Worms have shown they can live and reproduce in space -- raising the possibility of remotely raising animals in space and other planets and possibly even paving the way for humans to someday take refuge beyond Earth.
Twelve consecutive generations of worms have been successfully raised aboard the International Space Station, according to a new study that is the first to show that relatively long-term space travel in low Earth orbit does not harm the production of progeny and other basic life activities -- at least for the worm Caenorhabditis elegans.
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For now, the worm is serving as the proverbial guinea pig for what might happen to humans and other animals living in space over multiple generations.
"Clearly worms are not people," said Nathaniel Szewczyk, an associate professor in the Division of Clinical Physiology at The University of Nottingham, told Discovery News. "Yet C. elegans and man have roughly the same size genome and as many as 50 percent of genes are conserved or identical between this worm and man."
"The main reason for studying worms is that it is faster and easier to study them than man," added Szewczyk, who co-authored a study about the worms in the latest issue of the Journal of the Royal Society Interface.
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This particular worm species was the first multi-cellular organism to have its genetic structure completely mapped. Many of its 20,000 genes perform the same functions as those in humans, so geneticists and medical experts often use it for investigations relevant to human biology and health.
For the new study, Szewczyk and his colleagues blasted 4,000 C. elegans into space on board the International Space Station. The worms were housed in a contained system that permitted the scientists to observe them remotely, with no one even touching the organisms over the six-month voyage. For three of those months, the researchers were able successfully monitor the effect of low Earth orbit on a dozen worm generations.
While the space station provides an artificial environment that attempts to mimic the natural one of Earth, it can never precisely match conditions here. Szewczyk pointed out that gravity aboard the orbiting station is one tenth of that on Earth. It also receives 10 times the radiation exposure of what's experienced on Earth's surface.
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Despite how these possible differences might have affected the worms, they seemed to do just fine.
"Essentially the worms that were on the station appeared normal and healthy, albeit with adaptations to growth on the station," Szewczyk said. "When returned to Earth, they similarly had an adaptation period beyond which they appeared normal and healthy. For example, some of the worms post flight were more susceptible to infection, but this resolved soon after return."
Given this success, the researchers want to carry out similar experiments elsewhere, with the ultimate goal of learning if human colonization of other planets would be possible. The paper mentions that such a science fiction thought may become a necessity, mitigating against "Earth's periodic global extinction events," the next Ice Age, and other potentially devastating occurrences.
"We would love to send worms to places like Mars and/or other planets," Szewczyk said. "The key challenge, and a major goal of this publication, is to convince governments and/or funding agencies that this can and should be done. From our perspective, the specific destination is not important. Rather, traveling beyond the Van Allen belts and especially for three to six months beyond this is key."
"Nowadays, we know the effect of microgravity on organisms, including human astronauts, for several months," said Atsushi Higashitani, a professor in the Graduate School of Life Sciences at Tohoku University.
He added that "remote automated multi-generational growth (of other species) is very important to study the molecular effect of microgravity on genetic inheritance, including mutations and epigenetic controls, beyond a (single) generation."
Szewczyk and his team are already at work on another related paper, which will explain a mechanism by which muscles affected by space travel can repair themselves.