Research Article

Cytogenetic characterization of species of the family Heptapteridae (Teleostei: Siluriformes) from the Cuiabá and Ivaí River Basins, Brazil

Published: July 31, 2015
Genet. Mol. Res. 14 (3) : 8640-8649 DOI: 10.4238/2015.July.31.12

Abstract

We cytogenetically characterized three species of Hep­tapteridae (Pimelodella sp, Pimelodella taenioptera, and Imparfinis schubarti) by investigating the distribution of constitutive heterochro­matin and nucleolar organizer regions by silver nitrate impregnation (Ag-NOR) and fluorescence in situ hybridization. Pimelodella sp showed had a diploid number (2n) = 46 chromosomes, 26m + 10sm + 10st, and FN = 92; P. taenioptera, 2n = 52 chromosomes, 26m + 22sm + 4st, and FN = 104; and I. schubarti, 2n = 58 chromosomes, 28m + 28sm + 2st, and FN = 116. The two Pimelodella species had Ag-NORs sites on the submetacentric pair 14, located on the short arm in terminal position. In I. schubarti, the Ag-NORs sites were in an interstitial posi­tion on the long arm of the metacentric pair 1. C-banding revealed that Pimelodella sp contained a small amount of constitutive heterochroma­tin, whereas P. taenioptera contained a higher number of heterochro­matic regions, in the pericentromeric, interstitial, and telomeric posi­tions. I. schubarti had markers in centromeric and telomeric regions of a few chromosomes, and a large pericentromeric block on pair 1. Fluo­rochrome chromomycin A3 (CMA3) staining revealed positive signals on pair 14 in both Pimelodella species. Treatment with 4ꞌ,6-diamidino- 2-phenylindole (DAPI) revealed no markings in P. taenioptera, but an interstitial marking on the long arm of pair 14 in Pimelodella sp. In I. schubarti, positive signals of CMA3 were detected in the first pair, but negative signals were detected for DAPI staining. These results con­tribute to the karyotypic description of the less-studied species in the Brazilian Midwest.

We cytogenetically characterized three species of Hep­tapteridae (Pimelodella sp, Pimelodella taenioptera, and Imparfinis schubarti) by investigating the distribution of constitutive heterochro­matin and nucleolar organizer regions by silver nitrate impregnation (Ag-NOR) and fluorescence in situ hybridization. Pimelodella sp showed had a diploid number (2n) = 46 chromosomes, 26m + 10sm + 10st, and FN = 92; P. taenioptera, 2n = 52 chromosomes, 26m + 22sm + 4st, and FN = 104; and I. schubarti, 2n = 58 chromosomes, 28m + 28sm + 2st, and FN = 116. The two Pimelodella species had Ag-NORs sites on the submetacentric pair 14, located on the short arm in terminal position. In I. schubarti, the Ag-NORs sites were in an interstitial posi­tion on the long arm of the metacentric pair 1. C-banding revealed that Pimelodella sp contained a small amount of constitutive heterochroma­tin, whereas P. taenioptera contained a higher number of heterochro­matic regions, in the pericentromeric, interstitial, and telomeric posi­tions. I. schubarti had markers in centromeric and telomeric regions of a few chromosomes, and a large pericentromeric block on pair 1. Fluo­rochrome chromomycin A3 (CMA3) staining revealed positive signals on pair 14 in both Pimelodella species. Treatment with 4ꞌ,6-diamidino- 2-phenylindole (DAPI) revealed no markings in P. taenioptera, but an interstitial marking on the long arm of pair 14 in Pimelodella sp. In I. schubarti, positive signals of CMA3 were detected in the first pair, but negative signals were detected for DAPI staining. These results con­tribute to the karyotypic description of the less-studied species in the Brazilian Midwest.