Diurnal transcription after HDAC inhibition. (A) Quantification of phosphoenolpyruvate carboxylase (Pepc) heterogeneous nuclear RNA after treatment with the histone deacetylase inhibitor Trichostatin A. Numbers are values relative to leaves from plants 4 h after illumination. (B) H4K5 acetylation at an upstream (-1300 bp) and a core (-200 bp) promoter position of Pepc. Black columns = leaves from plants 4 h after illumination; light grey columns = leaves from plants 16 h after illumination. Data points are based on four independent experiments. Vertical lines indicate standard errors.