Tag Archives: Water bear

Amazing mold pigs trapped in 30-million-year-old amber

Amber is nature’s time capsule. Sometimes, tiny creatures and plants get trapped in a tree’s resin and, under the right condition, become preserved in minute details for millions of years. The picture below, for instance, shows a 30-million-year-old piece of amber containing microinvertebrates known as “mold pigs.”

A mold pig trapped in fossilized amber. Credit: Oregon State University.

You’ve likely heard about water bears, or tardigrades, before. These adorable-looking microscopic creatures are extremophiles that are able to withstand intense heat, cold, pressure, radiation, even the vacuum of space.

We don’t know if mold pigs were as resilient as water bears, but they sure look very similar. Technically, the species is called “Sialomorpha dominicana,” where “sialomorpha” is derived from the Greek words for “fat hog” and “shape.” Dominicana comes the Dominican Republic, where the amber was discovered not too long ago.

When a tree suffers a wound (like a broken branch) or if it is attacked by insects or fungi, it exudes thick resin that plugs up the injury and prevents further damage. It seals and sterilizes the injury.

When resin is secreted, it’s not certain that it will turn into amber. More often than not, it gets weathered away. First of all, the resin needs to be chemically stable and not degrade over time. It has to be resistant to sun, rain, extreme temperatures, and microorganisms like bacteria and fungi. There are two types of resin produced by plants that can fossilize. Terpenoids are produced by gymnosperms (conifers) and angiosperms (flowering plants). They are composed of ring structures made from isoprene (C5H8) units. Phenolic resins are only produced by angiosperms. An extinct type of tree called medullosans produced another unique type of resin.

The mold pig

George Poinar Jr. from Oregon State University recently published a paper in which he and colleagues closely examined the amber and the microscopic hogs trapped inside it, along with their fungal food source and other animals that lived in their habitat.  

“Every now and then we’ll find small, fragile, previously unknown fossil invertebrates in specialized habitats,” Poinar said. “And occasionally, as in the present case, a fragment of the original habitat from millions of years ago is preserved too. The mold pigs can’t be placed in any group of currently existing invertebrates – they share characteristics with both tardigrades, sometimes referred to as water bears or moss pigs, and mites but clearly belong to neither group.”

In total, the researchers have numbered several hundred individual fossils in the small piece of amber. Apart from mold pigs, the amber contains pseudoscorpions, nematodes, fungi, and protozoa.

Each mold pig is no longer than 100 micrometers and had flexible heads and four pairs of legs. The researchers assert that they must have grown by molting their exoskeleton and likely subsided on a diet of fungi and small invertebrates. Whereas mites and water bears have claws present at the end of their legs, mold pigs have none.

“The large number of fossils provided additional evidence of their biology, including reproductive behavior, developmental stages and food,” he said. “There is no extant group that these fossils fit into, and we have no knowledge of any of their descendants living today. This discovery shows that unique lineages were surviving in the mid-Tertiary.”

The researchers’ classification suggests that mold pigs represent a new phylum — a level of classification or taxonomic rank below kingdom and above class.

What researchers hope to answer in the future is when did this lineage originate and how long it lasted. Whether there are any living descendants to mold pigs is anyone’s guess at this moment.

Findings were published in the journal Invertebrate Biology.


Water bears reach the moon after lunar crash probe

A group of microscopic, near-indestructible creatures called tardigrades, also known as water bears, could now be living on the moon after the Israeli probe Beresheet crash-landed earlier this year, according to the group that loaded them onto the spacecraft.

Credit: Flickr

Tardigrades can survive in almost any environment and it’s even possible to bring them back to life after a 30-year deep freeze.  As “extremophiles,” they can shut down their metabolism and survive in hostile conditions for long periods. Now the question if they can even survive in space.

“We believe the chances of survival for the tardigrades are extremely high” based on an analysis of the crashed probe’s trajectory and the device in which the creatures were stored,” Nova Spivack, whose Arch Mission Foundation is dedicated to spreading “backups” of human knowledge and terrestrial biology beyond Earth, said.

Back in April, an Israeli spacecraft called Beresheet, which carried thousands of dehydrated tardigrades crashed on the moon. The Israeli spacecraft was also transporting Arch Mission’s first lunar library, a digital archive holding the equivalent of 30 million pages of information.

Based on Arch Mission’s analysis of the spacecraft’s path as well as the makeup of the lunar library itself, Spivack said he’s confident the library, a “DVD-sized object made of thin sheets of nickel,” survived the crash mostly intact. That doesn’t mean the water bears are in good shape.

“About the tardigrades in the Lunar Library: Some are sealed in epoxy with 100 million human, plant and microorganism cells,” Spivack tweeted. “Some are encapsulated onto the sticky side of a 1cm square piece of Kapton tape that is sealed inside the disc stack. They cannot reproduce on the moon.”

