Figure 5.

Induction of H4 hyperacetylation without promoter activation. A, Schematic overview of the experimental design. Seedlings were grown in a diurnal rhythm of 16-h light and 8-h darkness for 10 to 12 d and the last dark period was extended to 56 h ([1]). The leaves were detached in the dark and incubated in tap water ([3]) or Zeatin/KNO₃ ([4]) for a further 15 h. After this, one-half of the leaves were additionally illuminated for 8 h ([5] and [6]). Positive control plants were kept in the dark for 71 h and illuminated for 8 h ([2]). B, C₄-PEPC hnRNA synthesis. hnRNA was amplified from cDNA with a primer system specific for an intron (C3). A dilution series of PCR products of known concentrations was used as a standard. C, Histone H4 hyperacetylation at the C₄-PEPC promoter position P2. Values were normalized for the amount of input. Input is the amount of chromatin subjected to immunoprecipitation (see also “Materials and Methods”). All values were further normalized for the amount of hnRNA or precipitated chromatin, respectively, in the positive control ([2]). Each data point is based on four independent experiments. Vertical lines indicate ses.