Analysis of a piwi-related gene implicates small RNAs in genome rearrangement in tetrahymena

Cell. 2002 Sep 20;110(6):689-99. doi: 10.1016/s0092-8674(02)00909-1.


During development of the somatic macronucleus from the germline micronucleus in ciliates, chromosome rearrangements occur in which specific regions of DNA are eliminated and flanking regions are healed, either by religation or construction of telomeres. We identified a gene, TWI1, in Tetrahymena thermophila that is homologous to piwi and is required for DNA elimination. We also found that small RNAs were specifically expressed prior to chromosome rearrangement during conjugation. These RNAs were not observed in TWI1 knockout cells and required PDD1, another gene required for rearrangement, for expression. We propose that these small RNAs function to specify sequences to be eliminated by a mechanism similar to RNA-mediated gene silencing.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Argonaute Proteins
  • Base Sequence
  • Chromosome Breakage
  • DNA, Protozoan / genetics
  • Drosophila Proteins
  • Gene Rearrangement*
  • Genes, Protozoan*
  • Genome, Protozoan
  • Micronucleus, Germline / genetics
  • Micronucleus, Germline / metabolism
  • Models, Biological
  • Molecular Sequence Data
  • Open Reading Frames
  • Phylogeny
  • Proteins / genetics
  • Protozoan Proteins / genetics
  • Protozoan Proteins / physiology*
  • RNA, Protozoan / physiology*
  • RNA, Small Nuclear / physiology*
  • RNA-Induced Silencing Complex
  • Ribosomal Proteins / metabolism
  • Tetrahymena thermophila / genetics*
  • Tetrahymena thermophila / growth & development
  • Transgenes


  • Argonaute Proteins
  • DNA, Protozoan
  • Drosophila Proteins
  • Proteins
  • Protozoan Proteins
  • RNA, Protozoan
  • RNA, Small Nuclear
  • RNA-Induced Silencing Complex
  • Ribosomal Proteins
  • piwi protein, Drosophila
  • ribosomal protein L21

Associated data

  • GENBANK/AB084111