Figure 2.

Southern blot showing the time course of native mtDNA damage caused by 1 mM H₂O₂ and followed by the DNA repair by HEK293 cells. M: molecular weight marker; 0: control DNA (from untreated cells); The cells were exposed to 1 mM H₂O₂ and harvested after 30 min, 2 h, 4 h, 6 h, 24 h, respectively. 1 µg of total DNA was loaded on a 0.6% agarose gel prepared in tris-borate-EDTA (TBE) buffer and was run in the presence of 0.5 µg/mL ethidium bromide overnight at 40 V. After alkaline treatment and re-neutralization of the gel, the DNA was blotted to a Zeta-Probe membrane (Bio-Rad, Hercules, CA, USA) and immobilized by baking at 80 °C for 30 min. The blot was hybridized with a MT-ND6 probe.