Occurrence of two cytotypes in Bryconamericus aff. iheringii (Characidae): karyotype analysis by C- and G-banding and replication bands

Abstract

Cytogenetic analyses of Bryconamericus aff. iheringii specimens from the upper Paraná River basin (State of Paraná, Brazil) are provided. They had 2n = 52 chromosomes and two cytotypes with variations in their karyotypic formulae: cytotype I with 12 metacentric, 18 submetacentric, 8 subtelocentric and 14 acrocentric chromosomes with a fundamental number (FN) of 90; cytotype II with 8 metacentric, 28 submetacentric, 6 subtelocentric and 10 acrocentric chromosomes with a fundamental number (FN) of 94. Differences in C- and G-band patterns between the cytotypes, distinguishing marker chromosomes for each karyotype, were reported. The R-band pattern by 5-bromodeoxyuridine incorporation was obtained in chromosomes of the cytotype II sample. In some metaphases, the second pair of submetacentric chromosomes is distinctive: its short arm is heterochromatic (positive C-band), corresponding to a late replication region. In the same cytotype, a G- and R-band size heteromorphism w as recorded in the long arm of pair 9 (submetacentric). These methodologies revealed an actual karyotypic differentiation in the B. aff. iheringii population analyzed. Morphometrical comparative analyses and a discussion of evolutionary aspects of chromosome diversification in species of this genus are provided as well.

Karyotypic diversity in a population of Bryconamericus aff. iheringii (Characidae)

“…However, a wide variability in karyotypic macrostructure has been a characteristic of this genus ( Table 2). The occurrence of cytotypes in this species has already been documented by de Brito Portela-Castro et al (2008), who observed two cytotypes in the population of Keller River: I -12m+18sm+8st+14a (FN = 90) and II -8m+28sm+6st+10a (FN = 94). Distinct karyotypic formulae have also been documented for Bryconamericus sp B of Piracicaba River (Wasko et al, 1996;Wasko and Galetti Jr., 1998;1999) (FN = 92); and cytotype IV, with 10m+14sm+8st+20a (FN = 84).…”

“…iheringii of Três Bocas Stream and in other species and populations (Capistano et al, 2008;de Brito Portela-Castro et al, 2008;dos Santos et al, 2012), except for Bryconamericus sp E of the Avoadeira Stream, MT, which exhibits 54 chromosomes (Wasko and Galetti Jr., 1998). However, a wide variability in karyotypic macrostructure has been a characteristic of this genus ( Table 2).…”

“…Despite the great karyotypic diversity reported for the genus, the diploid number of 52 is very conserved (Capistano et al, 2008;de Brito Portela-Castro et al, 2008), except for Bryconamericus sp E of the Avoadeira Stream, MT, which shows 54 chromosomes (Wasko and Galetti Jr., 1998). Furthermore, the pattern of multiple nucleolar organizer regions (NORs) is the most common within the genus (Capistano et al, 2008), as well as the association of these sites with positive signals for chromomycin A 3 (CMA 3 + ) or mithramycin (MM + ) (Paintner-Marques et al, 2002;dos Santos et al, 2012), indicating that the association of the NORs with GC-rich base pair sequences is common.…”

“…In the genus Bryconamericus, the heterochromatin is distributed mainly in terminal and pericentromeric regions (Paintner-Marques et al, 2003;de Brito Portela-Castro et al, 2008), and terminal heterochromatin in subtelocentric chromosomes was regarded by Paintner-Marques et al (2003) as a chromosome marker for B. iheringii. Furthermore, the composition of heterochromatin may vary and is used to differentiate between cytotypes after staining with base-specific fluorochromes (dos , as well as distinguishing heterochromatic types in the same karyotype by digestion with AluI restriction enzyme (Paintner-Marques et al, 2003).…”

Inventory of the fish fauna from Ivaí River basin, Paraná State, Brazil

“…There are only few surveys on fish fauna in the Ivaí River basin, especially for the tributaries, Barra Bonita River (Maier et al 2008), Bonito River (Viana et al 2013), some streams located in the Perobas Biological Reserve (Delariva & Silva 2013) and a first-order stream in the municipality of Marialva (Araújo et al 2011); and there are few genetic studies with some species of Loricariidae (Zawadzki et al 2004, Portela-Castro et al 2007, Paiva et al 2013 or ecological studies (Luiz et al 2003, Luiz et al 2005) and description of new species (Graça & Pavanelli 2008, Roxo et al 2014, Tencatt et al 2014, Zawadzki et al 2016) with fish of this basin.…”