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Silica deposits on Mars with features resembling hot spring biosignatures
Characteristics of the DNA Double-Helix with a tetrahedral chiral water super-structure, forming a "spine of hydration

DNA will adopt two different forms of helices under different conditions--the B- and A-forms. These two forms differ in their helical twist, rise, pitch and number of base pairs per turn. The twist of a helix refers to the number of degrees of angular rotation needed to get from one base unit to another. 

In the B-form of helix, this is 36 degrees while in the A-form it is 33 degreesRise refers to the height change from one base pair to the next and is ~3.4 angstroms in the B-form and ~2.6 angstroms in the A-form. The pitch is the height change to get one full rotation (360 degrees) of the helix. This value is ~34 angstroms in the B-form since there are ten base pairs per turn. In the A-form, this value is ~28 angstroms since there are eleven base pairs per full turn.

Of the two forms, the B-form is far more common, existing under most physiological conditions. The A-form is only adopted by DNA under conditions of low humidity. RNA, however, generally adopts the A-form in situations where the major and minor grooves are closer to the same size and the base pairs are a bit tilted with respect to the helical axis. ... tion1.html

The twist of a helix refers to the number of degrees of angular rotation needed to get from one base unit to another. In the B-form of helix, this is ~36 degrees while in the A-form it is ~33 degrees. " QUOTE"

Chemical nuclease studies show that the activator form, but not the repressor, induces a unique alteration of the helical structure localized at the centre of the DNA-binding site. Data presented here indicate that this Hg-MerR-induced DNA distortion corresponds to a local underwinding of the spacer region of the promoter by about ~33 degrees relative to the MerR-operator complex. The magnitude and the direction of the Hg-MerR-induced change in twist angle are consistent with a positive control mechanism involving reorientation of conserved, but suboptimally phased, promoter elements and are consistent with a role for torsional stress in formation of an open complex. ... t=Abstract

The dimensions of DNA in solution*1

Marshal Mandelkern, John G. Elias, Don Eden and Donald M. Crothers

Department of Chemistry Yale University, New Haven, CT 06511, U.S.A.

Received 3 February 1981.  Available online 22 October 2004.


Combined measurement of the rotational and translational frictional coefficients of rod-like DNA molecules in dilute aqueous solution yields 22 to 26 Å for the hydrodynamic diameter and 3·34(± 0·1) Å for the length per base-pair.

*1 This work was supported by grants GM21966 and RR07015 from the National Institutes of Health.

"yields 22 to 26 Å for the hydrodynamic diameter and 3·34(± 0·1) Å for the length per base-pair."

3·34(± 0·1) Å = 3.33Å


3.33 eh?...I have a graphic concept I hope to share with the members.
But I would like the members to read this LMH interview.

No Way to Prove Genetic
Manipulation of Already-Evolving Primates by E. T.s?


I would think probably that we could not prove it. It would be very difficult for us to prove that. It’s very difficult to prove anything in the past, right? All you can do is look at the evidence and come up with a theory. But proof is something that you can just come up with the facts based on the current data and you can formulate a theory. And a theory is something that’s not just a wild story. It’s something that is sort of accepted to be what happened in the past, or what will happen in the future, based on what scientists believe. So, it’s sort of the accepted, current knowledge. But to actually prove something is extremely difficult.
I don't like that assertion:  No way'
There IS a "WAY"

1 angstrom = 1.0 × 10-10 meters ... ry=Science

In this experiment the average separation between a turn along the molecule was determined to be 33.3 angstroms. The accepted value for one turn is approximately 34 angstroms.

Once the tip, sample, and STM were prepared various images of DNA molecules were collected. The images were then filtered with a Fast-Fourier-Transform, LowPass filter, and Band Stop filter. Measurements for molecular width, and major/minor groove separations were obtained.

This is an 150 x150 angstrom image of the naked HOPG surface taken in constant height mode with the STM. Notice the regular array of carbon atoms. Also note the change in color from left to right. This color change denotes a gradual downward slope from left to right. In a previous experiment other images of the HOPG surface were obtained at various magnifications.

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Here is a 3750 x 3750 angstrom image of a glob of DNA dried on the HOPG substrate. Measuring the structure on the left-hand side of the glob reveals a length of about 1500 angstroms. The 450bp DNA used in this experiment has an approximate length of 1530 angstroms. 8 At first one might be tempted to believe that the three streaks running diagonally across the image are DNA molecules. However, these streaks represent a boundary between two layers in the graphite surface and are much too long to be the DNA dried on the surface. 

Such images as the one pictured above could been seen over the surface of the HOPG substrate. The frequency of these "globs" depended on the concentration of DNA dried on the surface. This particular substrate that produced the image above had 3 ul of 100 ng/l DNA in an aqueous solution. Below is an 150 x 150 angstrom image of a section of a DNA molecule captured on the HOPG substrate.

[Image: tr20.gif]
This image was captured using a bias voltage of 0.3 mV and a reference current of 1.2 nA. Some atomic structure in the DNA molecule (left) can be seen and the graphite substrate is visible on either side. The image was captured within ten minutes of the complete evaporation of the water on the substrate.

Below is a filtered and analyzed image of the DNA molecule pictured above. 

[Image: tr20_an1.gif]
This analysis represents a determination of the molecular width of the DNA molecule. Notice, first, the right-hand twist of the helix. Second, notice the relative uniformity in width of the molecule. Previous studies have determined the width to be 23.0 angstroms. 9 The average value of the data below yields a molecular width of 24.7 angstroms.
[Image: tr20_an4.gif]

[Image: tr20_an5.gif]

[Image: TR20_AN9.GIF]
This particular analysis represents the surface features down the central axis of the DNA molecule. Notice the regular repeat of peaks in the graph. These peaks probably represent major and minor grooves along the molecule. One turn in the DNA helix represent the combination of a major and minor groove. In this experiment the average separation between a turn along the molecule was determined to be 33.3 angstroms. The accepted value for one turn is approximately 34 angstroms. 10 Furthermore, the separation of the major and minor grooves was found to be about 22.55 and 10.75 angstroms, respectively.
[Image: TR20_AN2.GIF]

[Image: TR20_AN3.GIF]

The next series of images is another DNA molecule imaged on the surface of the HOPG substrate. The first image represents a 750 x 750 angstrom area. The actual image is on the left the filtered image is on the right. 

[Image: tr23.gif][Image: tr23_fil.gif]

This image was captured with a bias voltage of 0.35 mV and a reference current of 2.0 nA. The unfiltered image reveals some atomic detail but fails to yield any molecular substructure. 

[Image: tr24-1an.gif]

The filtered 3d image of the DNA molecule clearly reveals some aspects of its substructure. Notice the right-hand helix and the repeating major/minor grooves.

[Image: t24_3d_f.gif]

[Image: t24_ufp.gif]
This is the 150 x 150 angstrom, 2d, unfiltered DNA image. A cross sectional analysis reveals a repeating substructure with a length of about ~33 angstroms. Some structure within this length, as well.
[Image: t24_ufd.gif]

[Image: t24_uf.gif]

[Image: tr24_fil.gif]
This is the 150 x 150 angstrom, 2d, filtered, DNA molecule. Again, the substructure is quite evident. Cross section analysis graphically reveals the repeating turns in the molecule. The average turn length from the data yields about 29 angstroms.
[Image: tr24_an1.gif]

[Image: tr24_an2.gif]

The following data shows the spacing of the minor groove. The average minor groove spacing is about 8.3 angstroms.

[Image: tr24_an3.gif]

[Image: tr24_an4.gif]

EAWater is an Anomaly.

Water was/is on Mars.

This Research is backed by the chiral viral in the DNA spirals.

Quote: Wrote:The group's work employed chiral sum frequency generation spectroscopy (SFG), a technique Petersen detailed in a 2015 paper in the Journal of Physical Chemistry. SFG is a nonlinear optical method in which two photon beams – one infrared and one visible – interact with the sample, producing an SFG beam containing the sum of the two beams' frequencies, or energies. In this case, the sample was a strand of DNA linked to a silicon-coated prism.
More manipulation of the beams and calculation proved the existence of a chiral water superstructure surrounding DNA. 

Water forms 'spine of hydration' around DNA, group finds

May 25, 2017 by Tom Fleischman

[Image: waterformssp.jpg]
An illustration of what chiral nonlinear spectroscopy reveals: that DNA is surrounded by a chiral water super-structure, forming a "spine of hydration." Credit: Poul Petersen
Water is the Earth's most abundant natural resource, but it's also something of a mystery due to its unique solvation characteristics – that is, how things dissolve in it.

"It's uniquely adapted to biology, and vice versa,"

Solvation [Image: 72.bmp] Salvation

DNA ~ 33.3 

Due the math

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[Image: 8617242969_480791a783_b.jpg]

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 Arrow [Image: 8618421390_0a10d1b67c.jpg]
Along the vines of the Vineyard.
With a forked tongue the snake singsss...
'Halos' discovered on Mars widen time frame for potential life
May 30, 2017

[Image: halosdiscove.png]
A mosaic of images from the navigation cameras on the NASA Curiosity rover shows 'halos' of lighter-toned bedrock around fractures. These halos comprise high concentrations of silica and indicate that liquid groundwater flowed through the rocks in Gale crater longer than previously believed. Credit: NASA/JPL-Caltech
Lighter-toned bedrock that surrounds fractures and comprises high concentrations of silica—called "halos"—has been found in Gale crater on Mars, indicating that the planet had liquid water much longer than previously believed. The new finding is reported in a paper published today in Geophysical Research Letters, a journal of the American Geophysical Union.

"The concentration of silica is very high at the centerlines of these halos," said Jens Frydenvang, a scientist at Los Alamos National Laboratory and the University of Copenhagen and lead author of the paper. "What we're seeing is that silica appears to have migrated between very old sedimentary bedrock and into younger overlying rocks. The goal of NASA's Curiosity rover mission has been to find out if Mars was ever habitable, and it has been very successful in showing that Gale crater once held a lake with water that we would even have been able to drink, but we still don't know how long this habitable environment endured. What this finding tells us is that, even when the lake eventually evaporated, substantial amounts of groundwater were present for much longer than we previously thought—thus further expanding the window for when life might have existed on Mars."
Whether this groundwater could have sustained life remains to be seen. But this new study buttresses recent findings by another Los Alamos scientist who found boron on Mars for the first time, which also indicates the potential for long-term habitable groundwater in the planet's past.
The halos were analyzed by the rover's science payload, including the laser-shooting Chemistry and Camera (ChemCam) instrument, developed at Los Alamos National Laboratory in conjunction with the French space agency. Los Alamos' work on discovery-driven instruments like ChemCam stems from the Laboratory's experience building and operating more than 500 spacecraft instruments for national security.
Curiosity has traveled more than 16 km over more than 1,700 sols (martian days) as it has traveled from the bottom of Gale crater part way up Mount Sharp in the center of the crater. Scientists are using all the data collected by ChemCam to put together a more complete picture of the geological history of Mars.
The elevated silica in halos was found over approximately 20 to 30 meters in elevation near a rock-layer of ancient lake sediments that had a high silica content. "This tells us that the silica found in halos in younger rocks close by was likely remobilized from the old sedimentary rocks by water flowing through the fractures," said Frydenvang. Specifically, some of the rocks containing the halos were deposited by wind, likely as dunes. Such dunes would only exist after the lake had dried up. The presence of halos in rocks formed long after the lake dried out indicates that groundwater was still flowing within the rocks more recently than previously known.
[Image: 1x1.gif] Explore further: Veins on Mars were formed by evaporating ancient lakes
More information: J. Frydenvang et al, Diagenetic silica enrichment and late-stage groundwater activity in Gale crater, Mars, Geophysical Research Letters (2017). DOI: 10.1002/2017GL073323 
Journal reference: Geophysical Research Letters [Image: img-dot.gif] [Image: img-dot.gif]
Provided by: Los Alamos National Laboratory

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Along the vines of the Vineyard.
With a forked tongue the snake singsss...
Bacteria from hot springs solve mystery of metabolism
June 20, 2017

[Image: bacteriafrom.jpg]
The bacteria Thermus thermophilus lives in hot springs. Credit: Peter Brzezinski
Combustion is often a rapid process, as in the case of fire. How can cells control the burning process so well? The question has long puzzled researchers. Using bacteria from hot springs, researchers from Stockholm University now have the answer.

