RAB-35, CED-1, and CED-5 function in parallel to recognize cell corpses.

(A) Diagram outlining how the moments of cell corpse recognition and internalization are determined utilizing the CED-1ΔC::GFP reporter. The moment of recognition is defined as the first time point GFP is seen enriched in a region in contact between the engulfing and dying cell, with the moment of ventral enclosure used as a reference point (“0 min”). The time span between the moment of recognition and the moment when the nascent phagosome forms is the period of internalization. (B) Images of part of a 1.5-fold stage embryo expressing Pced-1ced-1ΔC::gfp. Cell corpses are identified under DIC optics. Red arrows mark an engulfed cell corpse, which is surrounded by a CED-1ΔC::GFP ring. Yellow arrows marks an unengulfed cell corpse, which lacks CED-1ΔC::GFP on its surface. (C) The fraction of cell corpses that have been engulfed (surrounded by a CED-1ΔC::GFP ring) in 1.5-fold to 2-fold stage embryos of various genotypes are presented as bars. For each genotype, at least 15 embryos were scored. (D) Time-lapse images before and after the formation of a phagosome carrying C3 in embryos of different genotypes expressing Pced-1ced-1ΔC::gfp. “0 min” is the moment ventral enclosure initiates. Arrowheads indicate extending pseudopods. A white arrow marks the nascent phagosome. Yellow arrows label the extending ventral hypodermal cell ABpraapppp. For each genetic background, a single asterisk marks the moment when recognition is first observed, while the double asterisks mark the moment when the nascent phagosome is formed.