Tardigrades are famous for being able to survive the most extreme conditions, so if they didn’t burn up in an explosion as the probe crashed to the lunar surface, they could theoretically survive for years, capable of withstanding huge amounts of radiation, heat, and cold, according to NASA biologist Cassie Conley.

But they’d need air, water, and food to grow, reproduce, and form a colony, fellow tardigrade expert William Miller argued, and the chance of another spacecraft coming to their rescue is slim.

The moon formed more than 4 billion years ago. For the entirety of its existence, it has been a completely sterile place. Humans first brought life to the moon 50 years ago with the Apollo mission, in the form of microbes hiding in feces and other human waste. And now, it has tardigrades too.

How the water bear defies death even in the vacuum of space by wrapping its cells in glass

Tardigrades are the toughest, most resilient animals we know of. They can survive temperatures from 1 K (−458 °F; −272 °C) to about 420 K (300 °F; 150 °C), pressures six times greater than those found in the deepest ocean trenches, ionizing radiation at doses hundreds of times higher than the lethal dose for a human, and the vacuum of outer space. One tardigrade female was brought back to life after being frozen for 30 years then birthed 14 healthy babies. 

Water bear don’t care

Simply put, the tardigrade, also known as the water bear, is the most extreme survivalist out there. If there’s an animal that knows how to make it against all odds, it’s this guy and, as you might imagine, a lot of people are interested to find out what its secret weapons are.

The water bear is able to withstand such extreme conditions by going into a sort of safe mode, as it dries up into a little barrel called a tun. In this form, neither heat, cold or the wretched vacuum of space can kill it. Essentially, the tiny bear which is smaller than 1 millimeter enters a state called anhydrobiosis during which the metabolism shuts down.

Now, researchers from the University of North Carolina at Chapel Hill have found another ace up the water bear’s sleeve. During a dry spell when water is scarce anti-dehydrating proteins called tardigrade-specific intrinsically disordered proteins (TDPs) become vitrified. When this happens all the tardigrade’s dehydration-sensitive tissue and cells become protected by a glass surface. This way, sensitive proteins and other biological molecules are locked in place. They can’t fold, they can’t break apart nor can they aggregate together, which explains how the animal can survive in space and then come back to life like nothing happened within an hour.

The video below shows how much the water bear shrinks when deprived of water.

https://www.youtube.com/watch?v=09U9tc-aaek

The team led by Thomas Boothby intentionally subjected the tardigrades to conditions that would force them to dry out. Meanwhile, they carefully monitored the animal’s gene activity. Boothby and colleagues noticed a spike of activity in a group of genes when the TDPs were produced. When such genes were blocked through genetic engineering, the tardigrade died of dehydration.

When bacteria and yeast were artificially infused with the aforementioned genes, these became much more resilient in the face of dehydration. This remarkable experiment suggests that, at least partly, the tardigrade’s tricks can be passed down to creatures. For instance, one interesting idea would be to produce new genetically modified crops that carry TDP genes to help them survive droughts. California’s worst drought in history, which is still not over and sure as heck isn’t the last, serves as a reminder that such crops are badly needed.

Previously, a 2008 study concluded that the tardigrade’s anhydrobiosis is linked to specialized sugars called trehalose. Tree frogs use the same sugar molecules to come with dry environments as well but not everyone was convinced the water bear uses the same mechanism because the study could only find trehalose-linked processes in only one species of tardigrade. Indeed, Boothby found tardigrades either don’t make or make very little amounts of trehalose.

It’s amazing however that TDPs work much in the same way as trehalose — they both protect cells by forming literally glass structures. So, what we’re essentially dealing with is yet another textbook example of convergent evolution — two animals (tardigrade and tree frog) totally unrelated from each other who evolved the same adaptive trait.

Another water bear trick involves using other proteins to shield its DNA against radiation. A previous research found  17.5 percent of a tardigrade’s genome was comprised of foreign DNA, including genes from bacterial species that can withstand extreme pressure and heat.

Next, the researchers plan on investigating other animals and even plant seeds which seem to survive desiccation to see whether they use the same proteins. Besides drought-resistant crops, such investigations might one day lead to amazing practical applications. One immediate application could be a new medium for storing vaccines and pharmaceuticals at room temperature by using dehydration instead of refrigeration. A much farther away application might involve dehydrating people to induce a hibernation-like state, which could be useful in interstellar flight.

tardigrade gif

Journal ref: T.C. Boothby et al., “Tardigrades use intrinsically disordered proteins to survive desiccation,” Molecular Cell, doi:10.1016/j.molcel.2017.02.018, 2017.

Computer generated tardigrade. Credit: Fox

Water bears, the amazing animals that can survive in outer space, have a unique adaptation that shields DNA from radiation

Computer generated tardigrade. Credit: Fox

Computer generated tardigrade. Credit: Fox

Tardigrades or water bears, as they’re often adorably called, are some of the most amazing animals out there. Considered the most extreme animal on the planet, the water bear can withstand intense heat, cold, pressure, radiation, even the vacuum of space. There’s a lot we could learn from it and a recent genome sequencing of the animal’s DNA might explain why it’s so freaking indestructible.

