Made available in DSpace on 2014-12-17T14:33:04Z (GMT). No. of bitstreams: 1 PabloAM.pdf: 4013213 bytes, checksum: 97a52b7c01ae798889ede43cc9641282 (MD5) Previous issue date: 2010-02-26 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Given the great diversity of fishes, the Order Tetraodontiformes stands to show genetic and morphological characteristics enough singular. The fishes of this order have a compact DNA which favors molecular studies, as well as comparisons with more basal species. Model of genome evolution, there are still many gaps in knowledge about their chromosomal patterns and how evolutionary rearrangements influence the marked variation in DNA content of this order. In view of this, we present cytogenetic analyzes of the species Acanthostracion quadricornis (Ostraciidae), A. polygonius (Ostraciidae) Melichthys niger (Balistidae) Cantherhines macrocerus (Monacanthidae) and C. pullus (Monacanthidae), Lagocephalus laevigatus, Colomesus psittacus and Canthigaster figueiredoi (Tetraodontidae), to contribute with cytogenetic data for this group. The analysis was performed by C-banding, Ag-RONs, coloring with base-specific fluorochromes DAPI-CMA3, restriction enzymes AluI, EcoRI, TaqI, PstI and HinfI and in situ hybridization with probes for ribosomal DNA 18S and 5S. The heterochromatic ultrastructure of A. quadricornis and A. polygonius revealed a outstanding heterochromatin content, which may indicate that the accumulation or loss of extensive heterochromatin content could be responsible for large variations in genomic content displayed in different Tetraodontiformes families. The species Cantherhines macrocerus, C. pullus (Monacanthidae) and Melichthys niger (Balistidae) shows a huge karyotypic similarity both numerically and structural. L. laevigatus showed similar cytogenetic features (2n = 44 and single RONs) to the species of the genus Takifugu, which reinforces the idea of their phylogenetic relationships. C. psittacus presented the highest diploid number described for the family (2n = 56) and large amount of HC, features that related with its sister family Diodontidae. Cytogenetic analysis in C. figueiredoi revealed heterochromatic polymorphisms, RONs multiple and Bs chromosomes. These events are rare in marine fishes, and are possibly associated with the strong restructuring and genomic reduction that this family has been suffered. These features, plus the morphological and molecular data suggests that these species share the same ancestral branch, with a possible monophyletic origin. In this study, new contributions to the knowledge of evolutionary patterns facing by Tetraodontiformes are provided and discussed under cytotaxonomyc, genomic and evolutionary perspectives. / Frente ? grande diversidade de peixes, a Ordem Tetraodontiformes se destaca por exibir caracter?sticas gen?ticas e morfol?gicas bastantes singulares. Os peixes desta Ordem apresentam um DNA compacto o que favorece estudos moleculares, assim como compara??es com esp?cies mais basais. Modelo de evolu??o gen?mica, ainda existem v?rias lacunas de conhecimento sobre seus padr?es cromoss?micos e como os rearranjos evolutivos influenciaram na marcante varia??o no conte?do de DNA desta Ordem. Diante disto o presente estudo apresenta an?lises citogen?ticas das esp?cies, Acanthostracion quadricornis (Ostraciidae), A. polygonius (Ostraciidae), Melichthys niger (Balistidae), Cantherhines macrocerus (Monacanthidae), C. pullus (Monacanthidae), Lagocephalus laevigatus, Colomesus psittacus e Canthigaster figueiredoi (Tetraodontidae) visando contribuir com mais dados citogen?ticos para o grupo. As an?lises foram realizadas atrav?s do bandamento C, Ag-RONs, colora??o com fluorocromos base-espec?ficos DAPICMA3, enzimas de restri??o AluI, EcoRI, TaqI, PstI e HinfI e pela hibrida??o in situ com sondas de DNA ribossomal 18S e 5S. A ultra-estrutura heterocromat?nica de A. quadricornis e A. polygonius, revelaram um marcante conte?do heterocrom?tico, situa??o que pode indicar que o ac?mulo ou perda de extenso conte?do de heterocromatinas poderiam ser respons?veis pelas extensas varia??es no conte?do gen?mico exibidas nas diferentes fam?lias dos Tetraodontiformes. As esp?cies Cantherhines macrocerus, C. pullus (Monacanthidae) e Melichthys niger (Balistidae) apresentam uma grande similaridade cariot?pica, tanto num?rica, como estruturalmente. Lagocephaluslaevigatus mostrou caracter?sticas citogeneticas similares (2n=44 e RONs simples) as esp?cies do g?nero Takifugu, o que refor?a a id?ia de seu relacionamento filogen?tico, e Colomesus psittacus apresentou o maior n?mero dipl?ide descrito para a fam?lia (2n=56) e grande quantidade de HC, caracter?sticas que o relacionariam com a fam?lia irm? Diodontidae. An?lises citogen?ticas em C. figueiredoi revelaram polimorfismos heterocrom?ticos, RONs m?ltiplas e cromossomos Bs, sendo estes eventos raros para peixes marinhos, estando possivelmente associados ? marcante reestrutura??o e redu??o gen?mica que esta fam?lia sofreu. Estas caracter?sticas, somadas aos dados morfol?gicos e moleculares sugerem que estas esp?cies compartilham de um mesmo ramo ancestral, com poss?vel origem monofil?tica. Neste trabalho novas contribui??es ao conhecimento dos padr?es evolutivos enfrentados pelos Tetraodontiformes s?o fornecidas e discutidas sob perspectivas citotax?nomicas, gen?micas e evolutivas.