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Defending the Christian Worldview, Creationism, and Intelligent Design

This is my personal virtual library, where i collect information, which leads in my view to the Christian faith, creationism, and Intelligent Design as the best explanation of the origin of the physical Universe, life, and biodiversity

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Defending the Christian Worldview, Creationism, and Intelligent Design » The catalog of life » Tardigrade extremophile with superpowers

Tardigrade extremophile with superpowers

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1Tardigrade  extremophile with superpowers Empty Tardigrade extremophile with superpowers Thu Apr 10, 2014 10:00 pm



Tardigrade extremophile with superpowers

Tardigrades (also known as waterbears or moss piglets) are water-dwelling, segmented micro-animals, with eight legs. They were first described by the German pastor J.A.E. Goeze in 1773. The name Tardigrada (meaning "slow stepper") was given three years later by the Italian biologist Lazzaro Spallanzani.

Tardigrades are classified as extremophiles, organisms that can thrive in a physically or geochemically extreme condition that would be detrimental to most life on Earth. For example, tardigrades can withstand temperatures from just above absolute zero to well above the boiling point of water, pressures about six times stronger than pressures found in the deepest ocean trenches, ionizing radiation at doses hundreds of times higher than the lethal dose for a person, and the vacuum of outer space. They can go without food or water for more than 10 years, drying out to the point where they are 3% or less water, only to rehydrate, forage, and reproduce.

Usually, tardigrades are about 0.5 mm (0.020 in) long when they are fully grown. They are short and plump with four pairs of legs, each with four to eight claws also known as "disks". The animals are prevalent in mosses and lichens and feed on plant cells, algae, and small invertebrates. When collected, they may be viewed under a very-low-power microscope, making them accessible to students and amateur scientists.

Tardigrades form the phylum Tardigrada, part of the superphylum Ecdysozoa. It is an ancient group, with fossils dating from 530 million years ago, in the Cambrian period.The first tardigrades were discovered by Johann August Ephraim Goeze in 1773. Since 1778, over 1,150 tardigrade species have been found.

Lengthy water bear survival without water has caught the interest of medical workers. Vaccines with both living and nonliving components are fragile and must typically be refrigerated until used. Research efforts are exploring whether chemicals similar to trehalose sugar may stabilize the vaccines, giving them a long shelf life without cooling. Such “dry vaccines” would greatly simplify their use in remote parts of the world. The valuable drying-out feature also might be extended to the storage of tissue samples, blood platelets and stem cells. 1

Besides water bears there are other organisms which exist without water for long time periods. These include the resurrection fern and brine shrimp. The latter are popularly called “sea monkeys” when in the dried state. These plants and animals can teach us how to extend the life of medicines and other medical samples. All are examples of biomimicry the application of features designed in the Creation for our eventual discovery and benefit.

Meet the miniature water bear: nature's ultimate survivor or an alien from another planet?
"…Tardigrades are known to enter cryptobiosis at any stage of their life cycle, from egg to adult. Cryptobiosis has to be considered a form of quiescence, being directly induced and maintained by the occurrence of adverse conditions for an active life, and promptly broken once the adverse conditions are removed…In tardigrades, there are several forms of cryptobiosis: anhydrobiosis, cryobiosis, anoxybiosis and osmobiosis. Anhydrobiosis is the most studied. Entering anhydrobiosis, tardigrades contract their body into a so-called tun, loosing most of their free and bound water (>95%), synthesizing cell protectants  (e.g., trehalose, glycerol, heat shock proteins…and strongly reducing or suspending their metabolism…" (Bertolani et al. 2004:16)

"Most incredible of all, however, is the virtually indestructible nature of tardigrades while they remain in cryptobiosis. In laboratory experiments, cryptobiotic specimens have been chilled in liquid helium to -457°F (-272°C), which is only marginally above absolute zero. They have also been heated to temperatures exceeding 300°F (149°C), exposed to radiation doses far in excess of the lethal dose for humans, immersed in vats of liquid nitrogen, concentrated carbolic acid, hydrogen sulphide, brine, and pure alcohol, and even bombarded by deadly streams of electrons inside an electron microscope. Yet when removed from all of these incredibly hostile environments - which would have proven fatal for any other form of animal life - and moistened with water, these astounding creatures recovered.

They simply emerge from their cryptobiotic state, rehydrate themselves, and amble away on their four pairs of stubby claw-tipped legs, completely unharmed. Even today, the physiological mysteries behind the tardigrades' unparalleled powers of endurance during cryptobiosis remain unsolved." (Shuker 2001:113)

The marine tardigrade (Actinarctus doryphorus ocellatus) is also known as a water bear or moss piglet, names that suggest size and heft. But this creature measures less than a millimeter long.
The hardy tardigrades mostly inhabit freshwater environments and can survive in many places, from Antarctica to rainforests.

To determine the animal’s position on the phylogenetic tree of life, researchers at the University of Hamburg-Zoological Museum Hamburg in Germany homed in on its nervous system and musculature, systems that may reflect evolutionary paths. Until this imaging, tardigrades were classified using external characteristics, leaving many questions unanswered.

