H3K9 methylation is enriched on chromosome arms, especially the arms with the pairing center. (A, red lines) Meiotic pairing center motif coordinates, obtained from a motif scan analysis (Phillips et al. 2009). On autosomes, >90% of these motifs lie within the pairing center regions, as do ∼65% of those on the X chromosome. (Below, black lines) Regions enriched in H3K9 methylation. (B) Average H3K9me1/2/3 signals around all pairing center motifs are shown in early embryo (EE) and L3 larvae (L3). (C) Approximate coordinates of chromosome arms and central regions as determined from enrichment of H3K9 methylation. The boundaries between chromosome arms and centers were determined by visual inspection, as the approximate midpoint of the transition region from high to low H3K9me enrichment (Supplemental Fig. S4).
