title: Chromosomal diversity in three species of electric fish (Apteronotidae, Gymnotiformes) from the Amazon Basin.
abstract: Cytogenetic studies were carried out on samples of Parapteronotus hasemani, Sternarchogiton preto and Sternarchorhamphus muelleri (Apteronotidae, Gymnotiformes) from the Amazon basin. The first two species exhibited both a 2n = 52 karyotype, but differed in their karyotypic formulae, distribution of constitutive heterochromatin, and chromosomal location of the NOR. The third species, Sternarchorhamphus muelleri, was found to have a 2n = 32 karyotype. In all three species the DAPI and chromomycin A3 staining results were consistent with the C-banding results and nucleolar organizer region (NOR) localization. The 18S rDNA probe confirmed that there was only one pair of ribosomal DNA cistron bearers per species. The telomeric probe did not reveal interstitial telomeric sequences (ITS). The karyotypic differences among these species can be used for taxonomic identification. These data will be useful in future studies of these fishes and help understanding the phylogenetic relationships and chromosomal evolution of the Apteronotidae.
authors.affiliation: Instituto de Ciências Biológicas , Universidade Federal do Pará , Belém, PA , Brazil .
authors.forename: Fernando Henrique Ramos
authors.initials: FH
authors.lastname: Silva
authors.affiliation: Instituto de Ciências Biológicas , Universidade Federal do Pará , Belém, PA , Brazil .
authors.forename: Julio Cesar
authors.initials: JC
authors.lastname: Pieczarka
authors.affiliation: Instituto de Ciências Biológicas , Universidade Federal do Pará , Belém, PA , Brazil .
authors.forename: Adauto Lima
authors.initials: AL
authors.lastname: Cardoso
authors.affiliation: Instituto de Ciências Biológicas , Universidade Federal do Pará , Belém, PA , Brazil .
authors.forename: Patrícia Corrêa
authors.initials: PC
authors.lastname: da Silva
authors.affiliation: Instituto de Desenvolvimento Sustentável Mamirauá , Tefé, AM , Brazil .
authors.forename: Jonas Alves
authors.initials: JA
authors.lastname: de Oliveira
authors.affiliation: Instituto de Ciências Biológicas , Universidade Federal do Pará , Belém, PA , Brazil .
authors.forename: Cleusa Yoshiko
authors.initials: CY
authors.lastname: Nagamachi
keywords: FISH; biodiversity; chromosomal rearrangements; fluorochromes