Tag: Life

Astronomers Spot Possible Signs Of Extraterrestrial Life In Venus’s Clouds

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There may be bizarre microbes living in the sulfuric acid-laden clouds of the hothouse planet, scientists said.

By Seth Borenstein

Astronomers have found a potential sign of life high in the atmosphere of neighboring Venus: hints there may be bizarre microbes living in the sulfuric acid-laden clouds of the hothouse planet.

Two telescopes in Hawaii and Chile spotted in the thick Venutian clouds the chemical signature of phosphine, a noxious gas that on Earth is only associated with life, according to a study in Monday’s journal Nature Astronomy.

Several outside experts — and the study authors themselves — agreed this is tantalizing but said it is far from the first proof of life on another planet. They said it doesn’t satisfy the “extraordinary claims require extraordinary evidence” standard established by the late Carl Sagan, who speculated about the possibility of life in the clouds of Venus in 1967.

“It’s not a smoking gun,” said study co-author David Clements, an Imperial College of London astrophysicist. “It’s not even gunshot residue on the hands of your prime suspect, but there is a distinct whiff of cordite in the air which may be suggesting something.”

As astronomers plan for searches for life on planets outside our solar system, a major method is to look for chemical signatures that can only be made by biological processes, called biosignatures. After three astronomers met in a bar in Hawaii, they decided to look that way at the closest planet to Earth: Venus. They searched for phosphine, which is three hydrogen atoms and a phosphorous atom.

On Earth, there are only two ways phosphine can be formed, study authors said. One is in an industrial process. (The gas was produced for use as chemical warfare agent in World War I.) The other way is as part of some kind of poorly understood function in animals and microbes. Some scientists consider it a waste product, others don’t.

Phosphine is found in “ooze at the bottom of ponds, the guts of some creatures like badgers and perhaps most unpleasantly associated with piles of penguin guano,” Clements said.

Study co-author Sara Seager, an MIT planetary scientist, said researchers “exhaustively went through every possibility and ruled all of them out: volcanoes, lightning strikes, small meteorites falling into the atmosphere. … Not a single process we looked at could produce phosphine in high enough quantities to explain our team’s findings.”

That leaves life.

The astronomers hypothesize a scenario for how life could exist on the inhospitable planet where temperatures on the surface are around 800 degrees (425 degrees Celsius) with no water.

“Venus is hell. Venus is kind of Earth’s evil twin,” Clements said. “Clearly something has gone wrong, very wrong, with Venus. It’s the victim of a runaway greenhouse effect.”

But that’s on the surface.

Seager said all the action may be 30 miles above ground in the thick carbon-dioxide layer cloud deck, where it’s about room temperature or slightly warmer. It contains droplets with tiny amounts of water but mostly sulfuric acid that is a billion times more acidic than what’s found on Earth.

The phosphine could be coming from some kind of microbes, probably single-cell ones, inside those sulfuric acid droplets, living their entire lives in the 10-mile-deep clouds, Seager and Clements said. When the droplets fall, the potential life probably dries out and could then get picked up in another drop and reanimate, they said.

Life is definitely a possibility, but more proof is needed, several outside scientists said.

Cornell University astronomer Lisa Kaltenegger said the idea of this being the signature of biology at work is exciting, but she said we don’t know enough about Venus to say life is the only explanation for the phosphine.

“I’m not skeptical, I’m hesitant,” said Justin Filiberto, a planetary geochemist at the Lunar and Planetary Institute in Houston who specializes in Venus and Mars and isn’t part of the study team.

Filiberto said the levels of phosphine found might be explained away by volcanoes. He said recent studies that were not taken into account in this latest research suggest that Venus may have far more active volcanoes than originally thought. But Clements said that explanation would make sense only if Venus were at least 200 times as volcanically active as Earth.

David Grinspoon, a Washington-based astrobiologist at the Planetary Science Institute who wrote a 1997 book suggesting Venus could harbor life, said the finding “almost seems too good to be true.”

“I’m excited, but I’m also cautious,” Grinspoon said. “We found an encouraging sign that demands we follow up.”

