I wanted to draw your attention to an interesting (if not immediately applicable) connection between two pieces of research. We'll start with a method of making oxidative stress glow:
Arterial calcification and coronary heart disease, neurodegenerative diseases such as Parkinson's and Alzheimer's, cancer and even the aging process itself are suspected to be partially caused or accelerated by oxidative stress. Oxidative stress arises in tissues when there is an excess of what are called reactive oxygen species (ROS). "However, up to now, nobody was able to directly observe oxidative changes in a living organism and certainly not how they are connected with disease processes," ... [Researchers] introduced genes for biosensors into the genetic material of fruit flies. These biosensors are specific for various oxidants and indicate the oxidative status of each cell by emitting a light signal - in realtime, in the whole organism and across the entire life span.
Up to now, many scientists have assumed that the aging process is associated with a general increase in oxidants throughout the body. However, this was not confirmed by the observations made by the investigators across the entire life span of the adult animals. They were surprised that almost the only age-dependent increase in oxidants was found in the fly's intestine. Moreover, when comparing flies with different life spans, they found out that the accumulation of oxidants in intestinal tissue even accelerated with a longer life span.
This will provide a great deal of grist for various mills, given the central role for oxidative stress in a broad range of aging research - there's nothing quite like finding an extra layer of complexity and a boatload of confounding data to get the grants flowing. Notice that the intestine is the location of rising oxidative stress in the fly, and then glance back at this recent research:
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.
PGC-1 is involved in regulation of mitochondrial biochemistry, and mitochondria are the go-to source for oxidative stress - they emit damaging oxidative molecules as a side-effect of normal operation. You can speculate on this and how it all hangs together; certainly there's not enough information yet to do more than that. To me, the immediately interesting part of this is the degree to which flies apparently march on their stomachs - but I think we'll be seeing much more of glowing biosensors in the near future. In the long term, similar whole-body biosensor methodologies deployed in mammals have the potential to remove much of the ambiguity that remains in our understanding of metabolism and its relationship to aging.