Resurrected protein's clue to origins of life

8 August 2013 Last updated at 16:19 GMT

By Simon RedfernReporter, BBC News

The earliest life would have survived at more than 100 C


New reconstructions of ancient proteins have provided clues to the habitat and origins of life on Earth.

The resurrected protein is thought to have existed almost four billion years ago in single-celled organisms linked to the earliest ancestor of all life.

The protein survives in the extreme environments of high acidity and temperature expected on early Earth and, intriguingly, also Mars.

Spanish and US scientists reported their study in the journal Structure.


“Maybe we have resurrected Martian proteins. Maybe the last universal common ancestor formed on Mars and transferred to Earth”

Professor Jose Sanchez-RuizGranada University

Gene sequences in a protein called thioredoxin, taken from a wide variety of modern organisms, were analysed and placed in an evolutionary context - locating them on a molecular-scale tree of life - to chart their progression from their primordial forms.

First, computer analysis was used to determine how modern genetic sequences developed from original codes, so the ancient DNA sequences in the protein from as far back as four billion years ago could be determined.Ancestral code

They then used modern bacteria to convert the ancient gene sequences into a chemically active protein that could be measured to determine its molecular structure and the properties of the ancient protein.

The thioredoxin protein is an enzyme which can break sulphur bonds in other molecules and has a number of metabolic functions in cells. It is shared by almost all life on Earth, from the simplest bacteria to complex animals including humans, indicating that the ultimate single-celled ancestor of all life on Earth would also have had the gene.

Prof Eric Gaucher of Georgia Tech, US, helped with the ancestral gene sequence reconstruction and commented: "A gene can become deactivated by as few as one or two mutations.

"If our ancestral sequences were incorrectly inferred by having a single mistake, that could have led to a dead gene. Instead, our approach created biochemically active proteins that fold up into three dimensional structures that look like modern protein structures, thus validating our approach."
Protein folding has survived billions of years

The group used molecular clocks to date the evolutionary branches back in time and linked them to geological changes in Earth's environment.

Changes in the protein's length appeared to occur in fits and starts, with its helix structure suddenly lengthening at the point that cells started to develop a nucleus (the transition from prokaryote to eukaryote), paving the way for higher life.

The results suggest that biological systems might evolve at the molecular level in discrete jumps rather than along continuous pathways, as has been suggested from studies of the evolution of species.Hell on Earth

The group studied how well the ancient thioredoxin coped with heat, and found that it survived temperatures of more than 110 C, as well as being stable in acidic environments.

"We have looked at a number of gene families now, and for all of them, we find the most ancient proteins are the most thermally stable. From this, we conclude that ancient life lived in a hot environment," Prof Gaucher told the BBC.

The early Earth was a hostile environment for life. It was hellish, and the first geological eon on Earth is termed the "Hadean" after Hades, the ancient Greek god of the underworld. Before four billion years ago it is thought that Earth suffered heavy bombardment from meteorites. It is likely that any atmosphere that survived was hot and possibly acidic four billion years ago.

The ancient protein's properties indicate that it may have been adapted to that environment. It shares features with "extremophiles" - bacteria found today in extreme environments like hot springs and even at depth within Earth's crustal rocks.

It may be that the only life that survived that heavy bombardment were the forms that could cope with high temperatures and energies, like this ancient protein.Alien resurrection?

Another intriguing possibility, although not discussed in this study. is that the ancient protein came to Earth having formed at an earlier time on another planet.

In particular, recent evidence from Nasa's Curiosity rover suggests that Mars may well have been a more conducive place for life to develop than Earth during the first 500 million years of the Solar System, before four billion years ago.

Many Martian meteorites have landed on Earth, with our planet acting like a local gravitational vacuum cleaner.

"Four billion years ago Mars was a much a safer place than Earth. Maybe we have resurrected Martian proteins. Maybe the last universal common ancestor (the first life) formed on Mars and transferred to Earth," commented Prof Sanchez-Ruiz.

From: http://www.bbc.co.uk/news/science-environment-23591470

If We Landed on Europa, What Would We Want to Know?

This artist's concept shows a simulated view from the surface of Jupiter's moon Europa. Europa's potentially rough, icy surface, tinged with reddish areas that scientists hope to learn more about, can be seen in the foreground. The giant planet Jupiter looms over the horizon. Image credit: NASA/JPL-Caltech

August 07, 2013

Most of what scientists know of Jupiter's moon Europa they have gleaned from a dozen or so close flybys from NASA's Voyager 2 spacecraft in 1979 and NASA's Galileo spacecraft in the mid-to-late 1990s. Even in these fleeting, paparazzi-like encounters, scientists have seen a fractured, ice-covered world with tantalizing signs of a liquid water ocean under its surface. Such an environment could potentially be a hospitable home for microbial life. But what if we got to land on Europa's surface and conduct something along the lines of a more in-depth interview? What would scientists ask? A new study in the journal Astrobiology authored by a NASA-appointed science definition team lays out their consensus on the most important questions to address.

"If one day humans send a robotic lander to the surface of Europa, we need to know what to look for and what tools it should carry," said Robert Pappalardo, the study's lead author, based at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "There is still a lot of preparation that is needed before we could land on Europa, but studies like these will help us focus on the technologies required to get us there, and on the data needed to help us scout out possible landing locations. Europa is the most likely place in our solar system beyond Earth to have life today, and a landed mission would be the best way to search for signs of life."