The animal that can withstand outer space and can come back from the dead

In 2007, researchers attached thousands of the 1mm-long tardigrades to a satellite and blasted them into space. Weeks later, after the satellite returned back to Earth, researchers found many of them had survived and, remarkably, some females even laid eggs — in space. The newly hatched younglings were healthy.

Tardigrades, who first appeared some 500 million years ago during the Cambrian, can even come back from the dead, as Japanese cryobiologists recently demonstrated. The Japanese researchers thawed some water bears that had been frozen for 30 years and found some of the defrosted creatures were still alive. What’s more, they could even manage to reproduce with one laying 19 eggs of which 14 successfully hatched.

To pull off these death-defying feats, tardigrades employ a couple of tricks. When faced with the prospect of annihilation, either due to lack of food or due to exposure to absolute zero temperatures, the water bear essentially dries out and retracts its head and its eight legs. It then enters a deep state of suspended animation that closely resembles death. Its metabolism slows to 0.01% of the normal rate and the body becomes almost devoid of water.  The video below shows how much the water bear shrinks when deprived of water.

https://www.youtube.com/watch?time_continue=6&v=09U9tc-aaek

This suspended state can be maintained for decades, as the Japanese researchers proved earlier, and the water bear can be revived when placed in contact with water.

The thing is, this process damages the DNA yet the extremophiles don’t seem to mind at all. In fact, they seem to flourish in spite of this.

Previously, researchers at University of North Carolina (UNC) at Chapel Hill sequenced a tardigrade’s genome and found 17.5 percent of it was comprised of foreign DNA. This means that some of its genes come from entirely different species. Most species, including humans, don’t have more than one percent foreign DNA in their genomes, so tardigrades have more foreign DNA than any other species. The previous record-holder was a microscopic animal known as a rotifer.

“Animals that can survive extreme stresses may be particularly prone to acquiring foreign genes — and bacterial genes might be better able to withstand stresses than animal ones,” Thomas Boothby, first author of the study said.

The UNC researchers found tardigrades had 6,000 foreign genes, mainly from bacteria. There are many bacterial species that can withstand extreme pressure and heat, which might explain the tardigrades’ resilience. Yet the study didn’t answer how the water bears cope with having their DNA damaged to the point of obliteration.

A new study published in the journal Nature Communications this week might be revealing in this respect. University of Tokyo researchers sequenced the genome of a water bear (Ramazzottius variornatus) and found the small aquatic animal has a gene coding a single protein which confers resistance to DNA damage in human cultured cells.

The protein is unique to the tardigrades and helps cells tolerate DNA damage. Besides this mysterious protein, the team led by Takekazu Kuieda found other genes responsible for the tolerance of stressful environments.

It’s still unclear how the tardigrades’ unique adaptations function at the molecular level, but evidence is piling up that these tiny critters evolved unique strategies to cope with stressful conditions. Until we know for sure what makes the water bear such an extreme hero, here’s a cute video of one such creature walking on moss.

Largest genetic complement identified, owned by the water bear

Also known as the water bear, the tardigrade has a lot to be proud of — this tiny organism is nigh-indestructible, known to have survived in extreme temperatures ( -272C to +151C / -457.6F to 303.8F) and to be the only animal that can brave the vacuum of space unprotected and live to tell the tale. A team from the University of North Carolina at Chapel Hill, curious as to how the tardigrade can accomplish such incredible feats, sequenced the genome of the microorganism. Their paper, published in the journal PNAS, reveals that a huge chunk of its DNA is of foreign origin — nearly 17.5% of the water bear’s genome (some 6000 genes) are primarily of bacterial origin, though genes from fungi and plants have also been identified.

Looks fluffy.
Image via wikimedia

Defined as the shifting of genetic material materially between organisms, horizontal gene transfer is widespread in the microscopic world. The process occurs in humans too but in a limited fashion, and via transposons and viruses. Microscopic animals however are known to have large complements of foreign genes.

Until today, the rotifer held the title for ” the greatest complement of foreign DNA of any microscopic organism,” but the newly-sequenced tardigrade genome includes twice as many genes as those boasted by the rotifer. And the authors have a theory as to why this extremely extensive gene transfer may have occurred.

Tardigrades have long been known to undergo and survive the process of desiccation (extreme drying out). The authors believe that this process is extremely harsh on the tardigrade’s genome, with strands of DNA suffering significant sheering and breakage, causing a general loss of integrity and leakiness of the water bear’s nucleus. This may allow foreign genetic material to easily exploit such gaps in the genome and integrate themselves, similar to the gene-transfer procedure known as electroportation.

For now, the tardigrade has a dual claim to fame, being the only known animal to survive the vacuum of space, and being the animal with the largest genetic complement.

Not bad for a 1.5mm long bug.