To get the best view, the team used a confocal laser scanning microscope, which creates sharply defined photographs with a shallow field of focus. Stacking several photographic layers, each assigned a different color, they obtained this well-defined image of the entire animal. 2

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Inside the Bizarre Genome of the World’s Toughest Animal

Tardigrades are sponges for foreign genes. Does that explain why they are famously indestructible?

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A tardigrade on its back Science Picture Co. / Corbis

The toughest animals in the world aren't bulky elephants, or cold-tolerant penguins, or even the famously durable cockroach. Instead, the champions of durability are endearing microscopic creatures called tardigrades, or water bears.

They live everywhere, from the tallest mountains to the deepest oceans, and from hot springs to Antarctic ice. They can even tolerate New York. They cope with these inhospitable environments by transforming into a nigh-indestructible state. Their adorable shuffling gaits cease. Their eight legs curl inwards. Their rotund bodies shrivel up, expelling almost all of their water and becoming a dried barrel called a “tun.” Their metabolism dwindles to near-nothingness—they are practically dead. And in skirting the edge of death, they become incredibly hard to kill.

In the tun state, tardigrades don't need food or water. They can shrug off temperatures close to absolute zero and as high as 151 degrees Celsius. They can withstand the intense pressures of the deep ocean, doses of radiation that would kill other animals, and baths of toxic solvents. And they are, to date, the only animals that have been exposed to the naked vacuum of space and lived to tell the tale—or, at least, lay viable eggs. (Their only weakness, as a researcher once told me, is “vulnerability to mechanical damage;” in other words, you can squish ‘em.)

Scientists have known for centuries about the tardigrades’ ability to dry themselves out. But a new study suggests that this ability might have contributed to their superlative endurance in a strange and roundabout way. It makes them uniquely suited to absorbing foreign genes from bacteria and other organisms—genes that now pepper their genomes to a degree unheard of for animals.

Thomas Boothby from the University of North Carolina at Chapel Hill made this discovery after sequencing the first ever tardigrade genome, to better understand how they have evolved. Of the 700 species, his team focused onHypsibius dujardini, one of the few tardigrades that’s easy to grow and breed in a lab.

At first, Boothby thought his team had done a poor job of assembling the tardigrade’s genome. The resulting data was full of genes that seemed to belong to bacteria and other organisms, not animals. “All of us thought that these were contaminants,” he says. Perhaps microbes had snuck into the samples and their DNA was intermingled with the tardigrade’s own.

But the team soon realized that these sequences are bona fide parts of the tardigrade’s genome.
By expelling their water, tardigrades have ironically become a sponge for foreign genes.
That wouldn't be unusual for bacteria, which can trade genes with each other as easily as humans might swap emails. But these “horizontal gene transfers” (HGT) are supposedly rare among animals. For the longest time, scientists believed that they didn't happen at all, and reported cases of HGT were met with extreme skepticism.

Recently, more and more examples have emerged. Ticks have antibiotic-making genes that came from bacteria. Aphids stole color genes from fungi. Wasps have turned virus genes into biological weapons. Mealybugs use genes from many different microbes to supplement their diets. A beetle kills coffee plants with a borrowed bacterial gene. Some fruit flies have entire bacterial genomes embedded in their own. And one group of genes, evocatively called Space Invaders, has repeatedly jumped between lizards, frogs, rodents, and more. But in all of these cases, it's usually one or two genes that have jumped across. At most, the immigrants make up 1 percent or so of their new native genome.

But Boothby found that foreign genes make up 17.5 percent of the tardigrade's genome—a full sixth. More than 90 percent of these come from bacteria, but others come from archaea (a distinct group of microbes), fungi, and even plants. “The number of them is pretty staggering,” he says.

Claims like these have been debunked before, so the team took extra care to confirm that the sequences did indeed come from outside sources.

For a start, they re-sequenced the genome using PacBio—a system that decodes single unbroken strands of DNA without first breaking them into smaller fragments. This revealed that the foreign genes are physically linked to the tardigrade’s native ones. They are all part of the same DNA strands, which means they couldn't have come from other contaminating microbes. They have also gained several features that are characteristic of animal genes, like an animal gloss over their fundamental bacterial character. John Logsdon from the University of Iowa, who studies genome evolution, is certainly convinced. “It’s a very interesting and technically robust paper,” he says.

So, how did these genes get into the tardigrade's genome in the first place? Boothby thinks that the answer lies in three quirks of tardigrade biology. First, they can dry themselves out, a process that naturally splits their DNA into small pieces. Second, they can stir back to life by rehydrating, during which their cells become leaky and able to take in molecules from the environment—including DNA. Finally, they are extremely good at repairing their DNA, sealing the damage that occurs when they dry out.

