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Underground life has a carbon mass hundreds of times larger than humans

A nematode (eukaryote) in a biofilm of microorganisms. This unidentified nematode (Poikilolaimus sp.) from Kopanang gold mine in South Africa, lives 1.4 km below the surface. Credit: Image courtesy of Gaetan Borgonie (Extreme Life Isyensya, Belgium).

Microorganisms living underneath the surface of the earth have a total carbon mass of 15 to 23 billion tons, hundreds of times more than that of humans, according to findings announced by the Deep Carbon Observatory and coauthored by UT Professor of Microbiology Karen Lloyd.

Carbon is the most prevalent element in living beings because it is part of almost all the molecules that are key for biological processes, including proteins, fats, and even DNA. Ninety percent of the earth’s carbon is in the subsurface.

“Knowing about how carbon is distributed and how living things use it is crucial for understanding not only life cycles but also our environment,” said Lloyd.

The report, which took an international multidisciplinary team 10 years to complete, also sheds light on other aspects of the incredible world of microbial dark matter.

For the research, scientists at hundreds of sites around the world drilled to a depth of 2.5 kilometers into the sea floor. They also took samples from continental mines and boreholes more than 5 kilometers deep into the earth.

In the samples from this deep biosphere, researchers identified members of all three domains of life: bacteria, archaea (microbes with a membrane nucleus), and eukarya (multicellular organisms that contain a nucleus–for example, humans).

“Ten years ago, we knew far less about the physiologies of the bacteria and microbes that dominate the subsurface biosphere,” said Lloyd. “Today we know that, in many places, they invest most of their energy into simply maintaining their existence and little into growth, which is a fascinating way to live.”

The report includes several other striking findings:

  • 70 percent of all earth’s bacteria live underground. This realization dramatically expands the visualization of the tree of life, a biological analogy first proposed in Charles Darwin’s On the Origin of Species to explain the relationship between living and extinct organisms.
  • The deep biosphere–the zone of life underneath earth’s surface–has a volume of between 2 and 2.3 billion cubic kilometers. This is almost as twice the volume of all oceans.

Since climate change is linked to carbon emissions, understanding how these microorganisms interact with carbon could help scientists produce mitigation strategies against climate change with additional time and research, Lloyd said.

“Some of these underground organisms emit carbon and some others sequester it and turn it into rock, for example. But we don’t know any of that yet. We have a lot to discover,” said Lloyd.

The post Underground life has a carbon mass hundreds of times larger than humans appeared first on Astrobiology Magazine.


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2018-12-10T18:12:12Z
Not in the DNA: Epigenetics discovered in single-celled archaea

University of Nebraska-Lincoln researchers have found revolutionary evidence that an evolutionary phenomenon at work in complex organisms is at play in their single-celled, extreme-loving counterparts, too.

As detailed in the journal PNAS, Nebraska’s Sophie Payne and colleagues have reported the first experimental evidence of epigenetics in single-celled archaea. Credit: Greg Nathan | University of Nebraska-Lincoln

Species most often evolve through mutations in DNA that get inherited by successive generations. A few decades ago, researchers began discovering that multicellular species can also evolve through epigenetics: traits originating not from genetic changes but from the inheritance of cellular proteins that control access to an organism’s DNA.

Because those proteins can respond to shifts in an organism’s environment, epigenetics resides on the ever-thin border between nature and nurture. Evidence for it had emerged only in eukaryotes, the multicellular domain of life that comprises animals, plants and several other kingdoms.

But a series of experiments from Nebraska’s Sophie Payne, Paul Blum and colleagues has shown that epigenetics can pass along extreme acid resistance in a species of archaea: microscopic, single-celled organisms that share features with both eukaryotes and bacteria.

“The surprise is that it’s in these relatively primitive organisms, which we know to be ancient,” said Blum, Charles Bessey Professor of biological sciences at Nebraska. “We’ve been thinking about this as something (evolutionarily) new. But epigenetics is not a newcomer to the planet.”

The team discovered the phenomenon in Sulfolobus solfataricus, a sulfur-eating species that thrives in the boiling, vinegar-acidic springs of Yellowstone National Park. By exposing the species to increasing levels of acidity over several years, the researchers evolved three strains that exhibited a resistance 178 times greater than that of their Yellowstone ancestors.

