Dealing with stress could be key to living longer

How well you respond to stress predicts how long you will live, at least if you are a little worm, US scientists reported yesterday.

Genetically identical worms respond to stress in greatly different ways - and those with more active stress reactions live much longer than worms with less active stress proteins, the researchers found. More active stress responses suggest the animal is coping with the stress.

The findings will almost certainly apply to humans in some way, they report in this week's issue of the journal Nature Genetics.

Shane Rea of the University of Colorado at Boulder tested more than 100,000 nematodes known as Caenorhabditis elegans - a worm favoured by scientists because it is easy to work with. Despite its tiny size, C. elegans is genetically complex and has much in common with "higher" animals such as humans.

The scientists genetically engineered the transparent worms to carry a jellyfish gene called green fluorescent protein, which glows green under certain light. They tagged this gene to a gene called hsp-16.2, a stress protein found in most organisms that is associated with the health of cells.

The more active the hsp-16.2 gene was, the brighter the worms glowed green and, presumably, the better they coped with stress.

In a typical experiment, the worms that glowed the brightest green lived about 16 days, compared to about three days for those that glowed the most weakly - under identical conditions.

"We have shown it's possible to predict the life span in an organism on the first day of adult life based on how it responds to stress," said Thomas Johnson, a professor who helped lead the study.

Most scientists say the lifespan of creatures is affected by a combination of genetic, environmental and chance factors. Studies done in twins suggest that genes are only about 15 per cent to 30 per cent responsible for how long an otherwise healthy person will live.

Said Rea: "This work starts to address the question of why genetically identical organisms raised in identical environments still age at different rates."

- REUTERS