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NASA is conducting a study on germs it sent as part of an experiment that returned home much more deadly.

NASA wanted to conduct an experiment on how pathogenic bacteria behaved outside the confines of Earth's gravity.  Its experiment bore some surprising results.

In September 2006, the Space Shuttle STS-115 launched, carrying in its cargo a sample of Salmonella bacteria.  The sample was part of a collaborative experiment with Arizona State University's Center for Infectious Diseases and Vaccinology, which wanted to investigate the effects of weightlessness and other space phenomena on pathogens.  ASU kept a separate sample in similar condition on earth as a control group.

When the sample from space returned, they proceeded to feed both strains of salmonella to lab mice.

The results were startling.  After 25 days, 40 percent of the earth-strain mice were still alive.  Only 10 percent of the group infected with the space-strain was still alive.  Researchers conducted additional studies which revealed that only 1/3 as many of the space-strain pathogens were needed to kill a healthy mouse as earth strain pathogens.  The conclusions--the space strain had become far more deadly on its journey into orbit.

Genetic studies revealed that the bacteria had mutated quickly in space and had a total of 167 genes changed. 

Professor Cheryl Nickerson, one of the study's researchers cautions that the cause for the increased toxicity is not definitively known (the 64 million dollar question as she puts it), but she says that it is thought to be due to fluid shear effects.

"Being cultured in microgravity means the force of the liquid passing over the cells is low… [The cells] are responding not to microgravity, but indirectly to microgravity in the low fluid shear effects."

"There are areas in the body which are low shear, such as the gastrointestinal tract, where, obviously, salmonella finds itself," she went on to say. "So, it's clear this is an environment not just relevant to space flight, but to conditions here on Earth, including in the infected host."

Nickerson sees the mutation as a natural adaptation to a changing environment in order to survive.  The increased toxicity is a side effect.

The research will be published in today's edition of “Proceedings of the National Academy of Sciences
(PNAS).

The research received funding and support from the National Aeronautics and Space Administration, Louisiana Board of Regents, Arizona Proteomics Consortium, National Institute of Environmental Health Sciences, Southwest Environmental Health Sciences Center, National Institutes of Health and the University of Arizona.



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zero gravity bacteria
By wallijonn on 9/26/2007 11:04:23 AM , Rating: 2
Is it really zero gravity or is it a combination of pure oxygen and an increase, or decrease, of background radiation? One would think that the increased Nitrogen in Earth's air at sea level may inhibit growth while the pure Oxygen atmosphere in a space capsule may facilitate 'pure' growth. Likewise the space capsule may be better shielded from microwave radiation (there are no cell phone transmitters in space), for all we know an increased gamma ray background could facilitate bacteria growth.

Since Earth conditions may not be able to be replicated in space, the next best thing would be to try to replicate space like conditions on Earth.




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