NASA hasn’t sent anything to Venus since 1989, though Russia, Europe and Japan have dispatched probes. The U.S. space agency is considering two possible Venus missions. One of them, called DAVINCI+, would go into the Venutian atmosphere as early as 2026.

Clements said his head tells him “it’s probably a 10% chance that it’s life,” but his heart “obviously wants it to be much bigger because it would be so exciting.”

https://www.huffpost.com/entry/venus-possible-life_n_5f5f878ac5b68d1b09c5ab9b

Sugars essential to life detected in meteorites, a first

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Scientists found three bio-essential sugars, including ribosome, in samples from a pair of meteorites. Photo by Yoshihiro Furukawa

By Brooks Hays

For the first time, scientists have identified sugars essential to life inside meteorites.

The discovery, described this week in the journal PNAS, supports the theory that a bombardment of meteorites provided ancient Earth with the building blocks required for the origin of life.

An international team of scientists identified a trio of bio-essential sugars, including ribose, arabinose and xylose, inside two carbon-rich meteorites.

“Ribose is an essential sugar for present life as a building block of RNA, which could have both stored information and catalyzed reactions in primitive life on Earth,” researchers wrote in their new paper.

Scientists have previously found other biomolecules in meteorites, including amino acids, which form proteins, and nucleobases, the building blocks of DNA and RNA. But until now, scientists hadn’t been able to find sugars.

“The research provides the first direct evidence of ribose in space and the delivery of the sugar to Earth,” Yoshihiro Furukawa, researcher at Tohoku University in Japan, said in news release. “The extraterrestrial sugar might have contributed to the formation of RNA on the prebiotic Earth which possibly led to the origin of life.”

To find the sugars, scientists used gas chromatography mass spectrometry to analyze the chemical components of powdered meteorite samples. The method identifies molecules by measuring their mass and electric charge.

The research team used isotopic analysis to confirm the sugar’s interplanetary origins. Their tests showed a higher concentration of carbon 13 in the sugars. Carbon 13 is a heavier carbon isotope that is less abundant in terrestrial samples.

While planetary scientists continue to search for signs of life on other planets, researchers are still trying to figure out how biology — or the first living organisms — emerged from non-biological chemical processes here on Earth.

While some scientists theorize that RNA and DNA evolved together, or emerged simultaneously, others estimate that RNA came first and evolved DNA. RNA can catalyze chemical reactions, as well as make copies of itself, something DNA can’t do. Some research suggests metabolism preceded both RNA and DNA.

The latest discovery supports the theory that RNA was the initial conductor of life’s assembly.

“The sugar in DNA, 2-deoxyribose, was not detected in any of the meteorites analyzed in this study,” said study co-author Danny Glavin, researcher at NASA’s Goddard Space Flight Center. “This is important since there could have been a delivery bias of extraterrestrial ribose to the early Earth which is consistent with the hypothesis that RNA evolved first.”

Scientists hope to gain additional insights into life’s origins as they probe other meteorite samples for evidence of sugar’s abundance.

https://www.upi.com/Science_News/2019/11/19/Sugars-essential-to-life-detected-in-meteorites-a-first/4421574186445/?sl=1

Early life on Earth may have existed as miniature droplets of jelly

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By Michael Marshall

Blobs of simple carbon-based compounds could have been the precursors to the first living cells. A new study suggests that such droplets could have formed quickly and easily on the young Earth.

“We were able to find these interesting microdroplet structures that could be synthesised from prebiotically available resources,” says Tony Jia of the Tokyo Institute of Technology in Japan. “Maybe they weren’t the direct precursors to modern cells, but perhaps they could have had some effect or had a role in the emergence of initial life.”

All modern cells are surrounded by an outer wall called a membrane, which is made of long chain-like molecules called lipids. Given the ubiquity of these membranes, many researchers studying how life began have made simple membrane-lined spheres, which they say could mimic the first simple cells.

The droplets Jia and his colleagues made are different. “They don’t have an outer layer,” says Jia. “In that sense they’re membrane-less.”

