Scientists are aware that a low-calorie diet has positive health benefits in species as different as yeast and humans, but the underlying cellular and molecular mechanisms have not been well understood.
A new study by Stephen Helfand and Blanka Rogina at the University of Connecticut Health Center in the US reveals that Sir2 is responsible for an increase in life span in the fruit fly Drosophila on a calorie-restricted diet.
In Drosophila, calorie restriction has previously been linked to an increase in activity of the protein Sir2, which aids DNA packing and unpacking in the cell cycle.
The researchers created a mutant fly line overexpressing Sir2, that according to the study authors lived up to 57 per cent longer than control flies. Compounding their findings, although the researchers disrupted the Sir2 gene in normal flies they did not find an increase in life span when they put the flies on a low-calorie diet.
Full findings of the paper, Sir2 mediates longevity in the fly through a pathway related to calorie restriction, are published in the Proceedings of the National Academy of Sciences, online early edition for the week of 25-29 October 2004.