A new study suggests that an organism's lifespan is predictable at early adulthood by looking at the activity of its cells' mitochondria.

Mitochondria are the organelles that supply energy to the cell. During energy production, mitochondria produce reactive oxygen molecules, such as free radicals, that can cause stress and damage the mitochondria. It was recently discovered that mitochondria sometimes produce these reactive oxygen molecules in short, repeated bursts; these are called mitoflashes.

Meng-Qui Dong and his colleagues at the National Institute of Biological Sciences in Beijing, China, visualized the mitoflashes produced by mitochondria in Caenorhabditis elegans by targeting the energy-producing organelles with a fluorescent protein that glows yellow when viewed under a microscope. In regular worms, two mitoflash bursts occurred: one during the worms' egg-laying period in early adulthood and one during senescence.

The team compared mitoflash rates in two mutant C. elegans strains, one with a shorter lifespan, lasting 21 d on average, and the other with a longer lifespan, lasting 30 d or more on average. Remarkably, the pace of mitoflashing in the first mitoflash burst was found to correlate with lifespan in the worms. The shorter-lived worms had more frequent mitoflashes than the longer-lived worms (Nature doi:10.1038/nature13012; published online 12 February 2014).

Recognizing that aging is determined not only by genetic factors but also by environmental factors, the researchers next gave different groups of worms various treatments that have been shown to alter the lifespan of C. elegans. Conditions that extend the lifespan of the worms, such as exposure to heat shock or starvation, resulted in less frequent mitoflashes during the early-adulthood burst. And conditions that reduce the lifespan of the worms, such as treatment with substances that increase production of reactive oxygen molecules, resulted in more frequent mitoflashes. These results suggest that the bursts of activity in the mitochondria of the worm's cells can accurately predict how long the worm will live. “Mitochondrial flashes have an amazing power to predict the remaining lifespan in animals,” Dong told Nature News.

A common theory suggests that mitochondria are the biological clock that drives aging. In addition to supplying energy to cells, mitochondria are also involved in cell death and the control of the cell cycle and cell growth. The findings of this study certainly support that theory by demonstrating the intricate link between mitochondrial activity and lifespan. Said Dong, “There is truth in the mitochondrial theory of aging.”