FIGURE 6.

CPT-cAMP treatment changes mitochondrial structure and increases autophagy. Electron microscopy showed medium to large mitochondria typically with long cristae (arrowhead) in WT S49 cells (a). b, similar mitochondrial structure (arrowhead) in kin⁻ S49 cells. c, CPT-cAMP-treated WT S49 cells have smaller mitochondria with fewer cristae (arrowhead) than do untreated WT cells. Scale bar, 500 nm for panels a, b, and c. d and e, lysosomal vesicles (arrowheads) are more prevalent in CPT-cAMP-treated WT cells (e) than in untreated WT cells (d), consistent with measurements (Table 3) that show decreased mitochondria volume density and size, but no change in number, suggesting degradation of a portion of individual mitochondria, likely by fission of the dysfunctional part and its subsequent autophagosomal digestion. Scale bar, 1000 nm and applies to panels d and e.