Spaceflight Increases Lifespan of Worms with Genes Similar to Humans
One of unknown factors in long-term space flight is the effect on the human body of very little gravity for long periods of time. Astronauts have shown that time in space can lead to bone and muscle loss, but scientists studying this very phenomenon have found that worms living in microgravity actually have a longer lifespan than expected.
The researchers sent a small colony of Caenorhabditis elegans worms on an 11-day journey to the International Space Station and back and upon their return, compared them with a control group on Earth.
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They found that spaceflight suppressed the accumulation of toxic proteins that normally plague aging muscles. They also identified a group of genes that are expressed - or activated to create proteins - at lower levels while in microgravity. When the expression of these same genes were lowered in worms back on Earth, the worms lived longer.
"We are not entirely certain, but it would appear that these genes are involved in how the worm senses the environment and signals changes in metabolism in order to adapt to the environment. For example, one of the genes we have identified encodes insulin which, because of diabetes, is well known to be associated with metabolic control. In worms, flies, and mice insulin is also associated with modulation of lifespan," said Nathaniel Szewczyk, an expert in muscle metabolism from The University of Nottingham who was part of the project.
C. elegans are a hearty but simple species routinely used to study the effect of spaceflight on humans. According to Discovery News, C. elegans was the first multi-cellular organism to have its genetic structure completely mapped. These worm possess 20,000 genes, many of which perform similar functions as equivalent genes in humans. Of particular interest are the 2,000 genes that have a role in promoting muscle function.
They have been taken as cargo on several flights to the ISS, and even survived the space shuttle Columbia disaster in 2003. They were found weeks later after making it through re-entry and impact on the ground in petri dishes enclosed in aluminium canisters.
The findings show that while exposure to microgravity can degrade muscles, the body may be able to compensate.
"Most of us know that muscle tends to shrink in space," Szewczyk told BBC News. "These latest results suggest that this is almost certainly an adaptive response rather than a pathological one."
"Counter-intuitively, muscle in space may age better than on Earth. It may also be that spaceflight slows the process of ageing," he said.
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