Outer space adventures could be bad for your immune system.
Drosophila flies' immune system are similar to humans'; a research team looked at how gravity affected the flies' immunity, a UC Davis news release reported.
The team first looked at the flies in hypergravity ("increased gravity") and then microgravity (the decreased gravity of spaceflight).
The team sent fly eggs on 12-day mission to space, these flies hatch and reach adulthood within 10 days. Once the flies returned to Earth the team tested their responses to both a fungus mediated by a toll receptor and a bacterial infection that is fought off with a gene called Imd.
"While the response through the Imd pathway was robust, the Toll pathway was "non-functional" in space-raised flies," Deborah Kimbrell, a researcher in the Department of Molecular and Cellular Biology in the UC Davis College of Biological Sciences, who led the study said according to the news release.
Flies that have been tested in a centrifuge under hypergravity conditions here on Earth showed evidence of a boosted Toll pathway and resistance to the same fungal infection. The "mutant yuri gagarin" did not seem to respond to gravitational fields, and was found to be normal in hypergravity.
"Future spacecraft designed for long missions could already include centrifuges that crew could use to keep up bone and muscle mass: it turns out that this might also have a beneficial effect on astronauts' immune systems," Kimbrell said, the news release reported.
The flies also showed a high expression of genes for heat-shock proteins; these are usually produced in times of physiological stress. The proteins bind with the mammalian Toll receptors, but could also moderate the Toll activation in Drosophila.
Another theory on why the immune system is affected by gravity is that it interferes with the behavior of proteins outside of cells, which is an "important area" for Toll signaling.
