The work was done under the leadership of Jadwiga Giebultowicz, an OSU professor of zoology, in collaboration with Dr. Doris Kretzschmar from the Oregon Health and Sciences University. The research was supported by the National Institutes of Health and the Oregon Partnership for Alzheimer's Research.
In control studies, the mutant flies with no functional "period" gene lived just about as long as normal flies, unless they were stressed. In experiments, researchers caused a mild metabolic stress an elevated level of reactive oxygen species for 24 hours to the flies at various times, which corresponded to their youth, middle age and old age. There was no significant change in the young flies. But in middle-age and older flies, significant damage began to occur.
Mutant flies lost some of their motor ability to climb, and morphologic examinations of their brains showed higher levels of neuronal degeneration, similar to neurodegenerative diseases such as Alzheimer's disease in humans. When exposed to a single stressful event in "middle age," the mutant flies had a 12 percent shorter lifespan than normal flies exposed to the same stress. And when exposed to a single stress in old age, their lifespan was 20 percent shorter.
The study concluded that expression of the "period" gene naturally declines with age. If the same is true for humans, that could help explain why people may lose some of their ability to handle oxidative and other stresses at a time of their life when they need it most.
The scientists theorized that the "period" gene is regulating pathways involved in removal of oxidative damage, and those without this function experienced the symptoms of aging more quickly. This could ultimately have impacts on everything from neurological damage to heart disease and cancer.
|Contact: Natraj Krishnan|
Oregon State University