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Author Notes:

Correspondence: emmaine@syr.edu (E.M.M.); william.kelly@emory.edu (W.G.K.)

We thank C. David Allis, Jun Kelly Liu, and Henry Epstein for antibodies, Tim Schedl and Rodolfo Aramayo for discussion, Katherine Walstrom, Rob Martienssen, John Belote, and anonymous reviewers for comments on the manuscript, Claudia Zraly and Larry Smart for advice on methods, and Meera Sundaram, Shohei Mitani, and Geraldine Seydoux for strains.


Research Funding:

Some strains used in this study were provided by the Caenorhabditis Genetics Center, which is funded by the National Institutes of Health National Center for Research Resources.

Funds for this study were provided by the National Science Foundation and Syracuse University (to E.M.M.) and the National Institutes of Health and Emory University Research Council (to W.G.K.).


  • Animals
  • Caenorhabditis elegans
  • Caenorhabditis elegans Proteins
  • Cell Cycle Proteins
  • DNA
  • Fluorescent Antibody Technique, Indirect
  • Gene Silencing
  • Heterochromatin
  • Histone Methyltransferases
  • Histone-Lysine N-Methyltransferase
  • Meiosis
  • Methylation
  • Models, Molecular
  • Mutation
  • Protein Methyltransferases
  • RNA Replicase

EGO-1, a putative RNA-dependent RNA polymerase, is required for heterochromatin assembly on unpaired DNA during C. elegans meiosis


Journal Title:

Current Biology


Volume 15, Number 21


, Pages 1972-1978

Type of Work:

Article | Post-print: After Peer Review


During meiosis in C. elegans, unpaired chromosomes and chromosomal regions accumulate high levels of histone H3 lysine 9 dimethylation (H3K9me2), a modification associated with facultative heterochromatin assembly and the resulting transcriptional silencing [1, 2]. Meiotic silencing of unpaired DNA may be a widely conserved genome defense mechanism [3-5]. The mechanisms of meiotic silencing remain unclear, although both transcriptional and posttranscriptional processes are implicated [3-5]. Cellular RNA-dependent RNA polymerases (RdRPs) function in development and RNA-mediated silencing in many species [3, 6, 7] and in heterochromatin assembly in S. pombe [3, 8]. There are four C. elegans RdRPs, including two with known germline functions. EGO-1 is required for fertility and robust germline RNAi [9-11]. RRF-3 acts genetically to repress RNAi and is required for normal meiosis and spermatogenesis at elevated temperatures [12] (S. L'Hernault, personal communication). Among C. elegans RdRPs, we find that only EGO-1 is required for H3K9me2 enrichment on unpaired chromosomal regions during meiosis. This H3K9me2 enrichment does not require Dicer or Drosha nuclease or any of several other proteins required for RNAi. ego-1 interacts genetically with him-17, another regulator of chromatin and meiosis [13], to promote germline development. We conclude that EGO-1 is an essential component of meiotic silencing in C. elegans.

Copyright information:

©2005 Elsevier Ltd All rights reserved.

This is an Open Access work distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (http://creativecommons.org/licenses/by-nc-nd/4.0/).

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