FIGURE 1.

Ers1 is essential for RNAi-dependent silencing and heterochromatin formation in S. pombe. A, reporter gene assays. Serial dilutions of cells of the indicated deletion and reporter genotypes were plated on the indicated media and incubated at 30 °C. B, ChIP analysis of histone methylation. Cells of the indicated genotypes (constructed in an imr1L::ura4⁺ background) were examined for H3 Lys⁹ dimethylation and trimethylation modifications. Samples were normalized for nucleosome density by performing ChIP with antibodies to H3. C, ChIP analysis of RITS recruitment. ChIP was performed using anti-hemagglutinin (HA) antibodies on strains of the indicated genotypes (constructed in an imr1L::ura4⁺ background). Signals were normalized to the untagged reporter strain. WT, wild-type.