Manuscript versionPrevious experiments in space (unmanned satellites,
space shuttle and the International Space Station, ISS),
have shown that adult Drosophila flies change their
motile behaviour in microgravity. A consistent increase
in motility in space was found in these experiments, but
mature flies (two weeks old) showed less increase than
recently hatched flies. In the case of relatively long
exposure to microgravity, the aging of male flies
measured upon return to Earth was increased, with flies
dying earlier than the corresponding in-flight 1g
centrifuge or ground controls. The older flies, which
experienced a smaller increase in motility, did not show
this acceleration in the aging process. More recently we
have performed comparative experiments using ground
simulation facilities. Preliminary experiments using a
random positioning machine (RPM) indicate that the
effects of this simulation approach on the behavior of
Drosophi l a a r e o f s m a l l e r m a g n i t u d e t h a n t h e
corresponding exposure to real microgravity. Further
experiments are in progress to confirm this effect.
However, when exposed to magnetic levitation, flies
exposed to simulated weightlessness increased
markedly their motile behavior compared with 1g
controls both inside and outside the magnet. This altered
gravity-related increase in motility was also less
pronounced in more mature flies. This motility effect at
the levitation position reproduces the results in real
microgravity indicating the interest for space science of
this simulation approach. Similar experiments are being
performed in the Larger Diameter Centrifuge (LDC)
located in ESTEC (the Netherlands) and indicate that
6g, 12g and 20g are key points in the hypergravity
response in flies. Our experiments have shown that
developmental processes from embryo to adult
proceeded normally in the magnet, the RPM and the
LDC. In terms of gene expression, preliminary results
i n d i c a t e t h a t t h e a f f e c t e d s e t o f g e n e s u n d e r
hypergravity responds in general in an opposite
direction than that induced by the real or simulated
microgravity exposure. The interest in conducting
comparative parallel experiments in the complete
spectrum of ground simulation methods is shown in the
above studies and will be achieved in the near future.Peer reviewe