RNA interference (RNAi) is important in directing heterochromatin assembly at centromeres in fission yeast, which is crucial for maintaining a stable genome through mitotic and meiotic divisions. In this issue, Buker et al. describe a new Argonaute siRNA chaperone (ARC) that converts duplex RNA to single-stranded RNA. This is a previously unknown step in the RNAi-directed heterochromatin-formation pathway.
