Dynamics of telomere length variation in Tetrahymena thermophila

Cell. 1987 Jul 31;50(3):477-83. doi: 10.1016/0092-8674(87)90501-0.


We have analyzed the mechanism and dynamics of telomere length variation in the macronucleus of Tetrahymena thermophila. In a newly differentiated macronucleus, the average length of the telomeric repeated sequence, (C4A2 X T2G4)n, is closely regulated. In contrast, in vegetatively dividing cells in log phase, all macronuclear telomeric sequences lengthen coordinately by 3-10 bp per generation until up to 1000 bp are added. In both elongated and short telomeres, characteristic single-stranded breaks on both strands are distally located. Reduction of elongated telomeres to their original length involves either the appearance of a novel type of variant cell, incapable of net telomere elongation, or, under stationary phase conditions, a reversible removal of telomeric sequences. The demonstration that telomeres are dynamic structures provides evidence for a model of telomere length regulation by activities that add and remove telomeric repeats.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Base Sequence
  • Chromosomes*
  • DNA Replication
  • DNA, Ribosomal / metabolism
  • Genetic Variation
  • Models, Genetic
  • Tetrahymena / genetics*


  • DNA, Ribosomal