Figure 2

The histone signature of nuclei in the vegetative cell. Nuclear types occurring in vegetative Stylonychia: the transcriptionally active macronucleus (M) consisting of two ovoid distal parts connected by a thin nucleoplasmic bridge, and the transcriptionally inert micronucleus (m). In situ antibody staining of histone H3 modifications (green) and DNA counterstaining (red). The cellular shape was visualized using an α-tubulin-antibody (grey). (A-J) Confocal image stack projections. (K, L) Mid light optical sections. Histone modifications detected in the macronucleus (M) are H3K9ac (A), H3K14ac (B), H3K4me1 (C), H3K4me3 (D), and H3S28p (J). Histone modifications found in the micronucleus of vegetative Stylonychia are H3K36me3 (E), H3K27me3 (I), and H3S28p (J), which is also a prominent micronuclear mitosis (m*) marker (Ja). H3K36ac (F), H3K9me3 (G) as well as H3K27me1 (H) are not detected in nuclei of vegetative cells.