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. 2022 Sep 29;12(19):2612.
doi: 10.3390/ani12192612.

Chromosomal Diversification in Pseudacanthicus Species (Loricariidae, Hypostominae) Revealed by Comparative Mapping of Repetitive Sequences

Kevin Santos da Silva  1 , Augusto César Paes de Souza  2 , Luís Reginaldo Ribeiro Rodrigues  3 , Julio Cesar Pieczarka  1 , Cleusa Yoshiko Nagamachi  1
Affiliations

Chromosomal Diversification in Pseudacanthicus Species (Loricariidae, Hypostominae) Revealed by Comparative Mapping of Repetitive Sequences

Kevin Santos da Silva et al. Animals (Basel). .

Abstract

Pseudacanthicus is a genus of Neotropical fish with eight valid species, in addition to numerous lineages not formally identified. It occurs along the Amazon and Tocantins River basins, in Suriname and in the Guiana shield. There are no karyotypic data in the literature for species of this genus. Here, the karyotypes of three Pseudacanthicus species (P. spinosus, P. leopardus and Pseudacanthicus sp.) were comparatively analyzed by classical cytogenetics and fluorescence in situ hybridization using 18S and 5S rDNA probes, U2 snDNA and telomeric sequences. The analyzed species presented 52 chromosomes and KF = 18 m + 34 sm. Constitutive heterochromatin occurred in blocks on a few chromosomes. The 18S rDNA occurred in a single pair; interestingly, P. leopardus presented only one locus of this sequence in its diploid genome. The 5S rDNA sequence occurred in only one pair in P. leopardus, and in multiple sites in Pseudacanthicus sp. and P. spinosus. The snDNA U2 occurred in only one pair in all analyzed species. Telomeric sequences did not show interstitial sites. Although Pseudacanthicus species share the same 2n and KF, repetitive sequence analysis revealed karyotypic diversity among these species. The occurrence of DNA double-strand breaks related to fragile sites, unequal crossing over and transpositions is proposed as the mechanism of karyotypic diversification, suggesting that the conservation of the karyotypic macrostructure is only apparent in this group of fish.

Keywords: comparative cytogenetics; neotropical ichthyofauna; rDNA; repetitive DNA; snDNA.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Karyotypes of Pseudacanthicus species. In (a,b) karyotypes of P. spinosus; in (c,d) karyotypes of P. leopardus; and in (e,f) karyotypes of Pseudacanthicus sp. after conventional staining with Giemsa and C-banding, respectively. The external coloration patterns of the analyzed Pseudacanthicus species are shown on the side, scale bar: 5 cm. Photos by Kevin Santos da Silva.
Figure 2
Figure 2
Fluorescence in situ hybridization indicating the physical location of rDNA and snDNA sequences in the karyotypes of Pseudacanthicus species. In (a) 18S rDNA, (b) 5S rDNA and (c) U2 snDNA in P. spinosus; in (d) 18S rDNA, (e) 5S rDNA and (f) U2 snDNA in P. leopardus; in (g) 18S rDNA, (h) 5S rDNA and (i) U2 snDNA in Pseudacanthicus sp. Hybridization signals were detected with FITC (green) and Cy3 (red), and chromosomes were counterstained with DAPI (blue).
Figure 3
Figure 3
Fluorescence in situ hybridization indicating the physical location of telomeric sequences in the karyotypes of P. seudacanthicus species. In (a) P. spinosus, in (b) P. leopardus, and in (c) Pseudacanthicus sp. Hybridization signals were detected with FITC (green) and Cy3 (red), chromosomes were counterstained with DAPI (blue).
See this image and copyright information in PMC

References

    1. Fricke R., Eschmeyer W.N., Van der Laan R., editors. Eschmeyer’s Catalog of Fishes: Genera, Species, References. 2021. [(accessed on 21 April 2021)]. Available online: http://researcharchive.calacademy.org/research/ichthyology/catalog/fishc....
    1. Armbruster J.W. Phylogenetic relationships of the suckermouth armoured catfishes Loricariidae with emphasis on the Hypostominae and the Ancistrinae. Zool. J. Linn. Soc. 2004;141:1–80. doi: 10.1111/j.1096-3642.2004.00109.x. - DOI
    1. Armbruster J.W. The genus Peckoltia with the description of two new species and a reanalysis of the phylogeny of the genera of the Hypostominae (Siluriformes: Loricariidae) Zootaxa. 2008;1822:1–76. doi: 10.11646/zootaxa.1822.1.1. - DOI
    1. Lujan N.K., Armbruster J.W., Lovejoy N.R., López-Fernández H. Multilocus molecular phylogeny of the suckermouth armored catfishes (Siluriformes: Loricariidae) with a focus on subfamily Hypostominae. Mol. Phylogenetics Evol. 2015;82:269–288. doi: 10.1016/j.ympev.2014.08.020. - DOI - PubMed
    1. Chamon C.C. Pseudacanthicus pitanga: A new species of Ancistrini (Siluriformes: Loricariidae: Hypostominae) from rio Tocantins Basin, North Brazil. Zootaxa. 2015;3973:309–320. doi: 10.11646/zootaxa.3973.2.6. - DOI - PubMed

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