June 21, 2006

Ruth Marlaire
NASA Ames Research Center, Moffett Field, Calif.
Phone: (650) 604-4709/9000

RELEASE: 06_43AR

NASA SENDS FLIES INTO SPACE TO TEST CHANGES IN IMMUNE SYSTEM

Thousands of tiny fruit flies soon will journey into space to help 
NASA scientists better understand changes in the human immune system 
caused by space flight.

Despite differences in size and complexity, the Drosophila 
melanogaster, or common fruit fly, may help scientists from NASA Ames 
Research Center unlock the secrets of why astronauts often develop 
changes in their immune system during space flight. The experiment 
will be part of the STS-121 space shuttle mission tentatively 
scheduled for launch on July 1.

“Understanding the immune system using fruit flies will be similar to 
the process we used to understand and build complex machines,” 
explained Sharmila Bhattacharya, the experiment’s principal 
investigator at NASA Ames Research Center, in California's Silicon 
Valley. “We start small and simple, and progress to more complicated 
and advanced concepts, thus extending our understanding in the future 
to helping optimize human performance in space.” Bhattacharya is 
leading the NASA Fungal Pathogenesis, Tumorigenesis and Effects of 
Host Immunity in Space (FIT) experiment that will compare fruit flies 
grown in space with a genetically identical control sample grown in a 
NASA Kennedy Space Center (KSC) laboratory.

Past experiments with organisms indicate that biological changes occur 
in microgravity, or the near-weightlessness of orbital space flight. 
The immune system may become suppressed and some bacteria may become 
more virulent when exposed to weightlessness. A suppressed immune 
system and more virulent bacteria create a hazardous situation and is 
reason for further investigation.

Scientists agree that the immune system has the ability to recognize 
potential pathogens, or disease-causing organisms in the body. 
Although there are two types of immune responses, this experiment 
focuses on the innate response, because of similarities between human 
and Drosophila innate immune system functions. The innate response 
produces blood cells, called hemoctyes, which can engulf the foreign 
invaders or produce chemicals to neutralize them. 

"When the phagocytes are activated, the body produces a higher blood 
cell count or increased levels of peptide proteins in the blood," 
Bhattacharya explained. To test the effects of space flight on the 
Drosophila immune system, scientists will quantify the blood count 
and the level of protein peptides after the flight and compare them 
with a control group maintained on Earth.

The STS-121 mission is scheduled to last 12 days, and each day’s 
progress will provide valuable information to help scientists 
understand space biology and how various biological systems work. 
Characteristics that make the fruit fly an ideal specimen are its 
ability to reproduce quickly; its short life span and resulting 
accelerated maturity rate; and a minimal resource requirement to 
support a large number of specimens in space. This allows for 
thousands of flies to be bred under space conditions.

During pre-flight operations, genetically identical fruit flies will 
be divided into two groups: a control group kept on Earth and a space 
flight group. External conditions for both groups will be kept 
identical in terms of temperature, humidity, food source and living 
quarters. This will allow a direct comparison of the space-bred flies 
with the Earth-bred control flies to determine changes induced by 
prolonged spaceflight.

Over the course of the experiment, these flies will undergo a complete 
metamorphosis and produce a second generation. The second generation 
will have matured from embryo to larva to adult entirely in a 
microgravity environment. As adults, they will make the descent to 
Earth, and a crew of scientists will begin a comparative analysis 
with their cousins. 

Immediate post-flight operations are critical, due to the rate of 
biological changes of these insects. Once in the lab, both sets of 
flies will be exposed to bacteria to test their immune system 
responses. Post-flight analyses will include blood cell count, blood 
level of antimicrobial peptides, phagocytosis, and blood clotting 
ability. 

For more information about the fruit fly research project, visit: 



http://exploration.nasa.gov/programs/station/FIT.html



For information about NASA and agency programs, please visit:



http://www.nasa.gov/home

	
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