The first cells?
The team made them from simple chemicals called alpha-hydroxy acids. These are made by the same processes that create amino acids, suggesting they were present on the early Earth, says team member Kuhan Chandru of the National University of Malaysia. “You can find them in meteorites as well.” He showed in 2018 that alpha-hydroxy acids link up to form complex molecules at a wide range of temperatures.

In the new study, the team simply dissolved the acids in water, then left them to dry out at 80 °C for a week – mimicking the conditions near a hot volcanic pond.

The acids turned into a thick jelly, because they had again formed complex molecules. When the researchers added water, the jelly formed hundreds of droplets a few micrometres across. Further experiments showed that crucial biological molecules, including protein and RNA, could enter the droplets and still perform their functions.

Cells without walls
Membrane-less droplets were a key element of the first popular hypothesis for life’s origin, which was set out by Russian biologist Alexander Oparin in the 1920s. However, the idea fell out of favour when it emerged that all cells have membranes.

The idea is now being re-assessed, says Kate Adamala of the University of Minnesota in Minneapolis. She suspects that life went through a “membrane-less stage” and that membranes only arose later.

Both droplets and membrane-based cells are a container for life’s components. This is crucial, says Adamala, because it keeps all the parts together, creating an individual organism from what would otherwise be a mess of chemicals.

But membranes are such good barriers that the first cells would have struggled to get food in and waste out, Adamala argues. So at the very beginning, membrane-less droplets would be better. “You don’t have to be shut off from the environment, because those droplets are permeable and you can have things diffusing in and out of them.”

Journal reference: PNAS, DOI: 10.1073/pnas.1902336116

Read more: https://www.newscientist.com/article/2210671-early-life-on-earth-may-have-existed-as-miniature-droplets-of-jelly/#ixzz5uVl0RAI6

For The First Time, Scientists Have Made Synthetic DNA With 4 Additional Letters

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by Mike McRae

Earth might have a dizzying array of life forms, but our biology ultimately remains a solitary data point – we simply don’t have a reference for life based on DNA different from our own. Now, scientists have taken matters into their hands to push the boundaries on what life could be like.

Research funded by NASA and led by the Foundation for Applied Molecular Evolution in the US has led to the creation of an entirely new flavour of the DNA double helix, one that has an additional four nucleotide bases.

It’s being called hachimoji DNA (from the Japanese words for ‘eight letters’) and it includes two new pairs to add to the existing partnerships of adenine (A) paired with thymine (T), and guanine (G) with cytosine (C).

This work to expand on nature’s own genetic recipe might sound a little familiar. The same scientists already successfully squeezed in two new letters in 2011. Only last year yet another version of an extended alphabet, also with six letters, was made to function inside a living organism.

Now, in what might seem like a case of overachievement, researchers have gone back to the drawing board to develop even more non-standard nucleotides.

They have a purpose for doubling the number of codes in the recipe book, though.

“By carefully analysing the roles of shape, size and structure in hachimoji DNA, this work expands our understanding of the types of molecules that might store information in extraterrestrial life on alien worlds,” says chemist Steven Benner.

We already know a lot about the stability and functionality of ‘natural’ DNA under a range of environmental conditions, and are slowly teasing apart possible scenarios describing its evolution from simpler organic materials to living chemistry.

But to really get a good sense of how a genetic system could evolve, we need to test the limits of its underlying chemistry.

Hachimoji DNA certainly allows for that. The new codes, labelled P, B, Z and S, are based on the same kind of nitrogenous molecules as existing ones, categorised as purines and pyrimidines.

Similarly, they link up with hydrogen bonds to form their own base pairs – S bonding with B, and P with Z.

That’s where the similarities fade out. These new ‘letters’ introduce dozens of new chemical parameters to the double helix structure that potentially affect how it zips and twists.

By devising models that predict the molecule’s stability and then observing actual structures made of this ‘alien’ DNA, researchers are better equipped what’s truly important when it comes to the fundamentals of a genetic template.

The researchers constructed hundreds of hachimoji helices made up of different configurations of natural and synthetic bases and then subjected them to a range of conditions to see how well they held up.

