ChIP analysis of control sequences. (a) Location of amplicons used in ChIP-QPCR analysis. The boxed regions indicate part of the coding sequence of maize actin 1 (genbank #J01238) and the reverse transcriptase sequence of the maize copia TY1 type retrotransposon (genbank #AF398212). The amplified sequences are indicated by bars. (b) ChIP-QPCR analysis of the actin 5' untranslated leader (UTR). (c) ChIP-QPCR analysis of the actin exon 2 fragment. (d) ChIP-QPCR analysis of the copia sequence (copia). ChIP-QPCR is performed as described in this paper. Input chromatin was isolated from leaves of 4 weeks old plants (young leaves) and from husks of 3 months old plants (husk leaves). The ChIP results obtained by 4 independent replicate experiments are represented as percentage of input (%IP), the error bars indicate the standard error. The ChIP signals are represented by closed bars, and open bars indicate the signals from the no-antibody control (NoAb).