciados de C.antennatus entre a costa Nordeste e Sudeste, sugerindo que os padr?es ecol?gicos de cada esp?cie, somados ?s condi??es do meio ambiente marinho, possam ser respons?veis pela delinea??o cariot?opica de cada esp?cie. As caracter?sticas citogen?ticas encontradas para as esp?cies C.macrocerus, C.pullus, M.niger, S.testudineus e C.antennatus somam-se aos dados dispon?veis para outras esp?cies de Tetraodontiformes. A partir dos dados obtidos no presente estudo, pode-se inferir que o conte?do de DNA possui rela??o direta com o comprimento total do genoma