When cells burn fat, sugar or protein containing the same amount of energy, they do not vanish into fire and smoke, but use the energy to activate muscles. How does the body control the burning process so well? Researchers at Stockholm University have finally been able to monitor the process and to uncover the mechanism.
"We have shown how oxygen is combusted after it has been transported by blood to our cells. We have also shown how the combustion of oxygen provides energy, for example, for muscle contraction or to generate electricity in our nerve cells," says Peter Brzezinski, professor at the Department of Biochemistry and Biophysics, Stockholm University.
The combustion of oxygen in our cells takes place in the so-called respiratory chain, which carefully controls the process. Electrons, which come from digestion, are transferred to the oxygen we breathe. The oxygen molecules bind to an enzyme in our mitochondria, the cellular power plant. However, the bound oxygen is not immediately combusted to form water, as in an uncontrolled fire, but is converted to water gradually in a carefully controlled process. Up until now, we only had a very basic knowledge about the mechanism of this process, since the reaction is too rapid to be studied using available techniques. One possibility would be to follow the reactions at low temperatures, at about -50 degrees Celsius, where they would be sufficiently slow. However, this is not practically possible.
In this project, researchers Federica Poiana and Christoph von Ballmoos studied oxygen combustion in a bacterium that lives in hot springs – they thrive in nearly boiling water. When the research group performed their studies at 10 degrees, the bacteria found it extremely cold – comparable to human mitochondria exposed to -40 degrees. The reactions were sufficiently slow to allow studies using available instruments. By combining their experimental studies with theoretical calculations, the researchers could translate their observations to the equivalent processes in human cells.
"In addition to just being curious and wanting learn how the process works, our studies are also motivated by trying to understand mitochondrial diseases caused by malfunction in oxygen combustion," says Peter Brzezinski.
[Image: 1x1.gif] Explore further: Natural gas facilities with no CO2 emissions
More information: Splitting of the O–O bond at the heme-copper catalytic site of respiratory oxidases, Science AdvancesDOI: 10.1126/sciadv.1700279 
Journal reference: Science Advances [Image: img-dot.gif] [Image: img-dot.gif]
Provided by: Stockholm University

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Along the vines of the Vineyard.
With a forked tongue the snake singsss...
Did life begin on land rather than in the sea?
July 18, 2017 by Peggy Townsend

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Professor David Deamer. Credit: Carolyn Lagattuta
For three years, Tara Djokic, a Ph.D. student at the University of New South Wales Sydney, scoured the forbidding landscape of the Pilbara region of Western Australia looking for clues to how ancient microbes could have produced the abundant stromatolites that were discovered there in the 1970s.

Stromatolites are round, multilayered mineral structures that range from the size of golf balls to weather balloons and represent the oldest evidence that there were living organisms on Earth 3.5 billion years ago.
Scientists who believed life began in the ocean thought these mineral formations had formed in shallow, salty seawater, just like living stromatolites in the World Heritage–listed area of Shark Bay, which is a two-day drive from the Pilbara.
But what Djokic discovered amid the strangling heat and blood-red rocks of the region was evidence that the stromatolites had not formed in salt water but instead in conditions more like the hot springs of Yellowstone.
The discovery pushed back the time for the emergence of microbial life on land by 580 million years and also bolstered a paradigm-shifting hypothesis laid out by UC Santa Cruz astrobiologists David Deamer and Bruce Damer: that life began, not in the sea, but on land.
Djokic's discovery—together with research carried out by the UC Santa Cruz team, Djokic, and Martin Van Kranendonk, director of the Australian Centre for Astrobiology—is described in an eight-page cover story in the August issue of Scientific American.
"What she (Djokic) showed was that the oldest fossil evidence for life was in fresh water," said Deamer, a lanky 78-year-old who explored the region with Djokic, Damer, and Van Kranendonk in 2015. "It's a logical continuation to life beginning in a freshwater environment."
The model for life beginning on land rather than in the sea could not only reshape our idea about the origin of life and where else it might be, but even change the way we view ourselves.
The right conditions for life
For four decades, ever since the research vessel Alvin discovered deep-sea hydrothermal vents that were habitats for specialized bacteria and worms that looked like something out of a science-fiction novel, scientists have theorized that these mineral- and gas-pumping vents were just what was needed for life to begin.
But Deamer, who describes himself as a scientist who loves playing with new ideas, thought the theory had flaws. For instance, molecules essential for the origin of life would be dispersed too quickly into a vast ocean, he thought, and salty seawater would inhibit some of the processes he knew are necessary for life to begin.

Deamer had spent the early part of his career studying the biophysics of membranes composed of soap-like molecules that form the microscopic boundaries of all living cells. Later, given a piece of the Murchison meteorite that had landed in Australia in 1969, Deamer found that the space rock also contained soap-like molecules nearly 5 billion years old that could form stable membranes. Still later, he demonstrated that membranes helped small molecules join together to form longer information-carrying molecules called polymers.
Trekking to volcanoes from Russia to Iceland and hiking through the Pilbara desert, Deamer and his colleagues' observations of volcanic activity suggested the idea that hot springs provided the right environment for the beginning of life. Deamer even built a machine that simulated the heat, acidity, and wet-and-dry cycles of hot springs and installed it in his lab on the UC Santa Cruz campus.
"I think, every once in awhile, you have to be brave enough and bold enough to try new ideas," Deamer said. "Of course, some of my colleagues think even 'foolish enough.' But that's the chance you take."
Rethinking the timeline
In Deamer's vision, ancient Earth consisted of a huge ocean spotted with volcanic land masses. Rain would fall on the land, creating pools of fresh water that would be heated by geothermal energy and then cooled by runoff. Some of the key building blocks of life, created during the formation of our solar system, would have fallen to Earth and gathered in these pools, becoming concentrated enough to form more complex organic compounds.
The edges of the pools would go through periods of wetting and drying as water levels rose and fell. During these periods of wet and dry, lipid membranes would first help stitch together the organic compounds called polymers and then form compartments that encapsulated different sets of these polymers. The membranes would act like incubators for the functions of life.
Deamer and his team believe the first life emerged from the natural production of vast numbers of such membrane-encased "protocells."
While there is still debate about whether life began on land or in the sea, the discovery of ancient microbial fossils in a place like the Pilbara shows that these geothermal areas—full of energy and rich in the minerals necessary for life—harbored living microorganisms far earlier than believed.
The search for life on other planets
According to Deamer and his colleagues, this discovery and their hot-springs-origins model also have implications for the search for life on other planets. If life began on land, then Mars, which was found to have a 3.65-billion-year-old hot spring deposits similar to those found in the Pilbara region of Australia, might be a good place to look.
For Damer, the new "end-to-end hypothesis" of how life began on land offers something else: that the origin of life was not just a simple story of individual, competing cells. Rather that a plausible new vision of life's start could be a communal unit of protocells that survived and evolved through collaboration and sharing of innovation rather than strict competition.
"That," he said, "is a fundamental shift that might impact how we think of our world, ourselves, and our future: as dependent on collaboration as much as being driven by competition."
Sitting in his fourth-floor office on campus, Deamer smiled as he recounted the letter Charles Darwin wrote to a friend in 1871, which speculated that life might have begun in "some warm little pond."
That's not far off the mark, Deamer said, "except we call ours 'hot little puddles.'"
[Image: 1x1.gif] Explore further: Oldest evidence of life on land found in 3.48-billion-year-old Australian rocks
Provided by: University of California - Santa Cruz

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Along the vines of the Vineyard.
With a forked tongue the snake singsss...
Elevated zinc and germanium levels bolster evidence for habitable environments on Mars
August 25, 2017 by Kelsey Simpkins, American Geophysical Union Blogs

[Image: elevatedzinc.jpg]
This view from the Mast Camera (Mastcam) on NASA’s Curiosity Mars rover shows a site with a network of prominent mineral veins below a cap rock ridge on lower Mount Sharp. The APXS instrument on Curiosity discovered unusual material in these veins that has the highest germanium concentrations found in Gale Crater. Credit: NASA
New data gathered by the Mars Curiosity rover indicates a potential history of hydrothermal activity at Gale Crater on the red planet, broadening the variety of habitable conditions once present there, scientists report in a new study.

Researchers found concentrations of the elements zinc and germanium to be 10 to 100 times greater in sedimentary rocks in Gale Crater compared to the typical Martian crust.
Zinc and germanium tend to be enriched together in high temperature fluids and often occur together on Earth in hydrothermal deposits containing sulfur. The elevated concentrations of zinc and germanium in Gale Crater can potentially be explained by hydrothermal activity that occurred in the region, according to Jeff Berger, a geologist at the University of Guelph, in Ontario, Canada and lead author of the new study published in Journal of Geophysical Research: Planets, a journal of the American Geophysical Union.
Extreme thermal environments on Earth are home to a diverse array of microbial life adapted to these conditions, and these organisms may have been some of the first to evolve on Earth.
Evidence of possible hydrothermal activity has been found by other Mars rovers in other locations on the red planet and in Martian meteorite samples. Researchers have used computer simulations, laboratory experiments and investigation of hydrothermal sites on Earth to try to understand potential past hydrothermal activity on Mars.
Now with potential evidence for hydrothermal conditions once present inside or near Gale Crater, Curiosity's mission takes another step toward determining if there were favorable environmental conditions for microbial life on Mars, according to the study's authors. Hydrothermal deposits are more likely to preserve evidence of microbial life or its precursors, according to Berger.
"You have heat and chemical gradients …  conditions favorable for the genesis and persistence life," Berger said.
The new measurements come from the Alpha Particle X-Ray Spectrometer (APXS) on the Curiosity rover, which is exploring Mount Sharp in Gale Crater, the rover's landing site.
Gale Crater formed 3.5 to 3.8 billion years ago from a meteor impact early in Mars's history. Over a period of several hundred million years after the impact, the crater was filled in with 1 to 2 kilometers (0.6 to 1.25 miles) of sediment from its rim. Previous research has shown evidence that this process of filling Gale Crater with sediment was associated with a lake and streams that probably existed intermittently for thousands to millions of years.

The rock record at Gale crater is fundamental for determining if Mars had environmental conditions favorable for microbial life, according to NASA. The new research illuminates what may have happened before and after the formation of the lake, according to Ashwin Vasavada, Curiosity mission project scientist at the NASA Jet Propulsion Laboratory in Pasadena, California, who was not a part of the new study.
In the new study, researchers used data from the Mars Science Laboratory APXS mounted on Curiosity's robotic arm to measure 16 major, minor and trace elements in the rocks at Gale Crater, including zinc, in addition to the Chemistry and Mineralogy instrument in the rover's body, which analyzes samples from its drill and scoop.
At concentrations that have been estimated for the average Martian crust, germanium is below the detection limit of the APXS instrument and scientists did not expect to see it. So when the data was analyzed for elements beyond the main 16 elements, the researchers were surprised to find germanium, like zinc, is at concentrations up to 100 times higher than in the average Martian meteorite, and even 300 times higher in one vein, Berger said. The new study is the first to include APXS measurements of germanium during the rover's first 1,360 sols, according to the study's authors. A sol is a Martian day, which is 24 hours and 39 minutes long.  
Germanium tends to follow silicon in the rocks on Mars, in a predictable ratio of germanium to silicon. The new study found germanium in Martian rocks that was not in its typical relationship with silicon and did not show the standard germanium-silicon ratio.
The presence of zinc and germanium clustered together in such high concentrations points to the potential for hydrothermal activity, according to the study's authors. These elements have an affinity for each other in minerals that solidify out of high temperature fluids and often occur together on Earth in hydrothermal deposits containing sulfur.
If the target region on Mars had sufficient water when Gale Crater was formed by a meteor impact, the energy of the impact could have heated the crust and caused the fluids to circulate in a hydrothermal system, which could have concentrated zinc and germanium, according to Berger. The elements could also have been concentrated by volcanic and impact activity that occurred before Gale Crater was formed. These enriched sediments could have then been carried by water, wind, and gravity to Gale Crater, he said.
The potential presence of hydrothermal systems during Mars' ancient history adds to a "whole variety of conditions that might all fall under the umbrella of being habitable," Vasavada said.
[Image: 1x1.gif] Explore further: Rover findings indicate stratified lake on ancient Mars
More information: Jeff A. Berger et al. Zinc and germanium in the sedimentary rocks of Gale Crater on Mars indicate hydrothermal enrichment followed by diagenetic fractionation, Journal of Geophysical Research: Planets (2017). DOI: 10.1002/2017JE005290 
Journal reference: Journal of Geophysical Research [Image: img-dot.gif] [Image: img-dot.gif]
Provided by: American Geophysical Union

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More inflexible than imagined

August 25, 2017 by Fabio Bergamin

[Image: moreinflexib.png]
The three sugar building blocks (below, yellow: fucose) form a rigid structure stabilised by a hydrogen bond (dotted line). Credit: Aeschbacher et al. Chemistry 2017
Oligosaccharides – chains of sugar building blocks – are essential for biological cells. Scientists had thought that these molecules were freely mobile, but an international research team has now shown that such sugar molecules can form rigid structures, previously found only in DNA and proteins.

