Cytogenetical analyses in three fish species of the genus Pimelodus(Siluriformes: Pimelodidae) from rio São Francisco: considerations about the karyotypical evolution in the genus

Abstract

Karyotypes and other chromosomal markers were investigated in three species of the catfish genus Pimelodus, namely P. fur, P. maculatus and Pimelodus sp., from municipality of Três Marias, Minas Gerais, Brazil, using differential staining techniques (C-banding, Silver nitrate and CMA3 staining). The diploid chromosome number was 2n = 56 in P. maculatus and Pimelodus sp., while in P. fur 2n = 54. The karyotype of P. fur consisted in 32M + 8SM + 6ST + 8A with fundamental number (NF) of 100, that of P. maculatus 32M + 12SM + 12A with NF = 112, and that of Pimelodus sp. had 32M + 12Sm + 6ST + 6A with NF = 106.The nucleolar organizer regions (NORs) in all three species were invariably detected in telomeres of longer arm of the 20th chromosome pair. These sites were also positive after CMA3 and C-banding. No heteromorphic sex chromosomes were detected and C-banding pattern was species specific. Inferences about the karyotype differentiation in Pimelodus and putative chromosomal rearrangements are hypohesized.<br>Cariótipos e outros marcadores cromossômicos de três espécies do gênero Pimelodus denominadas, P. fur, P. maculatus e Pimelodus sp., do município de Três Marias, Minas Gerais, Brasil, foram analisados utilizando técnicas de coloração diferenciais (Bandamento C, coloração por nitrato de prata e CMA3). O número diplóide observado foi 2n = 56 em P. maculatus e Pimelodus sp., enquanto em P. fur 2n = 54. O cariótipo de P. fur consistiu em 32M + 8SM + 6ST + 8A com número fundamental (NF) igual a 100, o de P. maculatus 32M + 12SM + 12A com NF = 112, e o de Pimelodus sp. possuía 32M + 12Sm + 6ST + 6A com NF = 106. As regiões organizadoras nucleolares (RONs) foram detectadas invariavelmente, para as três espécies, na região telomérica do braço longo do 20º par cromossômico, estas se mostraram positivamente coradas pela CMA3 e heterocromáticas. Nenhuma diferença cromossômica entre os sexos foi detectada e o padrão de bandamento C foi espécie-específico Inferências sobre a evolução cariotípica dentro do gênero Pimelodus e os possíveis rearranjos cromossômicos envolvidos neste processo são discutidos

Chromosomal analyses in Megalonema platanum (Siluriformes: Pimelodidae), an endangered species from South American rivers

“…1c). C-banding for most of the family Pimelodidae is similar to that seen in M. platanum with some heterochromatic regions in the terminal position, as for example, in species of the genus Pimelodus (Souza et al, 2004;Garcia & Moreira-Filho, 2005;Treco et al, 2008), Steindachneridion Eigenmann & Eigenmann, 1919(Swarça et al, 2005 and others. In several species and/or populations of the genus Pimelodus, chromosomal marker pairs, with interstitial heterochromatin, could also be seen (Borin & Martins-Santos, 2004;Treco et al, 2008).…”

“…1a). In a review on the cytogenetic studies of 27 species of the family Pimelodidae by Swarça et al (2007), 23 had a diploid number of 56 chromosomes, three had 2n = 50 chromosomes: Pinirampus pirinampu (Spix & Agassiz, 1829) (Swarça et al, 1999;Vasconcelos & Martins-Santos, 2000), Luciopimelodus pati (Valenciennes, 1835) (Sánchez, 2006), and Calophysus macropterus (Liechtenstein, 1819) (Ramirez-Gil et al, 1998), and one had 2n = 54 chromosomes: Pimelodus fur (Lütken, 1874) (Garcia & Moreira-Filho, 2005).…”

Karyotype variability in neotropical catfishes of the family Pimelodidae (Teleostei: Siluriformes)

“…In this context, according to Diniz et al (2009), the location of 5S and 18S rDNA sites on different chromosomes and different positions would be a way to restrict the setting of unfavorable rearrangements, for example, translocation of segments between these genes. Under the phylogenetics systematics light, this characterization may place the status of this character as an apomorphy, which is yet to be proven regarding other species from the genus, for example, Pimelodus fur has not exhibited this synteny (Garcia et al, 2005). Moreover, the character robustness must also be tested in relation to the same species in other populations.…”

Pimelodus maculatus (Siluriformes, Pimelodidae): complete mtDNA sequence of an economically important fish from the São Francisco river basin

“…Several genetic studies of partial mitochondrial and nuclear regions of P. maculatus have found a high degree of genetic diversity among populations (Garcia & Moreira Filho 2005;Paiva & Kalapothakis 2008;Carvalho et al 2011;Lundberg et al 2011;Pereira et al 2011;Ribolli et al 2012;Ferreira et al 2014;Frantine-Silva et al 2015). Here, we provide the first description of the complete mitochondrial DNA (mtDNA) sequence for P. maculatus, which could support the development of molecular markers studies to aid wildlife forensics, evolutionary approaches, and conservation and management studies.…”