Suggesting That Mitochondrial Changes Are Consequences, Not Causes of Aging
It is thought that mitochondrial DNA damage - and consequent mitochondrial dysfunction - is a contributing cause of aging. There is plenty of evidence to support that view, but it still lacks the sort of conclusive proof needed to sink all arguments, such as engineering longer life for laboratory animals through mitochondrial DNA repair, something that will soon be possible. Here, researchers look at specific forms of age-related mitochondrial change in nematodes and suggest that they are consequences, not causes of aging:
Mitochondrial dysfunction is a hallmark of skeletal muscle degeneration during aging. One mechanism through which mitochondrial dysfunction can be caused is through changes in mitochondrial morphology. To determine the role of mitochondrial morphology changes in age-dependent mitochondrial dysfunction, we studied mitochondrial morphology in body wall muscles of the nematode C. elegans.We found that in this tissue, animals display a tubular mitochondrial network, which fragments with increasing age. This fragmentation is accompanied by a decrease in mitochondrial volume. Mitochondrial fragmentation and volume loss occur faster under conditions that shorten lifespan and occur slower under conditions that increase lifespan. However, neither mitochondrial morphology nor mitochondrial volume of five- and seven-day old wild-type animals can be used to predict individual lifespan.
Our results indicate that while mitochondria in body wall muscles undergo age-dependent fragmentation and a loss in volume, these changes are not the cause of aging but rather a consequence of the aging process.
Link: http://www.impactaging.com/papers/v6/n2/full/100639.html
And just precisely what then causes aging? The mitochondria fail and disassemble with advancing age till only about 4% are working by age 80. There is an increase in labile (unstable) iron in mitochondria and calcification of lysosomes that leaders to accumulation of lipofuscin, a marker of aging. I persist in the theory that accumulation of minerals (calcium, copper, iron) is the chief cause of the speed of aging. Youth can be defined by the fact there is a shortage of minerals needed for making red blood cells (iron), connective tissue (copper) and bone (calcium). Once full growth is achieved the body progressively accumulates minerals, first in males, then later in menopausal females. The mitochondria and its unique genome age in relation to mineral accumulation.