Oligosaccharides – chains of sugar building blocks – are some of the most important molecules in living creatures. They make up a large part of the surface of cells and contribute to the immune system's ability to distinguish the body's own cells from pathogens or other foreign cells. Oligosaccharides on the surface of blood cells also determine our blood group and many proteins carry oligosaccharide appendages, which are essential for protein function.
Scientists had previously thought that these sugar molecules were freely mobile and did not form rigid structures. Rigid three-dimensional molecular structures – referred to by experts as secondary structures – had been found only in DNA, in which the molecules form a double helix, and in proteins, in which partial regions often form spirals or small surfaces with the structure of corrugated metal.
However, an international research team has now found such secondary structures in oligosaccharides. "We were able to show that the structure of certain oligosaccharides that contain the basic building block fucose have a characteristic rigidity," explains Mario Schubert, head of the research team. Schubert was at ETH Zurich for several years and now works at the University of Salzburg.
Stable arrangement
The newly discovered secondary structural element determines how the three sugar building blocks in the oligosaccharide are spatially related: the first building block – the sugar type fucose – and the third building block are stacked parallel to one another, while the middle block is at right angles to the other two. This structure is stabilised by a chemical hydrogen bond between the first and third blocks.
This structure, comprising three blocks, is a comparatively small-scale molecular unit. In comparison, spiral secondary structures in proteins can extend over several dozen protein building blocks.
Dogma disproved
Until now scientists had assumed that the hydrogen bonds between oligosaccharide building blocks were very weak and could therefore be neglected. The prevailing opinion was that no secondary structures existed in oligosaccharides. "Our work now shows that certain hydrogen bonds have to be taken into account. As a slight tip of the scales, they can help significantly in forcing the sugar building blocks into a rigid corset," says Schubert.
"Oligosaccharides with the newly discovered structural pattern are recognised easily by other molecules using the lock and key principle, because a rigid, inflexible structure simplifies molecular recognition," says Schubert. This lock and key principle in oligosaccharides is particularly important in the case of immune system molecules and stem cells. The new findings help to better understand the interactions of such molecules.
Present in many sugar molecules
Structural biologists often use computer programmes to determine the three-dimensional structure of molecules. "This software must now be expanded to account for the new oligosaccharide secondary structural element," says Schubert.
The researchers at ETH Zurich, University of Basel and Ecole Normale Supérieure in Paris detected the new structural element by nuclear magnetic resonance spectroscopy in two blood group oligosaccharides and four other oligosaccharides. However, the scientists assume that the structural element also appears in many other cell surface and protein oligosaccharides. They found evidence of such patterns in more than 200 oligosaccharides in a protein structure database.
[Image: 1x1.gif] Explore further: Protein-trapped sugar compounds nourish infant gut microbes
More information: Thomas Aeschbacher et al. A Secondary Structural Element in a Wide Range of Fucosylated Glycoepitopes, Chemistry - A European Journal (2017). DOI: 10.1002/chem.201701866 

Read more at:

Quote: Wrote:autocatalytic

Now there's the word Eye have been searching for!

New computational model of chemical building blocks may help explain the origins of life

August 24, 2017

[Image: newcomputati.jpg]
Ken Dill explains the computational model that shows how certain molecules fold and bind together in the evolution of chemistry into biology, a key step to explain the origins of life. Credit: Stony Brook University
Scientists have yet to understand and explain how life's informational molecules – proteins and DNA and RNA – arose from simpler chemicals when life on earth emerged some four billion years ago. Now a research team from the Stony Brook University Laufer Center for Physical and Quantitative Biology and the Lawrence Berkeley National Laboratory believe they have the answer. They developed a computational model explaining how certain molecules fold and bind together to grow longer and more complex, leading from simple chemicals to primitive biological molecules. The findings are reported early online in PNAS .

Previously scientists learned that the early earth likely contained the basic chemical building blocks, and sustained spontaneous chemical reactions that could string together short chains of chemical units. But it has remained a mystery what actions could then prompt short chemical polymer chains to develop into much longer chains that can encode useful protein information. The new computational model may help explain that gap in the evolution of chemistry into biology.

"We created a computational model that illustrates a fold-and-catalyze mechanism that amplifies polymer sequences and leads to runaway improvements in the polymers," said Ken Dill, lead author, Distinguished Professor and Director of the Laufer Center. "The theoretical study helps to understand a missing link in the evolution of chemistry into biology and how a population of molecular building blocks could, over time, result in the emergence of catalytic sequences essential to biological life."

In the paper, titled "The Foldamer Hypothesis for the growth and sequence-differentiation of prebiotic polymers," the researchers used computer simulations to study how random sequences of water-loving, or polar, and water-averse, or hydrophobic, polymers fold and bind together. They found these random sequence chains of both types of polymers can collapse and fold into specific compact conformations that expose hydrophobic surfaces, thus serving as catalysts for elongating other polymers. These particular polymer chains, referred to as "foldamer" catalysts, can work together in pairs to grow longer and develop more informational sequences.

This process, according to the authors, provides a basis to explain how random chemical processes could have resulted in protein-like precursors to biological life. It gives a testable hypothesis about early prebiotic polymers and their evolution.

"By showing how prebiotic polymers could have become informational 'foldamers', we hope to have revealed a key step to understanding just how life started to form on earth billions of years ago," explained Professor Dill.

[Image: 1x1.gif] Explore further: New theory of polymer length provides improved estimates of DNA and RNA size

More information: Elizaveta Guseva et al. Foldamer hypothesis for the growth and sequence differentiation of prebiotic polymers, Proceedings of the National Academy of Sciences (2017). DOI: 10.1073/pnas.1620179114 

Read more at:[url=]
Along the vines of the Vineyard.
With a forked tongue the snake singsss...
Couple this to Convergent Evolution. Assimilated

Quote:They found that the molecules, called depsipeptides, formed quickly and abundantly under conditions that would have been common on prebiotic Earth, and with ingredients that would have likely been plentiful.

And some of the depsipeptides evolved into new varieties in just a few days, Holycowsmile an ability that, eons ago, could have accelerated the birth of long molecules, called peptides, that make up proteins.

Discovery of boron on Mars adds to evidence for habitability
September 5, 2017

[Image: discoveryofb.png]
A selfie of the NASA Curiosity rover at the Murray Buttes in Gale Crater, Mars, a location where boron was found in light-toned calcium sulfate veins. Credit: NASA/JPL-Caltech/MSSS
The discovery of boron on Mars gives scientists more clues about whether life could have ever existed on the planet, according to a paper published today in the journal Geophysical Research Letters.

"Because borates may play an important role in making RNA—one of the building blocks of life—finding boron on Mars further opens the possibility that life could have once arisen on the planet," said Patrick Gasda, a postdoctoral researcher at Los Alamos National Laboratory and lead author on the paper. "Borates are one possible bridge from simple organic molecules to RNA. Without RNA, you have no life. The presence of boron tells us that, if organics were present on Mars, these chemical reactions could have occurred."
RNA (ribonucleic acid) is a nucleic acid present in all modern life, but scientists have long hypothesized an "RNA World," where the first proto-life was made of individual RNA strands that both contained genetic information and could copy itself. A key ingredient of RNA is a sugar called ribose. But sugars are notoriously unstable; they decompose quickly in water. The ribose would need another element there to stabilize it. That's where boron comes in. When boron is dissolved in water—becoming borate—it will react with the ribose and stabilize it for long enough to make RNA. "We detected borates in a crater on Mars that's 3.8 billion years old, younger than the likely formation of life on Earth," said Gasda. "Essentially, this tells us that the conditions from which life could have potentially grown may have existed on ancient Mars, independent from Earth."
The boron found on Mars was discovered in calcium sulfate mineral veins, meaning the boron was present in Mars groundwater, and provides another indication that some of the groundwater in Gale Cater was habitable, ranging between 0-60 degrees Celsius (32-140 degrees Fahrenheit) and with neutral-to-alkaline pH.
The boron was identified by the rover's laser-shooting ChemCam (Chemistry and Camera) instrument, which was developed at Los Alamos National Laboratory in conjunction with the French space agency. Los Alamos' work on discovery-driven instruments like ChemCam stems from the Laboratory's experience building and operating more than 500 spacecraft instruments for national defense.
The discovery of boron is only one of several recent findings related to the composition of Martian rocks. Curiosity is climbing a layered Martian mountain and finding chemical evidence of how ancient lakes and wet underground environments changed, billions of years ago, in ways that affected their potential favorability for microbial life.
As the rover has progressed uphill, compositions trend toward more clay and more boron. These and other chemical variations can tell us about conditions under which sediments were initially deposited and about how later groundwater moving through the accumulated layers altered and transported dissolved elements, including boron.
Whether Martian life has ever existed is still unknown. No compelling evidence for it has been found. When Curiosity landed in Mars' Gale Crater in 2012 the mission's main goal was to determine whether the area ever offered a habitable environment, which has since been confirmed. The Mars 2020 rover will be equipped with an instrument called "SuperCam," developed by Los Alamos and an instrument called SHERLOC, which was developed by the Jet Propulsion Laboratory with significant participation by Los Alamos. Both of these will search for signs of past life on the planet.
[Image: 1x1.gif] Explore further: 'Halos' discovered on Mars widen time frame for potential life
More information: Patrick J. Gasda et al, In situ detection of boron by ChemCam on Mars, Geophysical Research Letters (2017). DOI: 10.1002/2017GL074480 
Journal reference: Geophysical Research Letters [Image: img-dot.gif] [Image: img-dot.gif]
Provided by: Los Alamos National Laboratory

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Research shows how DNA molecules cross nanopores

September 5, 2017 by Daniel P. Smith

Research presented in a new paper co-authored by Northwestern University associate professor of mechanical engineering Sandip Ghosal sheds new light on how polymers cross tiny pores ten thousand times smaller than a human hair.

These findings could propel a deeper understanding of the biophysics of living cells, the measurement of polymer properties in diverse chemical industries such as plastics manufacturing and food processing, and the design of biosensors.
In the paper published Aug. 30 in Nature Communications, Ghosal and his co-authors present data showing how the speed of DNA changes as it enters or exits a nanopore. Surprisingly, the experiment showed that DNA molecules move faster as they enter a nanopore (forward translocation) and slower when they exit (backward translocation).
What's happening with the DNA, Ghosal explains, is something familiar to mechanical engineers: a concept called "buckling," studied by great scientific minds like Leonhard Euler and Daniel Bernoulli more than two centuries ago, but rarely studied at the molecular level.
Ghosal and his collaborators concluded that DNA molecules buckle under the influence of compressive forces when entering the nanopore, but are pulled straight by tensile forces when moving in the opposite direction. The resulting difference in the geometric configuration results in greater hydrodynamic drag on the molecule in the latter case.
The study was motivated by a desire to understand, in detail, the mechanics of a DNA molecule's passage through a nanopore, a subject of rich scientific curiosity and conjecture.
"We wanted to know what is happening to the DNA and why," says Ghosal, who also holds a courtesy appointment in the Department of Engineering Sciences and Applied Mathematics.
Rather than simply determining the DNA's average speed of translocation, Ghosal's U.K.-based collaborators - Ulrich F. Keyser, Maria Ricci, Kaikai Chen from the University of Cambridge, and Nicholas A.W. Bell, now of the University of Oxford -designed an innovative experiment to reveal the actual variation of the DNA's speed by inserting markers along the DNA molecule. This "DNA ruler" allowed the researchers to measure the speed of translocation at each instant. To then collect large amounts of data within a relatively short time period, the researchers repeatedly flipped the voltage across the pore, sending the DNA in and out of the nanopore in a "ping-pong" mode.
The group's work builds on the "resistive pulse" technique introduced nearly 20 years ago for detecting and characterizing single molecules. That idea has since been applied to a variety of research, including the search for an ultra-fast method of DNA sequencing and the effort to rapidly measure the mechanical properties of cells.
Ghosal describes his team's work as a potential "first step in extending the resistive pulse method to determining the mechanical characteristics of polymers."
Though Ghosal admits the work itself is purely curiosity-driven research designed to probe what more can be done with the resistive pulse technique, the findings could nevertheless have real-world applications in any area where the measurement of polymer properties is important.
polymer has a characteristic load at which it will buckle and, therefore, the difference between the forward and backward translocation times provide a way of gauging the bending rigidity of polymers," Ghosal said. "It is incredibly exciting that we can now observe this," Ghosal says.
[Image: 1x1.gif] Explore further: Researchers demonstrate continuous and controlled translocation of DNA polymer through a nanopore
Journal reference: Nature Communications [Image: img-dot.gif] [Image: img-dot.gif]
Provided by: Northwestern University

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Was the primordial soup a hearty pre-protein stew?