While there were a few minor differences in how the new letters behaved, there was no reason to believe hachimoji DNA wouldn’t work well as an information-carrying template that could mutate and evolve.

The team not only showed their synthetic letters could contribute to new codes without swiftly disintegrating, the sequences were also translated into synthetic RNA versions.

Their work falls well short of a second genesis. But a novel DNA format such as this is a step towards determining what living chemistry might – and might not – look like elsewhere in the Universe.

“Life detection is an increasingly important goal of NASA’s planetary science missions, and this new work will help us to develop effective instruments and experiments that will expand the scope of what we look for,” says NASA’s Planetary Science Division’s acting director, Lori Glaze.

Devising new bases that can operate alongside our own DNA also has applications closer to home, not only as a way to reprogram life with a different code base, but in our effort to build new kinds of nanostructures.

The sky really isn’t the limit with synthetic DNA. This is going to take us to the stars and back again.

This research was published in Science.

https://www.sciencealert.com/scientists-made-synthetic-dna-using-8-letters-and-it-could-help-us-find-aliens

50,000 year old strange life found trapped inside giant cave crystals, now woken up by NASA

On By A.P.In Life, NASALeave a comment

by Bec Crew

Strange microbes have been found inside the massive, subterranean crystals of Mexico’s Naica Mine, and researchers suspect they’ve been living there for up to 50,000 years.

The ancient creatures appear to have been dormant for thousands of years, surviving in tiny pockets of liquid within the crystal structures. Now, scientists have managed to extract them – and wake them up.

“These organisms are so extraordinary,” astrobiologist Penelope Boston, director of the NASA Astrobiology Institute, said on Friday at the annual meeting of the American Association for the Advancement of Science (AAAS) in Boston.

The Cave of Crystals in Mexico’s Naica Mine might look incredibly beautiful, but it’s one of the most inhospitable places on Earth, with temperatures ranging from 45 to 65°C (113 to 149°F), and humidity levels hitting more than 99 percent.

Not only are temperatures hellishly high, but the environment is also oppressively acidic, and confined to pitch-black darkness some 300 metres (1,000 feet) below the surface.

In lieu of any sunlight, microbes inside the cave can’t photosynthesise – instead, they perform chemosynthesis using minerals like iron and sulphur in the giant gypsum crystals, some of which stretch 11 metres (36 feet) long, and have been dated to half a million years old.

Researchers have previously found life living inside the walls of the cavern and nearby the crystals – a 2013 expedition to Naica reported the discovery of creatures thriving in the hot, saline springs of the complex cave system.

But when Boston and her team extracted liquid from the tiny gaps inside the crystals and sent them off to be analysed, they realised that not only was there life inside, but it was unlike anything they’d seen in the scientific record.

They suspect the creatures had been living inside their crystal castles for somewhere between 10,000 and 50,000 years, and while their bodies had mostly shut down, they were still very much alive.

“Other people have made longer-term claims for the antiquity of organisms that were still alive, but in this case these organisms are all very extraordinary – they are not very closely related to anything in the known genetic databases,” Boston told Jonathan Amos at BBC News.

What’s perhaps most extraordinary about the find is that the researchers were able to ‘revive’ some of the microbes, and grow cultures from them in the lab.

“Much to my surprise we got things to grow,” Boston told Sarah Knapton at The Telegraph. “It was laborious. We lost some of them – that’s just the game. They’ve got needs we can’t fulfil.”

At this point, we should be clear that the discovery has yet to be published in a peer-reviewed journal, so until other scientists have had a chance to examine the methodology and findings, we can’t consider the discovery be definitive just yet.

The team will also need to convince the scientific community that the findings aren’t the result of contamination – these microbes are invisible to the naked eye, which means it’s possible that they attached themselves to the drilling equipment and made it look like they came from inside the crystals.

“I think that the presence of microbes trapped within fluid inclusions in Naica crystals is in principle possible,” Purificación López-García from the French National Centre for Scientific Research, who was part of the 2013 study that found life in the cave springs, told National Geographic.

“[But] contamination during drilling with microorganisms attached to the surface of these crystals or living in tiny fractures constitutes a very serious risk,” she says. I am very skeptical about the veracity of this finding until I see the evidence.”

