Investigators at McGill University are disputing the decades-old theory that oxidative stress causes aging. Using C. elegans, they found that disabling their ability to get rid of the buildup of reactive oxygen species (ROS), did not actually decrease their lifespan as was previously thought.
The team disabled five genes responsible for producing a group of proteins called superoxide dismutases (SODs), which detoxify one of the main ROS. Earlier studies seemed to show that decreased SOD production shortened an organism's lifespan.
The McGill University team, however, observed the opposite. None of the worms showed a shorter life span compared to wild-type worms. In fact, one variety even displayed an increased lifespan.
“The mutation that increases longevity affects the main SOD found in mitochondria inside the animals’ cells,” says Siegfried Hekimi, Ph.D., of the department of biology. “This is consistent with earlier findings that mitochondria are crucial to the aging process. It seems that reducing mitochondrial activity by damaging it with ROS will actually make worms live longer.”
The paper is published in the February issue of PLoS Genetics.