%0 Journal Article
%T The role of chromosomal fusion in the karyotypic evolution of the genus Ageneiosus (Siluriformes: Auchenipteridae)
%A Roberto Laridondo Lui
%A Daniel Rodrigues Blanco
%A Juliana de F¨¢tima Martinez
%A Vladimir Pavan Margarido
%J Neotropical Ichthyology
%D 2013
%I Sociedade Brasileira de Ictiologia
%X Ageneiosus is the most widely distributed genus of the family Auchenipteridae among South American river basins. Although chromosome studies in the family are scarce, this genus has the largest number of analyzed species, with 2n = 54 to 56 chromosomes, differing from the rest of the family (2n = 58). This study aimed to analyze Ageneiosus inermis from the Araguaia River basin. The diploid number found was of 56 chromosomes. Heterochromatin was allocated in terminal region of most chromosomes, plus a pericentromeric heterochromatic block in pair 1, a pair distinguished by size in relation to other chromosomes pairs. AgNORs were detected in only one submetacentric chromosome pair, which was confirmed by FISH. 5S rDNA was present in only one metacentric chromosome pair. Hybridization with [TTAGGG]n sequence marked the telomeres of all chromosomes, in addition to an ITS in the proximal region of the short arm of pair 1. The repetitive [GATA]n sequence was dispersed, with preferential location in terminal region of the chromosomes. Ageneiosus has a genomic organization somewhat different when compared to other Auchenipteridae species. Evidences indicate that a chromosomal fusion originated the first metacentric chromosome pair in A. inermis, rearrangement which may be a basal event for the genus Ageneiosus ¨¦ o g¨ºnero da fam¨ªlia Auchenipteridae mais amplamente distribu¨ªdo em bacias da Am¨¦rica do Sul. Apesar dos estudos cromoss micos nesta fam¨ªlia serem escassos, este g¨ºnero tem o maior n¨²mero de esp¨¦cies analisadas, com n¨²mero diploide variando de 54 a 56 cromossomos, o que difere do restante da fam¨ªlia (2n = 58). Este estudo objetivou analisar Ageneiosus inermis da bacia do rio Araguaia. O n¨²mero diploide encontrado foi de 56 cromossomos. A heterocromatina se mostrou localizada na regi o terminal da maioria dos cromossomos, al¨¦m de um bloco heterocrom¨¢tico pericentrom¨¦rico no par 1, um par facilmente distingu¨ªvel no cari¨®tipo pelo seu maior tamanho quando comparado aos outros pares do complemento. AgRONs foram detectadas em somente um par de cromossomos submetac¨ºntricos, que foi confirmado pela FISH. 5S rDNA se mostrou presente em somente um par de cromossomos metac¨ºntricos. A hibridiza  o com a sequ¨ºncia [TTAGGG]n marcou os tel meros de todos os cromossomos, al¨¦m de um ITS (sequ¨ºncia telom¨¦rica intersticial) na regi o proximal do bra o curto do par 1. A sequ¨ºncia repetitiva [GATA]n se mostrou dispersa, com localiza  o preferencial na regi o terminal dos cromossomos. Ageneiosus apresenta uma organiza  o gen mica um pouco diferente quando comparada a outras
%K C banding
%K Cytogenetic Markers
%K [GATA]n sequence
%K rDNA-FISH
%K [TTAGGG]n sequence
%U http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1679-62252013005000413