Mitochondrial DNA and life span changes in normal and dewinged Drosophila at different temperatures

At 11 and 30 degrees C there was no change in the amount or in the buoyant density of nuclear DNA of male Oregon R Drosophila melanogaster with aging. When normal flies were maintained at 11 degrees C (at which temperature they do not fly), mitochondrial DNA content declined gradually with aging and 39.4% of the original mitochondrial DNA was lost at the median survival time of 152 days of age. For normal flies maintained at 30 degrees C, 86.5% of the mitochondrial DNA was lost during aging at the median survival time of 25 days. In contrast only a 39.2% decrease in the mitochondrial DNA occurred in dewinged flies maintained at 30 degrees C. A slow phase of mitochondrial DNA loss appears to be related to aging and a fast phase to flight activity. Removing the wings of flies eliminates the fast phase of DNA loss but only slightly improves life span (by less than 10%). Lowering the environmental temperatures to 11 degrees C also eliminates fast phase DNA loss and decreases the rate of the slow phase DNA loss. We conclude that mitochondrial DNA loss is related to both physical activity and to the aging process itself.