Spaceflight is hard on the body, but, even so, a new study has found that the tiny nematode (or roundworm) Caenorhabditis elegans appears to age more slowly in space than on the ground. Whether the same is true of human tissue remains to be seen, although many genes in the millimeter-long worm have analogues in our own bodies (a reason C. elegans is often used as a simplified model organism for studying humans and other complex species).
In 2004, researchers sent colonies of C. elegans to the International Space Station (ISS), to see how the worms fared in low Earth orbit. A new analysis of those worms by researchers in Japan and England has found that the trip to space inactivated seven genes that have been shown to extend life when shut down. The genes appear to play a part in the worms’ systems of neuronal and hormonal signaling, and the response of those systems to being in space may have led to the slowed aging. The work appeared online July 5 in the open-access journal Scientific Reports. (Scientific Reports and Scientific American are both parts of Nature Publishing Group.)
Now, there are some caveats. For starters, a prior study found that spaceflight adversely affected muscle development in C. elegans. And the researchers stop short of claiming that the worms’ lives were definitively extended by their time in space. (In fact, both the astro-worms and a control population on the ground were flash-frozen in liquid nitrogen at the end of the 10-day spaceflight, so all the worms died at the same time.) The genes whose activity was diminished in space have only been shown to boost longevity in lab studies on the ground. But the study’s authors did find that an aging biomarker—a fluorescent-tagged polyglutamine protein that tends to accumulate over time—was less prevalent in space-flown worms.
The researchers note that they don’t yet know which aspect (or aspects) of the space environment caused the genetic changes. Was it the microgravity of the ISS? The increased radiation doses endured during spaceflight? One way to distinguish between the two would be to fly worms in space inside a centrifuge that simulates the gravitational forces organisms feel on Earth.
For now, though, it’s looking like the nematodes might be gifted with certain genetic attributes that benefit them in space. If only we could train worms to take pictures from orbit or make repairs to the Hubble Space Telescope, NASA could get out of the astronaut business entirely.