“So we think tardigrades are drying out, and their DNA is fragmenting along with the DNA of bacteria and organisms in the environment,” explains Boothby. “That gets into their cells when they rehydrate. And when they stitch their own genomes together, they may accidentally put in a bacterial gene.” By expelling their water, tardigrades have ironically become a sponge for foreign genes.

Do these genes do anything? So far, the team have found that the tardigrades switch on several of their borrowed genes, which, in other organisms, are involved in coping with stressful environments. That's pretty tantalizing: It suggests that these animals might owe at least part of their legendary durability to genetic donations from bacteria.

Boothby imagines something like this: Ancient tardigrades could dry themselves out to an extent, which allowed some foreign genes to enter their genome. If some of these genes made them more tolerant to drying, the animals would have become even more susceptible to horizontal gene transfers. “This positive feedback loop builds up over time,” says Boothby. “That’s speculation on our part.”

It certainly bolsters his case that another microscopic animal—a rotifer—can also dry itself out during tough times, and also shows signs of extensive horizontal gene transfer. Almost 10 percent of its genes came from foreign sources. Boothby’s team now wants to check for similar genetic infiltrations in other animals that tolerate desiccation, including some nematode worms, fish, and insects. They are also planning to gradually inactivate the tardigrade’s borrowed genes to see if that compromises its fabled invincibility.

Ralph Schill from the University of Stuttgart also points out that Hypsibius dujardini is something of a wuss among tardigrades, and isn't actually very good at surviving desiccation. Perhaps the genomes of its hardier relatives—the ones that shrug off extreme cold, extreme heat, and open vacuums—will yield even bigger surprises.



The almost-invincible tardigrades

Tardigrade  extremophile with superpowers 432Echiniscus

This water bear (Echiniscus sp.) is about 0.3 mm long. Tardigrades of this type live in moss cushions, e.g. on rooftops exposed to much sunshine, where temperatures can be over 60°C. So they have to frequently convert (possibly every day!) from their active form to the dry (tun) form. Despite their small size, tardigrades’ considerable brain enables them to find their nutrition and their partners even in the most stunningly harsh environments on Earth.

But of all the organisms so far identified to be able to live in harsh environments, the toughest animals on Earth by far are the ‘tardigrades’. You can freeze them, boil them, dry them, starve them and even put them in a vacuum—yet they still bounce back.
The form of these little creatures (mostly less than 1 mm (one twenty-fifth of an inch) long) has earned them the nicknames of ‘moss piglets’, ‘bear animalcules’ and ‘water bears’. With their stumpy legs, tiny claws and slow, lumbering gait they really do look like a microscopic bear.19 Around 700 species of tardigrades have been found in habitats ranging from the freezing peaks of the Himalayas to the hottest, driest deserts, right down to the deepest ocean trenches of the Pacific.

Slow down, turn off … revive, survive!

How do they withstand such environmental extremes? By shutting down their metabolism during unfavourable conditions. When things become unbearably hot, or cold, or dry, e.g., many tardigrades curl in their head and legs and roll up into a barrel-like shape called a ‘tun’.20 They then make the biochemical preparations for shutting everything down—even their respiration ceases completely. But later, when favourable circumstances return, the tardigrade uncurls itself, again extending its legs and head, and life goes on as before.
The (known) record duration for survival (in this case, without water) is 120 years, for tardigrades taken from dried-out moss kept in a museum in Italy.21
And biologists are amazed at the sort of laboratory treatment that tardigrades can endure—often far worse than any conditions they would ever experience on Earth. For example, they have revived after having been frozen in liquid helium (-272ºC, or -458ºF), just a fraction above absolute zero (-273.15ºC, or -459.67ºF), the lowest temperature possible.22,23 At the other extreme, they have survived being heated to 151ºC (304ºF). They have survived being zapped with X-rays with an intensity 250 times stronger than that which would kill a human. Tardigrades can even survive being photographed by an electron microscope, which requires putting them in a vacuum and bombarding them with electrons.

Bearing up under pressure

At least two species of tardigrades (Macrobiotus occidentalis (order Eutardigrada) and Echiniscus japonicus (Heterotardigrada) have been shown to be able to survive extraordinarily highhydrostatic pressures, 600 MPa (6,000 atmospheres), i.e. six times greater than the pressure at the bottom of the deepest ocean on Earth.24,25 To put this in context, research has shown that when other animals are exposed to high pressures, their cell membranes, proteins and DNA are damaged. In most micro-organisms, growth and metabolism stops at pressures of around 30 MPa (300 atmospheres), and even among the microbes which are resilient to high pressures, most will die at 300 MPa (3,000 atmospheres). In addition, while there are organisms (other than tardigrades) that can survive very high pressures, a sudden change can be lethal to them—a danger to which human divers must be ever alert.26 But tardigrades not only can survive extended periods at 600 MPa (6,000 atmospheres!), but high-speed decompression as well.


