R- and G-band patterns in Astyanax scabripinnis paranae (Pisces, Characiformes, Characidae)

Abstract

The absence of longitudinal bands in fish chromosomes has been associated with technical problems in chromosome preparations or the absence of a structural compartmentalization in the fish genome. In the present study, a R-banding pattern was obtained using a replication banding technique by in vivo treatment with 5-bromodeoxyuridine (5-BrdU). G-banding patterns were obtained after trypsin treatment and also after chromosome cleavage by in situ treatment with the restriction endonuclease BamHI. A similar G-banding pattern was also obtained after cleavage with the endonuclease HinfI. Presence of a resolute R- and G-banding patterns shows that Astyanax scabripinnis paranae chromosomes could present an isochore-like structure similar to that found in other vertebrates.<br>A ausência de bandas longitudinais em cromossomos de peixes tem sido associada a problemas técnicos nas preparações cromossômicas ou à ausência de uma compartimentalização estrutural no genoma dos peixes. No presente estudo, um padrão de bandas R foi obtido usando a técnica de bandamento de replicação pelo tratamento in vivo com 5-BrdU. Padrões de bandamento G foram obtidos após tratamento dos cromossomos com tripsina e também após clivagem in situ com a endonuclease de restrição BamHI. Um padrão similar de bandamento G também foi obtido após clivagem dos cromossomos com a endonuclease HinfI. A presença de um resolutível padrão de bandamento R e G em Astyanax scabripinnis paranae mostra que seus cromossomos parecem apresentar estrutura "isochore" similar àquela encontrada em outros vertebrados

Paracentric Inversions Differentiate the Conservative Karyotypes in Two <b><i>Centropomus</i></b> Species (Teleostei: Centropomidae)

“…Replication bands have proved to be useful in fish comparative cytogenetics concerning chromosome evolution [Hellmer et al . , 1991;Maistro et al . , 1999], characterization of homeologous chromosome regions [Giles et al, 1988;Salvadori et al, 2003], heterochromatin replication dynamics, and origin and diversification of sex chromosomes [Bertollo et al, 1997;Molina and Galetti, 2007].…”

Mapping of Ribosomal DNA by FISH, EcoRI Digestion and Replication Bands in the Cardinalfish Apogon americanus (Perciformes)

“…Their origin could be derived from heterochromatin redistribution caused by paracentric inversions, relocating formerly pericentromeric heterochromatic blocks. Analyses using digestion with restriction endonucleases and replication bands have already been performed to elucidate the origin of B chromosomes and aspects of genome compartmentalization in fish (Maistro et al 1999), but they can also help us understand structural rearrangements or functional aspects of specific chromosomal regions.…”

B chromosomes in the fish <i>Astyanax scabripinnis</i> (Characidae, Tetragonopterinae): An overview in natural populations

“…Chromosome 24 represents a strong candidate from which the B M chromosome might have originated, considering that this is the only chromosome of the karyotype that presents an interstitial C-band (Vicente et al, 1996), which contains the As51 repetitive DNA which is also interstitially located in both B arms, although these data should not be considered conclusive (Mestriner et al, 2000). The alternative proposition that the B M chromosome might have originated from meiotic non-disjunction of the first metacentric pair of the karyotype, considering the similarities of shape and size of these chromosomes, followed by a complementary heterochromatinization (Salvador and Moreira-Filho, 1992), is not supported by chromosome banding data (Maistro et al, 1999;Ferro et al, 2003).…”