One of those strains evolved the resistance despite no mutations in its DNA, while the other two underwent mutations in mutually exclusive genes that do not contribute to acid resistance. And when the team disrupted the proteins thought to control the expression of resistance-relevant genes – leaving the DNA itself untouched – that resistance abruptly disappeared in subsequent generations.

“We predicted that they’d be mutated, and we’d follow the mutations, and that would teach us what caused the extreme acid resistance,” Blum said. “But that’s not what we found.”

Though epigenetics is essential to some of the most productive and destructive physiological processes in humans – the differentiation of cells into roughly 200 types, the occurrence of cancers – it remains difficult to study in eukaryotes.

The simplicity of archaea, combined with the fact that their cells resemble eukaryotes’ in some important ways, should allow researchers to investigate epigenetic questions much faster and more cheaply than was possible before, Blum said.

“We don’t know what flips the switch in humans that changes epigenetic traits,” Blum said. “And we sure don’t know how to reverse it very often. That’s the first thing we’ll go after: how to turn it on, how to turn it off, how to get it to switch. And that has benefits when you think about (managing) traits in us or traits in plants.”

Yet the discovery also raises questions, Payne said, especially about how both eukaryotes and archaea came to adopt epigenetics as a method of inheritance.

“Maybe both of them had it because they diverged from a common ancestor that had it,” said Payne, a doctoral student in biological sciences. “Or maybe it evolved twice. It’s a really interesting concept from an evolutionary perspective.”

Blum said the team is likewise curious about whether and how epigenetics might explain why no known archaea cause disease or wage antibiotic-armed warfare against their brethren, as bacteria do.

“There are no antibiotics going on in that world,” he said. “Why is that? We’re thinking (that) it’s got something to do with epigenetics, and so their interactions among each other are fundamentally different than bacteria.”

The discovery also introduces an even broader question, Blum said.

“What was the benefit for them to have this? We don’t know.”

The post Not in the DNA: Epigenetics discovered in single-celled archaea appeared first on Astrobiology Magazine.


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2018-12-09T17:00:59Z
Helium exoplanet inflated like a balloon, research shows

Astronomers have discovered a distant planet with an abundance of helium in its atmosphere, which has swollen to resemble an inflated balloon.

Credit: Denis Bajram

An international team of researchers, including Jessica Spake and Dr David Sing from the University of Exeter, have detected the inert gas escaping from the atmosphere of the exoplanet HAT-P-11b – found 124 light years from Earth and in the Cygnus constellation.

The remarkable breakthrough was led by researchers from the University of Geneva, who observed the exoplanet using the spectrograph called Carmenes, installed on the 4-metre telescope at Calar Alto, Spain.

For the first time, the data revealed the speed of helium atoms in the upper atmosphere of the exoplanet, which is equivalent in size to Neptune. The helium is in an extended cloud that is escaping from the planet, just as a helium balloon might escape from a person’s hand.

The research team believe that the ground-breaking study could open up new understandings of the extreme atmospheric conditions found around the hottest exoplanets.

The research is published in the leading journal, Science, on December 6 2018.

Jessica Spake, part of Exeter’s Physics and Astronomy department said: “This is a really exciting discovery, particularly as helium was only detected in exoplanet atmospheres for the first time earlier this year. The observations show helium being blasted away from the planet by radiation from its host star. Hopefully we can use this new study to learn what types of planets have large envelopes of hydrogen and helium, and how long they can hold the gases in their atmospheres.”

Helium was first detected as an unknown yellow spectral line signature in sunlight in 1868. Devon-based astronomer Norman Lockyer was the first to propose this line was due to a new element, and named it after the Greek Titan of the Sun, Helios. It has since been discovered to be one of the main constituents of the planets Jupiter and Saturn in our Solar System.

It is also the second most common element in the universe and was long- predicted to be one of the most readily-detectable gases on giant exoplanets. However, it was only successfully found in an exoplanet atmosphere earlier this year, in a pioneering study also led by Jessica Spake.

For this new study, the research team used the spectrograph, Carmenes, to pull apart the star’s light into its component colours, like a rainbow, to reveal the presence of helium. The ‘rainbow’ data, called a spectrum, also tells us the position and speed of helium atoms in the upper atmosphere of HAT-P-11b, which is 20 times closer to its star than the Earth is from the Sun.

