Loss of cbs-1 causes lysosomal dysfunction and developmental defects in C. elegans. (A and B) Representative images of GFP::LGG-2-positive structures in the hypodermis (A) and muscle (B) of WT, yq399, and yq357 animals at the indicated developmental stages. Bars, 5 μm. (C and D) Representative images of lysosomes in the hypodermis of WT, yq399, and yq357 animals (2 days after L4) co-expressing GFP::LGG-2 (C) or SCAV-3::GFP (D) and NUC-1::mCh. Bars, 5 μm. (E) DIC images (left) and quantification (right) of body length of adults (2 days after L4 stage) of WT, cbs-1(yq399), cbs-1(yq399) mutants expressing cbs-1::gfp (P_cbs-1cbs-1::gfp), and cbs-1(yq399) mutants expressing hCBS::gfp (P_semo-1hCBS::gfp). Bars, 200 μm. ≥15 animals were examined for each genotype. (F) Lifespan analysis of WT, yq399, and yq357 animals. 100 animals were scored for each genotype. Data (mean ± SEM) are from three independent experiments. (G) Rescue of enlarged lysosomes in cbs-1(yq399) mutants by transgenic expression of C. elegans CBS-1 (P_cbs-1cbs-1::gfp) and human CBS (P_semo-1hCBS::gfp). Left: representative images of NUC-1::mCh-labeled lysosomes and cytoplasmic CBS-1::GFP and hCBS::GFP. Bars, 5 μm. Right: quantification of lysosomes. ≥20 lysosomes from 3 animals were examined for each genotype. (H) Rescue of the gigantic GFP::LGG-2 structures in the muscle in cbs-1(yq399) mutants by CBS-1::mCh (P_cbs-1cbs-1::mCh). Left: representative images of GFP::LGG-2 and CBS-1:mCh. Bars, 5 μm. Right: quantification of lysosomes. ≥90 animals for each genotype were examined. For quantifications, data are presented as mean ± SEM. Statistical comparisons were performed using the two-sided Student’s t test. ***P < 0.001, ****P < 0.0001. DIC, differential interference contrast.