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Tanaka S, Sagara H, Kunieda.

Water Bears’ DNA Makes Them Practically Indestructible

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Tanaka S, Sagara H, Kunieda.

Burn it. Freeze it. Chuck it into space. Water bear don’t care. The water bear, also known as the tardigrade or moss piglet, is one of the weirdest and toughest creatures on the planet. Now new research published in the journal Nature Communications suggests we might someday be able to borrow its resilience to use in our own flimsy, floppy bodies.

Tardigrades are extremophiles—that is, they can keep trucking in unbelievably hostile environments, from scorching deserts to the vacuum of space. This astonishing near-indestructibility has, understandably, made them especially appealing to scientists, who have been working for years to pick apart the genetic basis of the microscopic creatures’ badassery. But the more we learn about these creatures, the weirder they seem to get.

In 2015, a group of researchers reported one possible source of the tardigrade’s toughness: burglary. While looking at the genome of the tardigrade species Hypsibius dujardini, the team said they found all kinds of genes that belonged to other organisms, including fungi and bacteria. Horizontal gene transfer (when one organism swipes genes from another) is not unheard of, but H. dujardini appeared to have taken it to the next level, with a full 17 percent of its genes yoinked from other species.

Even for the moss piglet, this seemed kind of, well, extreme. When other scientists tried to replicate the original team’s results, they found only tiny amounts of horizontal gene transfer—about 1 or 2 percent. They said the original team’s samples had likely been contaminated. #tardigate ensued. The tardigrade remained a tiny, scrappy enigma.

Scientists kept at it. The latest research, published today, may have cracked some of the mystery. Researchers in Japan examined the genome of an especially hardy water bear named Ramazzottius varieornatus. In comparing the tardigrade’s genetic codes with those of worms and flies, they found way more genes related to surviving stressful conditions.

In the video below, by researcher Daiki D. Horikawa, you can see R. varieornatus encounter one stressful condition: a lack of water. The tardigrade dries out and shrinks up, seemingly dead. But it isn't. Given a drop of water, it plumps right up, stretches its little legs, and begins to move around.

Then the team took the study to the next level. They found a resilience-boosting protein they called Damage suppressor (Dsup) that appears to be completely unique to tardigrades. Then they inserted Dsup into human cells, which then became more resistant to damage from x-ray radiation.

There’s a lot here to get excited about, says Sujai Kumar, a genome informatician at the University of Edinburgh and a co-author on the #tardigate-triggering study. “The Japanese team's genome sequencing methodology is exemplary,” he tells mental_floss. The depth and breadth of their investigation have yielded a huge quantity of information that will continue to help other researchers unravel the tardigrade mystery.

Even better, Kumar says, were the Japanese researchers’ “really cool” studies in human cells. “Although not quite at the level of a superheroine origin story,” he says, “this is a great example of a gene from an extremotolerant species conferring a 'super power' to a human cell, and is an exciting finding.”

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This Octopus Species in Northern Australia Can Hunt on Dry Land
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Most octopuses live in the ocean—but in northern Australia, a small, shallow-water species takes to land in search of food. Abdopus aculeatus is the only octopus that’s specially adapted to walk on dry ground. Using its long, sucker-lined arms, the slimy sea creature pulls itself along the shoreline as it searches tide pools for crabs.

Witness Abdopus aculeatus in action by watching BBC Earth’s video below.

[h/t BBC Earth]

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Weather Watch
Rising Temperatures Are Killing Off African Wild Dogs
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Over the last few decades, images of fluffy white harp seals, polar bears, and penguins have become shorthand for climate change's creeping destruction of our planet. But the poles aren't the only ecosystems in danger. A new study published in the Journal of Animal Ecology finds that rising temperatures near the equator are making it much harder for African wild dogs to survive.

"When people think about climate change affecting wildlife, they mostly think about polar bears," lead researcher Rosie Woodroffe of the Zoological Society of London told The Guardian. "But wild dogs are adapted to the heat—surely they'd be fine."

To find out, Woodroffe and her colleagues analyzed data from packs of African wild dogs (Lycaon pictus) in Kenya, Botswana, and Zimbabwe. The dog packs have been under scientist surveillance for years—some since the late 1980s—and at least one dog per pack is fitted with a radio collar.

The researchers overlaid information about local weather and temperature with data on the dogs' hunting habits, the size of each litter of pups, and how many pups from each litter survived.

These dogs are creatures of habit. Adults rise early and leave the den for a morning hunt. They range over their large territories, chasing antelopes. At midday, when the Sun is highest, they return to their pups with food. They may go out again in the evening as the temperature drops.

But like the polar bears' glaciers, the dogs' environment is gradually heating up. All three countries saw a temperature increase of about 1.8°F over the study period. This may not sound like much, but for the dogs, it was plenty. Between 1989 and 2012, the number of pups per litter in Botswana surviving to their first birthday dropped from 5.1 to 3.3. Dog packs in Zimbabwe saw a 14 percent decrease in pup survival; in Kenya, the rate declined by 31 percent.

"It's really scary," Woodroffe said.

"If you are an animal who makes your living by running around really fast, obviously you are going to get hot. But there are not enough hours in the day anymore that are cool enough to do that. It is possible that some of these big areas will become too hot for wild dogs to exist."

Woodroffe and her colleagues were not anticipating such clear-cut results. "It is shocking and surprising that even right on the equator these effects are being seen," she said. "It illustrates the global impact of climate change." 

[h/t The Guardian]


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