Using powerful magnets to levitate fruit flies can provide vital clues to how biological organisms are affected by weightless conditions in space, researchers say.
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SYDNEY: The weightlessness of space has been reproduced in insects using high-powered magnets.
Taking advantage of a fundamental magnetic property of atoms, a team of scientists from the University of Nottingham in England and the Centro de Investigaciones Biologicas in Madrid, Spain has offered a solution to the major stumbling block of performing experiments in a weightless environment: needing to be in outer space.
By moving the flies to different positions in a magnetic field, the researchers were able to simulate gravities between zero-g and 2g (twice the Earth's gravity conditions), enabling them to simulate the gravity on the Moon or Mars.
"The really exciting thing with this technique is that we can reproduce the effects of weightlessness on a biological organism without having to go into space, using a facility on the ground," said Richard Hill, co-author of the paper published in a recent issue of the Royal Society journal Interface, and senior research fellow at the University of Nottingham.
Recreating weightlessness in space
Exposure to weightlessness in space has a wide range of effects on biological systems. In humans this can be short-term illness such as space adaption syndrome, or more serious long-term loss of muscle mass and weakening of the immune system. As a result, investigating the effects of weightlessness has become an important issue when considering space travel for long periods of time.
But the study of weightlessness is a costly process, and the stresses that come with a rocket launch often negatively affect the experiments. The researchers involved in the study have found a way to reproduce the weightlessness of space on Earth using magnetic fields and a property of objects known as diamagnetism. Diamagnetism is present in all materials to various degrees. What this means is that if you place something in a strong enough magnetic field, it will be repelled by that magnetic field. In living things, the magnetic field required to produce this repulsion is incredibly large.
To levitate the fruit flies required a field of 16 Tesla: around 350,000 times stronger than the strength of the Earth's magnetic field. When the scientists placed the flies in the field they observed that the flies walked faster, a result also observed in similar experiments on the International Space Station.
Simulating low gravity
The reason behind the flies' brisk pace in low gravity isn't yet completely clear, though one theory presented by the researchers states that it could simply be due to the lower gravity requiring less energy to move a limb. This theory is supported by previous experiments from another research group that used a centrifuge to produce a higher gravity, causing the flies to walk slower.
Peter Christianen, a researcher at the High Field Magnet Laboratory at Radboud University in the Netherlands, was enthusiastic about the prospects of the experiment. "The availability of powerful ground based methods to simulate low gravity is extremely useful to perform feasibility studies to prepare for real space experiments," he said. "This method can do more than just simulate low gravity and I am convinced that this special feature will help us enormously to identify the gravity dependent processes and/or the gravi-sensors inside biological systems."
For now, the ability to reproduce weightlessness on Earth has opened up a range of experimental options for Hill and his research associates, including the effects of long-term exposure. "By using a superconducting magnet to levitate the organisms, we can maintain levitation for weeks, or even months at a time continuously. It would be very interesting to explore the effects of weightlessness over much longer periods using this technique."
Levitating flies mimic weightlessness of space
There might be an easier, and cheaper, way to measure the effects of weightlessness. Disable a fly's flight mechanism, put it on the outside of a rotating drum, set cameras up around the perimeter every 10 degrees (36 cameras in a circle) and strobe the cameras to take an image each time the fly came in front of the each lens. Assemble the images into a movie. As the rotation rate increased, it would have the effect of decreasing gravity and one could thus measure the fly's rate of movement (and energy use) against a scale etched on the drum surface.
If the drum were made of glass or acrylic, a single movie camera could be set at the centre of rotation which would then rotate with the drum. In this way, the fly could be imaged from beneath and thus provide a different set of movement parameters as "gravity" is increased. The camera could be geared to follow the path of the fly.
Gerry Porter
gerryporter1@gmail.com
Ottawa, Canada