title: Chromosomal Variability Between Populations of Electrophorus electricus Gill, 1864 (Pisces: Gymnotiformes: Gymnotidae).
abstract: The electric eel, Electrophorus electricus, the only species of its genus, has a wide distribution in the Amazon and Orinoco drainages. There is little previous information regarding the population variation in E. electricus, with only basic karyotype data from two populations (Amazon and Araguaia Rivers). Karyotypic description and analysis of CO1 barcode sequences were performed for E. electricus from three localities (Caripetuba, Irituia, and Maicuru Rivers). All samples share the 2n=52 (42 m-sm [meta-submetacentric] +10 st-a [subtelo-acrocentric]) with previously studied material. However, the Maicuru River samples differ from the other populations, as they have B chromosomes. The distribution of noncentromeric constitutive heterochromatin between samples is relatively divergent. All samples analyzed present the Nucleolar Organizer Region (NOR) located in a single chromosome pair. In the samples from Caripetuba, NORs were colocalized with a heterochromatin block, whereas the NOR was flanked by heterochromatin in Maicuru River samples and pericentromeric heterochromatin adjacent NOR was found in Irituia River samples. Alignment of CO1 barcode sequences indicated no significant differentiation between the samples analyzed. Results suggest that karyotypic differences between samples from the Caripetuba, Irituia, and Amazon Rivers represent chromosome polymorphisms. However, differences between the samples from the Maicuru and Araguaia Rivers and the remaining populations could represent interpopulation differentiation, which has not had time to accrue divergence at the CO1 gene level.
authors.affiliation: 1 Laboratório de Citogenética, Instituto de Ciências Biológicas, Universidade Federal do Pará-Campus do Guamá , Belém, Pará, Brazil .
authors.forename: Adauto Lima
authors.initials: AL
authors.lastname: Cardoso
authors.affiliation: 1 Laboratório de Citogenética, Instituto de Ciências Biológicas, Universidade Federal do Pará-Campus do Guamá , Belém, Pará, Brazil .
authors.forename: Jonathan Stuart
authors.initials: JS
authors.lastname: Ready
authors.affiliation: 1 Laboratório de Citogenética, Instituto de Ciências Biológicas, Universidade Federal do Pará-Campus do Guamá , Belém, Pará, Brazil .|2 Conselho Nacional de Desenvolvimento Científico e Tecnológico-CNPq, Lago Sul, Brasília, DF, Brazil .
authors.forename: Julio Cesar
authors.initials: JC
authors.lastname: Pieczarka
authors.affiliation: 1 Laboratório de Citogenética, Instituto de Ciências Biológicas, Universidade Federal do Pará-Campus do Guamá , Belém, Pará, Brazil .
authors.forename: Susana Suely Rodrigues
authors.initials: SS
authors.lastname: Milhomem
authors.affiliation: 1 Laboratório de Citogenética, Instituto de Ciências Biológicas, Universidade Federal do Pará-Campus do Guamá , Belém, Pará, Brazil .
authors.forename: Wilsea Maria Batista
authors.initials: WM
authors.lastname: de Figueiredo-Ready
authors.affiliation: 1 Laboratório de Citogenética, Instituto de Ciências Biológicas, Universidade Federal do Pará-Campus do Guamá , Belém, Pará, Brazil .
authors.forename: Fernando Henrique Ramos
authors.initials: FH
authors.lastname: Silva
authors.affiliation: 1 Laboratório de Citogenética, Instituto de Ciências Biológicas, Universidade Federal do Pará-Campus do Guamá , Belém, Pará, Brazil .|2 Conselho Nacional de Desenvolvimento Científico e Tecnológico-CNPq, Lago Sul, Brasília, DF, Brazil .
authors.forename: Cleusa Yoshiko
authors.initials: CY
authors.lastname: Nagamachi
mesh_terms: D063147:Animal Distribution; D000818:Animals; D001938:Brazil; D058893:DNA Barcoding, Taxonomic; D003576:Electron Transport Complex IV / Q000235:genetics / Q000378:metabolism; D004593:Electrophorus / Q000235:genetics* / Q000502:physiology; D014644:Genetic Variation; D059785:Karyotype; D009697:Nucleolus Organizer Region
chemical_list: D003576:Electron Transport Complex IV