Karyotypic variation of Glanidium ribeiroi Haseman, 1911 (Siluriformes, Auchenipteridae) along the Iguazu river basin

Abstract

The Iguazu river is a tributary of the left margin of the Paraná river, isolated from this basin about 22 million years ago with the appearance of the Iguazu Falls. The Iguazu river is characterized by high endemism due to two factors: its rugged topography and the old isolation caused by formation of the Iguazu Falls. This study analyzed cytogenetically a population of Glanidium ribeiroi collected in a region at the final stretch of this basin, by Giemsa staining, C-banding, impregnation by silver nitrate, and FISH with probes of 5S rDNA, 18S rDNA, telomeric sequence [TTAGGG] n , and [GATA] n repeats. The diploid number was equal to 58 chromosomes. The heterochromatin was present in the terminal region of almost all chromosomes. The Ag-NORs were simple and presented interstitially on the short arm of the submetacentric pair 14, which was confirmed by FISH with 18S rDNA probe. The 5S rDNA-FISH marked only the submetacentric pair 16 on the long arm in interstitial position. The FISH with [TTAGGG] n probe presented all telomeres labeled as expected, with an absence of Interstitial Telomeric Sequence (ITS). The repetitive [GATA] n sequence was dispersed throughout the genome, with preferential location in the terminal region of all chromosomes. The data obtained are discussed herein with other species of Auchenipteridae, and other previously analyzed populations of G. ribeiroi from the Iguazu river, verifying differences among these populations, which should be mainly related to the rugged topography of this basin.Keywords: geographical barriers, ribosomal DNA, Glanidium ribeiroi, Iguazu river. Variação cariotípica de Glanidium ribeiroi

An uncommon co-localization of rDNA 5S with major rDNA clusters in Callichthyidae (Siluriformes): a report case in Corydoras carlae Nijssen & Isbrücker, 1983

“…Therefore, the geographic isolation of Corydoras carlae may have facilitated the establishment of this numerical and structural karyotypic variation, as also observed in different populations of Glanidium ribeiroi Haseman, 1911 along the Iguassu River basin (Lui et al 2015). Thus, the lack of gene flow among Corydoras species in the Iguassu River basin could favor different changes in each sample, supposedly resulting in speciation.…”

Possible Common Origin of B Chromosomes in Neotropical Fish (Siluriformes, Auchenipteridae) Reinforced by Repetitive DNA Mapping

“…In A. inermis [19], P. galeatus [13,18,20,36], T. jaracatia, T. neivai [22], A. inermis [23], and Trachelyopterus sp. (this paper) NORs were terminal; in A. osteomystax [20], G. ribeiroi [20,21,24], and T. atronasus [19] NORs were interstitial. In all species that have 18S rDNA mapping data, it was confirmed the result obtained by silver nitrate impregnation (13,18,(21)(22)(23)(24).…”

“…in this paper reinforce this proximity, since they evidenced high chromosome similarities: maintenance of the diploid number (2n=58), heterochromatin dispersed in the terminal region of the most of A chromosomes, single terminal NORs located in the short arm of a subtelocentric pair (confirmed by FISH with 18S rDNA), two pairs bearing 5S rDNA sites, and similarities between B chromosomes. The few number of Auchenipteridae studies [13,[18][19][20][21][22][23][24]36] suggest that this conserved chromosome macrostructure is recurrent in the family, and most of the differences found are usually due to non-robertsonian rearrangements [18]. This situation of little variation is not unique to these species, since many groups of Neotropical fish exhibit relative karyotype conservatism [37][38][39].…”

“…Similar pattern of C-banding occurs in other Auchenipteridae species, like Auchenipterus osteomystax cit. Auchenipterus nuchalis [20], Glanidium ribeiroi [20,21,24], P. galeatus [13,18,20], Tatia jaracatia, Tatia neivai [22] and Tympanopleura atronasus cit. Ageneiosus atronasus [19], suggesting that this is a common feature of the family.…”

“…Auchenipteridae has two species that present B chromosomes; they are presented in this paper: Parauchenipterus galeatus [13,18] and Trachelyopterus sp. The other species of this subfamily which were chromosomally studied do not have B chromosomes [19][20][21][22][23][24].…”