title: Closely Related Syntopic Cytotypes of Astyanax taeniatus (Jenyns, 1842) from the Upper Piranga River, Upper Doce Basin in Southeastern Brazil.
abstract: Astyanax taeniatus occurs in coastal areas of southeastern Brazil, and it is very abundant in the Upper Doce River Basin. Our objective was to study C-, argyrophilic nucleolar organizer region (Ag-NOR) and fluorescent in situ hybridization (FISH) banding patterns using 5S, 18S, CA(15), and GA(15) repetitive DNA probes on a population of A. taeniatus present in the Piranga River, in the Doce Basin. Two syntopic cytotypes were found, both with 2n = 50: cytotype A (14m + 12sm + 16st + 8t) and cytotype B (10m + 14sm + 18st + 8t). In both cytotypes, heterochromatic blocks occurred in all the chromosomes; Ag-NOR sites were multiple, ranging from four to eight. The 5S rDNA probe marked eight chromosomes in both cytotypes, a unique condition within Astyanax, suggesting a recent divergence between these cytotypes. The 18S rDNA probe differed between the cytotypes, marking 10 and 8 chromosomes in cytotypes A and B, respectively. CA(15) and GA(15) FISH patterns were mainly subtelomeric, but CA(15) showed centromeric markings that were diagnostic for each cytotype. Although overall cytogenetic evidence suggests that these cytotypes are closely related, morphological and molecular data in progress will provide further hypothesis test on their phylogenetic relationship.
authors.affiliation: Laboratório de Sistemática Molecular-Beagle, Departamento de Biologia Animal, Universidade Federal de Viçosa , Viçosa, Minas Gerais State, Brazil .
authors.forename: Marina Souza da
authors.initials: MS
authors.lastname: Cunha
authors.affiliation: Laboratório de Sistemática Molecular-Beagle, Departamento de Biologia Animal, Universidade Federal de Viçosa , Viçosa, Minas Gerais State, Brazil .
authors.forename: Vinícius José Carvalho
authors.initials: VJ
authors.lastname: Reis
authors.affiliation: Laboratório de Sistemática Molecular-Beagle, Departamento de Biologia Animal, Universidade Federal de Viçosa , Viçosa, Minas Gerais State, Brazil .
authors.forename: Jorge Abdala
authors.initials: JA
authors.lastname: Dergam
mesh_terms: D000818:Animals; D001938:Brazil; D060126:Characidae / Q000235:genetics*; D015342:DNA Probes / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D005260:Female; D017404:In Situ Hybridization, Fluorescence; D059785:Karyotype; D008297:Male; D009697:Nucleolus Organizer Region / Q000235:genetics; D010802:Phylogeny
chemical_list: D015342:DNA Probes; D004275:DNA, Ribosomal