Inhibition of transcription with 5,6-dichloro-1-beta-D-ribofuranosylbenzimidizole (DRB) stimulates the incorporation of H3K9me2 and H3K9me3 into SV40 chromatin late in infection. Wild-type SV40 minichromosomes were isolated at 2 hr post-infection with or without incubation with 5,6-dichloro-1-beta-D-ribofuranosylbenzimidizole (DRB) from minus 2 hr until isolation and at 48 hr post-infection with or without incubation with DRB from 24 to 48 hr post-infection. The percentages of intact minichromosomes containing methylated H3K4 and H3K9 were determined by ChIP analyses followed by purification of the intact genomic DNA and PCR amplification with primers recognizing the promoter region. For each form of histone modification, the ratio of the percentage present in the treated minichromosomes compared to the untreated minichromosomes was calculated. The effects of DRB treatment on the introduction of methylated H3K4 and H3K9 from minus 2 hr to isolation at 2 hr post-infection is shown in (A). The corresponding effects of DRB treatment on the introduction of methylated H3K4 and H3K9 from 24 to 28 hr post-infection are shown in (B).