Karyotype variability in six Amazonian species of the family Curimatidae (Characiformes) revealed by repetitive sequence mapping

Abstract

Fishes of the Curimatidae family represent one of the most important freshwater ichthyofauna groups of Central and South America, with 117 recognized species distributed in eight genera. In this study, six species -Curimata inornata, Curimatella dorsalis, and Psectrogaster falcata collected from the Lower Araguaia River, Pará, Brazil; Curimata vittata, Curimatella meyeri, and Psectrogaster rutiloides collected from the Catalão Lake, Amazonas, Brazil -were cytogenetically analyzed, investigate the occurrence and distribution of repetitive DNA classes in the karyotypes. All species had 2n=54 metacentric/submetacentric chromosomes. Despite the conservative diploid number, we observed variations in the karyotypic structure among species. Ribosomal DNA (rDNA) 18S and 5S were found in single or multiple sites, with the first report of synteny in Curimatella dorsalis, and the occurrence of several interstitial telomeric sequences (ITSs) in species of the genera Curimatella and Psectrogaster. Interspecific karyotypic diversity both concerning structure and location/position of the nucleolar organizer regions (NOR) and ribosomal DNA, suggesting the occurrence of several non-Robertsonian rearrangements driving the evolution of this family.

Chromosomal characterization of three species of Serrasalmini (Serrasalmidae: Characiformes)

“…Another fact that deserves to be highlighted is the syntenic location of the 18S and 5S rDNA in C. absconditus and P. denticulatus species, for which the Fiber-FISH analysis showed the intercalated location of these rDNA sites (Figure 3). The location of the rDNA sequences on different chromosomes decreases the chances of disadvantageous rearrangements occurring during cell division (Martins and Wasko, 2004); however, in some species, the syntenic location of these rDNA sequences occur without observable damage to the host (Guimarães et al, 2016;Favarato et al, 2021;Souza et al, 2021;Moraes et al, 2022). In Serrasalmidae, for example, the synteny between 18S and 5S rDNA was evidenced in three species of Metynnis and may confer an adaptive advantage for the maintenance of this organization (Favarato et al, 2021).…”

Karyotype Description and Comparative Chromosomal Mapping of 5S rDNA in 21 species

“…With advances in science and technology, the occurrence of 5S rDNA has been confirmed in an increasing amount of species (de Barros et al 2023, de Moraes et al 2023, Kroupin et al 2023, Rodríguez-González et al 2023). Whether the reported length of 5S rDNA is a complete or partial sequence, there is no doubt there is a big difference among these 5S rDNA, including the length and base pair (Röser et al 2001, Kulak et al 2002, Moraes et al 2022).…”

“…Conversely, 5S rDNA FISH signal sites in previous research ranged from 1 to 71 (Rodríguez-González et al 2023). Quite of species conserve 5S rDNA, including only two stable chromosomes with two 5S rDNA signal sites (Zhang et al 2016, Moraes et al 2022, Yurkevich et al 2022, Alexandrov et al 2022, Khensuwan et al 2023). Nevertheless, a few species occupy visible 5S rDNA FISH signals, including the numbers of both major and visible dispersed sites.…”

Karyotype Description and Comparative Chromosomal Mapping of 5S rDNA in 42 Species

“…With advances in science and technology, 5S rDNA has been confirmed in an increasing number of species [3,22,65,66]. However, whether the reported length of 5S rDNA is a complete or partial sequence, there are no doubt considerable differences among these 5S rDNAs, including the length and base pair [17,67,68].…”

“…In previous research, the number of 5S rDNA FISH signal sites ranged from 1 to 71 [3]. Some species conserve 5S rDNA, including only two stable chromosomes with two 5S rDNA signal sites [14][15][16][17][18]. However, a few species occupy visible 5S rDNA FISH signals, including the numbers of both major and visible dispersed sites.…”