Differential Localization and Independent Acquisition of the H3K9me2 and H3K9me3 Chromatin Modifications in the Caenorhabditis elegans Adult Germ Line
Figure 4
Distinct properties of H3K9me2 and H3K9me3-enriched domains.
(A) axIs36 male pachytene nuclei co-stained with anti-H3K9me2, anti-H3K9me3 and DAPI. H3K9me2 remains restricted to the X chromosome, while H3K9me3 is restricted to axIs36. (B) him-8; axIs36 hermaphrodite pachytene nuclei co-stained with anti-H3K9me2, anti-H3K9me3 and DAPI. Top: a nucleus where both X chromosomes carrying axIs36 stain for H3K9me2 and H3K9me3. 11 of 20 nuclei examined showed two distinct H3K9me2 signals and two distinct H3K9me3 signals. Bottom: a nucleus where one X chromosome carrying axIs36 is stained only for H3K9me3 and the other X chromosome is stained for both H3K9me2 and H3K9me3. 5 of 20 nuclei examined showed two distinct H3K9me3 signals but only one H3K9me2 signal (see text for additional information). In both (A,B), H3K9me3 staining also corresponds to the presence of a DAPI-faint region. (C) axIs36 male nucleus stained only with anti-H3K9me2 and DAPI. A gap in the H3K9me2 staining indicates the position of the axIs36 transgene array inserted into the X chromosome and also corresponds to a region of reduced DAPI intensity, demonstrating that a DAPI-faint region corresponding to axIs36 is still observed in experiments that do not include anti-H3K9me3 antibody. (D) axIs36 male nucleus co-stained with anti-H3K9me2, anti-H3K9me3 and Höechst dye #33258. These data indicate that faint chromatin staining coincident with axIs36 can be seen using Höechst as well as DAPI. (E) mIs10 hermaphrodite nucleus co-stained for anti-H3K9me2, anti-H3K9me3 and DAPI. A DAPI-faint domain corresponds to the presence of the mIs10 high-copy array. Green = H3K9me2, Red = H3K9me3, Blue = DAPI or Höechst. Scale bar = 5 µm.