The fruit flies were exposed to hypergravity on a centrifuge at UC Davis. The results found from study in hypergravity led to the spaceflight investigation, Fungus, Immunity and Tumorigenesis (FIT), during space shuttle Discovery's STS-121 mission to the International Space Station in 2006. The 12-day mission allowed a small population of fruit flies to fully develop into adults in space. The flies were then returned to Earth for further analysis and comparison of the effects of two extreme environments on these living organisms.
Researchers discovered that hypergravity and microgravity produced opposite cell-based responses in fruit fly immunity. When exposed to increased gravity, the flies responded to infection by a fungus, Beauveria bassiana, using the Toll pathway. This was in direct contrast to the flies flown in space, since the space flies' Toll pathway failed to respond to the exact same type of fungal infection. However, the Imd pathway response to E. coli bacteria was robust in flies exposed to hypergravity and microgravity.
"What we found is that in one kind of infection in flies that were raised in space, they did fine, and in another kind of infection, they really didn't respond at all," said Kimbrell. "The pathway that did not respond, the Toll pathway, is critical in humans for all kinds of health-related issues, both for functioning and for over-functioning. The Toll pathway (TLR4) response is involved in sepsis, which is still a big problem in human health."
In fact, when the flies infected with a fungus were exposed to increased gravity, they survived significantly better than flies with the same infection at normal gravity, sugges
|Contact: Laura Niles|
NASA/Johnson Space Center