Genetica

, Volume 136, Issue 1, pp 135–139

Astyanax bockmanni Vari and Castro, 2007: an ambiguous karyotype in the Astyanax genus

  • Karine Frehner Kavalco
  • Rubens Pazza
  • Lurdes Foresti de Almeida-Toledo
Article

DOI: 10.1007/s10709-008-9325-z

Cite this article as:
Kavalco, K.F., Pazza, R. & de Almeida-Toledo, L.F. Genetica (2009) 136: 135. doi:10.1007/s10709-008-9325-z

Abstract

Despite the widespread distribution of Astyanax bockmanni in streams from Upper Paraná River system in central, southeastern, and southern Brazil, just recently, it has been identified as a distinct Astyanax species. Cytogenetic studies were performed in two populations of this species, revealing conservative features. A. bockmanni shows 2n = 50 chromosomes, a karyotypic formula composed of 10 M + 12SM + 12ST + 16A and multiple Ag-NORs. Eight positive signals in subtelocentric/acrocentric chromosomes were identified by fluorescent in situ hybridization (FISH) with 18S rDNA probes. After FISH with 5S rDNA probes, four sites were detected, comprising the interstitial region of a metacentric pair and the terminal region on long arms of another metracentric pair. Little amounts of constitutive heterochromatin were observed, mainly distributed at distal region in two chromosomal pairs. Additionally, heterochromatin was also located close to the centromeres in some chromosomes. No positive signals were detected in the chromosomes of A. bockmanni by FISH with the As-51 satellite DNA probe. The studied species combines a set of characteristics previously identified in two different Astyanax groups. The chromosomal evolution in the genus Astyanax is discussed.

Keywords

Astyanax bockmanniMolecular cytogeneticsFISHKaryotypical evolution

Copyright information

© Springer Science+Business Media B.V. 2008

Authors and Affiliations

  • Karine Frehner Kavalco
    • 1
  • Rubens Pazza
    • 2
  • Lurdes Foresti de Almeida-Toledo
    • 1
  1. 1.Departamento de Genética e Biologia Evolutiva, Instituto de BiociênciasUniversidade de São PauloSão PauloBrazil
  2. 2.Campus Rio ParanaíbaUniversidade Federal de ViçosaRio ParanaíbaBrazil