That said, microbiologist Brent Christner from the University of Florida in Gainesville, who was also not involved in the research, thinks the claim isn’t as far-fetched as López-García is making it out to be, based on what previous studies have managed with similarly ancient microbes.

“[R]eviving microbes from samples of 10,000 to 50,000 years is not that outlandish based on previous reports of microbial resuscitations in geological materials hundreds of thousands to millions of years old,” he told National Geographic.

For their part, Boston and her team say they took every precaution to make sure their gear was sterilised, and cite the fact that the creatures they found inside the crystals were similar, but not identical to those living elsewhere in the cave as evidence to support their claims.

“We have also done genetic work and cultured the cave organisms that are alive now and exposed, and we see that some of those microbes are similar but not identical to those in the fluid inclusions,” she said.

Only time will tell if the results will bear out once they’re published for all to see, but if they are confirmed, it’s just further proof of the incredible hardiness of life on Earth, and points to what’s possible out there in the extreme conditions of space.

http://www.sciencealert.com/ancient-life-has-been-found-trapped-inside-these-giant-cave-crystals

Venus could have been habitable while life evolved on Earth

On By A.P.In Space and Time, VenusLeave a comment

By Aviva Rutkin

Nicknamed Earth’s evil twin, Venus seems like everything our planet is not: scorching hot, dried out and covered in toxic clouds.

But a mere one or two billion years ago, these two wayward siblings might have been more alike. New computer simulations suggest that early Venus might have looked a lot like our home planet – and it might even have been habitable.

“It’s one of the big mysteries about Venus. How did it get so different from Earth when it seems likely to have started so similarly?” says David Grinspoon at the Planetary Science Institute in Tucson, Arizona. “The question becomes richer when you consider astrobiology, the possibility that Venus and Earth were very similar during the time of the origin of life on Earth.”

Grinspoon and his colleagues aren’t the first to imagine that Venus was once hospitable. It’s similar to Earth in size and density, and the fact that the two planets formed so close together suggests that they’re made of the same bulk materials. Venus also has an unusually high ratio of deuterium to hydrogen atoms, a sign that it once housed a substantial amount of water, mysteriously lost over time.

Venus, but snowy
To simulate early Venus, the researchers turned to a model of environmental conditions often used to study climate change here on Earth. They created four versions for Venus, each varying slightly in details such as the amount of energy the planet received from the sun, or the length of a Venusian day. Where information was scant about Venus’s climate, the team filled in educated guesses. They also added a shallow ocean, 10 per cent the volume of Earth’s ocean, covering about 60 per cent of the planet’s surface.

Looking at how each version might have evolved over time, the researchers say they were encouraged to believe that the planet might have looked much like an early Earth, and remained habitable for a substantial portion of its lifetime. The most promising of the four Venuses enjoyed moderate temperatures, thick cloud cover and even the occasional light snowfall.

Could life have emerged on this early Venus? If it did, it’s certainly no more, thanks to the oceans later boiling away and volcanoes drastically reshaping the landscape around 715 million years ago. But the team is not ruling it out.

“There’s great uncertainties in understanding Earth, not only its climate history but the history of how life began,” says Michael Way at the NASA Goddard Institute for Space Studies in New York City. If it began in oceans on Earth – a theory we’ve yet to confirm – the same could be true on a waterlogged Venus. “There’s no reason that life on this world would not have existed in these oceans. But that’s about all you can say.”

Alternative histories
“Both planets probably enjoyed warm liquid water oceans in contact with rock and with organic molecules undergoing chemical evolution in those oceans,” says Grinspoon. “As far as we understand at present, those are the requirements for the origin of life.”

To bolster their findings, the team suggests a future mission to Venus should look out for signs of water-related erosion near the equator, which would provide evidence for the oceans detailed in their simulation. Such signs have already been detected by missions at Mars. NASA is currently weighing up two potential Venus projects, although neither has been confirmed. One mission would drop a probe through the clouds down to the surface, while another would orbit around the planet and image its surface.

