In a screening for maternal effect lethal mutations on chromosome V of C.elegans, we found three alleles (named
t2070,
t2129 and
t2170) of the same gene showing accumulation of persistent apoptotic corpses in embryos and in the hermaphrodite adult gonad. We cloned the three mutations using three factor mapping followed by SNP mapping. They define three alleles of the gene F58G11.6. Persistent corpses in the gonad of
t2070,
t2129 and
t2170 mutant worms were positively stained with Acridine Orange (AO) indicating that its accumulation is not due to a defect in engulfment. Instead it suggested that, in these mutants, corpses were efficiently engulfed and accumulated within phagosomes as undigested corpses. Electron microscopy further confirmed that these persistent corpses were completely engulfed within the sheath cells. Consistent with this result F58G11.6::YFP localizes in halos around the apoptotic corpse containing phagosomes. The results suggest that F58G11.6 plays a role in phagosome maturation, the process that allows other vesicles, such as lysosomes, to bind and fuse to the phagosome first acidifying and second digesting the apoptotic corpse. Our genetic analysis indicates that F58G11.6 acts at the level of the HOPS complex in the phagosome maduration pathway during the digestion of the apoptotic corpses.