Chromosoma

, Volume 111, Issue 1, pp 45–52

Molecular and cytogenetic analysis of the telomeric (TTAGGG)n repetitive sequences in the Nile tilapia, Oreochromis niloticus (Teleostei: Cichlidae)

  • Joyce S. Chew
  • Claudio Oliveira
  • Jonathan M. Wright
  • Melanie J. Dobson
Original Article

Abstract.

The majority of chromosomes in Oreochromis niloticus, as with most fish karyotyped to date, cannot be individually identified owing to their small size. As a first step in establishing a physical map for this important aquaculture species of tilapia we have analyzed the location of the vertebrate telomeric repeat sequence, (TTAGGG)n, in O. niloticus. Southern blot hybridization analysis and a Bal31 sensitivity assay confirm that the vertebrate telomeric repeat is indeed present at O. niloticus chromosomal ends with repeat tracts extending for 4–10 kb on chromosomal ends in erythrocytes. Fluorescent in situ hybridization revealed that (TTAGGG)n is found not only at telomeres, but also at two interstitial loci on chromosome 1. These data support the hypothesis that chromosome 1, which is significantly larger than all the other chromosomes in the karyotype, was produced by the fusion of three chromosomes and explain the overall reduction of chromosomal number from the ancestral teleost karyotype of 2n=48 to 2n=44 observed in tilapia.

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Copyright information

© Springer-Verlag 2002

Authors and Affiliations

  • Joyce S. Chew
    • 1
  • Claudio Oliveira
    • 2
  • Jonathan M. Wright
    • 2
  • Melanie J. Dobson
    • 1
  1. 1.Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada B3H 4H7
  2. 2.Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada B3H 4J1
  3. 3.Present address: Departamento de Morfologia, Instituto de Biociências, UNESP, Botucatu, São Paulo, Brazil

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