The researchers would also like to run simulations of further alternative pasts for Venus – perhaps one where it was a desert world, or submerged in as much water as Earth, to find out which scenario is most likely to lead to the Venus we see today.

The study could also aid astronomers in their search for exoplanets, says James Kasting at Pennsylvania State University. If Venus might have once been habitable, then it suggests that other planets close to their stars might be, too. “If you make the habitable zone really wide, that raises the probability of finding an Earth.”

Reference: arxiv.org/abs/1608.00706

https://www.newscientist.com/article/2100191-venus-could-have-been-habitable-while-life-evolved-on-earth/

Fungi in outer space

On By A.P.In Alien life, Mars, Nature, Space and TimeLeave a comment

By Jennifer Frazer

In addition to irritatingly lodging themselves everywhere from shower grout to the Russian space station Mir, fungi that live inside rocks in Antarctica have managed to survive a year and half in low-Earth orbit under punishing Mars-like conditions, scientists recently reported in the journal Astrobiology. A few of them even managed to cap their year in Mars-like space by reproducing.

Why were they subjected to such an ordeal? Scientists have concluded over the past decade that Mars (which like Earth is about four and a half billion years old) supported water for long periods during its first billion years, and they wonder if life that may have evolved during that time may remain on the planet in fossilized or even fresh condition. The climate back then was more temperate than today, featuring a thicker atmosphere and a more forgiving and moist climate.

But how do you search for that life? Using life that exists in what they believe is this planet’s closest analogue, a team of scientists from Europe and the United States hoped to identify the kind of biosignatures that might prove useful in such a search, while also seeing if the Earthly life forms might be capable of withstanding current Mars-like conditions.

Which is to say, not nice.

The temperature on Mars fluctuates wildly on a daily basis. The Mars Science Laboratory rover has measured daily swings of up to 80°C (that’s 144°F), veering from -70°C(-94°F) at night to 10°C(50°F) at Martian high noon. If you can survive that, you also have to get past the super-intense ultraviolet radiation, an atmosphere of 95% carbon dioxide (the effect of which on humans was vividly illustrated at the end of Total Recall), a pressure of 600 to 900 Pascals (Earth: 101,325 Pascals), and cosmic radiation at a dose of about .2mGy/day (Earth: .001 mGy/day). I don’t know about you, but Mars is not my first vacation choice.

And it’s probably not Cryomyces antarcticus’s either, in spite of the extreme place it calls home. Cryomyces antarcticus and its relative Cryomyces minteri – the two fungi tested independently in this study — are members of a group called black fungi or black yeast for their heavily pigmented hulls that allow them to withstand a wide variety environmental stresses. Members of the group somewhat notoriously turned up a few years ago in a study that found two species of the group commonly live inside dishwashers in people’s homes (they were opportunistic human pathogns, but most humans are immune to them). But most of these fungi live quietly in the most extreme environments on earth.

The particular black fungi used in this experiment, generally considered the toughest on the planet, live in tiny tunnels of their own creation inside Antarctic rocks. This is apparently the only place they can grow without being annihilated by the crushing climate and blistering ultraviolet radiation of Antarctica. Antarctica also happens to be the place on Earth most similar – although still not particularly similar, as you have seen — to our friendly neighborhood Red Planet. This endurance has made both black fungi and their neighbors the lichens popular test pilots for Mars-like conditions on the international space station.

For example, lichen-forming fungi that create the common and beautiful orange Xanthoria elegans and also Acarospora made the same trip to the ISS previously, in a European module of the International Space Station called EXPOSE-E. Both survived the experience, and Acarospora even managed to reproduce.

But this seems to be the first time a non-lichen forming fungus has received the ISS treatment.

These particular two fungi – Cryomyces antarcticus and Cryomyces minteri – were collected from the McMurdo Dry Valleys of Antarctica in Southern Victoria Land, supposedly the most Mars-like place on Earth. They were isolated from dry sandstone onto a plate of fungus food called malt extract agar. This gelatinous disc was then dried along with the fungus living on it inside a dessicator, and sent into space like that.

