tter grades you know them you love them and you couldn't kill one even if you tried and believe me we have tried over Decades of research we have subjected tardigrades to some of the most extreme conditions imaginable they've been shot from a gun at 900 m/s they've survived the coldest temperatures in the universe being boiled at 150° Centigrade subjected to pressures of 400 times that of normal atmospheric pressure they've been stored in a freezer for over 30 years and then finally fin were left in space and blasted with Cosmic radiation and none of this seems to have phased them in the slightest the underlying reason for why these adorable microorganisms are just such Elite survivalists comes inherent to their biology but as of a study published last month we finally think we know how they're doing it and if the lessons learned from it can be adapted into our own biology they could stop us getting diseases like cancer survive on off-world habitats with weak or no atmosphere like the moon or Mars enable us to travel into deep space through the universe's high levels of radiation and maybe even let us survive cryosleep so we can live out our true sci-fi future fantasies tardigrades may just be the best survivors on the planet but of course the story of how we came to know these microscopic super survivors is just as fascinating as the extremes that they've endured in 1773 German biologist Johan goz peered into a microscope and saw something strange unlike other microscopic animals he studied which preferred to swim wriggle or beat their all like fella to move around he saw a small wrinkly creature making its way across a micro algae using eight Stumpy legs each tipped with tiny claws with a deep sigh of German reverence and foresight into the hearts and minds of an Internet generation 300 years in the future he announced he had just discovered the water bear a name that instantly indoctrinated this creature into a place in all of our hearts a creature so tiny it fits in between the grooves of a fingerprint it wasn't until 3 years later in an act of unusually poor branding for Italians that Abott and biologist Lazaro fanari gave them the more official tardigrada meaning slow Walker based on their unusual choice of moving around in 1842 Tarter grades again caught the attention of science as Louie deer a French zoologist and agronomist began to run experiments where he observed tardigrades being actively adorable in their natural environments moist mosses and lyans what was strange was when he accidentally underwatered the Tarter grad's habitat one day and it dried out under the warmth of the microscope lamp he watched as the tardigrades actively slowed to a crawl as if moving in suspended animation he came back a few hours later and swore that his test subjects had disappeared panning around frantically the micro environment he realized it was now covered instead in small dark debris The Remains he assumed of the tardigrades repeating the experimental conditions as the second sample dried out deer observed his tardigrade family slowly transform from inquisitive water bears into shriveled desiccated balls a phrase you should never utter on the internet in this state later called a ton all movement stopped the creatures seemed utterly dead but when doer left a sample to rehydrate in the room something remarkable happened the tardigrades slowly stirred back to life something impossible for normal organisms or cells as extreme dehydration leads to cell collapse breaking the internal Machinery of a cell usually Beyond repair doer however found that he could keep his tardra suspended for between a few days up to several months and could expose them to hot cold high pressure and still reliably they would pop back to life as if nothing ever happened in his thesis Memoir on the organization and natural relationships of tardigrades which sounds like a political Manifesto for these tiny survivalists deer documents one of the first ever cases of cryptobiosis crypto meaning hidden and biosis meaning life a physiological state in which metabolic activity is reduced to an almost undetectable level the world's smallest zombie jerky in this state at gr's metabolism Slows To as low as 0.01% of its normal rate that's 10,000 times slower to put that in perspective if you usually consume 2,000 calories a day this would represent a drop in your caloric intake to 0.2 calories you would be capable of surviving on about 1 tenth of a McDonald's fry or about 10 grains of rice per day but the question is shriveling into a ton like some sort of microscopic raisin is impressive in itself but it hardly explains how tardigrades can brush off lethal doses of radiation extreme dehydration or the cellular damage that should arise from Ice Crystals forming within their cells what is actually happening Beyond this simple transformation before we answer that question though I have to quickly thank today's sponsor who is preventing me from 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the video in a 2017 study led by Thomas boothby and his team at the University of North Carolina researchers were determined to get to the bottom of how Tarter grades were surviving in extreme temperatures and conditions that would prove fatal to basically all other forms of life on the planet when we expose organisms to extreme environments like the vacuum of space or Ultra cold temperatures water becomes a major problem water makes up 60 to 80% of most organisms and it is the solvent that enables life's Machinery to function but at temperatures below freezing water turns into a formidable enemy as water freezes to ice it expands by about 9% if ice forms inside of a cell it can rupture the cell's membrane or damage internal cellular structures low temperatures can also make the lipid by layer of the cell membrane brittle and cause breaks in DNA as a result Nature has evolved to avoid freezing at all costs and while we can freeze and Thor some individual cells such as reproductive cells like eggs and sperm with minimal damage to the disappointment