Figure 2. Uptake and degradation of DNA by isolated lysosomes. (A) Isolated lysosomes were incubated with 0.5 μg of purified DNA for 5 min in the presence or absence of ATP (energy regenerating system), and pelleted by centrifugation. The levels of DNA remaining in solution outside of lysosomes, and the levels of DNA in the precipitated lysosomes were analyzed. (B) Isolated lysosomes were incubated with or without DNA for 5 min in the presence of ATP (energy regenerating system), and then immunogold labeling was performed using an anti-DNA antibody followed by anti-mouse IgG coupled with 10 nm of gold particles (left and middle, respectively). As a control assay, immunogold labeling was performed without primary antibody (right). Gold particles are observed in the lysosomes in the left panel, while no gold particles are observed in the lysosomes in the middle and the right panels. (C) Isolated lysosomes were incubated with 1 μg of purified DNA for 5 min in the presence or absence of ATP (energy regenerating system), and total levels of DNA in the incubated samples were analyzed.