The evolutionary path to first proteins may have been paved with relatively easy, small steps


September 5, 2017


Georgia Institute of Technology

How proteins evolved billions of years ago, when Earth was devoid of life, has stumped many a scientist. A little do-si-do between amino acids and their chemical lookalikes may have done the trick. Evolutionary chemists tried it and got results by the boatload.
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Discovering paths the chemicals of life likely took on Earth could make it possible to calculate probabilities of life on other planets.

[i]Credit: NASA/Ames/JPL-Caltech[/i]

[i]The primordial soup that sloshed around billions of years ago, and eventually led to first life on our planet, might have been teeming with primal precursors of proteins.

Ancestors of the first protein molecules, which are key components of all cells, could have been bountiful on pre-life Earth, according to a new study led by researchers at the Georgia Institute of Technology, who formed hundreds of possible precursor molecules in the lab. Then they meticulously analyzed the molecules with latest technology and new doink-head.
They found that the molecules, called depsipeptides, formed quickly and abundantly under conditions that would have been common on prebiotic Earth, and with ingredients that would have likely been plentiful.
And some of the depsipeptides evolved into new varieties in just a few days, an ability that, eons ago, could have accelerated the birth of long molecules, called peptides, that make up proteins.
Sans cataclysm, please
The new NASA-affiliated research adds to a growing body of evidence suggesting that the first polymers of life may have arisen in variations of daily processes still observed on Earth today, such as the repeated drying and refilling of pond water. They may not have all zapped into existence as a result of blazing cataclysms, an image often associated with the creation of the first chemicals of life.
"We want to stay away from scenarios that are not readily possible," said Facundo Fernández, a professor in Georgia Tech's School of Chemistry and Biochemistry, and one of the study's principal investigators. "Don't deviate from conditions that would have been realistic and reasonably common on prebiotic Earth. Don't invoke any unreasonable chemistry."
Scientists have long puzzled over how the very first proteins formed. Their long-chain molecules, polypeptides, can be tough to make in the lab under abiotic conditions.
Some researchers have toiled to build tiny chains, or peptides, sometimes under more extreme scenarios that probably occurred less often on early Earth. The yields have been modest, and the resulting peptides have had only a couple of component parts, whereas natural proteins have a large variety of them.
Step-by-step evolution
But complex molecules of life likely did not arise in one dramatic step that produced final products. That's the hypothesis that drives the research of Fernández and his colleagues at the NSF/NASA Center for Chemical Evolution, headquartered at Georgia Tech and based on close collaboration with the Scripps Research Institute.
Instead, multiple easier chemical steps likely produced plentiful in-between products that were useful in subsequent reactions that eventually led to the first biopolymers. The depsipeptides produced in this latest study could have served as such a chemical stepping stone.
They look a lot like regular peptides and can be found today in biological systems. "Many antibiotics, for example, are depsipeptides," Fernández said.
Fernández, his Georgia Tech colleagues Martha Grover and Nicholas Hud, and Ram Krishnamurthyfrom Scripps published their study on August 28, 2017, in the journal Proceedings of the National Academy of Sciences. First author Jay Forsythe, formerly a postdoctoral researcher at Georgia Tech, is now an assistant professor at the College of Charleston. Research was funded by the National Science Foundation and the NASA Astrobiology Program.
The new study joins similar work about the formation of RNA precursors on prebiotic Earth, and about possible scenarios for the formation of the first genes. The collective insights may someday help explain how first life arose on Earth and also aid astrobiologists in determining the probability of life existing on other planets.
Understanding depsipeptide Lego
To understand depsipeptides and the significance of the researchers' results, it's helpful to start by looking at peptides, which are chains of amino acids. When the chains get really long they are called polypeptides, and then proteins.
Living cells have machinery that reads instructions in DNA on how to link up amino acids in a specific order to build very specific peptides and proteins that have functions in a living cell. For a protein to have function in a cell, its polypeptide chains have to clump up like sticky yarn to form useful shapes.
Before cells and DNA existed on an Earth devoid of life, for polypeptides to form, amino acids had to somehow jostle together in puddles or on the banks of rivers or lakes to form chains. But peptide bonds can be tough to form, especially long chains of them.
Amino stand-in double
Other bonds, called ester bonds, form more easily, and they can link up amino acids with very similar molecules called hydroxy acids. Hydroxy acids are so much like amino acids that they can, in some cases, function as their stand-in doubles.
The researchers mixed three amino acids with three hydroxy acids in a water solution and they formed depsipeptides, chains of amino acids and hydroxy acids held together by intermittent ester and peptide bonds. The hydroxy acids acted as an enabler to put the chains together that would have otherwise been difficult to form.
The primordial soup may have lapped its depsipeptides onto rocks, where they dried out in the sun, then rain or dew dissolved them back into the soup, and that happened over and over. The researchers mimicked this cycle in the lab and watched as the depsipeptide chains further developed.
Death Valley heat
"We call it an environmental cycling approach to making these early peptides," said Fernández, who is Vasser Woolley Foundation Chair in Bioanalytical Chemistry. Like nature: Make the soup, dry it out, repeat.
In the lab, the drying temperature was 85 degrees Celsius (185 degrees Fahrenheit), although the reaction has been shown to work at temperatures of 55 and 65 degrees Celsius (131 to 149 degrees Fahrenheit). "If you think about early Earth having a lot of volcanic activity and an atmospheric mix that promoted warming, those temperatures are realistic on many parts of an early Earth," Fernández said.
Early Earth took hundreds of millions of years to cool, and temperatures in the hundreds of degrees are hypothesized to have been commonplace for a long time. Even today, the hottest deserts can reach over 55 degrees Celsius.
Ester do-si-do
Since ester bonds break more easily, in the experiment, the chains tended to come apart more at the hydroxy acids and hold together between the amino acids, which were connected by the stronger peptide bonds. As a result, chains could re-form and link up more and more amino acids with each other into sturdier peptides.
In a kind of square-dance, the stand-in hydroxy acids often left their amino acid partners in the chain, and new amino acids latched onto the chain in their place, where they held on tight. In fact, a number of the depsipeptides ended up being composed almost completely of amino acids and had only remnants of hydroxy acids.
"Now we know how peptides can form easily," Fernández said. "Next, we want to find out what's needed to get to the level of a functional protein."
Ten trillion depsipeptides
To identify the more than 650 depsipeptides that formed, the researchers used mass spectrometry combined with ion mobility, which could be described as a wind tunnel for molecules. Along with mass, the additional mobility measurement gave the researchers data on the shape of the depsipeptides.
doink-head created by Georgia Tech researcher Anton Petrov processed the data to finally identify the molecules.
To illustrate how potentially bountiful depsipeptides could have been on prebiotic Earth: The researchers had to limit the number of amino acids and hydroxy acids to three each. Had they taken 10 each instead, the number of theoretical depsipeptides could have climbed over 10,000,000,000,000.
"Ease and bounty are key," Fernández said. "Chemical evolution is more likely to progress when components it needs are plentiful and can join together under more ordinary conditions."
Georgia Tech's Calvin Millar and Sheng-Sheng Yu also coauthored this study. The research was funded by the National Science Foundation and the NASA Astrobiology Program, under the NSF/NASA Center for Chemical Evolution (CHE-1504217). Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the sponsoring agencies.

Story Source:
[url=]Materials provided by Georgia Institute of Technology. Original written by Ben Brumfield. Note: Content may be edited for style and length.

Journal Reference:

  1. Jay G. Forsythe, Anton S. Petrov, W. Calvin Millar, Sheng-Sheng Yu, Ramanarayanan Krishnamurthy, Martha A. Grover, Nicholas V. Hud, Facundo M. Fernández. Surveying the sequence diversity of model prebiotic peptides by mass spectrometryProceedings of the National Academy of Sciences, 2017; 201711631 DOI: 10.1073/pnas.1711631114

Georgia Institute of Technology. "Was the primordial soup a hearty pre-protein stew? The evolutionary path to first proteins may have been paved with relatively easy, small steps." ScienceDaily. ScienceDaily, 5 September 2017. <>.
Along the vines of the Vineyard.
With a forked tongue the snake singsss...
Quote:That work set the stage for the current study. Knowing precisely how evolution played out in the past, Thornton's group asked: Was this the only evolutionary path to evolving the new function? Was it the most effective one, or the easiest to achieve? Or was it simply one of many possibilities?
Alternate histories
Starting with a resurrected version of an ancient protein that evolved a new function some 500 million years ago - a function critical to human biology today—the researchers synthesized a massive library of genetic variants and used deep mutational scanning to analyze their functions. They found more than 800 different ways that the protein could have evolved to carry out the new function as well, or better than, the one that evolved historically.

Tyler N. Starr et al, Alternative evolutionary histories in the sequence space of an ancient protein, 
Nature (2017). DOI: 10.1038/nature23902 

Scientists create alternate evolutionary histories in a test tube
September 13, 2017

[Image: 1-uchicagoscie.jpg]
University of Chicago graduate student Tyler Starr holds a vial of yeast cells engineered with a library of proteins comprising millions of possible evolutionary paths from our ancient ancestor to its modern function. Credit: Matt Wood, University of Chicago
Scientists at the University of Chicago studied a massive set of genetic variants of an ancient protein, discovering a myriad of other ways that evolution could have turned out and revealing a central role for chance in evolutionary history.

The study, published this week in Nature by University of Chicago graduate student Tyler Starr and his advisor Professor Joseph Thornton, is the first to subject reconstructed ancestral proteins to deep mutational scanning—a state-of-the-art technique for characterizing massive libraries of protein variants. The authors' strategy allowed them to compare the path that evolution actually took in the deep past to the millions of alternative routes that could have been taken, but were not.
Starting with a resurrected version of an ancient protein that evolved a new function some 500 million years ago - a function critical to human biology today—the researchers synthesized a massive library of genetic variants and used deep mutational scanning to analyze their functions. They found more than 800 different ways that the protein could have evolved to carry out the new function as well, or better than, the one that evolved historically.
The researchers showed that chance mutations early in the protein's history played a key role in determining which ones could occur later. As a result, the specific outcome of evolution depended critically on the way a serial chain of chance events unfolded.
"By comparing what happened in history to all the other paths that could have produced the same result, we saw how idiosyncratic evolution is," said Tyler Starr, a graduate student in biochemistry and molecular biology at UChicago, who performed the paper's experiments. "People often assume that everything in biology is perfectly adapted for its function. We found that what evolved was just one possibility out of many that were just as good, or even better, functionally than what we happened to end up with today."
Molecular time travel
Over the last 15 years, Joe Thornton, PhD, senior author on the new study and a professor of ecology and evolution and human genetics at UChicago, led research that pioneered "molecular time travel" using ancestral protein reconstruction. In 2013, his team resurrected and analyzed the functions of the ancestors of a family of proteins called steroid hormone receptors, which mediate the effects of hormones like testosterone and estrogen on sexual reproduction, development, physiology, and cancer. The body's various receptors recognize different hormones and, in turn, activate the expression of different target genes, which they accomplish by binding specifically to DNA sequences called response elements near those targets

