Cytogenetic Mapping of H1 Histone and Ribosomal RNA Genes in Hybrids between Catfish Species <b><i>Pseudoplatystoma corruscans</i></b> and <b><i>Pseudoplatystoma reticulatum</i></b>

Abstract

A physical chromosome mapping of the H1 histone and 5S and 18S ribosomal RNA (rRNA) genes was performed in interspecific hybrids of Pseudoplatystoma corruscans and P. reticulatum. The results showed that 5S rRNA clusters were located in the terminal region of 2 chromosomes. H1 histone and 18S ribosomal genes were co-localized in the terminal portion of 2 chromosomes (distinct from the chromosomes bearing 5S clusters). These results represent the first report of association between H1 histone and 18S genes in fish genomes. The chromosome clustering of ribosomal and histone genes was already reported for different organisms and suggests a possible selective pressure for the maintenance of this association.

Chromosomal Mapping of Repetitive DNA and Cytochrome C Oxidase I Sequence Analysis Reveal Differentiation among Sympatric Samples of <b><i>Astyanax</i></b><b><i>fasciatus</i></b> (Characiformes, Characidae)

“…Few data reporting the chromosomal location of the histone genes in fishes are available [Pendás et al, 1994b;Hashimoto et al, 2011Hashimoto et al, , 2012Lima-Filho et al, 2012;Pansonato-Alves et al, 2013]. In the present study, the H1 and H3 histone clusters are colocalized and conserved in the same chromosome pair in both karyomorphs, corroborating previous data for the genus Astyanax [Hashimoto et al, 2011;Silva et al, 2013] and reinforcing the conserved distribution pattern of these sequences.…”

Scattered organization of the histone multigene family and transposable elements in Synbranchus

“…Despite the restricted sampling, these studies revealed some particular characteristics, such as differential dispersion of sites and association with 5S or 18S rDNA (Hashimoto et al , 2011, 2013; Lima-Filho et al , 2012; Pansonato-Alves et al , 2013a, 2013b). More recent studies also showed that H1, H3 and H4 histone genes are clustered at the same site in fishes of genus Astyanax (Pansonato-Alves et al , 2013b; Silva et al , 2013).…”

“…In fish species, data about chromosomal location of histone sequences are restricted to eight species mapped for H1 genes (Pendás et al , 1994; Hashimoto et al , 2011, 2013; Lima-Filho et al , 2012) and only five species with mapped H3 sites (Pansonato-Alves et al , 2013a, 2013b; Silva et al , 2013), all of them presenting histone sequences as conspicuous blocks in chromosomes. Despite the restricted sampling, these studies revealed some particular characteristics, such as differential dispersion of sites and association with 5S or 18S rDNA (Hashimoto et al , 2011, 2013; Lima-Filho et al , 2012; Pansonato-Alves et al , 2013a, 2013b).…”

“…However, the vast majority of mapping studies carried out on Neotropical fishes were focused on the location of ribosomal sites, and there is still very little information regarding other types of sequences, such as histone genes and transposable elements (TEs). Even though studies on physical mapping of histone genes and TEs are few, interesting features about those sequences have been revealed, such as association with other repetitive families (Cioffi et al , 2010; Hashimoto et al , 2011, 2013; Lima-Filho et al , 2012), distinct modes of organization (Valente et al , 2011; Ferreira et al , 2011a), and influences on karyotype diversification (Pansonato-Alves et al , 2013a). …”

Introgressive hybridization as a promoter of genome reshuffling in natural homoploid fish hybrids (Cyprinidae, Leuciscinae)

“…PDU and PPO were characterized by a small and stable number of ribosomal DNA (rDNA) clusters, contrasting with the polymorphisms observed in AOL . Still, there are few studies using in-depth molecular cytogenetic analyses on natural fish hybrids (Fujiwara et al, 1997;Zhu et al, 2006;Gromicho et al, 2006b;Hashimoto et al, 2012;Rampin et al, 2012).…”