A tandemly repetitive centromeric DNA sequence of the fish Hoplias malabaricus (Characiformes: Erythrinidae) is derived from 5S rDNA

Abstract

A substantial fraction of the eukaryotic genome consists of repetitive DNA sequences that include satellites, minisatellites, microsatellites, and transposable elements. Although extensively studied for the past three decades, the molecular forces that generate, propagate and maintain repetitive DNAs in the genomes are still discussed. To further understand the dynamics and the mechanisms of evolution of repetitive DNAs in vertebrate genome, we searched for repetitive sequences in the genome of the fish species Hoplias malabaricus. A satellite sequence, named 5SHindIII-DNA, which has a conspicuous similarity with 5S rRNA genes and spacers was identified. FISH experiments showed that the 5S rRNA bona fide gene repeats were clustered in the interstitial position of two chromosome pairs of H. malabaricus, while the satellite 5SHindIII-DNA sequences were clustered in the centromeric position in nine chromosome pairs of the species. The presence of the 5SHindIII-DNA sequences in the centromeres of several chromosomes indicates that this satellite family probably escaped from the selective pressure that maintains the structure and organization of the 5S rDNA repeats and become disperse into the genome. Although it is not feasible to explain how this sequence has been maintained in the centromeric regions, it is possible to hypothesize that it may be involved in some structural or functional role of the centromere organization.

Chromosomal localization of rDNA genes and genomic organization of 5S rDNA in Oreochromis mossambicus, O. urolepis hornorum and their hybrid

“…The 5S rDNA is often located on a single chromosome pair in fish (Pendás et al 1994;Fujiwara et al 2007;Morescalchi et al 2008;Nirchio et al 2009) and in some mammals (Suzuki et al 1996;Laura et al 2003), probably representing a more ancient condition among animal groups. The occurrence of multiple 5S rDNA sites found in the present study, as well as in some other fish represents derived conditions in their evolutionary dynamic (Ferro et al 2001;Martins et al 2002Martins et al , 2006Zhu et al 2006). The 5S rDNA sites are also present on multiple chromosomes in humans (Lomholt et al 1995) and other mammals like Rhinolophus hipposideros (Puerma et al 2008).…”

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

“…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).…”