Chromosomal distribution of the As51 satellite DNA in two species complexes of the genus Astyanax (Pisces, Characidae)

Abstract

The chromosomal localization of the As51 satellite DNA was identified by fluorescent in situ hybridization (FISH) in specimens of the characid fish Astyanax scabripinnis and Astyanax fasciatus, which are considered species complexes because of their extensive karyotypical and morphological variability. A conserved chromosomal distribution of the As51 satellite, coincident with distal C-banded segments was demonstrated. The alternative interstitial localization of this satellite DNA and possible alterations of its structure suggest that this sequence underwent quantitative, positional and structural variations, as the A. scabripinnis and A. fasciatus complexes diverged.

A comparative structural cytogenetic study in three allopatric populations of Astyanax scabripinnis (Teleostei: Characidae)

“…Some authors suggest that the polymorphism for heterochromatin can be caused by the presence of transposable elements through genomic mechanisms of invasion (TAFALLA et al 2006, SLOTKIN & MARTIENSSEN 2007. Such variation in heterochromatic content has been also often reported in other Astyanax species (SOUZA et al 1996, MANTOVANI et al 2004, ABEL et al 2006. Although additional sampling and biogeographic distribution studies are needed, it is interesting to note that the two main patterns of heterochromatin content coincide with the geographic distribution of the A. scabripinnis populations studied herein.…”

Chromosome polymorphism of heterochromatin and nucleolar regions in two populations of the fish Astyanax bockmanni (Teleostei: Characiformes)

“…The first cytogenetic study of A. bockmanni was carried out by Kavalco et al (2009) who described the karyotypes of two populations originating from the Paranapanema River basin. The karyotype of this species differs from other Astyanax species such as A. scabripinnis and A. fasciatus for which intensive chromosomal polymorphism was reported (Moreira-Filho & Bertollo, 1991;Abel et al, 2006;Artoni et al, 2006).…”

Satellite DNA sites in four species of the genus Astyanax (Teleostei, Characiformes)

“…Its GCpositive heterochromatin distribution was similar to the one reported for other populations from the Tietê river basin (Souza et al, 1996). The exceptions were the single chromosome with a fluorescence signal, an exclusive trait of the population herein analyzed (Figure 2-a), and the distribution of the As-51 satellite DNA (Figure 3-a), less abundant than in the populations from the upper Paraná river basin (Mantovani et al, 2004;Abel et al, 2006). 532 Kavalco et al In A. parahybae, the heterochromatin was distributed in the pericentromeric regions of almost all chromosomes and in the terminal regions of a few ones (Figure 1-b).…”

“…Its taxonomic status was defined by Melo (2001) in a revision of Astyanax species from the Serra dos Órgãos, Paraí-ba do Sul river basin. It is relevant that other A. fasciatus populations, from the Piracicaba river (Abel et al, 2006) and from the Mogi-Guaçu river basin (Pazza, 2005) also presented such satellite DNA. Thus, its detection in A. parahybae could indicate a closer relationship between both species.…”

“…The macrokaryotypic diversification that occurs in species from the "A. scabripinnis" and "A. fasciatus" complexes extends to heterochromatin variation, with frequent heteromorphisms on the nature and location of C-bands among populations, individuals and homologues (Moreira-Filho and Bertollo, 1991;Souza et al, 1996;Mantovani et al, 2000;Fernandes and Martins-Santos, 2005;Abel et al, 2006;among others). No heteromorphisms were observed in the A. scabripinnis population herein studied (Figure 1-a), possibly due to the small sample.…”