As creationists have pointed out before, the ability of tardigrades to survive being subjected to such extreme laboratory treatments (radiation, cold temperature, hydrostatic pressure), far more severe than any Earth environment, poses a very clear difficulty for evolutionary theory.27 As one scientific writer put it, ‘With such an arsenal of adaptations for survival, tardigrades appear to be over-engineered.’21
And, not just tardigrades—as this latest surge of exploration and laboratory research reveals yet more extremophile microbes and other organisms able to withstand far harsher conditions than anywhere on Earth, the challenge to evolutionary theory becomes even more intractable. This is because natural selection can only select characteristics necessary for immediate survival. Consequently, evolution cannot be expected to ‘overequip’ creatures for a host of environments they have never faced.
For Christians, though, the ‘over-design’ of these creatures speaks of a Designer ([url= 1.20]Romans 1:20[/url]), and it is not surprising that God also built into the living things of His creation the capacity to move out and ‘fill’ the whole world, just as He had commanded (Genesis 1). And so indeed, we see today that living things inhabit the harshest environments from ocean to mountaintop and from pole to pole—even at the very extremities of the Earth. Just as the Lord (who knew, incidentally, prior to Creation, of the coming effects of the Curse and the later Flood on future environments) intended for them to do.



Tardigrades return from the dead

If you go into outer space without protection, you'll die.
The lack of pressure would force the air in your lungs to rush out. Gases dissolved in your body fluids would expand, pushing the skin apart and forcing it to inflate like a balloon. Your eardrums and capillaries would rupture, and your blood would start to bubble and boil. Even if you survived all that, ionising radiation would rip apart the DNA in your cells. Mercifully, you would be unconscious in 15 seconds.
How do these seemingly insignificant creatures survive in such extreme conditions?
But one group of animals can survive this: tiny creatures called tardigrades about 1mm long. In 2007, thousands of tardigrades were attached to a satellite and blasted into space. After the satellite had returned to Earth, scientistsexamined them and found that many of them had survived. Some of the females had even laid eggs in space, and the newly-hatched young were healthy.
It's not just the harsh environs of outer space that tardigrades can survive in. The little critters seem adept at living in some of the harshest regions of Earth. They have been discovered 5546m (18,196ft) up a mountain in the Himalayas, in Japanese hot springs, at the bottom of the ocean and in Antarctica. They can withstand huge amounts of radiation, being heated to 150 °C, and being frozen almost to absolute zero.
How do these seemingly insignificant creatures survive in such extreme conditions, and why have they evolved these superpowers? It turns out that tardigrades have a host of tricks up their sleeves, which would put most organisms to shame.

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Tardigrades, at first glance, are intimidating. They have podgy faces with folds of flesh, a bit like a Doctor Who monster. They have eight legs, with ferocious claws resembling those of great bears. Their mouth is also a serious weapon, with dagger-like teeth that can spear prey.
Fossils of tardigrades have been dated to the Cambrian period over 500 million years ago
But there's no need to worry. Tardigrades are one of nature's smallest animals. They are never more than 1.5 mm long, and can only be seen with a microscope. They are commonly known as "water bears".
There are 900 known species. Most feed by sucking the juices from moss, lichens and algae. Others are carnivores, and can even prey on other tardigrades.
They are truly ancient. Fossils of tardigrades have been dated to the Cambrian period over 500 million years ago, when the first complex animals were evolving. And ever since they were discovered, it has been clear that they are special.

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Tardigrades were discovered in 1773 by a German pastor named Johann August Ephraim Goeze. Three years later, the Italian clergyman and scientist Lazzaro Spallanzani discovered that they had superpowers.
Spallanzani added water to sediment from a rain gutter, and looked under a microscope. He found hundreds of little bear-shaped creatures swimming around. In his book "Opuscoli di Fisica Animale, e Vegetabile", he named them "il Tardigrado", meaning "slow-stepper", because they moved so slowly.
In 1995, dried tardigrades were brought back to life after 8 years
In truth, this wasn't a first. Back in 1702, the Dutch scientist Anton van Leeuwenhoek sent a letter to the Royal Society in London, entitled "On certain animalcules found in the sediment in gutters on the roofs of houses". He took dry, apparently lifeless dust from a gutter and added water. Using a microscope of his own devising, Leeuwenhoek found that within an hour many small "animalcules" became active, and began swimming and crawling around.
These animals were rotifers, tiny aquatic creatures that look like they have wheels on their heads. They could seemingly survive months without water.
However, tardigrades may be able to survive without it for decades. In 1948, the Italian zoologist Tina Franceschi claimed that tardigrades found in dried moss from museum samples over 120 years old could be reanimated. After rehydrating a tardigrade, she observed one of its front legs moving.
This finding has never been replicated. But it does not seem impossible. In 1995,dried tardigrades were brought back to life after 8 years.

