title: An uncommon co-localization of rDNA 5S with major rDNA clusters in Callichthyidae (Siluriformes): a report case inCorydoras carlaeNijssen & Isbrücker, 1983.
abstract: CorydorasLacepède, 1803 is the most specious genus of Corydoradinae subfamily and many of its species are still unknown in relation to molecular cytogenetic markers. However, the diploid number and karyotypic formula were recorded for many species of this group. In current study, we provided the first cytogenetic information ofCorydoras carlaeNijssen & Isbrücker, 1983, an endemic fish species from Iguassu River basin, Paraná State, Brazil. The individuals were collected in Florido River, a tributary of Iguassu River and analysed with respect to diploid number, heterochromatin distribution pattern, Ag-NORs and mapping of 5S and 18S ribosomal genes. The karyotype of this species comprises 46 chromosomes arranged in 22m+22sm+2st. The heterochromatin is distributed in centromeric and pericentromeric positions in most of the chromosomes, and also associated with NORs. The Ag-NORs were detected in the terminal position on the long arm of the metacentric pair 6. The double-FISH technique showed that 5S rDNA and 18S rDNA were co-localized in the terminal portion on the long arm of the metacentric pair 6. This condition of co-localization of ribosomal genes inCorydoras carlaeseems to represent a marker for this species.
authors.affiliation: Universidade Estadual do Oeste do Paraná, Centro de Engenharias e Ciências Exatas, 85903-000 Toledo, Paraná, Brazil.
authors.forename: Rafael Henrique
authors.initials: RH
authors.lastname: da Rocha
authors.affiliation: Universidade Estadual do Oeste do Paraná, Centro de Ciências Biológicas e da Saúde, 85819-110 Cascavel, Paraná, Brazil.
authors.forename: Lucas
authors.initials: L
authors.lastname: Baumgärtner
authors.affiliation: Universidade Estadual do Oeste do Paraná, Centro de Ciências Biológicas e da Saúde, 85819-110 Cascavel, Paraná, Brazil; Universidade Estadual de Maringá, Centro de Ciências Biológicas, 87020-900 Maringá, Paraná, Brazil.
authors.forename: Leonardo Marcel
authors.initials: LM
authors.lastname: Paiz
authors.affiliation: Universidade Estadual do Oeste do Paraná, Centro de Ciências Biológicas e da Saúde, 85819-110 Cascavel, Paraná, Brazil; Universidade Estadual de Maringá, Centro de Ciências Biológicas, 87020-900 Maringá, Paraná, Brazil.
authors.forename: Vladimir Pavan
authors.initials: VP
authors.lastname: Margarido
authors.affiliation: Universidade Estadual de Mato Grosso do Sul, Unidade Universitária de Mundo Novo, 79980-000 Mundo Novo, Mato Grosso do Sul, Brazil.
authors.forename: Carlos Alexandre
authors.initials: CA
authors.lastname: Fernandes
authors.affiliation: Universidade Estadual do Oeste do Paraná, Centro de Engenharias e Ciências Exatas, 85903-000 Toledo, Paraná, Brazil.
authors.forename: Éder André
authors.initials: ÉA
authors.lastname: Gubiani
keywords: Ag-NORs; cytogenetic markers; heterochromatin; karyotype; ribosomal DNA