Romain Allart, PhD student at the University of Geneva and first author of the study said: “We suspected that this proximity with the star could impact the atmosphere of this exoplanet. The new observations are so precise that the exoplanet atmosphere is undoubtly inflated by the stellar radiation and escapes to space.”

These new observations are supported by a state-of-the-art computer simulation, led by Vincent Bourrier, co-author of the study and member of the European project FOUR ACES, used to track the trajectory of helium atoms.

Vincent Bourrier explained: “Helium is blown away from the day side of the planet to its night side at over 10,000 km an hour. Because it is such a light gas, it escapes easily from the attraction of the planet and forms an extended cloud all around it.”

It is this phenomenon that makes HAT-P-11b so inflated, like a helium balloon.

The first detection of helium earlier this year, led by University of Exeter researchers, opened a new window to observe the extreme atmospheric conditions reigning in the hottest exoplanets. These new observations from Carmenes demonstrate that such studies, long thought feasible only from space, can be achieved with greater precision from ground-based telescopes equipped with the right kind of instruments.

The post Helium exoplanet inflated like a balloon, research shows appeared first on Astrobiology Magazine.


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2018-12-08T17:00:44Z
Mantle neon illuminates Earth’s formation

This is an artist’s impression of a young star surrounded by a protoplanetary disk in which planets are forming. Based on measures of neon isotopes, UC Davis researchers conclude that the Earth formed relatively quickly from this cloud of dust and gas, collecting water, carbon and nitrogen in the deep Earth. Credit: European Southern Observatory

The Earth formed relatively quickly from the cloud of dust and gas around the Sun, trapping water and gases in the planet’s mantle, according to research published Dec. 5 in the journal Nature. Apart from settling Earth’s origins, the work could help in identifying extrasolar systems that could support habitable planets.

Drawing on data from the depths of the Earth to deep space, University of California Davis Professor Sujoy Mukhopadhyay and postdoctoral researcher Curtis Williams used neon isotopes to show how the planet formed.

“We’re trying to understand where and how the neon in Earth’s mantle was acquired, which tells us how fast the planet formed and in what conditions,” Williams said.

Neon is actually a stand-in for where gases such as water, carbon dioxide and nitrogen came from, Williams said. Unlike these compounds that are essential for life, neon is an inert noble gas, and it isn’t influenced by chemical and biological processes.

“So neon keeps a memory of where it came from even after four and a half billion years,” Mukhopadhyay said.

There are three competing ideas about how the Earth formed from a protoplanetary disk of dust and gas over four billion years ago and how water and other gases were delivered to the growing Earth. In the first, the planet grew relatively quickly over two to five million years and captured gas from the nebula, the swirling cloud of dust and gas surrounding the young Sun. The second theory suggests dust particles formed and were irradiated by the Sun for some time before condensing into miniature objects called planetesimals that were subsequently delivered to the growing planet. In the third option, the Earth formed relatively slowly and gases were delivered by carbonaceous chondrite meteorites that are rich in water, carbon and nitrogen.

These different models have consequences for what the early Earth was like, Mukhopadhyay said. If the Earth formed quickly out of the solar nebula, it would have had a lot of hydrogen gas at or near the surface. But if the Earth formed from carbonaceous chondrites, its hydrogen would have come in the more oxidized form, water.

Neon from ocean floor to deep space

To figure out which of the three competing ideas on planet formation and delivery of gases were correct, Williams and Mukhopadhyay accurately measured the ratios of neon isotopes that were trapped in the Earth’s mantle when the planet formed. Neon has three isotopes, neon-20, 21 and 22. All three are stable and non-radioactive, but neon-21 is formed by radioactive decay of uranium. So the amounts of neon-20 and 22 in the Earth have been stable since the planet formed and will remain so forever, but neon-21 slowly accumulates over time. The three scenarios for Earth’s formation are predicted to have different ratios of neon-20 to neon-22.

The closest they could get to the mantle was to look at rocks called pillow basalts on the ocean floor. These glassy rocks are the remains of flows from deep in the Earth that spilled out and cooled in the ocean, later to be collected by a drilling expedition led by the University of Rhode Island, which makes its collection available to other scientists.