Thornton's group inferred the genetic sequences of ancient receptor proteins by statistically working their way back down the tree of life from a database of hundreds of present-day receptor sequences. They synthesized genes corresponding to these ancient proteins, expressed them in the lab, and measured their functions.
[Image: 2-uchicagoscie.jpg]
University of Chicago graduate student Tyler Starr holds a vial of yeast cells engineered with a library of proteins comprising millions of possible evolutionary paths from our ancient ancestor to its modern function. Credit: Matt Wood, University of Chicago
They found that the ancestor of the family behaved like an estrogen receptor - recognizing only estrogens and binding to estrogen response elements - but during one specific interval of history, they evolved into a descendant group capable of recognizing other steroid hormones and binding to a new class of response elements. The researchers found that three key mutations before the emergence of vertebrate animals caused the ancestral receptor to evolve its ability to bind to the new target sequences.
That work set the stage for the current study. Knowing precisely how evolution played out in the past, Thornton's group asked: Was this the only evolutionary path to evolving the new function? Was it the most effective one, or the easiest to achieve? Or was it simply one of many possibilities?
Alternate histories
Starr began working on the project during his first year as a graduate student, developing the technique to assess massive numbers of variants of the ancestral receptor for their ability to bind the new response element. First, he engineered strains of yeast in which the ancestral or new response elements drive expression of a fluorescent reporter gene. He then synthesized a library of ancestral proteins containing all possible combinations of amino acids at the four key sites in the receptor that recognize DNA - 160,000 in all, comprising all possible evolutionary paths that this critical part of the protein could have followed - and introduced this library into the engineered yeast. He sorted hundreds of millions of yeast cells by their fluorescence using a laser-driven device, and then used high-throughput sequencing to associate each receptor variant with its ability to carry out the ancestral function and the new function.
Most of the variants failed to function at all, and some maintained the ancestral function. But Starr found 828 new versions of the protein that could carry out the new function as well, or better than, the one that evolved during history. Remarkably, evolution could have accessed many of these even more easily than the historical "solution," but it happened not to, apparently wandering around the space of possible mutations until it arrived at the version of the protein in our bodies today.
"We all share the same gene sequence for this protein, so it might seem like evolutionary destiny, as if we've arrived at the best possible version. But there are hundreds of other directions that evolution could just as well have taken," Thornton said. "There's nothing special about the history that happened, except that a few chance steps brought us to this singular chance outcome."
Thornton said that deep mutational scanning will be a powerful tool for evolutionary biologists, geneticists and biochemists, and he looks forward to using the approach on successive ancestors at different points in history to see how the set of possible outcomes changed through time.
"We have a molecular time machine to go back to the past, and once we're there, we can simultaneously follow every alternate history that could possibly have played out," Thornton said. "It's a molecular version of every evolutionary biologist's dream."
The study, "Alternate evolutionary histories in the sequence space of an ancient protein," was supported by the National Institutes of Health and the National Science Foundation. Lora Picton, a former research scientist in Thornton's lab at the University of Chicago, was also co-author.
[Image: 1x1.gif] Explore further: Resurrecting ancient proteins, team finds just two mutations set stage for evolution of modern hormone signaling

More information: Tyler N. Starr et al, Alternative evolutionary histories in the sequence space of an ancient protein, Nature (2017). DOI: 10.1038/nature23902 
Journal reference: Nature [Image: img-dot.gif] [Image: img-dot.gif]
Provided by: University of Chicago Medical Center

Read more at:[/url]

Quote:A remote expedition to the deepest layer of the Earth's oceaniccrust has revealed a new ecosystem living over a kilometre beneath our feet. It is the first time that life has been found in the crust's deepest layer, and an analysis of the new biosphere suggests lifecould exist lower still.Nov 17, 2010

Life is found in deepest layer of Earth's crust | New Scientist

New gravity map suggests Mars has a porous crust
September 13, 2017 by Elizabeth Zubritsky

[Image: newgravityma.jpg]
A new map of the thickness of Mars' crust shows less variation between thicker regions (red) and thinner regions (blue), compared to earlier mapping. This view is centered on Valles Marineris, with the Tharsis Montes near the terminator to its west. The map is based on modeling of the Red Planet's gravity field by scientists at NASA's Goddard Space Flight Center in Greenbelt, Maryland. The team found that globally Mars' crust is less dense, on average, than previously thought, which implies smaller variations in crustal thickness. Credit: NASA/Goddard/UMBC/MIT/E. Mazarico
NASA scientists have found evidence that Mars' crust is not as dense as previously thought, a clue that could help researchers better understand the Red Planet's interior structure and evolution.

A lower density likely means that at least part of Mars' crust is relatively porous. At this point, however, the team cannot rule out the possibility of a different mineral composition or perhaps a thinner crust.
"The crust is the end-result of everything that happened during a planet's history, so a lower density could have important implications about Mars' formation and evolution," said Sander Goossens of NASA's Goddard Space Flight Center in Greenbelt, Maryland. Goossens is the lead author of a Geophysical Research Letters paper describing the work.
The researchers mapped the density of the Martian crust, estimating the average density is 2,582 kilograms per meter cubed (about 161 pounds per cubic foot). That's comparable to the average density of the lunar crust. Typically, Mars' crust has been considered at least as dense as Earth's oceanic crust, which is about 2,900 kilograms per meter cubed (about 181 pounds per cubic foot).
The new value is derived from Mars' gravity field, a global model that can be extracted from satellite tracking data using sophisticated mathematical tools. The gravity field for Earth is extremely detailed, because the data sets have very high resolution. Recent studies of the Moon by NASA's Gravity Recovery and Interior Laboratory, or GRAIL, mission also yielded a precise gravity map.
The data sets for Mars don't have as much resolution, so it's more difficult to pin down the density of the crust from current gravity maps. As a result, previous estimates relied more heavily on studies of the composition of Mars' soil and rocks.
"As this story comes together, we're coming to the conclusion that it's not enough just to know the composition of the rocks," said Goddard planetary geologist Greg Neumann, a co-author on the paper. "We also need to know how the rocks have been reworked over time."
Goossens and colleagues started with the same data used for an existing gravity model but put a new twist on it by coming up with a different constraint and applying it to obtain the new solution. A constraint compensates for the fact that even the best data sets can't capture every last detail. Instead of taking the standard approach, known to those in the field as the Kaula constraint, the team created a constraint that considers the accurate measurements of Mars' elevation changes, or topography.
"With this approach, we were able to squeeze out more information about the gravity field from the existing data sets," said Goddard geophysicist Terence Sabaka, the second author on the paper.
Before taking on Mars, the researchers tested their approach by applying it to the gravity field that was in use before the GRAIL mission. The resulting estimate for the density of the moon's crust essentially matched the GRAIL result of 2,550 kilograms per meter cubed (about 159 pounds per cubic foot).
From the new model, the team generated global maps of the crust's density and thickness. These maps show the kinds of variations the researchers expect, such as denser crust beneath Mars' giant volcanoes.
The researchers note that NASA's InSight mission—short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport—is expected to provide the kinds of measurements that could confirm their finding. This Discovery Program mission, scheduled for launch in 2018, will place a geophysical lander on Mars to study its deep interior.
[Image: 1x1.gif] Explore further: Proposed Mars mission has new name
Provided by: NASA's Goddard Space Flight Center

Read more at:[url=]
Along the vines of the Vineyard.
With a forked tongue the snake singsss...
Quote:RE: Silica... :

The researchers note that
asteroids closer to the rocky planets (called S-type asteroids) tend to contain silicate, similar to the inner planets. By contrast, asteroids in the belt closer to the gas giants (called C-type asteroids) tend to contain more carbon, making them more like the gas giants. This, the researchers note, suggests that the asteroids actually came from the planets as they were forming—excess material was essentially kicked away into the asteroid belt, where it remains today.

New theory on origin of the asteroid belt

September 14, 2017 by Bob Yirka report

[Image: 59ba526563c43.jpg]
The asteroid belt may be have started out empty and was populated by objects from across the Solar System. Credit: Sean Raymond,
(—A pair of researchers with Université de Bordeaux has proposed a new theory to explain the origin of the asteroid belt. In their paper published in Science Advances, Sean Raymond and Andre Izidoro describe their theory and what they found when trying to model it.

The asteroid belt (sometimes referred to as the main asteroid belt) orbits between Mars and Jupiter. It consists of asteroids and minor planets forming a disk around the sun. It also serves as a sort of dividing line between the inner rocky planets and outer gas giants. Current theory suggests that the asteroid belt was once much more heavily populated, but the gravitational pull of Jupiter flung approximately 99 percent of its former material to other parts of the solar system or beyond. Astronomers also assumed that Jupiter's gravity prevented the material in the belt from coalescing into larger planets. In this new effort, the researchers propose a completely different explanation of the asteroid belt's origin—suggesting that the belt started out as an empty space and was subsequently filled by material flung from the inner and outer planets.
The researchers note that asteroids closer to the rocky planets (called S-type asteroids) tend to contain silicate, similar to the inner planets. By contrast, asteroids in the belt closer to the gas giants (called C-type asteroids) tend to contain more carbon, making them more like the gas giants. This, the researchers note, suggests that the asteroids actually came from the planets as they were forming—excess material was essentially kicked away into the asteroid belt, where it remains today.
To test their theory, the researchers created a model mimicking the early solar system, during which the asteroid belt starts out as empty. Running the model forward, they report, showed that it was possible that material from the other planets could have made its way to the belt, resulting in the disk observed today. They plan to continue their research to see if they can find more evidence for their theory, or for the conventional view.
[Image: 1x1.gif] Explore further: Astronomers identify oldest known asteroid family
More information: Sean N. Raymond et al. The empty primordial asteroid belt, Science Advances (2017). DOI: 10.1126/sciadv.1701138
The asteroid belt contains less than a thousandth of Earth's mass and is radially segregated, with S-types dominating the inner belt and C-types the outer belt. It is generally assumed that the belt formed with far more mass and was later strongly depleted. We show that the present-day asteroid belt is consistent with having formed empty, without any planetesimals between Mars and Jupiter's present-day orbits. This is consistent with models in which drifting dust is concentrated into an isolated annulus of terrestrial planetesimals. 

Gravitational scattering during terrestrial planet formation causes radial spreading,  youareaduck 
transporting planetesimals from inside 1 to 1.5 astronomical units out to the belt

Several times the total current mass in S-types is implanted, with a preference for the inner main belt. C-types are implanted from the outside, as the giant planets' gas accretion destabilizes nearby planetesimals and injects a fraction into the asteroid belt, preferentially in the outer main belt. These implantation mechanisms are simple by-products of terrestrial and giant planet formation. The asteroid belt may thus represent a repository for planetary leftovers that accreted across the solar system but not in the belt itself. 
Journal reference: Science Advances

Read more at:[/url]

Quote:Gravitational scattering during terrestrial planet formation causes radial spreading,  youareaduck

transporting planetesimals from inside 1 to ~1.52 astronomical units out to the belt

edge a =1


edge b =1.52

[Image: arittri.gif]
edge c =1.82

angle A =33.3

angle B =56.7

area =0.76

square units


Wickramasinghe will have his day.

Could interstellar ice provide the answer to birth of DNA?
September 14, 2017

[url=][Image: meteorite.jpg]

Credit: CC0 Public Domain
Researchers at the University of York have shown that molecules brought to Earth(/Mars) in meteorite strikes could potentially be converted into the building blocks of DNA.

They found that organic compounds, called amino nitriles, the molecular precursors to amino acids, were able to use molecules present in interstellar ice to trigger the formation of the backbone molecule, 2-deoxy-D-ribose, of DNA.
It has long been assumed that amino acids were present on earth before DNA, and may have been responsible for the formation of one of the building blocks of DNA, but this new research throws fresh doubt on this theory.
Dr Paul Clarke, from the University of York's Department of Chemistry, said: "The origin of important biological molecules is one of the key fundamental questions in science. The molecules that form the building blocks of DNA had to come from somewhere; either they were present on Earth when it formed or they came from space, hitting earth in a meteor shower.
"Scientists had already shown that there were particular molecules present in space that came to Earth in an ice comet; this made our team at York think about investigating whether they could be used to make one of the building blocks of DNA. If this was possible, then it could mean that a building block of DNA was present before amino acids."
In order for cellular life to emerge and then evolve on earth, the fundamental building blocks of life needed to be synthesised from appropriate starting materials - a process sometimes described as 'chemical evolution'.
The research team showed that amino nitriles could have been the catalyst for bringing together the interstellar molecules, formaldehyde, acetaldehyde, glycolaldehyde, before life on Earth began. Combined, these molecules produce carbohydrates, including 2-deoxy-D-ribose, the building blocks of DNA.
DNA is one of the most important molecules in living systems, yet the origin 2-deoxy-D-ribose, before life on earth began, has remained a mystery.
Dr Clarke said: "We have demonstrated that the interstellar building blocks formaldehyde, acetaldehyde and glycolaldehyde can be converted in 'one-pot' to biologically relevant carbohydrates - the ingredients for life.
"This research therefore outlines a plausible mechanism by which molecules present in interstellar space, brought to earth by meteorite strikes, could potentially be converted into 2-deoxy-D-ribose, a molecule vital for all living systems."
[Image: 1x1.gif] Explore further: Scientists say the 'R' in RNA may be abundant in space
More information: Phillip R. A. Chivers et al, Spatially-resolved soft materials for controlled release – hybrid hydrogels combining a robust photo-activated polymer gel with an interactive supramolecular gel, Chem. Sci. (2017). DOI: 10.1039/C7SC02210G 
Provided by: University of York

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Levin will have his day.
Along the vines of the Vineyard.
With a forked tongue the snake singsss...
Quote:However, as the continental crust evolved to a composition more like today's, olivine virtually disappeared. Without that mineral to react with water and consume oxygen, the gas was finally allowed to accumulate. Oceans eventually became saturated, and oxygen crossed into the atmosphere.

