It was long known that children typically have the same life expectancy at birth, regardless of whether their father is 20 years old or 80. This must mean that the man's reproductive cells somehow reset their clocks, but how they do this has been a mystery, until now.
Now a gene that reverses ageing effects in yeast is providing some clues to the unknown mystery.
Under stressful conditions yeast cells forgo asexual reproduction and split into four spores, each containing half the chromosomes of a typical cell, like human eggs and sperm. As the cells get older, they acquire clumps of proteins and extra pieces of DNA, but when Angelika Amon at the Massachusetts Institute of Technology and colleagues tracked spores from old and young yeast cells they found that such abnormalities disappeared, meaning all spores had the same lifespan. Clumped protein seems to be cleared through autophagy, in which the cell "eats" itself.
During sporulation, a gene called NDT80 was expressed. Switching on NDT80 in ageing cells doubled their lifespan. The closest relative of NDT80 in mammals is p53, a gene that regulates cell cycles.
"We may have found a way to rejuvenate cells and erase ageing markers," New Scientist quoted Amon as saying.
The study has been published in Science.