Cytogenetic characterization through chromosomic banding of Pinirampus pirinampu (Pisces, Pimelodidae) from the Tibagi river basin PR/Brazil

Specimens of Pinirampus pirinampu were analyzed cytogenetically. Fifteen individuals were obtained from the Tibagi river near Sertaneja, PR, Brazil. A karyotypic structure consisting of 50 chromosomes distributed as 26M+12SM+2ST+10A was observed. The nucleolar organizing regions ( NORs) were identified on the short arm of a pair of subtelocentric chromosomes. A variation in size of the NOR regions was observed among the paired chromosomes. Chromomycin (CMA 3) staining established not only the nucleolar chromosome pair, but also fluorescent marking in the telomeric and centromeric regions of other chromosomes which seem to correspond to the distribution patterns of the constitutive heterochromatin. Restriction enzyme Alu I was employed and the reaction pattern obtained also corresponded to the heterochromatin constitutive distribution.