of all of the Walt Disney's body is secretly Frozen beneath Disneyland conspiracy theorists unfortunately freezing entire bodies still poses significant challenges except in some very rare examples some species have evolved antifreeze like properties to survive the slightly less adorable Antarctic toothfish the snow flea and the wood frog use natural antifreeze compounds to lower the freezing point of their bodily fluids to protect internal cellular structures but these adaptations are limited to temperatures just below freezing far from the extremes and this is where tardigrades really stand apart they didn't just survive slightly Sub-Zero conditions or mild dehyd ation in their ton State these microscopic creatures can survive down to temperatures as low as - 270° c a range so cold that Atomic movement almost entirely halts researchers had previously found that as a tardigrade encounters extreme conditions it begins preemptively to slowly dehydrate itself this process isn't instantaneous by any means it can take several hours but it means that the tardigrade can lose 97% of its total water content this significantly reduces the likelihood of ice crystals damaging cells while also Contracting the grd's body to minimize its surface area and exposure to the Hazardous environment but that doesn't explain how the tardigrade doesn't then succumb to the cell collapse of extreme dehydration boothby and his team were intrigued by the idea that a hidden mechanism was slowly allowing these tiny water bears to cheat death they set out to solve this puzzle starting by examining what happens at the molecular level when tardigrades enter their ton state to do this they looked at the proteins being produced in these extreme conditions and what they found was unexpected rather than typical proteins that fold neatly into specific shapes they discovered a class of proteins with no fixed structure free floating like loose threads inside the cell in normal conditions these proteins seemed reasonably unremarkable but under stress when the tardigrade was drying out they slowly started to transform and solidify forming a glass-like matrix inside the tardra cells here the best description I can come up with is it's like dipping hand Solo in carbonite protein damage occurs normally within a cell due to denaturing either when the cell is too hot too cold or too mechanically stressed protein structures break and then don't go back together this is what's happening for example when you fry an egg the nicely coiled natural proteins break and unravel so are no longer ordered and transparent and instead start to SC at light in all directions appearing white these newly discovered proteins in the tardigrade cell now called tardigrade specific intrinsicly disordered proteins or tdps which I find particularly catchy this process combined with a then later discovered cytoplasmic abundant heat soluble or cach protein discovered later in 2021 formed a further protective gel-like Network preventing the mechanical stress of dehydration or extreme temperature from breaking the general proteins within tardigrade cells in order to prove their theory that this is how the Todd grade was gleaning some level of extreme environment resistance boothby and his team wanted to see if tdps were truly the key to tardigrade survival boothby and his team took the genes responsible for producing these proteins and inserted them into other organisms specifically yeast and bacteria these organisms which normally cannot survive desiccation was suddenly able to endure extreme drying just like the Tarter grades the tdps worked the same way in these foreign organisms creating that protective glass-like shield and proving that these proteins were a key component of the tardigrades Arsenal but that wasn't the end of the story while tdps Safeguard cellular structures they cannot prevent the ionizing effect of radiation from breaking DNA strands the median lethal dose or ld50 is approximately 0.6 to 0.9 gray for mice it's about 2.5 to 4.5 grays for human beings if a human is exposed to a dose of approximately 50 Grays even for a short time this causes severe convulsions and death within just 5 days it was found that grades can survive not just 50 Grays but up to 4,000 Grays without any meaningful sign of degradation in 2024 a team of researchers again at the University of North Carolina at Chapel Hill this time led by biologist Bob gold ran a study to discover how tardigrade cells could survive such extreme radiation damage the team chose a specific tardigrade called the hippius exemplaris which sounds like it could be straight out of Harry Potter for their experiment a model organism known for its resilience but like all life forms still susceptible to DNA damage from gamma radiation the first phase of the experiment involves subjecting the tardigrades in their ton states to intense doses of gamma rays far beyond what would be lethal to humans the team then used Advanced genomic sequencing and proteomics to study what happens at the molecular level as soon as this damage occurs and they discovered again something uniquely remarkable about tardigrades instead of Simply weathering the radiation and then killing off the damaged cells like our bodies do radiation exposure to the cell appeared to trigger the tardigrades to activate hundreds of genes responsible for flooding the tarr's bodies with DNA repair and protection proteins during their analysis two key proteins in particular stood out dsup a damage suppressing protein was found to bind directly to DNA strands and wrap around them and act as a sacrificial barrier to protect the DNA from radiation damage in populations where dup was expressed they were found to have significantly reduced rates of double stranded breaks the other protein of Interest was trd1 a newly discovered protein while dup helps prevent damage trd1 play plays a role in stabilizing chromosomes even when they begin to fray under radiation stress this protein acts essentially like a molecular glue temporarily rebinding the chromosomes