Loss of sorf-1 and sorf-2 partially suppresses defective organelle fusion in vps-18 mutants and causes enlargement of endosomes. (A) Representative confocal images of endosomes and lysosomes in coelomocytes in N2, vps-18(tm1125), vps-18(tm1125);sorf-1(tm3855), and vps-18(tm1125);sorf-2(yq4) animals. DIC images are shown together with RME-8::RFP (white arrows), LMP-1::GFP (yellow arrows), and merged fluorescence images. Bars, 5 µm. (B and C) Proportion of cells containing enlarged RME-8::RFP- or LMP-1::GFP-positive vesicles in animals with the indicated genotype. ≥70 coelomocytes (one coelomocyte/animal) were scored. (D) Representative images of endosomes labeled with GFP-RAB-5 or RME-8::GFP and lysosomes labeled with LMP-1::GFP in coelomocytes of the indicated animals. Bars, 5 µm. (E and F) Peak sizes of endosomes positive for GFP::RAB-5 (n > 100) and RME-8::GFP (n > 100). (G) Sizes of LMP-1::GFP-positive lysosomes (n > 500). For all quantifications, error bars represent SEM derived from three independent experiments. **, P < 0.01; ***, P < 0.001. In E–G, each symbol represents an endosome or lysosome; the horizontal line indicates the mean peak diameter.