When NASA's final space shuttle mission successfully launched this morning, along with four astronauts and thousands of pounds of jet fuel Atlantis was carrying some unusual passengers: yeast cells. Sadly, the astronauts won't be playing Martha Stewart in space and baking zero-gravity brioches. The goal is to look for defects in yeast cells, which are remarkably similar to human cells, in the hopes of better understanding human diseases.

The common yeast cells are part of the Micro-4 project developed by scientists at the University of Toronto. In two separate experiments, researchers will study the effects of microgravity on cell growth and how different mutant genes might affect susceptibility to a microgravity situation.

As Atlantis soars 17,000 miles an hour above Earth during its 12-day mission, the astronauts will take yeast cells that have been kept at 4° C and increase the temperature to 30° C, allowing the cells to grow for 48 hours before they're cooled back down and eventually returned to Toronto for analysis.

In the second experiment, 6,000 different yeast cells, each identified by a special “barcode,” will be grown in liquid broth and transferred to fresh liquid broth twice during the course of the mission.

These experiments will allow the Canadian scientists to see how the space environment and the cell's genetic background impact cell growth and survival.

“This information could inform future planned missions to Mars as well as longer-term settlement of moon and Mars-based colonies,” says University of Toronto researcher Brenda Andrews. Some yeast cells are bound for bread, some for glory.

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