Living for periods at low gravity may alter your DNA, according to a new study of worms aboard the International Space Station (ISS).
The Caenorhabditis elegans worms – animals with a length of 1mm and a life expectancy of two weeks – showed alterations in an estimated 1,000 genes. While most changes were subtle, scientists noticed microgravity had a stronger effect on genes associated with the nervous and immune systems.
As they share several physiological features and muscle genes with humans, it's hoped the worms can provide a better understanding of how periods in low gravity impact astronauts.
“These changes might help explain why the body reacts badly to space flight. It also gives us some therapy targets in terms of reducing these health effects, which are currently a major barrier to deep-space exploration,” said the University of Exeter’s Dr Timothy Etheridge, one of the lead researchers on the new project.
After being hatched on the ISS, the tiny worms were kept in flasks of liquid (containing bacterial food) for 4 or 10 days. They were then frozen and examined after their return to Earth using DNA microarrays, tools which can scan a collection of genes.
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Spending long periods in microgravity has been previously shown to drastically alter the human body. Although dedicating several hours a day to exercise, astronauts can lose up to 40 per cent of their muscle mass after 180 days on the ISS. This is a significant problem considering it could take future manned missions to Mars 10 months to reach the surface.
During the acceleration of lift-off and landing, astronauts are also briefly exposed to hypergravity, forces of gravity greater than those found in normal Earth conditions. By placing more worms in a centrifuge, the new study indicated spending four days in gravity 15 times stronger that of Earth could alter around 1,360 genes. Similar to microgravity, genes impacting the immune system were most affected.
Fortunately, astronauts are unlikely to spend several days in such levels of hypergravity, unless flying close to objects such as the Sun or sharply accelerating for long periods (roughly by 330mph each second).
Q&A: How big does something have to be for gravity to act on it?
Everything is affected by gravity, regardless of size – even particles of light. This makes gravity unique among all the fundamental forces of the Universe – and also causes theorists enormous problems. And that’s because gravity also acts on itself, causing runaway ‘feedback loops’ in their equations making them tricky to solve.
But gravity is also the weakest of the fundamental forces, and so in many everyday situations its effects are small enough to be ignored. For example, the shapes of solid objects as big as mountains are dictated principally by the chemical bonds between their constituent molecules, rather than their own gravity. In general, gravity only begins to dictate the overall shape of objects bigger than several hundred kilometres in size – such as small moons and asteroids.
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