together long enough for normal repair processes to take place in order to test whether this unique T gradeability could be harnessed for human use the researchers introduced the trd1 protein into human cells researcher Keda tazu and his team from the University of Tokyo engineered cultured human embryonic kidney cells to EXP Express the dup and trd1 proteins and subjected them to radiation when compared against controls these cells had higher survival rates when exposed to x-rays exhibiting 40% less x-ray induced damage to their DNA what is a strange question worth asking ourselves here is why why did tardigrades go to such extreme genetic lengths to survive such extreme environments the ancestral environment Theory suggests that tarr's ancestors may have lived in more extreme environments than their present day counterparts and the ability to survive harsh conditions may have been retained as an ancestral trait for example in Earth's early history conditions were much more volatile with extreme and frequent fluctuations in temperature radiation exposure and water availability but why would this survival capability be pushed to also work in places like the vacuum of space or at the coldest temperatures in the universe to me this feels more like an unexpected outcome rather than an evolutionary adaptation The evolutionary byproduct Theory suggests that tardigrades extreme resilience may have evolved as an accidental byproduct of other more common stressors for instance desiccation tolerance is really useful if you happen to live in a moss or lyen environment because these exhibit poor water retention so frequently dry out then rehydrate maybe many times per day the same mechanism that allows tardigrades to survive desiccation like the production of the tardigrade specific intrinsically disordered proteins or tdps really wanted to just say it one more time in this video and other molecular defenses are incidentally the exact same sort of protection mechanisms needed for surviving Ultra cold environments these dehydrating and rehydrating processes still likely cause DNA damage so the evolution of a Rapid Repair mechanism that is frequently activated to repair desiccation damage makes sense to evolve and inadvertently makes them incredibly good at repairing damage from radiation exposure some people just think T grades came from space which I can kind of understand but I'm disappointed they didn't come with cooler gadgets I suppose though what they could teach us may actually unlock the future of human exploration and survival as we set out to explore extraterrestrial environments tardigrades could become a key Ally in our journey with NASA's planned emus missions to establish a base on the moon and then deep space beyond that these environments lacking the protective atmosphere of Earth expose astronauts to Cosmic radiation which is a significant risk to DNA damage over time possibly limiting or maybe even preventing our long-term survival in space we quite recently covered a technology being developed by NASA that could be the very first re life force field capable of deflecting radiation away from habitation zones or crew Quarters on deep space missions but this would limit astronauts to only short excursions outside of these habitats a far future looking solution might be to engineer gr's trd1 ability into our own genes plus upregulate existing repair mechanisms within our own bodies so that DNA damage could be quickly repaired that feels like a very long way away but with the experiments out of the University of Tokyo we see that it is actually on the horizon of things worth exploring that obviously might be a fair distance in the future but there are also some shorter term winds being explored in a somewhat horrifying 2020 paper research discovered a new species of tardigrade that was capable of surviving intense doses of ultraviolet radiation when they investigated further they found that the grade was actually fluorescing absorbing shorter UV wavelengths and emitting longer ones protecting their cells from radiation damage in the process in a slightly disturbing twist the researchers then ground up the grades and applied the tardigrade paste to small worms with the paste applied the worms were then able to tolerate much higher doses of UV radiation could this be developed into a grade sunscreen coming to a store near you sometime soon hopefully not but maybe a synthetic version could be a bit more wholesome and effective where I've seen the most interesting work though is in applying the grade unique proteins like tdps and cach proteins to prevent damage to things like organs as they're being transplanted between patients and even things like life-saving medicines many medicines from things like insulin for diabetics to Cold and Flu vaccines need to be constantly kept cold so they don't break down this isn't really too hard in developed countries but is a nightmare if say you want to get a medicine to a remote Village or to maybe carry something like a snake bite antivenom kit with you while you go hiking through the woods researchers out of the University of Wyoming are working to improve the thermal stability of several medicines using the unique tarrade proteins to protect these medicines in the same glassy gel-like state that prevents damage to tardigrade cells tardigrades hold a special place in our hearts but they also hold a special place in science and potentially a special place in building us a healthier future I love stories like this and understanding how we might take better inspiration from things around us there was a ton of stuff that I didn't cover like how tdd grade eggs are spiky which is kind of horrifying if you like this video and would like to support us consider joining the patreon or joining the channel here or leaving us a like or a comment you might also like a video that we did recently on bats who also refused to die but for a totally different set of reasons you can check it out here as always thank you so much for watching I'll see you guys next week goodbye