"It really appears to have been the starting point for life diversification as we know it," Smit said. "After that change, the Earth became much more habitable and suitable for the evolution of complex life, but that needed some trigger mechanism, and that's what we may have found."

Changes in Earth's crust caused oxygen to fill the atmosphere
September 18, 2017

[Image: changesinear.jpg]
Matthijs Smit of the University of British Columbia examines ancient rocks from the deep crust in Norway during the summer of 2017. Credit: Matthijs Smit
Scientists have long wondered how Earth's atmosphere filled with oxygen. UBC geologist Matthijs Smit and research partner Klaus Mezger may have found the answer in continental rocks that are billions of years old.

"Oxygenation was waiting to happen," said Smit. "All it may have needed was for the continents to mature."
Earth's early atmosphere and oceans were devoid of free oxygen, even though tiny cyanobacteria were producing the gas as a byproduct of photosynthesis. Free oxygen is oxygen that isn't combined with other elements such as carbon or nitrogen, and aerobic organisms need it to live. A change occurred about three billion years ago, when small regions containing free oxygen began to appear in the oceans. Then, about 2.4 billion years ago, oxygen in the atmosphere suddenly increased by about 10,000 times in just 200 million years. This period, known as the Great Oxidation Event, changed chemical reactions on the surface of the Earth completely.
Smit, a professor in UBC's department of earthocean & atmospheric sciences, and colleague, professor Klaus Mezger of the University of Bern, were aware that the composition of continents also changed during this period. They set out to find a link, looking closely at records detailing the geochemistry of shales and igneous rock types from around the world—more than 48,000 rocks dating back billions of years.
"It turned out that a staggering change occurred in the composition of continents at the same time free oxygen was starting to accumulate in the oceans," Smit said.
Before oxygenation, continents were composed of rocks rich in magnesium and low in silica - similar to what can be found today in places like Iceland and the Faroe Islands. But more importantly, those rocks contained a mineral called olivine. When olivine comes into contact with water, it initiates chemical reactions that consume oxygen and lock it up. That is likely what happened to the oxygen produced by cyanobacteria early in Earth's history.
However, as the continental crust evolved to a composition more like today's, olivine virtually disappeared. Without that mineral to react with water and consume oxygen, the gas was finally allowed to accumulate. Oceans eventually became saturated, and oxygen crossed into the atmosphere.
"It really appears to have been the starting point for life diversification as we know it," Smit said. "After that change, the Earth became much more habitable and suitable for the evolution of complex life, but that needed some trigger mechanism, and that's what we may have found."
As for what caused the composition of continents to change, that is the subject of ongoing study. Smit notes that modern plate tectonics began at around the same time, and many scientists theorize that there is a connection.
The study is published in Nature Geoscience.
[Image: 1x1.gif] Explore further: How continents were recycled
More information: Primitive continents suppressed Earth's early O2 cycle, Nature GeoscienceDOI: 10.1038/ngeo3030 
Journal reference: Nature Geoscience [Image: img-dot.gif] [Image: img-dot.gif]
Provided by: University of British Columbia

Read more at:[url=][/url]
Along the vines of the Vineyard.
With a forked tongue the snake singsss...
Hope to discover sure signs of life on Mars? New research says look for the element vanadium
September 21, 2017 by Brendan M. Lynch

[Image: hopetodiscov.jpg]
A rendering of the Mars 20/20 Rover, courtesy of NASA.
The search for biology on neighbor planet Mars won't play out like a Hollywood movie starring little green men. Rather, many scientists agree if there was life on the Red Planet, it probably will present itself as fossilized bacteria. To find it, astrobiologists likely will need to decode the chemical analysis of rock samples performed by a rover (like the one NASA plans to send to Mars in 2020). Only then might humankind know conclusively that life exists beyond Earth.

A new paper in the journal Astrobiology suggests NASA and others hunting for proof of Martian biology in the form of "microfossils" could use the element vanadium in combination with Raman spectroscopy on organic material as biosignatures to confirm traces of extraterrestrial life.
"You've got your work cut out if you're looking at ancient sedimentary rock for microfossils here on Earth—and even more so on Mars," said Craig Marshall, the paper's lead author and an associate professor of geology at the University of Kansas. "On Earth, the rocks have been here for 3.5 billion years, and tectonic collisions and realignments have put a lot of stress and pressure on rocks. Also, these rocks can get buried, and temperature increases with depth."
Marshall likens a potential ancient Martian microorganism to a cut of steak from the supermarket in a pressure cooker.
"You can see a steak looks biological—there's blood dripping from it," he said. "Then, you put it in a pressure cooker for very long time, and you end up with charcoal. It could be abiotic charcoal, or it could be made from heat and pressure on organic materials. A lot of biological compounds get destroyed and ripped apart from heat and pressure, and you're left with carbon residue. We can see this carbon with Raman spectroscopy."
Indeed, for some time paleontologists and astrobiologists hunting for bits of life on Mars have made use of Raman spectroscopy, a technique that can reveal the cellular composition of a sample.
[Image: hopetodiscov.png]
Bright field photomicrograph image of the large leiosphaerid acritarch analyzed in this work. Credit: University of Kansas
"People say, 'If it looks like life and has a Raman signal of carbon, then we have life,'" Marshall said. "But, of course, we know there can be carbonaceous materials made in other processes—like in hydrothermal vents—consistent with looking like microfossils that also have some carbon signal. People also make wonderful carbon structures artificially that look like microfossils—exactly the same. So, we're at a juncture now where it's really hard to tell if there's life only based on morphology and Raman spectroscopy."
In the new paper, Marshall and his co-authors offer a path toward ironclad verification that microfossils once were alive. According to the researchers, the proposed technique could be possible to perform with instrumentation already planned for the NASA 2020 rover mission to explore areas of Mars where the ancient environment could have fostered microbial life.

Researchers included Alison Olcott Marshall at KU, Jade Aitken and Peter Lay of the University of Sydney, Barry Lai of Argonne National Laboratory, Pierre Breuer of the Saudi Arabian Oil Co. and Philippe Steemans of the University de Liege.
[Image: 1-hopetodiscov.png]
False-color micro-XRF distribution maps for V, Fe, and S of a single leiosphaerid. Maximal area densities are given in μg/cm2 for each element at the top of each map. The scatter is shown in the Sa, which can be used as an indicator of thickness and density of the sample. Credit: University of Kansas
"We applied a new technique called X-ray fluorescence microscopy—it looks at elemental composition," said Marshall. "Vanadium is an element in the periodic table, a transition metal. It's been shown it can substitute into biological compounds. If you can't unambiguously assign if something is biology or not with morphology and Raman spectroscopy in tandem—maybe we could look for a known biological element, like vanadium. Then, if the material that looked like a microfossil, and looked carbonaceous with Raman spectroscopy—and had vanadium—that's a new way forward for finding out if something really was biology."
According to the researchers, vanadium can be found in crude oil, asphalt and black shale, formed from acknowledged biological sources.
"Vanadium gets complexed in the chlorophyll molecule," Marshall said. "Chlorophylls typically have magnesium at the center—under burial, vanadium replaces the magnesium. The chlorophyll molecule gets entangled within the carbonaceous material, thus preserving the vanadium. It's like if you have a rope stored in your garage and before you put it away you wrap it so you can unravel it the next time you need it. But over time on the garage floor it becomes tangled, things get caught in it. Even when you shake that rope hard, things don't come out. It's a tangled mess. Similarly, if you look at carbonaceous material there's a tangled mess of sheets of carbon and you've got the vanadium mixed in."
Marshall and his colleagues proved the concept of testing for vanadium on known microfossils with acknowledged biological origins on Earth—organic microfossils called acritarchs that might not be far from the kinds of traces of life possibly existing on the Red Planet.
"We tested acritarchs to do a proof-of-concept on a microfossil where there's no shadow of a doubt that we're looking at preserved ancient biology," Marshall said. "The age of this microfossil we think is Devonian. These guys are aquatic microorganisms—they're thought to be microalgae, a eukaryotic cell, more advanced than bacterial. We found the vanadium content you'd expect in cyanobacterial material."
The work was supported by an ARC International Research Grant (IREX) looking for biosignatures for extracellular life, the Australian Synchrotron, and the Department of Energy at the Advanced Photon Source, Argonne National Laboratory.
When Marshall was an ARC Fellow at the University of Sydney, prior to coming to KU, he worked with co-author Lay's group.
"We plan to undertake further Raman spectroscopic work on the carbonaceous materials using nanospectroscopic imaging," Lay said. "This research is also of interest to researchers in the European space program on the Mars Explorer, since another investigator on the ARC grant, although not working on this aspect, was Howell Edwards, who was involved in instrumentation for the Mars Explorer."
Marshall said his research team's vanadium-based verification technique deserves attention from NASA scientists planning for the Mars 2020 mission. Luckily, the KU researcher has good contacts at the space agency.
"Hopefully someone at NASA reads the paper," said Marshall. "Interestingly enough, the scientist who is lead primary investigator for the X-ray spectrometer for the space probe, they call it the PIXL, was his first graduate student from Macquarie University, before his KU times. I think I'll email her the paper and say, 'This might be of interest.'"
[Image: 1x1.gif] Explore further: Researchers hone technique for finding signs of life on Mars
More information: Astrobiology (2017). … 0.1089/ast.2017.1709 
Journal reference: Astrobiology [Image: img-dot.gif] [Image: img-dot.gif]
Provided by: University of Kansas

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Along the vines of the Vineyard.
With a forked tongue the snake singsss...
Quote:LilD —about half a billion years earlier LilD  than currently thought.  Doh

Analysis of titanium in ancient rocks creates upheaval in history of early Earth
September 22, 2017 by Louise Lerner

[Image: analysisofti.jpg]
While previous studies had argued that Earth’s crust 3.5 billion years ago looked like these Hawaiian lavas, a new study led by UChicago scientists suggests by then much of it had already been transformed into lighter-colored felsic rock by plate tectonics. Credit: University of Chicago
The Earth's history is written in its elements, but as the tectonic plates slip and slide over and under each other over time, they muddy that evidence—and with it the secrets of why Earth can sustain life.

A new study led by UChicago geochemists rearranges the picture of the early Earth by tracing the path of metallic element titanium through the Earth's crust across time. The research, published Sept. 22 in Science, suggests significant tectonic action was already taking place 3.5 billion years ago—about half a billion years earlier than currently thought.
The crust was once made of uniformly dark, magnesium- and iron-rich mafic minerals. But today the crust looks very different between land and ocean: The crust on land is now a lighter-colored felsic, rich in silicon and aluminum. The point at which these two diverged is important, since the composition of minerals affects the flow of nutrients available to the fledgling life struggling to survive on Earth.
"This question has been discussed since geologists first started thinking about rocks," said lead author Nicolas Dauphas, the Louis Block Professor and head of the Origins Laboratory in the Department of the Geophysical Sciences and the Enrico Fermi Institute. "This result is a surprise and certainly an upheaval in that discussion."
To reconstruct the crust changing over time, geologists often look at a particular kind of rock called shales, made up of tiny bits of other rocks and minerals that are carried by water into mud deposits and compressed into rock. The only problem is that scientists have to adjust the numbers to account for different rates of weathering and transport. "There are many things that can foul you up," Dauphas said.
To avoid this issue, Dauphas and his team looked at titanium in the shales over time. This element doesn't dissolve in water and isn't taken up by plants in nutrient cycles, so they thought the data would have fewer biases with which to contend.
They crushed samples of shale rocks of different ages from around the world and checked in what form its titanium appeared. The proportions of titanium isotopes present should shift as the rock changes from mafic to felsic. Instead, they saw little change over three and a half billion years, suggesting that the transition must have occurred before then.
[Image: 1-analysisofti.jpg]
These granite peaks are an example of felsic rock, created via plate tectonics. Credit: Basil Greber
This also would mark the beginning of plate tectonics, since that process is believed to be needed to create felsic rock.

