Chromosomal Variability among Allopatric Populations of Erythrinidae Fish <i>Hoplias malabaricus</i>: Mapping of Three Classes of Repetitive DNAs

Abstract

Karyotype and chromosomal characteristics from 3 allopatric populations of Hoplias malabaricus, cytogenetically the most studied Erythrinidae taxon, were investigated using different staining techniques (C-, Ag-, and CMA₃ banding) as well as fluorescent in situ hybridization (FISH) to detect 18S rDNA, 5S rDNA, and 5SHindIII satellite DNA sites. The isolation, cloning and characterization of an 18S rDNA probe from H. malabaricus genome were also performed for the first time in order to develop a more specific probe. The 3 populations, named PR, CR, and DR, showed identical karyotypes, with 2n = 42 chromosomes composed of 11 m pairs and 10 sm pairs, without heteromorphic sex chromosomes, which characterize the populations as belonging to karyomorph A. In all populations C-positive heterochromatin was situated in the centromeric/pericentromeric regions of the chromosomes, as well as in the telomeric region of several pairs. A conspicuous proximal heterochromatic block on the long arm of pair No. 16 was the only GC-rich segment in the karyotypes. 5SHindIII satellite DNA was always mapped in the centromeric region of several chromosomes. The 18S rDNA sites were situated on the telomeric or centromeric regions, whereas the 5S rDNA showed an interstitial or proximal location in some pairs. Several chromosomes bearing these repetitive DNA sequences were shared by the 3 populations, alongside with some exclusive chromosomal markers. In this sense, population CR was the most differentiated one, including a syntenic condition for the 18S and 5S rDNA probes, as confirmed by double FISH. Thus, despite their inclusion in the same major karyotypic group, the distinct populations cannot be considered an absolute evolutionary unit, as evidenced by their inner chromosomal differentiations.

Karyotypic diversity between allopatric populations of the group Hoplias malabaricus (Characiformes: Erythrinidae): evolutionary and biogeographic considerations

“…Bitelomeric NORs (those that are present in both telomeric regions in a single chromosome) are a recurring characteristic in the different H. malabaricus karyomorphs (Bertollo, 1996;Vicari et al, 2005;Blanco et al, 2009;Cioffi et al, 2009) as well as in some other species of teleost fish, such as Pyrrhulina cf. australis (Oliveira et al, 1991), Poecilia latipunctata (Galetti Jr. & Rash, 1993) and Astyanax scabripinnis (Mantovani et al, 2005).…”

“…Karyomorph A has wide geographic distribution and is found in the main hydrographic basins of Brazil, such as the Paraná, São Francisco, Araguaia, Amazon Rivers as well as basins in the eastern portion of the country. Smaller karyotype variations between populations of this karyomorph have also been detected (Born & Bertollo, 2001;Vicari et al, 2005;Cioffi et al, 2009).…”

“…Fluorescent in situ hybridization (FISH) was performed based on the method described by Pinkel et al (1986), with some modifications, using the 18S rDNA (Cioffi et al, 2009), 5S rDNA and 5SHindIII satellite DNA probes (Martins et al, 2006). The probes were tagged with biotin-14-dATP by nick translation, following the manufacture's instructions (Bionick Labeling System -Invitrogen).…”

Highly conserved Z and molecularly diverged W chromosomes in the fish genus Triportheus (Characiformes, Triportheidae)

“…The Z probes were labeled via PCR with SpectrumOrange-dUTP (Vysis, Downers Grove, IL, USA) and the W probes with SpectrumGreen-dUTP (Vysis) in a 30-cycle label PCR with degenerate oligonucleotide primer using 1 μl of the primary degenerate oligonucleotide primed-PCR products as template DNA (Yang et al, 2009). 18S and 5S rDNA probes were obtained according to Cioffi et al (2009) and Martins et al (2006), respectively. The 18S rDNA probe was labeled with Cyanine 5-dUTP, whereas 5S rDNA was labeled with Spectrum Green-dUTP using nick-translation method (Roche, Mannheim, Germany).…”

Taxonomic study of Hoplias microlepis (Günther, 1864), a trans-Andean species of trahiras (Ostariophysi: Characiformes: Erythrinidae)

“…Meristic and morphometric data of specimens greatly overlap throughout the distribution range of the species (e.g., Bifi, 2013), and there is a large number of nominal species currently considered junior synonyms (e.g., Oyakawa, 2003), many of which without known type material. In addition, numerous cytogenetic studies have suggested that H. malabaricus represents a species complex (e.g., Bertollo et al, 1986;Dergam & Bertollo, 1990;Bertollo et al, 1997;2000;Born & Bertollo, 2001;Cioffi et al, 2009aCioffi et al, , 2009bRosa et al, 2009;Santos et al, 2009;Blanco et al, 2010;2011;Cioffi & Bertollo, 2010;Cioffi et al, 2011aCioffi et al, , 2011bCioffi et al, , 2011cCioffi et al, , 2011dMarques et al, 2013).…”