system can be used as a biodosimeter because DNA damage generated by space radiation is
thought to accumulate in the preserved cells during the mission.
Certain cell samples were incubated for 8 days under
1G or microgravity in a CO 2 incubator, then refrozen,
returned to Earth, and compared to ground control
samples to determine the influence of microgravity on
cell survival and mutation induction. The results for
both conditions varied from experiment to experiment,
yielding a large standard deviation, but the microgravity
sample results differed significantly from the 1G sample
results for each of 2 experiments, with the mean ratio
of microgravity to 1G being 0.55 for the concentration
of viable cells and 0.59 for the fraction of TK- mutants.
Among the^ mutants, point mutations were less
frequent (31%) after microgravity incubation than after
1G incubation, which might be explained by the
influence of microgravity on cellular metabolic or
physiological function. Additional experiments are
needed to clarify the effect of microgravity interferes
on DNA repair.
PUBLICATION(S)
Yatagai F, Honma M, Ukai A, et al. Preliminary results of space experiment: Implications for the
effects of space radiation and microgravity on survival and mutation induction in human cells.
Advances in Space Research. 2012;49(3):479-486. doi: 10.1016/j.asr.2011.10.015.
Yatagai F, Honma M, Takahashi A, et al. Frozen human cells can record radiation damage
accumulated during spaceflight: Mutation indction and radioadaptation. Radiation and
Environmental Biophysics. 2010;50(1):125-134. doi: 10.1007/s00411-010-0348-3.
Gordon A, Halliday JA, Blankschien MD, Burns PA, Yatagai F, Herman C. Transcriptional infidelity
promotes heritable phenotypic change in a bistable gene network. PLOS Biology.
2009;7(2):e1000044. doi: 10.1371/journal.pbio.1000044.
Yatagai F, Takahashi A, Honma M, et al. LOH analyses for biological effects of space radiation:
Human cell culture in Kibo of International Space Station. Biological Sciences in Space.
2009;23(1):11-16. doi: 10.2187/bss.23.11.
This investigation is complete and all results are published.
Detection of LOH by color-changing of
culture medium on 96-well microplate.
The frozen cells returned from ISS were
cultured at 37 °C in a CO 2 incubator. After
2-3 days, the exponentially growing cells
were plated in each well of a fresh 96-well
plate by the limiting dilution method. The
medium color of the cells lost
heterozygosity, changes to yellow from red
after incubating cells on 96-well microplate
for 2 weeks. JAXA image.