AASS functions are evolutionarily conserved between C. elegans and humans. (A) Images representing the rescuing effect on aass-1(yq170) mitochondria by ectopic expression of worm MTS- and mCherry-fused hAASS (MTS::hAASS::mCh). Bars, 5 µm. (B) Images representing the rescuing effects on aass-1(yq170) mitochondria by ectopic expression of worm MTS- and mCherry-fused hLKR (MTS::hLKR::mCh; top), hSDH (MTS::hSDH::mCh; middle), and hSDH(T719A) (MTS::hSDH(T719A)::mCh; bottom). Bars, 5 µm. (C) Quantification of animals as shown in A and B with abnormally enlarged mitochondria (area ≥12 µm²). 90 animals or more were scored for each genotype. (D and E) Images (D) and quantification (E) of enlarged mitochondria in N2 animals and aass-1 mutants (yq246, yq277, and yq246yq170) containing mutations corresponding to hAASS mutations in hyperlysinemia patients. 90 animals or more were scored for each genotype. Bars, 5 µm. (F) TEM images of mitochondria in hypodermal cells in aass-1(yq246), aass-1(yq277), and aass-1(yq246yq170) animals. Boxed regions showing crista structures are magnified (3×) and shown in the bottom left corner in each image. The red arrowhead indicates a broken mitochondrial membrane. Bars, 1 µm. (G and H) Fold change of saccharopine (G) or lysine (H) levels in N2, aass-1(yq170), aass-1(yq246), aass-1(yq277), and aass-1(yq246yq170) animals. Data (mean ± SEM) are from three independent experiments as shown in Fig. S2 and are normalized to the levels of saccharopine or lysine in N2 animals. (I) Fold change of ATP levels in the hypodermis of the indicated animals. Data (mean ± SEM) are from three independent experiments and are normalized to ATP levels in N2 animals. (J) Analysis of body lengths of adult animals with the indicated genotypes. 10 synchronized animals of each genotype were analyzed at every time point. Comparisons are between N2 and mutants. For all quantifications, *, P < 0.05; **, P < 0.01; and ***, P < 0.001. Error bars represent SEM.