Researchers from the University of California, San Francisco (UCSF) found that the yeast Saccharomyces cerevisiae ensures the health of its budding offspring by pushing essential internal structures known as mitochondria into them.
Mitochondria are the mini powerhouses of living cells, supplying the chemical energy all yeast and higher life forms need to survive. Like all cellular life, yeast need these structures to survive.
Researchers found that yeast cells ferry just the right amount of mitochondria along a network of protein tracks and molecular motors into the young yeastlings which bud off their mother.
Surprisingly, yeast mothers continued to give generous amounts of their mitochondria to their offspring even when it meant hastening their own death.
"The mom will pump in as many as [the bud] needs. The bud gets more and more as it grows, and mom doesn't get any more," lead researcher Wallace Marshall said in a statement.
Working with yeast, the UCSF team developed sophisticated microscope and computer techniques that allowed them to track the movement of mitochondria within cells.
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If these structures had divided randomly, they would expect to find fewer in the bud than in the mother (since the buds are smaller than the mother).
Instead, they found that the yeast mothers gave a consistent amount of mitochondria to their offspring at each generation, and so over time they had fewer and fewer of the organelles themselves.
The price they paid to ensure their offspring was healthy was steep: The yeast mothers would eventually give away too many of the mitochondria to survive and begin to die off after 10 generations. By 20 generations, most of the mothers had died.
Mutant forms of yeast, which were much more stingy in giving up their mitochondria, lived much longer.
The study was published in the journal Science.