A conserved mechanism for post-transcriptional gene silencing?

Proteins with homology to RNA-directed RNA polymerases function in post-transcriptional gene silencing: in quelling in the fungus Neurospora crassa, RNAi in the nematode Caenorhabditis elegans, and co-suppression in the mustard plant Arabidopsis thaliana. These findings are consistent with a conserved mechanism operating in these diverse species.