Cytogenetic characterization of the strongly electric Amazonian eel, Electrophorus electricus (Teleostei, Gymnotiformes), from the Brazilian rivers Amazon and Araguaia

Fonteles, Soraia Barreto Aguiar; Lopes, C. E. Ferreira; Akama, Alberto; Fernandes, Flora Maria de Campos; Porto‐Foresti, Fábio; Senhorini, José Augusto; Daniel-Silva, Maria de Fátima Zambelli; Foresti, Fausto; Almeida-Toledo, Lurdes Foresti de

doi:10.1590/s1415-47572008000200010

Cited by 10 publications

(7 citation statements)

References 9 publications

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“…Besides this, our studies demonstrate that GJO and GCO have multiple NORs with different patterns of distribution of rDNA loci, involving different chromosomes. The same can be said about the “single NOR” trait, for Sternopygus also has a single NOR, but the chromosome involved is different from that in the G. carapo group (data not shown), as well as in Electrophorus [26]. So it cannot be claimed a priori that the single or multiple NOR conditions can be primitive or derived per se , since each of these conditions in one species can have an origin and composition very divergent from the one found in other species.…”

Section: Discussionmentioning

confidence: 78%

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Are NORs Always Located on Homeologous Chromosomes? A FISH Investigation with rDNA and Whole Chromosome Probes in Gymnotus Fishes (Gymnotiformes)

et al. 2013

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Gymnotus (Gymnotiformes, Gymnotidae) is the most diverse known Neotropical electric knife fish genus. Cytogenetic studies in Gymnotus demonstrate a huge karyotypic diversity for this genus, with diploid numbers ranging from 34 to 54. The NOR are also variable in this genus, with both single and multiple NORs described. A common interpretation is that the single NOR pair is a primitive trait while multiple NORs are derivative. However this hypothesis has never been fully tested. In this report we checked if the NOR-bearing chromosome and the rDNA site are homeologous in different species of the genus Gymnotus: G. carapo (2n = 40, 42, 54), G. mamiraua (2n = 54), G. arapaima (2n = 44), G. sylvius (2n = 40), G. inaequilabiatus (2n = 54) and G. capanema (2n = 34), from the monophyletic group G. carapo (Gymnotidae-Gymnotiformes), as well as G. jonasi (2n = 52), belonging to the G1 group. They were analyzed with Fluorescence in situ hybridization (FISH) using 18S rDNA and whole chromosome probes of the NOR-bearing chromosome 20 (GCA20) of G. carapo (cytotype 2n = 42), obtained by Fluorescence Activated Cell Sorting. All species of the monophyletic G. carapo group show the NOR in the same single pair, confirmed by hybridization with CGA20 whole chromosome probe. In G. jonasi the NORs are multiple, and located on pairs 9, 10 and 11. In G. jonasi the GCA20 chromosome probe paints the distal half of the long arm of pair 7, which is not a NOR-bearing chromosome. Thus these rDNA sequences are not always in the homeologous chromosomes in different species thus giving no support to the hypothesis that single NOR pairs are primitive traits while multiple NORs are derived. The separation of groups of species in the genus Gymnotus proposed by phylogenies with morphologic and molecular data is supported by our cytogenetic data.

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Section: Discussionmentioning

confidence: 78%

“…pantherinus , G. mamiraua and G. arapaima [1], [5], [15]–[25]. In Electrophorus electricus a single NOR was found on a sample from River Araguaia and three NOR-bearing chromosomes were identified in a fish from River Amazonas [26]. On the other hand, in G .…”

Section: Introductionmentioning

confidence: 99%

Are NORs Always Located on Homeologous Chromosomes? A FISH Investigation with rDNA and Whole Chromosome Probes in Gymnotus Fishes (Gymnotiformes)

et al. 2013

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“…Gymnotiformes is the order that includes the electric fishes of the Neotropical region. These species have a high karyotypic variability that is reflected in diploid numbers (2n), karyotypic formula (KF), number and distribution of the nucleolar organizer regions, occurrence of B chromosomes and sex chromosome systems ( Almeida-Toledo et al , 1984 , 1993 , 2000a , b , 2001 , 2002 ; Fernandes-Matioli et al , 1998 ; Fernandes et al , 2005 ; Silva and Margarido, 2005 ; Fonteles et al , 2008 ; Milhomem et al , 2007 , 2008 , 2012a , b ; Silva et al , 2009 ; Cardoso et al , 2011 ; Scacchetti et al , 2011 ; Mendes et al , 2012 ; Silva et al , 2013 ). The group presents simple and multiple sex chromosome systems and heterogamety of males and females ( Table 1 ).…”

