MES-4 is unable to provide detectable de novo H3K36 methylation. The maternal effect sterile (MES)-4 protein is expressed zygotically in the primordial germ cells (PGCs) of (A,B) embryos or (C,D) L1 larvae could not provide detectable H3K36me3 to animals that did not inherit maternal chromatin with H3K36me3. H3K36me3 was detectable in (A) mes-4 M-Z+;met-1 M-Z+ larval PGCs, but not in (B) mes-4 M-Z+;met-1 M-Z- PGCs. Similarly H3K36me3 was observed in (C), mes-4 M-Z+;met-1 M-Z+ ~500 cell embryo PGCs but not in (D) mes-4 M-Z+;met-1 M-Z- PGCs. MES-4 indicates anti-MES-4 antibody staining. Arrows mark PGCs. Scale bars: 3 μm.