Yeast Joins RNAi Club RNA interference (RNAi) silences gene expression via small interfering (si) RNAs that bind to target sequences. RNAi has been found in almost all eukaryotes examined, with the notable exception of the budding yeast, Saccharomyces cerevisiae , one of the most prominent organisms used in the study of molecular biology. Indeed, RNAi has been thought to be missing from all budding yeast. Drinnenberg et al. (p. 544 , published online 10 September; see the Perspective by Moazed ) now show that several species of budding yeast do possess RNAi, which seems to act primarily on transposable elements and subtelomeric repeats. A noncanonical Dicer protein generates siRNAs that are loaded onto Ago1 protein in S. castellii . Introduction of these two genes into S. cerevisiae was sufficient to reconstitute RNAi, where it also acted to dampen the activity of transposons.