Scientists 'extremely surprised' after flatworm grows 2nd head in space
Biologists at Tufts University in Massachusetts sent a bunch of flatworms to space for five weeks just to see what would happen, and were taken aback by the results.
"This one worm, due to its space travel experience, the cells got confused, and grew a head at the posterior end," biologist Michael Levin, co-author of the study, told As It Happens host Carol Off.
The researchers sent a group of planarian flatworms — some amputated and some whole — to the International Space Station aboard a SpaceX commercial resupply vessel on Jan. 10, 2015, to find out how the experience would affect their regenerative abilities.
One of the dissected worms came back with an extra pair of googly eyes.
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"We were extremely surprised," Levin said. "It's quite a change to their normal regenerative pattern, so we knew something important had happened to it up in space."
While flatworms are known for the ability to re-grow their heads and tails, the spontaneous generation a second head is so rare it's almost unheard of. Under normal circumstances, the worm would have simply generated a new tail.
Levin says he's seen two-headed worms before. In fact, he's made some in his lab. But it's not something that occurs naturally.
"So we knew it was possible," he said. "We had no idea this would happen from space travel."
The change appears to be permanent. The scientists have since cut off both the creature's heads, and it grew them both back.
"As it turns out, the two-headedness is just the tip of the iceberg, because we also found out that these worms were different with respect to their microbiomes, their behaviour, and so on," he said.
When the worms returned to Earth, scientists took them out of their five-week-old water and put them in a petri dish with fresh water.
The worms went into "water shock," curling up and refusing to move for about two hours — something that would normally only happen if they'd been placed in an unfamiliar solution.
"So something happened to that water in space, which they obviously got used to," Levin said.
They also got over their natural fear of light.
Levin's team observed the space worms in their lab 20 months after they returned to Earth, comparing their bodies and behaviours to a group of worms that never left the planet.
When exposed to light in the petri dish, the space worms did not seek out darker corners, as other worms did.
"So their behaviour had changed and enabled them to spend more time in the light, Levin said.
"This we measured about a year and a half after the worms had come back. So they had already been in our lab, eating the same foods and living in the same environment as the Earth-bound controls for well over a year, and still their behaviour was still altered."
The worms had also changed on a fundamental, biological level.
"We found out that even a year-and-a-half later, the complement of bacteria and the profile of different bacterial species that live in these worms is now quite a bit different between the ones that had been to space and the ones that had been left behind," Levin said.
It's not entirely clear what caused these changes, but there are numerous possibilities.
"I mean these worms have been through basically the space travel experience, and the space travel experience is not one thing," Levin said, noting they expected changes in vibrations, the gravitational field, the geomagnetic field and more.
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While it would be unwise to compare worms to astronauts — so far, Chris Hadfield has not grown any new limbs that we know of — the results of the study could shed some light on how space travel affects us on a cellular level, Levin said.
What's more, the team's findings could have implications a little closer to home.
"Part of the importance of these kinds of experiments is not just for space travel, but for learning about how physical factors like geomagnetic fields, like gravitational forces and so on, how these affect cell behaviours," Levin said.
"We may be able to exploit those for regenerative medicine applications here on Earth."
The study was published Tuesday in the journal Regeneration.