Nematodes that orbited Earth had reduced signs of aging

By Tina Hesman Saey

Web edition: July 5, 2012
Print edition: August 11, 2012; Vol.182 #3 (p. 16)

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TELL-TALE SIGN OF AGING

Tiny worms that spent time in space (like the one shown here) have fewer clumps of aging-related proteins (green) than worms that stayed on the ground. That could mean that worms live longer in microgravity.

Credit: Richard Morimoto/Northwestern Univ.

In space they can barely see you age, at least if you’re a worm.

Tiny, transparent nematodes that spent 11 days on the International Space Station — the equivalent of about 16 years for a person — appeared to age much more slowly than earthbound worms, Yoko Honda of the Tokyo Metropolitan Institute of Gerontology and colleagues report online July 5 in Scientific Reports.  

The result is the opposite of what some scientists expected, based on experience with human spaceflight and studies of other animals. Mammals, including people, in the microgravity of space are under physiological stress, says D. Marshall Porterfield, director of NASA’s Space Life and Physical Sciences Research and Applications Division in Greenbelt, Md. In low gravity, muscles atrophy and aging accelerates.

While the space station worms, from the species Caenorhabditis elegans, may have been under stress, they didn’t have those side effects. Their muscles did not degrade, and clumps of aging-related proteins known as Q35 aggregates did not build up in them as much as in worms on the ground, indicating that worms don’t age as fast in space as on Earth. Worms that visited the space station were frozen immediately after returning to Earth, so the researchers weren’t able to test whether time in space enabled the critters to live longer.

The researchers also discovered that relative to ground-based nematodes, the space-faring worms had lower activity of 199 genes, including 11 genes involved in transmitting information through the nervous or endocrine systems. For seven of the 11 genes, mutations that lowered the genes’ activity also caused ground-based worms in a separate experiment to live longer.

Reduced activity of three of the life-extending genes — called gar-3, cha-1 and shk-1 — also lowered the number of Q35 clumps that built up in aging worms. Those genes encode proteins that are produced in the nervous system, and two of them also encode proteins that are made in muscles. 

Lowering the levels of those proteins during spaceflight might affect how worms perceive their environment, leading the nematodes to reduce their metabolism and extend their life spans, says Catharine Conley, NASA’s planetary protection officer. Conley helped develop the substance that worms grow in while in space.

Studying worms in space may help scientists learn more about how low gravity affects organisms, regardless of the impact on life span, Porterfield says. “It doesn’t really matter what the outcome is if we learn about the biophysical environment,” he says. That knowledge may help engineers design ways of better protecting the health of astronauts.