Pretty much since the dawn of the Space Age, scientists have come up with ingenious ways to test the effects of G forces and microgravity on the human body, right down to amusement park rides. One of the mechanisms used by the Apollo program was the dreaded human centerfuge; a 10×6 foot hollow sphere mounted on the end of a 50-foot arm that spun around rapidly to simulate "dynamic flight."

Astronaut John Glenn memorably described it as "dreaded" and "sadistic" in his memoir, adding, "You were straining every muscle of your body to the maximum.... If you even thought of easing up, your vision would narrow like a set of blinders and you'd start to black out." It was kind of a baptism by fire.

NASA has long since discontinued the use of centrifuges, although the US Air Force still operates a human centrifuge at its base in New Mexico. And their use aboard spacecraft has been proposed as a means of simulating gravity for long-duration manned space missions of the future, thereby reducing the effects of microgravity on astronauts (notably bone decalcification and muscle atrophy).

And now centrifuges are being used, apparently, to subject other creatures to the same conditions. A new paper by a team of US and Russian scientists that appeared this week on PLoS investigated the effects of microgravity on, well, snails. You heard me. Snails.

Blogger Scicurious summed up the many advantages of snails in space that the authors outlined in their paper: "They don't eat much, they take up very little space so you'll still be under your weight limit, they can easily stay active.... They don't get bored and tear up the joint." In short, "Snails make great little astronauts."

Snails have a very similar mechanism for balance and motion detection. Human beings have a full-fledged vestibular system in their ears, but snails have something called a scatocyst. It's a tiny piece of calcium carbonate inside the snail that moves around as the snail changes its orientation. This change is detected by hairs called setae, which then signal the brain so the snail can re-orient itself to gravity.

It's only natural to wonder, given the similar mechanism, how snails respond to being in the microgravity of space, and that's what the US/Russian team set out to learn. They got a bunch of snails, sent half to space for a bit and kept the other half earthbound as a control.

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When the space-bound snails returned home, they put both groups onto a wire mesh and tilted it 180 degrees - pretty much what happens in nature when a snail's weight bends the leaf upon which it is oozing its way along. That change in orientation is detected by the scatocyst and the snail knows to turn itself around and retreat before it falls off the leaf.

The scientists found that the snails who'd been to space reoriented themselves and turned around much more quickly than the Earth-bound snails. Apparently it's because their setae were much quicker to respond to changes in orientation, i.e., when the mesh screen was tilted. (That response was measured by sticking electrodes into the poor snails - is there no such thing as a Gastropod Geneva Convention?)

To figure out the mechanism, the team of researchers took a page from NASA's playback: they put the space snails into a centrifuge. I'll let Scicurious sum up what they found:

When they looked at gene expression, the space snails had more hPEP in their statocyst receptors, which is a protein that is stimulated under "load", meaning when the cells are stimulated by the calcium carbonate falling against them, indicating the tilt of the snail. The space snails had more staining, indicating they had undergone a lot of "tilt" in space. And thus might be more sensitive to further tilt.

So I guess snails are not the worst potential astronauts in the animal kingdom. They're probably better than cats:

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