title: Karyoevolutionary Inferences in Enigmatic Taxon Astyanax (Teleostei: Characidae).
abstract: Accessing the taxonomy of fish is a basic condition for the conservation of species, and the understanding of their evolutionary relationships. Many Neotropical species of fishes of the order Characiformes are considered incertae sedis because of a lack of consistent evidence of monophyly, with the genus Astyanax among them. With a cytotaxonomic and evolutionary purpose, we compared the karyotype of two species of Astyanax: Astyanax paranae and Astyanax elachylepis. Conventional cytogenetic analyses revealed 2n = 50 chromosomes for the two species, with interspecific and interpopulation karyotype variations. Heterochromatin was primarily localized in the pericentromeric regions, and it was associated with organized regions of the nucleolus (NORs) and/or telomeric regions in some acrocentric chromosomes. The in situ localization of 18S ribosomal DNA (rDNA) and 5S probes varied among A. paranae populations. In A. elachylepis, only one chromosome pair was stained by the 18S probe and another by the 5S probe, confirming a simple NORs pattern. These results support the utility of chromosome markers in Astyanax taxonomy and reveal the conserved characteristics of the karyotype of A. elachylepis, consisting exclusively of two chromosome arms, and the occurrence of simple homologous and non-syntenic sites for 18S and 5S rDNA in this species.
authors.affiliation: 1 Centro Universitário do Triângulo , Campus UNITRI, Uberlândia, Brazil .|2 Instituto de Genética e Bioquímica, Universidade Federal de Uberlândia , Uberlândia, Brazil .
authors.forename: Luana Pereira
authors.initials: LP
authors.lastname: Dos Santos
authors.affiliation: 2 Instituto de Genética e Bioquímica, Universidade Federal de Uberlândia , Uberlândia, Brazil .
authors.forename: Carine Mendonça
authors.initials: CM
authors.lastname: Francisco
authors.affiliation: 3 Programa de Pós-Graduação em Genética Evolutiva e Biologia Molecular, Universidade Federal de São Carlos , São Carlos, Brazil .
authors.forename: Jonathan Pena
authors.initials: JP
authors.lastname: Castro
authors.affiliation: 3 Programa de Pós-Graduação em Genética Evolutiva e Biologia Molecular, Universidade Federal de São Carlos , São Carlos, Brazil .
authors.forename: Patrícia
authors.initials: P
authors.lastname: Barbosa
authors.affiliation: 2 Instituto de Genética e Bioquímica, Universidade Federal de Uberlândia , Uberlândia, Brazil .
authors.forename: Sandra
authors.initials: S
authors.lastname: Morelli
authors.affiliation: 4 Departamento de Biologia Estrutural, Molecular e Genética, Programa de Pós-Graduação em Biologia Evolutiva, Universidade Estadual de Ponta Grossa , Ponta Grossa, Brazil .
authors.forename: Luiz Antonio
authors.initials: LA
authors.lastname: de Oliveira
authors.affiliation: 3 Programa de Pós-Graduação em Genética Evolutiva e Biologia Molecular, Universidade Federal de São Carlos , São Carlos, Brazil .|4 Departamento de Biologia Estrutural, Molecular e Genética, Programa de Pós-Graduação em Biologia Evolutiva, Universidade Estadual de Ponta Grossa , Ponta Grossa, Brazil .
authors.forename: Roberto Ferreira
authors.initials: RF
authors.lastname: Artoni
mesh_terms: D000818:Animals; D005075:Biological Evolution; D001938:Brazil; D060126:Characidae / Q000145:classification / Q000235:genetics*; D005819:Genetic Markers; D059785:Karyotype; D012337:RNA, Ribosomal, 18S / Q000235:genetics*; D012341:RNA, Ribosomal, 5S / Q000235:genetics*
chemical_list: D005819:Genetic Markers; D012337:RNA, Ribosomal, 18S; D012341:RNA, Ribosomal, 5S
keywords: chromosome; fish; karyotype; ribosomal DNA; taxonomy