Overaccumulation of yolk in b1028 mutants. (A–F) YP170::GFP trafficking in adult hermaphrodites. In WT worms, YP170::GFP is efficiently endocytosed by oocytes (A). In the b1028 mutant worms, YP170::GFP accumulation in the body cavity is greatly increased (B). (C and D) Both WT and b1028 mutant worms show comparable levels of YP170::GFP in oocytes. WT worms show detectable levels of YP170::GFP in the intestine, while b1028 worms show increased accumulation of enlarged YP170::GFP positive vesicles in the intestine (E–F). (G and H) The localization of yolk receptor RME-2::GFP is unaltered in b1028 mutant oocytes. Images were taken through the middle focal plane of oocytes. Insets show enlarged top focal plane images of oocytes, demonstrating RME-2::GFP positive cortical endosomes. Bars (A and B), 100 μm; (C–F), 20 μm. (I) YP170::GFP fluorescence quantification in one- and two-cell embryos, results are expressed as arbitrary units of fluorescence intensity ± SD, asterisks indicate statistical differences (t-test, P ≤ 0.001). (J) Size measurement of WT and various rme mutant worms (n ≥ 12), results are expressed in micrometers ± SD, asterisks indicate statistical differences (t-test, P ≤ 0.001). (K) Real-time PCR analysis of vit-2 expression in WT and b1028 mutant worms. eif-3.C was used as a reference mRNA. Results are expressed as a fold change ± SD; asterisks indicate statistical differences (t-test, P ≤ 0.05).