"Many of the genes whose activity was down-regulated in the space-flown mice play important roles in maintaining that balance," Lebsack said. "Potentially, you could get more cell death aboard a spacecraft because of these differences."
The results fit in with experiments carried out on the ground to study how microgravity affects immune cells. In these experiments, scientists mimicked weightlessness using clinostats - apparatuses that slowly rotate the study object so the Earth's gravitational pull is never perceived as coming from one consistent direction.
"Previous studies with cell cultures in clinostats showed increased cell death in T-cells when you take away the gravity stimulus," said Lebsack, "so it was a logical step to test whether we find the same effects in animals exposed to an actual lack of gravity."
"We observed an overall pattern about the genes whose expression was changed by space flight: All of them are involved, in one way or another, in the development, control and programmed cell death of immune cells."
This study represents the first use of microarray technology to investigate gene expression in thymus tissue of space-flown mice, according to the authors. Complex research undertakings like this require specialists combining their different areas of expertise.
Lebsack worked with research specialist Jose Munoz-Rodriguez at the Arizona Genomics Core Microarray Facility to compare and analyze the activity levels of thousands of genes in thymus tissue from the space-flown mice and the control group. The vast amount of data generated in this process were then processed with input from David Mount, who heads the Informatics/Bioinformatics Shared Service, and graduate student Ann Manziello, who is a co-author on the stu
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University of Arizona