Deeper understanding of the molecular mechanisms of yeast's genetic response to microgravity will help NASA scientists identify which genes enable cell survival. Molecular biologists have added 'signature tags' to every gene in the yeast genome, so that the effects of microgravity on each gene can be studied. The benefit of using yeast cells is that it serves as a benchmark microbe for biological research studying human or other mammalian cells that have a very large and complex set of genes.

"Understanding gene expression patterns and how they are altered when cells are grown in the low-gravity, or microgravity, environment inside the International Space Station will help scientists learn how humans respond to gravity," said principal investigator Dr. Cheryl Nickerson from the Tulane University Health Sciences Center, who is working with co-investigator Dr. Tim Hammond of Tulane University and the Veterans Affairs Medical Center in New Orleans.

Two Yeast Group Activation Packs (GAP) that hold the yeast cultures, liquid growth medium and fixative used to preserve cells in space will be flown onboard the Russian Progress launch vehicle 13P scheduled to launch on Jan. 29 from the Baikonur Cosmodrome in Kazakhstan. After a two-day flight, the payload will be transferred to the International Space Station, where the experiment will remain for several months.

"This experiment will be among the first set of U.S. biological experiments that will be sent into space since the Columbia accident," said Dr. Beverly Girten, chief of the Science Payloads Operations Branch and small payloads project manager at NASA Ames Research Center, Moffett Field, Calif.

To activate the experiment, an International Space Station crewmember will insert a hand crank into the top of the GAP. Turning the crank will cause the yeast cells to mix with the liquid growth solution and begin growing. Following the growth period, the hand crank will be inserted into the top of the GAP again and turned, which will allow fixative to mix with the growing yeast colony, thus preserving the cells.

The preserved cells will be contained within the GAP for up to one year following experiment activation. They will be returned to Earth where scientists will compare them to identical yeast cells grown inside a ground control unit. By comparing the yeast genes expressed during ground-based growth with those expressed when the organism is grown in space, scientists can determine how microgravity alters the genetic expression profile and survival of cells.

"This experiment is a collaborative effort between peer-reviewed investigators funded through NASA's Office of Biological and Physical Research's (OBPR) Fundamental Space Biology Division, commercial groups working through OBPR's Space Product Development, and several NASA centers," said Girten. "This shared effort is particularly important since the shuttle fleet is not flying and there are limited opportunities to conduct science in space right now."

Life Science at Ames
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