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For most animals, life without water is completely impossible.
"When a typical cell dries out its membranes rupture and leak, and its proteins unfold and aggregate together, making them useless," says extremophile researcher Thomas Boothby  of the University of North Carolina in Chapel Hill. "DNA will also start to fragment the longer it is dry."
The tardigrade curls up into a dry husk
Somehow tardigrades avoid all this. "Since water bears can survive drying, they must have tricks for preventing or fixing the damage that cells like ours would die from," says Boothby.
How do they do it? One of the key discoveries came in 1922, courtesy of a German scientist named H. Baumann. He found that when a tardigrade dries out it retracts its head and its eight legs. It then enters a deep state of suspended animation that closely resembles death.
Shedding almost all the water in its body, the tardigrade curls up into a dry husk. Baumann called this a "Tönnchenform", but it is now commonly known as a "tun"Its metabolism slows to 0.01% of the normal rate. It can stay in this state for decades, only reanimating when it comes into contact with water.

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Besides tardigrades, some nematode worms, yeast and bacteria can also survive desiccation. They do this by making a lot of a particular sugar called trehalose. This sugar forms a glass-like state inside their cells that stabilises key components, such as proteins and membranes, which would otherwise be destroyed.
Tardigrades might have unique tricks for surviving desiccation
Trehalose can also wrap itself around any remaining water molecules, stopping them from rapidly expanding if the temperature rises. Rapidly expanding water molecules are dangerous because they can rupture cells, which can be fatal.
You might expect that tardigrades would use this trick to survive drying, but according to Boothby, only some species seem to make trehalose. "Some species do not appear to contain trehalose, or make it at such low levels that the sugar is undetectable," he says.
"This suggests that tardigrades might have unique tricks for surviving desiccation," says Boothby. "We know that, as they start to dry out, tardigrades make protectants that allow them to survive becoming completely dry. But what exactly these protectants are is still a mystery."

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When tardigrades start to dry out, they seem to make a lot of antioxidants. These are chemicals, like vitamins C and E, that soak up dangerously reactive chemicals. This may mop up harmful chemicals in the tardigrades' cells.
The tun state is key to tardigrades' ability to cope with being dried out
Tardigrades face a particular threat from "reactive oxygen species". These substances are produced as by-products of normal cell function, but can break down the main components of a cell, including its DNA. Animals exposed to environmental stress often have lots of them floating around.
The antioxidants may explain one of tardigrades' neatest abilities. If a tardigrade stays in its dry tun state for a long time, its DNA gets damaged. But after it reawakens it is able to quickly fix it.
It's clear that the tun state is key to tardigrades' ability to cope with being dried out. But long before Baumann discovered it, tardigrades had revealed other superpowers.

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For starters, they seem not to care what temperature it is. In 1842 a French scientist named Doyère showed that a tardigrade in its tun state could survive being heated to temperatures of 125 °C for several minutes. In the 1920s, a Benedictine friar named Gilbert Franz Rahm brought tardigrades back to life after heating them to 151 °C for 15 minutes.
Rahm also tested them in the cold. He immersed them in liquid air at -200 °C for 21 months, in liquid nitrogen at -253 °C for 26 hours, and in liquid helium at -272 °C for 8 hours. Afterwards the tardigrades sprang back to life as soon as they came into contact with water.
We now know that some tardigrades can tolerate being frozen to -272.8 °C, just above absolute zero. To put that into perspective, the lowest temperature ever recorded on Earth was a balmy -89.2 °C in central Antarctica in 1983. The tardigrades coped with a profound chill that does not occur naturally and must be created in the lab, at which atoms come to a virtual standstill.

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The biggest hazard tardigrades face in the cold is ice. If ice crystals form inside their cells, they can tear apart crucial molecules like DNA.
Tardigrades can actually tolerate ice forming within their cells
Some animals, including some fish, make antifreeze proteins that lower the freezing point of their cells, ensuring that ice doesn't form. But these proteins haven't been found in tardigrades.
Instead it seems tardigrades can actually tolerate ice forming within their cells. Either they can protect themselves from the damage caused by ice crystals, or they can repair it.
Tardigrades may produce chemicals called ice nucleating agents. These encourage ice crystals to form outside their cells rather than inside, protecting the vital molecules. Trehalose sugar may also protect those that produce it, as it prevents the formation of large ice crystals that would perforate the cell membranes.

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But while we have some idea of how tardigrades cope with the cold, we have no idea how they cope with heat. At scorching temperatures like 150 °C, proteins and cell membranes should unravel, and the chemical reactions that sustain life cease to happen.
The most heat-tolerant organisms known are bacteria that live around the edges of hydrothermal vents in the deep sea. They can still grow at 122 °C. If Rahm is to be believed, tardigrades can survive even higher temperatures.
Many animals that have evolved to live in hot places, like hot springs and scorching deserts, produce chemicals called heat shock proteins. These act as chaperones for proteins inside cells, helping them keep their shape. They also repair heat-damaged proteins.

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That's all well and good, but there is no conclusive evidence that tardigrades produce these chemicals. Factor in the other things they can survive, and the picture becomes even more baffling.
In 1964, scientists exposed tardigrades to lethal doses of X-rays and found that they could survive.  Later experiments showed they can also cope with excessive amounts of alpha, gamma and ultraviolet radiation – even if they're not in the tun state.
Radiation was one of the biggest threats facing the tardigrades sent into space in 2007. Those exposed to higher levels of radiation fared worse than those protected, but the mortality rate was not 100%.