Section: Introductionmentioning

confidence: 99%

X1X1X2X2/X1X2Y sex chromosome systems in the Neotropical Gymnotiformes electric fish of the genus Brachyhypopomus

2015

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Several types of sex chromosome systems have been recorded among Gymnotiformes, including male and female heterogamety, simple and multiple sex chromosomes, and different mechanisms of origin and evolution. The X1X1X2X2/X1X2Y systems identified in three species of this order are considered homoplasic for the group. In the genus Brachyhypopomus, only B. gauderio presented this type of system. Herein we describe the karyotypes of Brachyhypopomus pinnicaudatus and B. n. sp. FLAV, which have an X1X1X2X2/X1X2Y sex chromosome system that evolved via fusion between an autosome and the Y chromosome. The morphology of the chromosomes and the meiotic pairing suggest that the sex chromosomes of B. gauderio and B. pinnicaudatus have a common origin, whereas in B . n. sp. FLAV the sex chromosome system evolved independently. However, we cannot discard the possibility of common origin followed by distinct processes of differentiation. The identification of two new karyotypes with an X1X1X2X2/X1X2Y sex chromosome system in Gymnotiformes makes it the most common among the karyotyped species of the group. Comparisons of these karyotypes and the evolutionary history of the taxa indicate independent origins for their sex chromosomes systems. The recurrent emergence of the X1X1X2X2/X1X2Y system may represent sex chromosomes turnover events in Gymnotiformes.

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“…The location of NORs present in one chromosome pair is a common feature found among the Gymnotiformes (FONTELES et al, 2008). However, in both G. carapo populations here analyzed, as well as other populations already studied, had a simple NOR system, located in the interstitial region of the fi rst metacentric pair.…”

Section: Discussionmentioning

confidence: 59%

Comparative Cytogenetic Study Among Three Fish Species: An Analysis From a Water Divide Region

Moreira-Filho¹,

Neto²,

Oliveira³

et al. 2011

Publ. Biologicas

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The aim of the present study was to characterize chromosomal differences between two populations separated in the past for a water divide. Processes of differentiation have been identifi ed in the species studied, being justifi ed by the separation of streams from past for a water divide. Karyotypic data were presented for Astyanax altiparanae, Geophagus brasiliensis and Gymnotus carapo populations of two different river systems of the upper Parana: ribeirão do Pântano (Tietê basin) and ribeirão do Feijão (Mogi Guaçu basin) in the São Carlos region, state of São Paulo. The Astyanax altiparanae, presented a diploid number of 2n=50 chromosomes. The Geophagus brasiliensis diploid numbers was 2n=48 chromosomes and Gymnotus carapo a diploid number of 2n=54 chromosomes. An analysis was made of constitutive heterochromatin by C-banding, detection of nucleolar organizer regions and the technique of Hybridization in situ Fluorescent with probes 18S rDNA and 5S rDNA. These results indicate that the species analysed showed differences of karyotype, showing that each population follows its own evolution, as a result of a restrictive process of gene fl ow.

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Cytogenetic characterization of the strongly electric Amazonian eel, Electrophorus electricus (Teleostei, Gymnotiformes), from the Brazilian rivers Amazon and Araguaia

Cited by 10 publications

References 9 publications

Are NORs Always Located on Homeologous Chromosomes? A FISH Investigation with rDNA and Whole Chromosome Probes in Gymnotus Fishes (Gymnotiformes)

Are NORs Always Located on Homeologous Chromosomes? A FISH Investigation with rDNA and Whole Chromosome Probes in Gymnotus Fishes (Gymnotiformes)

X1X1X2X2/X1X2Y sex chromosome systems in the Neotropical Gymnotiformes electric fish of the genus Brachyhypopomus

Comparative Cytogenetic Study Among Three Fish Species: An Analysis From a Water Divide Region

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