 This study investigates the accumulation of somatic mutations in the mitochondrial DNA, MTDNA, of aged mice. The researchers found that there was an increase in the number of mutations in the MTDNA of aged mice compared to younger ones. They also observed that certain types of mutations were more likely to occur in specific organs, such as the heart and kidney. Furthermore, they discovered that the presence of certain mutations could be reduced when the mice were given treatments that targeted oxidative stress. This suggests that the accumulation of these mutations may be due to oxidative stress, rather than simply being a result of aging. This article was authored by Monica Sanchez Contreras, Maria T. Sweetwine, Cristina Santillas, and others.