Each colony was about 1mm in diameter, and each yeast cell in it was 10 micrometers in size. Like most black yeast/fungi, they have a dark outer wall.

The scientists also tested an entire community of “cryptoendolithic” organisms – those that live secretly inside rocks, including not just fungi but also rock-dwelling blue-green algae – by testing whole fragments of rocks collected on Battleship Promontory in Southern Victoria Land, Antarctica. The various organisms live in bands of varying color and depth within 1 centimeter of the rock surface.

The fungi were launched into space in February 2008 and returned to Earth on September 12, 2009. During that time they were placed in a bath of gasses as similar as possible to the atmosphere of Mars and exposed to simulated full Martian UV radiation, one-thousandth Martian UV, or kept in the dark. They also endured the cosmic background radiation of space and temperature swings between -21.7°C and 42.9°C – much warmer than Mars, but the best that could be done. Control samples remained in the dark on Earth.

Once back on Earth, the colonies and rock samples were rehydrated. Their appearance had not changed during their voyage. They were then tested for viability by diluting them in water and plating the resulting solution to see how many new colonies formed. They also estimated the percentage of cells with undamaged cell membranes by using a chemical that can only penetrate damaged cell membranes.

The scientists found that the black yeast’s ability to form new colonies was severely impaired by its time on “Mars”, but it was not zero. When kept in the dark on the ISS, about 1.5% of C. antarcticus was able to form colonies post-exposure, while only .08% of C. minteri could. Surprisingly, those exposed to .1% of Mars UV did better, with 4-5 times more surviving: just over 8% for C. antarcticus and 2% for C. minteri. Perhaps the weak radiation stimulated mutations or stress-response proteins that might have helped the fungi somehow.

With the full force of Martian radiation, the survival rates were about the same as for those samples kept in the dark, which is to say, nearly nil. By comparison, about 46% of control C. antarcticus samples kept in the dark back on Earth yielded colony forming units, while only about 17% of C. minteri did. Not super high rates, but still much higher than their space-faring comrades.

On the other hand, the percentage of cells with intact cell membranes was apparently much higher than the number that could reproduce. 65% of C. antarcticus cells remained intact regardless of UV exposure, while C. minteri’s survival rates fluctuated between 18 and 50%, again doing better with UV exposure than in the dark. Colonized rock communities yielded the highest percentage of intact cells of any samples when kept in the dark – around 75%, but some of the lowest when exposed to solar UV, with just 10-18 % surviving intact.

What explains this apparent survival discrepancy between being alive and being able to reproduce? It may be that the reproductive apparati of the fungi are more sensitive to cosmic radiation than their cell membranes and walls, the authors suggest.

The authors’ results also suggest to them that DNA is the biomolecule of choice to use to search for life on Mars, as it, like the cell membranes, survived largely intact even in cells that could no longer reproduce.

Although Mars-based life may not use DNA genetic material, then again, it just might. It certainly seems to have worked well for us here on Earth.

Even though few of the fungi exposed to Mars-like conditions survived well enough to reproduce, in all cases, at least a fraction did. Perhaps that is the material thing. A similar previous experiment showed one green alga, Stichococcus, and one fungus, Acarospora were able to reproduce after a very similar trip on the space station. Another experiment with the bacterium Bacillus subtilis found that up to 20% of their spores were able to germinate and grow after Mars-like exposure. Theoretically, it only takes one or two to hang on and adapt to these conditions to found a whole lineage of Mars-tolerant life (the major reason, by the way, for NASA’s Planetary Protection Program).

On the other hand, some have suggested that long-term survival of Earthly life is impossible on Mars. Given the extremely low reproductive ability after just 1.5 years, this study did nothing to undermine that idea either.

But all of our studies have tested life that evolved on Earth. What about life that evolved on Mars? There’s just no telling how similar or dissimilar such creatures — supposing they exist or ever existed – might be.

http://blogs.scientificamerican.com/artful-amoeba/fungi-in-space/

Amino acid and phosphorous building blocks of life on Earth found in comet’s atmosphere

On By A.P.In comet, Kebmodee, Space and TimeLeave a comment

67p-jets
Instruments on the Rosetta spacecraft have detected compounds critical to life, including the amino acid glycine and the element phosphorus, in the shroud of gases surrounding Comet 67P/Churyumov-Gerasimenko

For the first time, scientists have directly detected a crucial amino acid and a rich selection of organic molecules in the dusty atmosphere of a comet, further bolstering the hypothesis that these icy objects delivered some of life’s ingredients to Earth.