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They can also cope with extreme pressure that would squash most animals flat, according to a study published in 1998 by Kunihiro Seki and Masato Toyoshima of Kanagawa University in Hiratsuka, Japan. They found that tardigrades in the tun state could survive a pressure of 600 megapascals (MPa).
At these crushing pressures, proteins and DNA are ripped apart
This is beyond anything they might encounter in nature. The deepest part of the sea is the Challenger Deep in the Mariana Trench in the Pacific Ocean, which goes down 10,994 m. There, the water pressure is around 100 MPa. Somehow the tardigrades survived six times that.
At these crushing pressures, proteins and DNA are ripped apart. Cell membranes, which are composed of fat, become solid like butter in a fridge. Most microorganisms stop metabolising at 30 MPa, and bacteria can't survive much beyond 300 MPa.
The sheer variety of stressors that tardigrades can survive is almost dizzying. But maybe the explanation is surprisingly simple.

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Extreme heat and cold, radiation and high pressures all have one thing in common: they damage DNA and other bits of the tardigrades' cells. Heat and cold both cause proteins to unfold, stick together and stop working. Radiation tears up DNA and other crucial molecules. High pressures solidify the fatty membranes around cells.
So if all the stressors cause similar problems, maybe the tardigrades only need a handful of tricks to survive them. "Nobody knows for sure," says Boothby. But "there are certainly some good reasons to think that overlapping strategies might be used to cope with some of these extremes."
Freezing a tardigrade and drying it out both cause the same problem
For instance, being dried out and being exposed to radiation both damage the tardigrades' DNA. "So it would make sense that tardigrades response to these two conditions in a similar way," says Boothby: by making antioxidants and repairing the damaged DNA.
If that's true, tardigrades' resistance to radiation is a happy accident: a side-effect of their adaptation to sudden drought. Similarly, freezing a tardigrade and drying it out both cause the same problem: not enough liquid water in the animal's cells.
Oddly enough the tun state, their most famous trick, is also the least versatile. "Tardigrades can survive freezing, radiation, and low-oxygen conditions without forming a tun," says Boothby. "So the tun state is probably a specific adaptation for dealing with or slowing water loss." However it does also allow them to survive extreme pressure.

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This idea, that tardigrades are only using one or two survival tricks, might help explain the other big question about them: why do they bother?
They have evolved to cope with environments so extreme, they don't even exist on Earth
Unlike bacteria that live in boiling hot springs or other extreme sites, most tardigrades live in relatively unremarkable places. They tend to live in or near water, and there's nothing a tardigrade likes more than a good chunk of moss and lichen. Their lives aren't even that exciting: while most creatures their size dart about frantically, tardigrades are sluggish.
Yet despite their rather tedious lifestyle, they have evolved to cope with environments so extreme, they don't even exist on Earth.
Or rather, some of them have. The oldest and most primitive group of tardigrades, the Arthrotardigrada, cannot survive extreme conditions or suspend their metabolism. These more vulnerable creatures offer a clue to why the other tardigrades got so tough.

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Arthrotardigrada only live in the ocean. It's only land-dwelling and fresh-water species that have the extreme survival skills. That suggests leaving the ocean was the key.
Today they can be found in some of the driest places on Earth
"One reason that marine tardigrades aren't as good at surviving extremes is that they just don't need to be," says Boothby. "Oceans are so big that they don't undergo rapid changes in temperature or salinity, and they certainly don't dry up overnight."
By contrast, the land is dangerously changeable. Tardigrades need a thin layer of water around their bodies to breath, eat, mate and move around. But in many parts of the land, drought is a risk. "The tardigrades that live in these places need to be able to cope when their environments suddenly change," says Boothby.
So it makes sense that land-dwelling tardigrades would evolve a way to survive suddenly being dried out. It was a matter of survival. What's more, once they had it, the land tardigrades could exploit new habitats. Today they can be found in some of the driest places on Earth, where other animals cannot survive.

Tardigrade  extremophile with superpowers P02lwt03

But this idea just raises another question. If being able to survive drying out is so useful for land animals, why don't they all do it? Why didn't frogs, earthworms and humans evolve the same ability?
Similarly, why can't other animals survive the heat, cold and radiation that tardigrades can? Perhaps the question isn't why tardigrades are so tough, but why other animals are so vulnerable.
Going into the tun state is a risky decision
"There are probably several reasons why more animals and plants haven't evolved the tardigrades' abilities," says Boothby. "Many animals probably just don't need to. They either don't live in environments that can quickly dry out, or they can develop ways of avoiding drying out, like the camel."
But beyond that, there are surely costs to the tardigrades' abilities – costs that other animals have avoided paying. In particular, going into the tun state is a risky decision.
"When a tardigrade completely dries out, it becomes inactive and is unable to actively avoid dangers in its surroundings," says Boothby. An inactive tardigrade might not die of thirst, but it could get eaten. "We know that a lot of desiccation-tolerant organisms have to make xenoprotectants: molecules that keep bacteria and fungi from basically eating them while they are in their inactive state."
It may be that becoming as tough as a tardigrade wouldn’t pay off for other animals. But it has worked for them. They are 500 million years old and live all over the planet, so they aren't going anywhere.



