Genetics and Molecular Biology (Jan 2013)

Cytogenetic comparison of Podocnemis expansa and Podocnemis unifilis: a case of inversion and duplication involving constitutive heterochromatin

  • Ricardo José Gunski,
  • Isabel Souza Cunha,
  • Tiago Marafiga Degrandi,
  • Mario Ledesma,
  • Analía Del Valle Garnero

Journal volume & issue
Vol. 36, no. 3
pp. 353 – 356

Abstract

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Podocnemis expansa and P. unifilis present 2n = 28 chromosomes, a diploid number similar to those observed in other species of the genus. The aim of this study was to characterize these two species using conventional staining and differential CBG-, GTG and Ag-NOR banding. We analyzed specimens of P. expansa and P. unifilis from the state of Tocantins (Brazil), in which we found a 2n = 28 and karyotypes differing in the morphology of the 13th pair, which was submetacentric in P. expansa and telocentric in P. unifilis. The CBG-banding patterns revealed a heterochromatic block in the short arm of pair 13 of P. expansa and an interstitial one in pair 13 of P. unifilis, suggesting a pericentric inversion. Pair 14 of P. unifilis showed an insterstitial band in the long arm that was absent in P. expansa, suggesting a duplication in this region. Ag-NORs were observed in the first chromosome pair of both species and was associated to a secondary constriction and heterochromatic blocks.

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