A technique that accurately predicts the lifespan of nematode worms has been developed by scientists monitoring mitochondrial activity.
Mitochondria generate energy in cells, and large amounts of free radicals - highly reactive molecules - are a by-product of this process. These free radicals are thought to cause damage to DNA and cell proteins and thus underpin the ageing process.
Dr Meng-Qiu Dong and her team from the National Institute of Biological Sciences in Beijing introduced proteins that fluoresce when they interact with these free radicals. Using a special frequency-specific camera to record the number of flashes produced by this interaction, they discovered that there were two major bursts of mitochondrial activity: first at three days into development and another near the end of the nematode's life. Only the earlier bout of activity had an effect on the nematode's longevity.
The team discovered that the fewer 'mitoflashes' that take place, the more likely the nematode is to live for the average lifespan of 21 days.
'Mitochondrial flashes have an amazing power to predict the remaining lifespan in animals', Dr Dong told Nature News. 'There is truth in the mitochondrial theory of ageing'.
In the next stage of the study, the researchers used another type of worm, C. elegans, that had been genetically altered to have life spans much shorter and much longer than the average 39 days. In each experiment the same pattern was present: worms that had a low average frequency of mitoflashes early in their life lived much longer than those with a higher-than-average flash frequency.
The most startling result came from one experiment where Dong's team treated a sample of the long-lived nematode worms to produce more reactive oxygen molecules, which led to a greater frequency of mitoflashes and a shorter lifespan for the worm.
This is the first time that the lifespan of an organism has been accurate predicted while it is still alive. They hope that other teams will find a similar link between free radical production and mitochondria in other organisms.
'The finding that mitoflash frequency in early adulthood predicts lifespan corresponds well with our earlier observations that some early-life events and conditions could be good longevity predictors', Dr Leonid Gavrilov from the University of Chicago, who researches ageing in humans, told New Scientist.