Strikingly, analysis of the previously uncharacterized H3.3 homologs revealed that
his-70 and
his-74 show germ line-restricted expression patterns. His-74 expression is restricted to the germ line at all stages of development in both males and hermaphrodites. HIS-74::GFP is only faintly visible in early embryos, and robustly reappears in the primordial germ cells (PGCs; the germ line precursor cells that will give rise to the entire germ line of the worm) and faintly in some cells surrounding the PGCs.