DNA deletions and clonal mutations drive premature aging in mitochondrial mutator mice
Mitochondrial DNA (mtDNA) mutations are thought to have a causal role in many age-related pathologies. Here we identify mtDNA deletions as a driving force behind the premature aging phenotype of mitochondrial mutator mice, and provide evidence for a homology-directed DNA repair mechanism in mitochondria that is directly linked to the formation of mtDNA deletions. In addition, our results demonstrate that the rate at which mtDNA mutations reach phenotypic expression differs markedly among tissues, which may be an important factor in determining the tolerance of a tissue to random mitochondrial mutagenesis.
The historic takeover of Fannie Mae and Freddie Mac, which could come as soon as this weekend, moved to the forefront of the presidential campaign Saturday.
In the arena that night, the whole last minute was drowned out by cheers — and then when the soaring music swelled, the confetti rained down as the harbinger of balloons and the hopeful first family took the stage, forget about it — it was a perfect end to a convention that last Monday, no one even knew if it would happen. But it did, and I'm so glad to have been there.
