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Space Travel Causes Liver Damage in Mice

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Don’t book that trip to Mars just yet: According to a study recently published in the journal PLOS ONE, a quick trip aboard the space shuttle was enough to cause liver disease in mice.

As space technology races ahead, doctors and scientists scurry along, trying to ensure that our travelers will be safe. We know that returning astronauts often experience dizziness, vision problems, weakened immune systems, and more. Yet somehow the liver—which is kind of an important organ—had been more or less ignored. To physicist and biomedical researcher Karen Johnscher of the University of Colorado, this was a pretty big oversight.

So Jonscher and her colleagues sent 15 female mice into orbit aboard STS-135, the last flight of the Space Shuttle Atlantis. Another 15 stayed on Earth as a control group. The rodents’ voyage was a short one, lasting just 13 and a half days. Once the mice had returned, the researchers euthanized all the mice, weighed them, and took samples of their livers.

These samples underwent a battery of tests, from DNA sequencing and metabolomics (looking at small molecules called metabolites) to chromatography and spectroscopy (to analyze the exact chemical makeup of the tissue samples). Sections of liver were examined under high-powered microscopes.

The differences between the two groups of mice were apparent immediately. All the mice had lost some weight, but those that had gone to space lost nearly twice as much as their counterparts on the ground—even though they’d all eaten the same amount of food. And the weight loss came from different types of tissue. Mice on the ground tended to lose more fat, while the shuttle mice lost lean muscle, which left them with a higher percentage of fat in their bodies. The traveling mice also drank 20 percent less water.

Changes were also evident in the rodents’ livers. Shuttle mice were storing more fat there, they had lower levels of Vitamin A, and the trip appeared to have activated harmful cells called hepatic stellate cells. These cells can lead to inflammation and severe fibrosis, or scarring. The mice appeared to be in the early stages of a condition called non-alcoholic fatty liver disease (NAFLD). And all this in less than two weeks.

"It generally takes a long time, months to years, to induce fibrosis in mice, even when eating an unhealthy diet," Jonscher said in a press statement. "If a mouse is showing nascent signs of fibrosis without a change in diet after 13 ½ days, what is happening to the humans?"

The researchers noted that high levels of stress can trigger hormonal changes and inflammation, and that going up in a space shuttle could certainly cause high levels of stress.

"Whether or not this is a problem is an open question," Jonscher said. "We need to look at mice involved in longer duration space flight to see if there are compensatory mechanisms that come into play that might protect them from serious damage."

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Big Questions
What's the Difference Between Gophers and Groundhogs?
Gopher or groundhog? (If you chose gopher, you're correct.)
Gopher or groundhog? (If you chose gopher, you're correct.)
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Gophers and groundhogs. Groundhogs and gophers. They're both deceptively cuddly woodland rodents that scurry through underground tunnels and chow down on plants. But whether you're a nature nerd, a Golden Gophers football fan, or planning a pre-spring trip to Punxsutawney, Pennsylvania, you might want to know the difference between groundhogs and gophers.

Despite their similar appearances and burrowing habits, groundhogs and gophers don't have a whole lot in common—they don't even belong to the same family. For example, gophers belong to the family Geomyidae, a group that includes pocket gophers (sometimes referred to as "true" gophers), kangaroo rats, and pocket mice.

Groundhogs, meanwhile, are members of the Sciuridae (meaning shadow-tail) family and belong to the genus Marmota. Marmots are diurnal ground squirrels, Daniel Blumstein, a UCLA biologist and marmot expert, tells Mental Floss. "There are 15 species of marmot, and groundhogs are one of them," he explains.

Science aside, there are plenty of other visible differences between the two animals. Gophers, for example, have hairless tails, protruding yellow or brownish teeth, and fur-lined cheek pockets for storing food—all traits that make them different from groundhogs. The feet of gophers are often pink, while groundhogs have brown or black feet. And while the tiny gopher tends to weigh around two or so pounds, groundhogs can grow to around 13 pounds.

While both types of rodent eat mostly vegetation, gophers prefer roots and tubers (much to the dismay of gardeners trying to plant new specimens), while groundhogs like vegetation and fruits. This means that the former animals rarely emerge from their burrows, while the latter are more commonly seen out and about.

Groundhogs "have burrows underground they use for safety, and they hibernate in their burrows," Blumstein says. "They're active during the day above ground, eating a variety of plants and running back to their burrows to safety. If it's too hot, they'll go back into their burrow. If the weather gets crappy, they'll go back into their burrow during the day as well."

But that doesn't necessarily mean that gophers are the more reclusive of the two, as groundhogs famously hibernate during the winter. Gophers, on the other hand, remain active—and wreck lawns—year-round.

"What's really interesting is if you go to a place where there's gophers, in the spring, what you'll see are what is called eskers," or winding mounds of soil, Blumstein says [PDF]. "Basically, they dig all winter long through the earth, but then they tunnel through snow, and they leave dirt in these snow tunnels."

If all this rodent talk has you now thinking about woodchucks and other woodland creatures, know that groundhogs have plenty of nicknames, including "whistle-pig" and "woodchuck," while the only nicknames for gophers appear to be bitter monikers coined by Wisconsin Badgers fans.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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Animals
Watch Christmas Island’s Annual Crab Migration on Google Street View
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Google

Every year, the 45 million or so red crabs on the remote Australian territory of Christmas Island migrate en masse from their forest burrows down to the ocean to mate, and so the female crabs can release their eggs into the sea to hatch. The migration starts during the fall, and the number of crabs on the beach often peaks in December. This year, you don’t have to be on Christmas Island to witness the spectacular crustacean event, as New Atlas reports. You can see it on Google Street View.

Watching the sheer density of crabs scuttling across roads, boardwalks, and beaches is a rare visual treat. According to the Google blog, this year’s crabtacular finale is forecasted for December 16, and Parks Australia crab expert Alasdair Grigg will be there with the Street View Trekker to capture it. That is likely to be the day when crab populations on the beaches will be at their peak, giving you the best view of the action.

Crabs scuttle across the forest floor while a man with a Google Street View Trekker walks behind them.
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Google Street View is already a repository for a number of armchair travel experiences. You can digitally explore remote locations in Antarctica, recreations of ancient cities, and even the International Space Station. You can essentially see the whole world without ever logging off your computer.

Sadly, because Street View isn’t live, you won’t be able to see the migration as it happens. The image collection won’t be available until sometime in early 2018. But it’ll be worth the wait, we promise. For a sneak preview, watch Parks Australia’s video of the 2012 event here.

[h/t New Atlas]

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