The gases are found in tiny bubbles within the basalt. Using a press, Williams cracked basalt chips in a sealed chamber, allowing the gases to flow into a sensitive mass spectrometer.

Now for the space part. Previous researchers established the neon isotope ratio for the “solar nebula” (early rapid formation) model with data from the Genesis mission, which captured particles of the solar wind. Data for the “irradiated particles” model came from analyses of lunar soils and of meteorites. Finally, carbonaceous chondrite meteorites provided data for the “late accretion” model.

Minimum size for a habitable planet

The isotope ratios they found were well above those for the “irradiated particles” or “late accretion” models, Williams said, and support rapid early formation.

“This is a clear indication that there is nebular neon in the deep mantle,” Williams said.

Neon, remember, is a marker for those other volatile compounds. Hydrogen, water, carbon dioxide and nitrogen would have been condensing into the Earth at the same time — all ingredients that, as far as we know, go into making up a habitable planet.

The results imply that to absorb these vital compounds, a planet must reach a certain size — the size of Mars or a little larger — before the solar nebula dissipates. Observations of other solar systems show that this takes about two to three million years, Williams said.

Does the same process happen around other stars? Observations from the Atacama Large Millimeter Array, or ALMA, observatory in Chile suggest that it does, the researchers said.

ALMA uses an array of 66 radiotelescopes working as a single instrument to image dust and gas in the universe. It can see the planet-forming disks of dust and gas around some nearby stars. In some cases, there are dark bands in those disks where dust has been depleted.

“There are a couple of ways dust could be depleted from the disk, and one of them is that they are forming planets,” Williams said.

“We can observe planet formation in a gas disk in other solar systems, and there is a similar record of our own solar system preserved in Earth’s interior,” Mukhopadhyay said. “This might be a common way for planets to form elsewhere.”

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2018-12-08T14:00:04Z
Combination of Space-based and Ground-based Telescopes Reveals more than 100 Exoplanets

Distribution of discovered exoplanet orbits animation. Small exoplanets are Mercury sized, large ones are Jupiter sized. The colors indicate those planets’ temperatures; blue indicates roughly Earth’s temperature; white shows temperatures similar to the surface of Venus; and red shows lava like temperatures. Credit: John H. Livingston

An international team of astronomers using a combination of ground and space based telescopes have reported more than 100 extrasolar planets (here after, exoplanets) in only three months. These planets are quite diverse and expected to play a large role in developing the research field of exoplanets and life in the Universe.

Exoplanets, planets that revolve around stars other than the Sun, have been actively researched in recent years. One of the reasons is the success of the Kepler Space Telescope, which launched in 2009 to search for exoplanets. If a planet crosses (transits) in front of its parent star, then the observed brightness of the star drops by a small amount. The Kepler Space Telescope detected many exoplanets using this method. However, such dimming phenomena could be caused by other reasons. Therefore, confirmation that the phenomena are really caused by exoplanets is very important. The Kepler space telescope experienced mechanical trouble in 2013, which led to a successor mission called K2. Astronomers around the world are competing to confirm exoplanets suggested by the K2 data.

An international research team involving researchers at the University of Tokyo and Astrobiology Center of the National Institutes of Natural Sciences investigated 227 K2 exoplanet candidates using other space telescopes and ground-based telescopes. They confirmed that 104 of them are really exoplanets. Seven of the confirmed exoplanets have ultra-short orbital periods less than 24 hours. The formation process of exoplanets with such short orbital periods is still unclear. Further study of these ultra-short period planets will help to advance research into the processes behind their formation. They also confirmed many low-mass rocky exoplanets with masses less than twice that of the Earth as well as some planetary systems with multiple exoplanets.

Mr. John Livingston, a Ph.D. student at the University of Tokyo and lead author of the papers reporting the exoplanets, explains, “Although the Kepler Space Telescope has been officially retired by NASA, its successor space telescope, called TESS, has already started collecting data. In just the first month of operations, TESS has already found many new exoplanets, and it will continue to discover many more. We can look forward to many new exciting discoveries in the coming years.”

The new study was published in The Astronomical Journal on November 26, 2018.

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2018-12-07T20:02:52Z
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