Strange “Water Bears” Lead to Discovery of a New Glass Material

Tardigrade  extremophile with superpowers 1024px-Waterbear_%28Tardigrade%29_from_the_drainage_of_a_hot_spring_in_Lassen_County%2C_California_-_Stacked_Macro_10x

Best known for their ability to survive the vacuum of space, tardigrades have now inspired the creation of a new type of glass that defies its typical structure.

Odd-looking, microscopic animals called tardigrades — or less scientifically known as “water bears” — live just about anywhere: in bubbling hot springs, moss and lichens, Antarctic ice... the list goes on. Impressively, they’ve even withstood the extreme cold and radiation of outer space. The little creatures are nearly invisible and indestructible, and they recently led scientists to the exciting discovery of a new glass material that could improve the efficiency of technologies like solar cells, optical fibers, and LED lights.
Juan de Pablo, a professor of molecular engineering at the University of Chicago, became fascinated with tardigrades after reading about how scientists could dry them out and then revive them years later with water. Thus, his 20-year exploration of the unusual properties of glass began with these unusual water bears.

SEE ALSO: Scientists Created Lenses That Work Like Insect Eyes

De Pablo explains that once the water is removed in the procedure, tardigrades rapidly coat themselves in glassy molecules. This process is what allows them to stay in a state of “suspended animation,” or a deathlike state without final termination.
The degree molecular order in the tardigrade’s glassy material shocked the researchers. “Randomness is almost the defining feature of glasses,” de Pablo said. “At least we used to think so.” In fact, by definition, glass has an amorphous structure, meaning the material is less rigidly defined than regular, crystalline solids. However, the new type of glass created by researchers at the University of Chicago and the University of Wisconsin-Madison has well-defined molecular organization, just like a crystal.
“What we have done is to demonstrate that one can create glasses where there is some well-defined organization,” says de Pablo. “And now that we understand the origin of such effects, we can try to control that organization by manipulating the way we prepare those glasses.”
The new glass material was produced through a method called “physical vapor deposition” — the molecules are evaporated in a vacuum and then left to condense on top of a temperature-controlled support structure. Then, the researchers analyzed the material by measuring the way light interacted with the glass, a technique called “spectroscopic ellipsometry.”
The finding that all or most of the molecules were aligned in the same direction was certainly unanticipated since most glasses have random molecular structures. However, lead study author Shakeel Dalal, a graduate student at the University of Wisconsin-Madison, says that molecularly-structured glass isn’t just hard to come by — it’s also extremely desirable.
Researchers who make things like solar cells and LED lights need materials with structured molecules because, if the molecules point in a certain direction, it’s easier to manipulate them to carry charges or emit light. Until now, researchers were unsure about what exactly caused the molecules in certain glasses to “cooperate” and point in the right direction — they assumed certain glass molecules were just better at organizing themselves than others. But this new study suggests otherwise.
During the previously explained process of “physical vapor deposition,” the temperature difference between the glass molecules and the temperature-controlled structure is what prompts the structured orientation of the new glass material. To expand on this discovery, de Pablo and researchers from several institutions in the United States and France conducted tests to see if this temperature finding held true, and it did.
Not only did de Pablo and fellow colleagues create a new glassy material inspired by the biology of the unique tardigrade, but this discovery will help others create structure-oriented glasses in the future. The efficiency of solar cells, optical fibers, LED lights and more will be revolutionized — all thanks to the microscopic, funny-looking water bears.



The secret of the crazy-tough waterbear, finally revealed 1

THE WORLD KNOWS no toughness like that of the water bear, which looks like a cannon wearing a pair of wrinkled khakis. This microscopic critter can survive boiling water (and alcohol too, just to be safe), some of the lowest temperatures in the universe, and blasts of radiation that would kill a human. In the slightly edited but still immortal words of Austin Powers: “Why won’t the water bear die?”

The question has for decades baffled scientists, who suspected the water bear—also known as a tardigrade—mobilizes a sugar called trehalose to reinforce its body and keep its cells from swift destruction. But no longer. In a paper out today in Molecular Cell, researchers claim they’ve found an exclusively tardigradean protein that the creature produces, forming it into a glass bead. It’s in this state that the water bear can pull off such extreme feats of survival—which might be very convenient for human medicine one day.

