Fig. 3. Histone H3 lysine 9 methylation in male germ cells. Methanol/acetone fixed gonads from N2 (A-C) and PD7271 transgenic males (D) were stained with -H3 methyl-K9 alone (green) and counter stained with DAPI (red; A,B), or stained with both -H3 methyl-K9 (red) and -phosphoacetyl H3 (green; C,D). The curved arrow in A shows the direction of meiotic progression. Arrows in B-D indicate a chromosome enriched in H3 modified by methyl-K9 (green in B, red in C), and under-modified by the phosphoacetyl epitope (green in C). Arrowheads in D indicate inactive transgenes. Scale bars: 5 µm.