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Chromosome Research

, Volume 6, Issue 5, pp 345–350 | Cite as

Multiple Locations of the rDNA Sites in Holocentric Chromosomes of Rhynchospora (Cyperaceae)

  • André L. l. Vanzela
  • Angeles Cuadrado
  • Nicolás Jouve
  • Modesto Luceño
  • Marcelo Guerra
Article

Abstract

Several cytogenetic studies have shown that representatives of the family Cyperaceae have holocentric chromosomes. Despite their interesting chromosome morphology, the chromosome organization has not been studied. This paper reports on the number and distribution of 18S–5.8S–26S ribosomal RNA sites by fluorescence in situ hybridization in eight Brazilian species of Rhynchospora. The signal of the rDNA probe was always localized in the telomeric regions. A high degree of variation was observed in the number of labelled sites, ranging from 4–8 in karyotypes with 2n = 10 to 30 sites in a karyotype with 50 chromosomes. It is possible that the same mechanism involved in the multiplication of these regions in organisms with monocentric chromosomes also plays a role in the polymorphism observed in holocentric chromosomes of Rhynchospora. An interesting feature of most hybridization sites was their diffuse state observed through to early metaphase. The decondensed state probably reflects the later transcription of this region during the cell cycle.

Cyperaceae holocentric chromosomes in situ hybridization multiple rDNA sites Rhynchospora 

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Copyright information

© Kluwer Academic Publishers 1998

Authors and Affiliations

  • André L. l. Vanzela
    • 1
  • Angeles Cuadrado
    • 2
  • Nicolás Jouve
    • 2
  • Modesto Luceño
    • 3
  • Marcelo Guerra
    • 4
  1. 1.Departamento de Botânica, Instituto de BiociênciasUniversidade de São PauloSão PauloBrazil
  2. 2.Departmanto de Biología Celular y GenéticaUniversidade de AlcaláAlcalá de Henares (Madrid)Spain
  3. 3.Real Jardín Botânico, C.S.I.C.MadridSpain
  4. 4.Departamento de Botânica, Centro de Ciências BiológicasUniversidade Federal de Pernambuco, RecifePEBrazil.

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