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A Study of the Effects of Space Flight on the Immune Response in Drosophila melanogaster    Thomas F. Fahlen1, Max Sanchez1, Jennifer Chang1, June Sunga1, Matt Lera2 and Sharmila Bhattacharya3
1Lockheed Martin Space Operations,NASA Ames Research Center,  Mail Stop N261-2,     2Education Associates Program, NASA Ames Research Center, Mail Stop N261-2 

3NASA Ames Research Center, Mail Stop 236-5
   Drosophila melanogaster (fruit fly) is a small, highly tractable and well-characterized organism that is ideal for the study of molecular, cellular, developmental, and physiological processes.  Many of these processes are very similar to those in humans, which makes the fruit fly an excellent model organism.  In our lab we are using D. melanogaster to study the biological effects of hyper-gravity, hypo-gravity, and radiation.  We present here the ground testing used to develop our experiment aboard the Space Shuttle.
   We will fly D. melanogaster aboard the Space Shuttle and will assess the function of the immune system through bacterial challenge, phagocytosis, and transcriptional assays in the future.  In order to do so, we have verified that the planned growth conditions for the flight will support D. melanogaster containment, culture, and reproduction and these data are presented here. In baseline testing, bacterial clearance assays show significant reduction in bacterial load at 5 days post infection that is coincident with increases in mRNA for the antimicrobial peptides Attacin, Drosomycin and Diptericin.  In the future, a comparison will be made between flown samples and ground controls.  An important component of the D. melanogaster immune system is the blood cell (hemocyte) which behaves similarly to the macrophage in humans.  The strain chosen for the flight ( hml-GFP) features GFP labeled hemocytes that allow identification and quantification of these important immune cells for comparison to ground controls. In addition, we have developed a fixation procedure that will allow preservation of flown tissues for subsequent phenotypic assays such as antibody staining.