The amino acid glycine, along with some of its precursor organic molecules and the essential element phosphorus, were spotted in the cloud of gas and dust surrounding Comet 67P/Churyumov-Gerasimenko by the Rosetta spacecraft, which has been orbiting the comet since 2014. While glycine had previously been extracted from cometary dust samples that were brought to Earth by NASA’s Stardust mission, this is the first time that the compound has been detected in space, naturally vaporized.

The discovery of those building blocks around a comet supports the idea that comets could have played an essential role in the development of life on early Earth, researchers said.

“With all the organics, amino acid and phosphorus, we can say that the comet really contains everything to produce life — except energy,” said Kathrin Altwegg of the University of Bern in Switzerland, the principal investigator for the Rosetta mission’s ROSINA instrument.

“Energy is completely missing on the comet, so on the comet you cannot form life,” Altwegg told Space.com. “But once you have the comet in a warm place — let’s say it drops into the ocean — then these molecules get free, they get mobile, they can react, and maybe that’s how life starts.”

Getting a glimpse

Glycine, one of the simplest amino acids, is usually bound up as a solid, which means it’s difficult to detect from afar, Altwegg said.

While scientists have searched for glycine through telescopes in star-forming regions of the sky, the newly reported detection marks the first sighting of the compound in space. In this case, the orbiting Rosetta was close enough to pick up the glycine released by the comet’s dust grains as they heated up in the sun.

The study is a powerful confirmation of earlier, earth-bound detections of life’s building blocks in comet and meteor material.

“We know the Earth was pretty heavily bombarded both with asteroidal material and cometary material,” said Michael A’Hearn, a comet researcher at the University of Maryland who was not involved in the new study.

“There have been various claims of amino acids in meteorites, but all of them have suffered from this problem of contamination on Earth. The Stardust [samples] — which are from a comet, not an asteroid — are probably the least susceptible to the terrestrial contamination problem, but even there the problem is severe,” A’Hearn told Space.com. “I think they [Stardust] really did have glycine, but this is a much cleaner detection in many ways.”

Cooking up life
Amino acids form the basis of proteins, which are complexly folded molecules that are critical to life on Earth. Altwegg’s team searched for other amino acids around the comet as well, but located only glycine — the only one that can form without liquid water (as in the frigid reaches of space).

The glycine probably didn’t form on the comet itself, Altwegg said, but rather in the broad stretches of dust and debris that made up the solar system before planetary bodies formed.

“The solar system was made out of material which formed in a disk, in a solar nebula,” Altwegg said. “In these clouds, it’s pretty cold, so the chemistry you do there is catalytic chemistry on the dust surfaces. And these very small dust grains [1 micron in size] are very good to lead to organic chemistry. This is also done in the lab.” Earth itself was far too hot for similar delicate amino acids to survive its formation, Altwegg said; only the smallest solar system bodies stayed cold.

So glycine formed during that time could have provided a boost to newly forming life if it was delivered to Earth by comets.

“It’s not that it couldn’t have formed on Earth — it certainly could — it’s just that it didn’t have to,” A’Hearn said. “Basically, the Earth got a head start.”

Other, more complex amino acids require liquid water, and so would have likely formed on Earth itself, Altwegg said. This idea is supported by the fact that Rosetta has not identified any amino acids other than glycine near Comet 67P.

Phosphorus is also vital to life as we know it. Among other things, the element is a key constituent of DNA and adenosine triphosphate (ATP), a molecule that stores the chemical energy used by cells.

See more at: http://www.space.com/33011-life-building-blocks-found-around-comet.html#sthash.47SrU6BY.dpuf

Thanks to Kebmodee for bringing this to the attention of the It’s Interesting community.