title: Evolutionary trends in the family Curimatidae (Characiformes): inferences from chromosome banding.
abstract: The family Curimatidae is a fish group usually considered chromosomally conserved in their diploid number. However, some studies show small changes in the karyotype microstructure, and the presence of B chromosomes, indicating a chromosomal diversification within the group, even if structural changes in the karyotypes are not visible. Few studies associate this trait with an evolutionary pattern within the family. This study aimed to characterize the karyotype, nucleolus organizer regions (NORs), and heterochromatin distribution of six species of Curimatidae of the genera Cyphocharax Fowler, 1906 and Steindachnerina Fowler, 1906: Cyphocharax voga (Hensel, 1870), Cyphocharax spilotus (Vari, 1987), Cyphocharax saladensis (Meinken, 1933), Cyphocharax modestus (Fernández-Yépez, 1948), Steindachnerina biornata (Braga et Azpelicueta, 1987) and Steindachnerina insculpta (Fernández-Yépez, 1948) and contribute data to a better understanding of the mechanisms involved in the chromosomal evolution of this group of fish. All specimens had 2n=54, m-sm, and B microchromosomes. Five species exhibited single NORs, except for Steindachnerina biornata, which showed a multiple pattern of ribosomal sites. NORs were chromomycin A3 positive (CMA3 (+)) and 4'-6-diamino-2-phenylindole (DAPI(-)) negative, exhibiting differences in the pair and chromosomal location of each individual of the species. FISH with 5S rDNA probe revealed sites in the pericentrometic position of a pair of chromosomes of five species. However, another site was detected on a metacentric chromosome of Cyphocharax spilotus. Heterochromatin distributed both in the pericentromeric and some terminal regions was revealed to be CMA3 (+)/DAPI(-). These data associated with the previously existing ones confirm that, although Curimatidae have a very conservative karyotype macrostructure, NORs and heterochromatin variability are caused by mechanisms of chromosome alterations, such as translocations and/or inversions, leading to the evolution and diversification of this group of fish.
authors.affiliation: Departamento de Biologia Geral, CCB, Universidade Estadual de Londrina, P.O Box 6001, Londrina, Paraná CEP 86051-970, Brazil.
authors.forename: Tatiane Ramos
authors.initials: TR
authors.lastname: Sampaio
authors.affiliation: Departamento de Biologia Geral, CCB, Universidade Estadual de Londrina, P.O Box 6001, Londrina, Paraná CEP 86051-970, Brazil.
authors.forename: Larissa Bettin
authors.initials: LB
authors.lastname: Pires
authors.affiliation: Departamento de Biologia Geral, CCB, Universidade Estadual de Londrina, P.O Box 6001, Londrina, Paraná CEP 86051-970, Brazil.
authors.forename: Natália Bortolazzi
authors.initials: NB
authors.lastname: Venturelli
authors.affiliation: Departamento de Biologia Geral, CCB, Universidade Estadual de Londrina, P.O Box 6001, Londrina, Paraná CEP 86051-970, Brazil.
authors.forename: Mariana Campaner
authors.initials: MC
authors.lastname: Usso
authors.affiliation: Departamento de Biologia Geral, CCB, Universidade Estadual de Londrina, P.O Box 6001, Londrina, Paraná CEP 86051-970, Brazil.
authors.forename: Renata
authors.initials: R
authors.lastname: da Rosa
authors.affiliation: Departamento de Biologia Geral, CCB, Universidade Estadual de Londrina, P.O Box 6001, Londrina, Paraná CEP 86051-970, Brazil.
authors.forename: Ana Lúcia
authors.initials: AL
authors.lastname: Dias
keywords: Fluorochromes; heterochromatin; karyotype evolution; pisces; rDNA