Clr-C Required for Heterochromatin Establishment Figure 1. Clr-C component rik1+ is required for establishment of repressive chromatin at the centromere. A. Cartoon representing the dg and dh repeat structure within the outer repetitive sequences (otr) at centromere 1. In the cen::ura4+ strain, the ura4+ marker gene is located within dg. A and B represent PCR fragments for real-time PCR analyses from dh and dg respectively, and probes used for siRNA detection are also PLoS Genetics | www.plosgenetics.org 4 October 2010 | Volume 6 | Issue 10 | e1001174