"With a null response like that, seeing no change, it's difficult to imagine an alternate explanation," said Matouš Ptáček, a UChicago graduate student who co-authored the study.
"Our results can also be used to track the average composition of the continental crust through time, allowing us to investigate the supply of nutrients to the oceans going back 3.5 billion years ago," said Nicolas Greber, the first author of the paper, then a postdoctoral researcher at UChicago and now with the University of Geneva.
Phosphorous leads to life
The question about nutrients is important for our understanding of the circumstances around a mysterious but crucial turning point called the great oxygenation event. This is when oxygen started to emerge as an important constituent of Earth's atmosphere, wreaking a massive change on the planet—and making it possible for multi-celled beings to evolve.
The flood of oxygen came from a surge of photosynthetic microorganisms; and in turn their work was fostered by a surge of nutrients to the oceans, particularly phosphorus. "Phosphorus is the most important limiting nutrient in the modern ocean. If you fertilize the ocean with phosphorus, life will bloom," Dauphas said.
The titanium timeline suggests that the primary trigger of the surge of phosphorus was the change in the makeup of mafic rock over time. As the Earth cooled, the mafic rock coming out of volcanoes and underground melts became richer in phosphorus.
"We've known for a long time that mafic rock changed over time, but what we didn't know was that their contribution to the crust has stayed rather consistent," Ptáček said.
[Image: 1x1.gif] Explore further: Changes in Earth's crust caused oxygen to fill the atmosphere
More information: Nicolas D. Greber et al. Titanium isotopic evidence for felsic crust and plate tectonics 3.5 billion years ago, Science (2017). DOI: 10.1126/science.aan8086 
Journal reference: Science [Image: img-dot.gif] [Image: img-dot.gif]
Provided by: University of Chicago

Read more at:[/url][url=]
Along the vines of the Vineyard.
With a forked tongue the snake singsss...
that is called ... not even close in horseshoes Whip

Quote:... suggests significant tectonic action was already taking place 3.5 billion years ago—
half a billion years Hi  earlier than currently thought.

0.857143 accuracy in this old science ... being taught to geology students ... in universities.


thatza broken horsehoe.

NASA sent some dimbo here to this university to teach "planetary science".
She was nice enough, though she looked completely lost in this sleepy town to be honest.
Her presentations are less than 0.857143 accuracy in her mentally pre recorded responses to the public.
It's not all her fault. 
She was taught to teach that large factor of error as acceptable NASA gospel  Tp
as long as it complies Whip with their politically correct nonsense.

Half a billion years off here on Mother Earth where evidence is so tangible,
and yet they want us believe what they preach about Mars.
5.7-Million-Year-Old Hominin Footprints Challenge Human Evolutionary Timeline

[Image: extra_large-1504273054-cover-image.jpg]
If the discoveries over the past few decades have told us anything, it’s that the evolution of humans is anything but simple. Now, a new discovery on the Mediterranean island of Crete might be about to put yet another cat among those pigeons, as researchers claim that hominin footprints found on the island date back some 5.7 million years.

The fossils have been found in Trachilos, western Crete, and appear to show many hominin-like characteristics at a time when it has long been believed hominins were evolving in relative isolation in East Africa. The tracks are bipedal, and seem to indicate that the creature that made them had a prominent ball of the foot, a large forward facing big toe, and a lack of claws, all of which are indicative of a hominin creator.
Published in the journal Proceedings of the Geologists’ Association, the researchers argue that despite lacking any other fossil bones, the footprints indicate that bipedal apes, with hominin features were clearly present in Europe some 5.7 million years ago. This assertion is likely to be heavy picked apart by other anthropologists, not least because 4.4 million years ago the oldest hominin known from a fairly complete fossil, Ardipithecus ramidus, was still walking on ape-like feet in Ethiopia.
[Image: content-1504273199-footprints.PNG]
The researchers argue that the big toe (1) is indicative of hominins, rather than apes. Gierliński et al. 2017

“This discovery challenges the established narrative of early human evolution head-on and is likely to generate a lot of debate,” explains Per Ahlberg, co-author of the latest paper, in a statement. “Whether the human origins research community will accept fossil footprints as conclusive evidence of the presence of hominins in the Miocene of Crete remains to be seen.”

Interestingly, the timing of this latest discovery fits somewhat with another that was announced earlier this year, in which researchers suggest that our ancient ancestors may not have split from chimpanzees in the savanna’s of Africa, but instead in the grasslands of Europe. This notion was based on two fossil jaw bones dating to 7.2 million years old in which the teeth are like modern humans' rather than chimpanzees'.
As more and more finds are made, the history of us gets more and more complicated. Rather than just a nice, simple evolutionary line from ape to human, the picture that emerges is one of a dense thicket of species that form a convoluted and confusing image of our past. This latest study simply adds to that tangle, and as newer finds are made, hopefully more sense will be able to be made of it.


Half a billion years off here on Mother Earth where evidence is so tangible,

and yet they want us believe what they preach about Mars.

Arrow What Whence Was Walking West-World-Ward Wander We Wonder 5.7 MYA ???
Along the vines of the Vineyard.
With a forked tongue the snake singsss...
Model sheds new light on the formation of terrestrial planets and Earth
September 29, 2017

[Image: modelshedsne.jpg]
The photo shows a slice of the Allende meteorite with silicate globules of the size of a millimetre. These so-called chondrules were formed during short-duration flash-heating events in the solar nebula. Chondrite meteorites are considered as primordial material of the planets in our solar system. Some chondrite classes have up to a few percent of carbon in the dark rock matrix, but not in the chrondules, in which it got lost because of flash-heating events. The formation of the Earth from chondritic rock material in the inner solar system can explain the relatively low carbon content. Credit: Institute of Earth Science, Heidelberg University
The element carbon and its compounds form the basics for life on Earth. Short-duration flash-heating events in the solar nebula prior to the formation of planets in our solar system were responsible for supplying the Earth with a presumably ideal amount of carbon for life and evolution. This shows a carbon chemistry model developed by Heidelberg University researchers. The research findings of Prof. Dr Hans-Peter Gail of the Centre for Astronomy and Prof. Dr Mario Trieloff of the Klaus Tschira Laboratory for Cosmochemistry at the Institute of Earth Sciences were recently published in the journal Astronomy & Astrophysics.

"On Earth, carbon is a relatively rare element. It is enriched close to the Earth´s surface, but as a fraction of the total matter on Earth it is a mere one-half of 1/1000th. In primitive comets, however, the proportion of carbon can be ten percent or more," states Prof. Trieloff. According to the geochemist, comets originate in the cool outer regions of the solar system where volatile water and carbon compounds condensed into ice. Researchers assume that asteroid and comet impacts contributed these volatile elements to the newly formed Earth. But it is a puzzle why the amount of carbon on Earth is so low. "A substantial portion of the carbon in asteroids and comets is in long-chain and branched molecules that evaporate only at very high temperatures. Based on the standard models that simulate carbon reactions in the solar nebula where the sun and planets originated, the Earth and the other terrestrial planets should have up to 100 times more carbon," states Prof. Gail.
The Heidelberg researchers assume that the short-duration flash-heating events were responsible for the loss of carbon. They suspect that all the matter in the inner regions of our solar system was heated, in some cases repeatedly, to temperatures between 1.300 and 1.800 degrees Celsius before small planetesimals and ultimately the terrestrial planets and Earth formed. The researchers believe the evidence lies in chondrules, the round grains that formed as molten droplets during these heating events before their accretion to meteorites. "Only the spikes in temperature derived from the chondrule formation models can explain today's low amount of carbon on the inner planets. Previous models did not take this process into account, but we apparently have it to thank for the correct amount of carbon that allowed the evolution of the Earth's biosphere as we know it," says Hans-Peter Gail.
The researchers speculate that a carbon "overdose" would have probably been detrimental to the evolution of life. In its oxidised state, carbon forms the greenhouse gas CO2, which is removed from the Earth's atmosphere especially by the silicate-carbonate cycle, which acts like a thermostat. "Whether 100 times more carbon would permit effective removal of the greenhouse gas is questionable at the very least. The carbon could no longer be stored in carbonates, where most of the Earth's CO2 is stored today. This much CO2 in the atmosphere would cause such a severe and irreversible greenhouse effect that the oceans would evaporate and disappear," states Mario Trieloff.
[Image: 1x1.gif] Explore further: Mystery of rare volcanoes on Venus
More information: Hans-Peter Gail et al. Spatial distribution of carbon dust in the early solar nebula and the carbon content of planetesimals, Astronomy & Astrophysics (2017). DOI: 10.1051/0004-6361/201730480 
Journal reference: Astronomy & Astrophysics [Image: img-dot.gif] [Image: img-dot.gif]
Provided by: Heidelberg University

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Evidence suggests life on Earth started after meteorites splashed into warm little ponds

October 2, 2017

[Image: 1-evidencesugg.jpg]
A figure representing the various influences acting on chemicals in warm little ponds during the dry phase and wet phase of the cycle. Credit: McMaster University
Life on Earth began somewhere between 3.7 and 4.5 billion years ago, after meteorites splashed down and leached essential elements into warm little ponds, say scientists at McMaster University and the Max Planck Institute in Germany. Their calculations suggest that wet and dry cycles bonded basic molecular building blocks in the ponds' nutrient-rich broth into self-replicating RNA molecules that constituted the first genetic code for life on the planet.

The researchers base their conclusion on exhaustive research and calculations drawing in aspects of astrophysics, geology, chemistry, biology and other disciplines. Though the "warm little ponds" concept has been around since Darwin, the researchers have now proven its plausibility through numerous evidence-based calculations.
Lead authors Ben K.D. Pearce and Ralph Pudritz, both of the McMaster's Origins Institute and its Department of Physics and Astronomy, say available evidence suggests that life began when the Earth was still taking shape, with continents emerging from the oceans, meteorites pelting the planet - including those bearing the building blocks of life - and no protective ozone to filter the Sun's ultraviolet rays.
"No one's actually run the calculation before," says Pearce. "This is a pretty big beginning. It's pretty exciting."
"Because there are so many inputs from so many different fields, it's kind of amazing that it all hangs together," Pudritz says. "Each step led very naturally to the next. To have them all lead to a clear picture in the end is saying there's something right about this."
Their work, with collaborators Dmitry Semenov and Thomas Henning of the Max Planck Institute for Astronomy, has been published today in the Proceedings of the National Academy of Science.
"In order to understand the origin of life, we need to understand Earth as it was billions of years ago. As our study shows, astronomy provide a vital part of the answer. The details of how our solar system formed have direct consequences for the origin of life on Earth," says Thomas Henning, from the Max Planck Institute for Astronomy and another co-author.
[Image: evidencesugg.jpg]
Photo of a warm little pond on present day Earth on the Bumpass Hell trail in Lassen Volcanic National Park in California. Credit: Ben K.D. Pearce, McMaster University
The spark of life, the authors say, was the creation of RNA polymers: the essential components of nucleotides, delivered by meteorites, reaching sufficient concentrations in pond water and bonding together as water levels fell and rose through cycles of precipitation, evaporation and drainage. The combination of wet and dry conditions was necessary for bonding, the paper says.

In some cases, the researchers believe, favorable conditions saw some of those chains fold over and spontaneously replicate themselves by drawing other nucleotides from their environment, fulfilling one condition for the definition of life. Those polymers were imperfect, capable of improving through Darwinian evolution, fulfilling the other condition.
"That's the Holy Grail of experimental origins-of-life chemistry," says Pearce.
That rudimentary form of life would give rise to the eventual development of DNA, the genetic blueprint of higher forms of life, which would evolve much later. The world would have been inhabited only by RNA-based life until DNA evolved.
"DNA is too complex to have been the first aspect of life to emerge," Pudritz says. "It had to start with something else, and that is RNA."
The researchers' calculations show that the necessary conditions were present in thousands of ponds, and that the key combinations for the formation of life were far more likely to have come together in such ponds than in hydrothermal vents, where the leading rival theory holds that life began in roiling fissures in ocean floors, where the elements of life came together in blasts of heated water. The authors of the new paper say such conditions were unlikely to generate life, since the bonding required to form RNA needs both wet and dry cycles.
The calculations also appear to eliminate space dust as the source of life-generating nucleotides. Though such dust did indeed carry the right materials, it did not deposit them in sufficient concentration to generate life, the researchers have determined. At the time, early in the life of the solar system, meteorites were far more common, and could have landed in thousands of ponds, carrying the building blocks of life.Pearce and Pudritz plan to put the theory to the test next year, when McMaster opens its Origins of Life laboratory that will re-create the pre-life conditions in a sealed environment.
"We're thrilled that we can put together a theoretical paper that combines all these threads, makes clear predictions and offers clear ideas that we can take to the laboratory," Pudritz says.
[Image: 1x1.gif] Explore further: Studying the roots of life
More information: Ben K. D. Pearce el al., "Origin of the RNA world: The fate of nucleobases in warm little ponds," PNAS (2017). 
Journal reference: Proceedings of the National Academy of Sciences[Image: img-dot.gif] [Image: img-dot.gif]
Provided by: McMaster University

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Along the vines of the Vineyard.
With a forked tongue the snake singsss...
Levin will have his day.

