PCG-1 is known to be connected to the benefits of calorie restriction in a range of species, and here researchers are working with flies: "One of the few reliable ways to extend an organism's lifespan, be it a fruit fly or a mouse, is to restrict calorie intake. Now, a new study in fruit flies is helping to explain why such minimal diets are linked to longevity and offering clues to the effects of aging on stem cell behavior. Scientists [found] that tweaking a gene known as PGC-1, which is also found in human DNA, in the intestinal stem cells of fruit flies delayed the aging of their intestine and extended their lifespan by as much as 50 percent. ... While little is known about the biological mechanisms underlying this phenomenon, studies have shown that the cells of calorie-restricted animals have greater numbers of energy-generating structures known as mitochondria. In mammals and flies, the PGC-1 gene regulates the number of these cellular power plants, which convert sugars and fats from food into the energy for cellular functions. ... The researchers found that boosting the activity of dPGC-1, the fruit fly version of the gene, resulted in greater numbers of mitochondria and more energy-production in flies - the same phenomenon seen in organisms on calorie restricted diets. When the activity of the gene was accelerated in stem and progenitor cells of the intestine, which serve to replenish intestinal tissues, these cellular changes correspond with better health and longer lifespan."