Testing for the linearity of ChIP efficiency with antibodies against histone H3. ChIP was done on 2 × 107 cells of Chlamydomonas strain CRR16 crosslinked with 0.35% formaldehyde. Cells were not subjected to stress. Chromatin was sonicated to fragments of ~200-bp and immunoprecipitated with affinity-purified antibodies against VIPP2 (mock) or with the indicated volumes of a suspension containing antibodies against histone H3. Precipitated DNA was amplified by qPCR using primers targeting promoters RBCS2, HSP70A, and CYC6. Shown are standard errors from 3 technical replicates. Values are normalized against those obtained with 10% input DNA.