Mars study yields clues to possible cradle of life

October 6, 2017 by Guy Webster

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This view of a portion of the Eridania region of Mars shows blocks of deep-basin deposits that have been surrounded and partially buried by younger volcanic deposits. Credit: NASA/JPL-Caltech/MSSS
The discovery of evidence for ancient sea-floor hydrothermal deposits on Mars identifies an area on the planet that may offer clues about the origin of life on Earth.

A recent international report examines observations by NASA's Mars Reconnaissance Orbiter (MRO) of massive deposits in a basin on southern Mars. The authors interpret the data as evidence that these deposits were formed by heated water from a volcanically active part of the planet's crust entering the bottom of a large sea long ago.
"Even if we never find evidence that there's been life on Mars, this site can tell us about the type of environment where life may have begun on Earth," said Paul Niles of NASA's Johnson Space Center, Houston. "Volcanic activity combined with standing water provided conditions that were likely similar to conditions that existed on Earth at about the same time—when early life was evolving here."
Mars today has neither standing water nor volcanic activity. Researchers estimate an age of about 3.7 billion years for the Martian deposits attributed to seafloor hydrothermal activity. Undersea hydrothermal conditions on Earth at about that same time are a strong candidate for where and when life on Earth began. Earth still has such conditions, where many forms of life thrive on chemical energy extracted from rocks, without sunlight. But due to Earth's active crust, our planet holds little direct geological evidence preserved from the time when life began. The possibility of undersea hydrothermal activity inside icy moons such as Europa at Jupiter and Enceladus at Saturn feeds interest in them as destinations in the quest to find extraterrestrial life.
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The Eridania basin of southern Mars is believed to have held a sea about 3.7 billion years ago, with seafloor deposits likely resulting from underwater hydrothermal activity. Credit: NASA
Observations by MRO's Compact Reconnaissance Spectrometer for Mars (CRISM) provided the data for identifying minerals in massive deposits within Mars' Eridania basin, which lies in a region with some of the Red Planet's most ancient exposed crust.
"This site gives us a compelling story for a deep, long-lived sea and a deep-sea hydrothermal environment," Niles said. "It is evocative of the deep-sea hydrothermal environments on Earth, similar to environments where life might be found on other worlds—life that doesn't need a nice atmosphere or temperate surface, but just rocks, heat and water."

Niles co-authored the recent report in the journal Nature Communications with lead author Joseph Michalski, who began the analysis while at the Natural History Museum, London, andco-authors at the Planetary Science Institute in Tucson, Arizona, and the Natural History Museum.
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This diagram illustrates an interpretation for the origin of some deposits in the Eridania basin of southern Mars as resulting from seafloor hydrothermal activity more than 3 billion years ago. Credit: NASA
The researchers estimate the ancient Eridania sea held about 50,000 cubic miles (210,000 cubic kilometers) of water. That is as much as all other lakes and seas on ancient Mars combined and about nine times more than the combined volume of all of North America's Great Lakes. The mix of minerals identified from the spectrometer data, including serpentine, talc and carbonate, and the shape and texture of the thick bedrock layers, led to identifying possible seafloor hydrothermal deposits. The area has lava flows that post-date the disappearance of the sea. The researchers cite these as evidence that this is an area of Mars' crust with a volcanic susceptibility that also could have produced effects earlier, when the sea was present.
The new work adds to the diversity of types of wet environments for which evidence exists on Mars, including rivers, lakes, deltas, seas, hot springs, groundwater, and volcanic eruptions beneath ice.
"Ancient, deep-water hydrothermal deposits in Eridania basin represent a new category of astrobiological target on Mars," the report states. It also says, "Eridania seafloor deposits are not only of interest for Mars exploration, they represent a window into early Earth." That is because the earliest evidence of life on Earth comes from seafloor deposits of similar origin and age, but the geological record of those early-Earth environments is poorly preserved.
[Image: 1x1.gif] Explore further: Elevated zinc and germanium levels bolster evidence for habitable environments on Mars
More information: Joseph R. Michalski et al. Ancient hydrothermal seafloor deposits in Eridania basin on Mars, Nature Communications (2017). DOI: 10.1038/ncomms15978 
Journal reference: Nature Communications [Image: img-dot.gif] [Image: img-dot.gif]
Provided by: Jet Propulsion Laboratory

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This story is republished courtesy of NASA's Astrobiology Magazine. Explore the Earth and beyond at . 

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Are plate tectonics key to life? Maybe not, say scientists
October 12, 2017 by Astrobiology Magazine

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A picture showing the relative sizes of (from left to right) Mercury, Venus, Earth and Mars. (The images were collected from multiple space missions, then mounted and resized in a single image.) Credit: NASA
Earlier this year, researchers announced they had found fossils of microbial life in the rocks of northern Quebec, Canada dating to at least 3.77 billion years old, making them the oldest known life form on Earth. It was an astounding assertion, given that the Earth itself is less than a billion years older and is a sign that if life could arise relatively quickly on Earth it may be common in the Universe.

The discovery has set off an active debate in the scientific community because the purported fossils, a set of filaments and tubes left behind by iron-eating bacteria, could instead be a product of geological processes over time. Although the University College London team which produced the findings remains confident of them, this development in origins of life research exposes the challenges of conducting microbiology studies in the ancient era of Earth's history.
Now, a new paper takes a different look at examining rocks from the Hadean era. Guillaume Caro, a geochemist at the University of Lorraine in France, is the lead author of a study examining how traces of the Earth's earliest crust could be preserved in the ancient rocks that laid the foundation for Earth's geologic history. He looked at rocks in northern Quebec from the Hadean period, a geologic era ranging from 4 billion to 4.5 billion years ago when the oceans first formed, continents began to grow, and life may have first appeared.
Caro sought evidence of rocks that had been recycled inside the Earth during early periods, specifically mafic (igneous) rocks in the Ukaliq supracrustal belt in northern Quebec, and found anomalies in a short-lived radioactive element called neodymium 142.
"It can only have been produced prior to 4 billion years old, so we can use it to track what happens with the earliest terrestrial proto-crust," said Caro.
He suggested that the isotopic anomalies in the rocks, which are themselves 3.8 billion years old, indicate leftovers of an older crust from 600 million years earlier. This old crust sank into the mantle and its recycling triggered new magmatism.
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A night view of magma flowing from Hawaii’s Kilauea Volcano, considered one of the most active volcanoes on the planet. Credit: NASA
Caro explained that while the older crust is no longer there, hints of what it looked like are apparent through the geochemical and isotopic signatures it left behind. Previously, researchers thought that the rocks were about 4.3 billion years old, based on anomalies in an isotope of neodynium. Caro's team instead states that the rocks are 3.75 billion years old—more than half a billion years younger—and the anomalies are actually remnants of the old crust.

Rocks routinely get recycled into the mantle. Even though their form is destroyed, it is possible to detect signatures of the molten material through its isotopic properties. However, this same process also makes it difficult to detect older life in the fossils because the microfossils can get distorted through geological activity.
Caro's study, "Sluggish Hadean geodynamics: Evidence from coupled 146,147Sm–142,143Nd systematics in Eoarchean supracrustal rocks of the Inukjuak domain (Québec)," was published earlier this year in Earth and Planetary Science Letters.
Changing crusts
The results may be highly significant given an impact event from 4.4 billion years ago, the time he and other scientists suggest the first-generation crust was formed. A world about the size of Mars smashed into Earth, creating a ring of debris encircling our planet that eventually coalesced into our modern day Moon. This collision, he pointed out, would have melted the mantle and created a global magma ocean that then cooled down, solidified and ultimately generated the first terrestrial crust.
"This was the process by which the first terrestrial crust was produced," he said. "The signature we found was not this 4.4-billion-year-old rock, but the signature inherited from it after recycling."
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Artist’s impression of worlds colliding. Scientific research suggests that a Mars-sized body impacted the Earth about 4.4 billion years ago, creating a temporary global magma ocean on Earth. The debris eventually coalesced into our moon. Credit: NASA
Even more strangely, it took 600 million years to recycle the material, an amount of time substantially greater than then 100 million-year timeframe of modern-day plate tectonics.
"What it means is the Earth was in a sluggish plate tectonic mode, or a stagnated mode, like Venus," Caro said. "This is something often suggested by models of geo-dynamics, but hard to demonstrate by observation."
The main theory behind this sluggishness is a hotter mantle, which makes the subduction of the crust slower, he said.
"If you want to connect the story to the issue of early life, I think you could look at it under the angle of plate tectonics. A number of people have recently suggested that plate tectonics is an 'ingredient' of life because it helps regulate the climate system by recycling carbon into the mantle," Caro said.
He added that life may have formed at a time when Earth's plate tectonics were not as active, which could open up possibilities of life in other locations in the Universe where tectonics are non-active or dormant, such as Mars.
"If our interpretations are correct, and the Hadean Earth was in a stagnant or sluggish tectonic regime," Caro said, "then it would imply that crustal recycling was much less efficient in the Hadean compared to the present-day, and therefore that life emerged on a planet in which geochemical cycles and climate were not regulated by plate tectonics as they have been through much of Earth's history.
[Image: 1x1.gif] Explore further: New timeline proposed for plate tectonics
More information: G. Caro et al. Sluggish Hadean geodynamics: Evidence from coupled 146,147Sm–142,143Nd systematics in Eoarchean supracrustal rocks of the Inukjuak domain (Québec), Earth and Planetary Science Letters (2016). DOI: 10.1016/j.epsl.2016.09.051 
Journal reference: Earth and Planetary Science Letters [Image: img-dot.gif] [Image: img-dot.gif]

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Microbes leave 'fingerprints' on Martian rocks
October 17, 2017

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Metallosphaera sedula. Credit: University of Vienna
Scientists around Tetyana Milojevic from the Faculty of Chemistry at the University of Vienna are in search of unique biosignatures, which are left on synthetic extraterrestrial minerals by microbial activity. The biochemist and astrobiologist investigates these signatures at her own miniaturized "Mars farm" where she can observe interactions between the archaeon Metallosphaera sedula and Mars-like rocks. These microbes are capable of oxidizing and integrating metals into their metabolism. The original research was currently published in the journal Frontiers in Microbiology.

At the Department of Biophysical Chemistry at the University of Vienna, Tetyana Milojevic and her team have been operating a miniaturized "Mars farm" in order to simulate ancient and probably extinct microbial life – based on gases and synthetically produced Martian regolith of diverse composition. The team investigates interactions between Metallosphaera sedula, a microbe that inhabits extreme environments, and different minerals which contain nutrients in form of metals. Metallosphaera sedula is a chemolithotroph, means being capable of metabolizing inorganic substances like iron, sulphur and uranium as well.
To satisfy microbial nutritional fitness, the research team uses mineral mixtures that mimic the Martian regolith composition from different locations and historical periods of Mars: "JSC 1A" is mainly composed of palagonite – a rock that was created by lava; "P-MRS" is rich in hydrated phyllosilicates; the sulfate containing "S-MRS," emerging from acidic times on Mars and the highly porous "MRS07/52" that consists of silicate and iron compounds and simulates sediments of the Martian surface.
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Synthetic Martian Regolith. Credit: University of Vienna
"We were able to show that due to its metal oxidizing metabolic activity, when given an access to these Martian regolith simulants, M. sedula actively colonizes them, releases soluble metal ions into the leachate solution and alters their mineral surface leaving behind specific signatures of life, a 'fingerprint," so to say," explains Milojevic. The observed metabolic activity of M. sedula coupled to the release of free soluble metals can certainly pave the way to extraterrestrial biomining, a technique which extracts metals from ores, launching the biologically assisted exploitation of raw materials from asteroids, meteors and other celestial bodies.
Using electron microscopy tools combined with analytical spectroscopy techniques, the researchers were able to examine the surface of bioprocessed Martian regolith simulants in detail. Cooperation with the workgroup of chemist Veronika Somoza from the Department of Physiological Chemistry was valuable to achieve these results. "The obtained results expand our knowledge of biogeochemical processes of possible life beyond earth, and provide specific indications for detection of biosignatures on extraterrestrial material – a step further to prove potential extra-terrestrial life," says Tetyana Milojevic.
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Microspheroids. Credit: University of Vienna
[Image: 1x1.gif] Explore further: Mimetic Martian water is under pressure
More information: Denise Kölbl et al. Exploring Fingerprints of the Extreme Thermoacidophile Metallosphaera sedula Grown on Synthetic Martian Regolith Materials as the Sole Energy Sources, Frontiers in Microbiology (2017). DOI: 10.3389/fmicb.2017.01918 
Provided by: University of Vienna

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