Tardigrades Use Intrinsically Disordered Proteins to Survive Desiccation 2

Tardigrades (water bears) comprise a phylum of microscopic animals renowned for their ability to survive a vast array of environmental extremes, including essentially complete desiccation for up to a decade (Goldstein and Blaxter, 2002). Although they have fascinated scientists for more than 250 years, little is known about how tardigrades survive such extreme environmental stresses, and no molecular mediators of tardigrade desiccation tolerance have been experimentally confirmed. The disaccharide trehalose has been proposed and often assumed to play a role in mediating desiccation tolerance in tardigrades (Hengherr et al., 2008, Jönsson and Persson, 2010, Westh and Ramløv, 1991). Trehalose is essential for some organisms to survive desiccation and is thought to protect organisms by vitrifying their cellular contents (Erkut et al., 2011, Sakurai et al., 2008, Tapia and Koshland, 2014). However, some desiccation-tolerant animals do not require or even appear to make this sugar (Lapinski and Tunnacliffe, 2003). Currently, the use and presence of trehalose in tardigrades are unclear; some studies report low levels of this sugar, while others failed to identify trehalose at all in the same species (Guidetti et al., 2011, Hengherr et al., 2008, Jönsson and Persson, 2010, Westh and Ramløv, 1991).

In addition to trehalose and other sugars, a number of protein families and classes have been implicated in mediating desiccation tolerance in other systems, including heat-shock proteins, antioxidant enzymes, and some intrinsically disordered protein (IDP) families (Hincha and Thalhammer, 2012, Hoekstra et al., 2001). This latter class of proteins is enigmatic, in that unlike typical globular proteins, they lack persistent tertiary structure. In the past two decades, myriad cellular roles for IDPs have emerged, including roles in transcription, post-translational modification, development, cellular organization, and abiotic stress tolerance (Chakrabortee et al., 2012, Garay-Arroyo et al., 2000, Hincha and Thalhammer, 2012, Iakoucheva et al., 2004, Nott et al., 2015, Xie et al., 2007, Zhang et al., 2015). However, the role of IDPs in tardigrade desiccation tolerance remains untested.

The problem with the trehalose theory, as it turned out, was that while many other organisms like nematode worms and brine shrimp use it to survive desiccation, not all water bear species produce the sugar under stress. Some of those other organisms produce enough trehalose to make up 20 percent of their body weight. The water bear? Only about 2 percent. Pitiful, really.

That didn’t jibe with the water bear’s uncanny toughness. So researchers looked closely at the genes that turned on as water bears dried out. At the top of the list of the switched-on genes: those that encode what are known as intrinsically disordered proteins. Those amino acid chains don’t have a neat 3-D structure like most proteins, so they act very loosey-goosey and strange. “One of the things we’re really interested in is figuring out how exactly these tardigrade intrinsically disordered proteins are working,” says biologist and study co-author Thomas C. Boothby of University of North Carolina at Chapel Hill. “It’s a really interesting question about how a protein without a defined three-dimensional structure can actually carry out its function in a cell.”

Regardless, Boothby and his colleagues seem to have pinpointed the genes that make the water bear’s life-saving proteins. “We went on to show that if you reduce expression of these genes in tardigrades, they can no longer survive desiccation very well,” Boothby says. “If you take those genes and put them into organisms like bacteria and yeast, which normally do not have these proteins, they actually become much more desiccation-tolerant.” The water bear’s secret ingredient can make other organisms up to 100 times hardier.

The mechanism of these intrinsically disordered proteins looks a lot like how the trehalose sugar protects animals like nematode worms from dessication. Like something out of a fairy tale or the very least an ‘80s movie, the protein turns the water bear into a frozen glass figurine, a process known as vitrification. Normally, dessication crystallizes living cells, shredding up proteins and DNA in the process. But with the gentler, smoother process of vitrification, the water bear can ride out the desiccation, only to reanimate once it hits water perhaps 30 years later.

Great news for the hardy little water bear, and potentially even better news for humanity. Vaccines, for instance, are extremely fragile, requiring refrigeration as doctors ship them around the world. That costs a whole lot of money and means the vaccines are easily destroyed. “One potential application would be to use these tardigrade proteins to stabilize vaccines or pharmaceuticals in a dry state that you can keep at room temperature and not have to worry about refrigeration during transportation and storage,” says Boothby.

Not bad, little water bear. Consider me sorry for the cannon-wearing-khakis thing.




Tardigrade trapped in amber is a never-before-seen species

Scientists discovered an incredibly rare fossil suspended in 16 million-year-old amber: a never-before-seen species of tardigrade, a pudgy, aquatic critter that rarely crops up in the fossil record.

Modern-day tardigrades, also known as water bears or moss piglets, can be found in just about any environment with liquid water, from the depths of the ocean to the thin water films that coat terrestrial mosses. The tiny creatures are famous for their survival skills; by expelling most water from their bodies and drastically slowing their metabolism, tardigrades enter a state akin to suspended animation in which they can withstand extreme temperatures, pressure and radiation.

But although tardigrades are nearly impossible to destroy when alive, their small size and lack of hard tissue mean that very few tardigrade fossils have ever been discovered — only three, to be exact. The species of two of these fossils, found in Canada and New Jersey, have been formally named; the other, found in West Siberia, remains unnamed.

A tardigrade in Dominican amber

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