The paper was authored by scientists from a number of other NASA centers and universities, including the Johns Hopkins University Applied Physics Laboratory, Laurel, Md.; University of Colorado, Boulder; University of Texas, Austin; and the NASA Goddard Space Flight Center, Greenbelt, Md. The team found the most important questions clustered around composition: what makes up the reddish "freckles" and reddish cracks that stain the icy surface? What kind of chemistry is occurring there? Are there organic molecules, which are among the building blocks of life?

Additional priorities involved improving our images of Europa - getting a look around at features on a human scale to provide context for the compositional measurements. Also among the top priorities were questions related to geological activity and the presence of liquid water: how active is the surface? How much rumbling is there from the periodic gravitational squeezes from its planetary host, the giant planet Jupiter? What do these detections tell us about the characteristics of liquid water below the icy surface?

"Landing on the surface of Europa would be a key step in the astrobiological investigation of that world," said Chris McKay, a senior editor of the journal Astrobiology, who is based at NASA Ames Research Center, Moffett Field, Calif. "This paper outlines the science that could be done on such a lander. The hope would be that surface materials, possibly near the linear crack features, include biomarkers carried up from the ocean."

This work was conducted with Europa study funds from NASA's Science Mission Directorate, Washington, D.C. JPL is a division of the California Institute of Technology, Pasadena.

From: http://www.jpl.nasa.gov/news/news.php?release=2013-243

Giant Maya Carvings Found in Guatemala

See more photos from the website: 

http://news.nationalgeographic.com/news/2013/08/pictures/130807-maya-frieze-discovered-holmul-guatemala-archaeology/

Big Discovery

Photograph courtesy Francisco Estrada-Belli

Archaeologist Anya Shetler cleans an inscription below an ancient stucco frieze recently unearthed in the buried Maya city of Holmul in the Peten region of Guatemala. Sunlight from a tunnel entrance highlights the carved legs of a ruler sitting atop the head of a Maya mountain spirit.

The enormous frieze—which measures 26 feet by nearly 7 feet (8 meters by 2 meters)—depicts human figures in a mythological setting, suggesting these may be deified rulers. It was discovered in July in the buried foundations of a rectangular pyramid in Holmul.



Maya archaeologist Francisco Estrada-Belli and his team were excavating a tunnel left open by looters when they happened upon the frieze. "The looters had come close to it, but they hadn't seen it," Estrada-Belli said.

According to Estrada-Belli, the frieze is one of the best preserved examples of its kind. "It's 95 percent preserved. There's only one corner that's not well preserved because it's too close to the surface, but the rest of it isn't missing any parts," said Estrada-Belli, who is affiliated with Tulane University, Boston University, and the American Museum of Natural History and who is also a National Geographic Explorer. His excavations at Holmul were supported by the National Geographic Society/Waitt Grants Program.

Maya archaeologist Marcello Canuto agreed, calling the frieze "amazingly and beautifully preserved."

"We often dream of finding things this well preserved, and Francisco did it," said Canuto, who is the director of the Middle American Research Institute at Tulane University in New Orleans; he was not involved in the project.

For example, despite being mostly faded away now, traces of red, blue, green, and yellow paint are still visible on the frieze.

"It gives you an idea of how intricate and ornate these sites that we are excavating must have been during their apogee," Canuto said. "These sites must have been a feast for the eyes when they were inhabited."



David Stuart, a Maya hieroglyph expert at the University of Texas at Austin, pointed out that archaeologists think most large Maya temples were probably decorated with similar sorts of designs.



"But not all temples were so carefully buried and preserved like this," said Stuart, who did not participate in the project. "Also, each temple facade was slightly different and therefore unique in terms of its detail and message." (Explore an interactive map of key Maya sites.)



Caught Between Two Great Powers

The section of the temple at Holmul where the frieze was found dates back to about 590 A.D., which corresponds to the Maya classical era, a period defined by the power struggles between two major Maya dynasties: Tikal and Kaanul.

The two kingdoms competed with one another for resources and for control of other, smaller Maya city-states. Until now, however, it had been unclear which dynasty Holmul owed its allegiance to, but an inscription on the newly discovered frieze reveals that the temple was commissioned by Ajwosaj, ruler of a neighboring city-state called Naranjo, which archaeologists know from other discoveries was a vassal city of the Kaanul kingdom.

"We now know that Holmul was under the influence of the Kaanul dynasty," Canuto said.

In 2012, Canuto's team found and deciphered a series of hieroglyphically inscribed panels at another Maya city of a similar size to Holmul, called La Corona, which was also under the patronage of the Kaanul kingdom.

Recent discoveries at sites like La Corona and Holmul are helping reveal how these sites, despite being relatively small compared with some of their neighbors, were important players on the region's larger geopolitical stage.



"We're now beginning to appreciate how all these hierarchical levels of sites were involved in a larger political game that put them on [the side of either Tikal or Kaanul]," Canuto explained. (See "Why the Maya Fell.")

All About Location

Why was Holmul—a minor city that was home to only 10,000 to 20,000 people—so important to the Tikal and Kaanul dynasties?

Previous work by Estrada-Belli suggests Holmul occupied a strategic position for both kingdoms. The city lay along the best east-west route between the Tikal dynasty's capital city, also called Tikal, and the coast. It also lay along a north-south route between the Kaanul capital city of Dzibanche and the Guatemalan highlands that did not pass through Tikal territory.

The Guatemalan highlands contained precious resources such as basalt, obsidian, and jade that were coveted by both kingdoms.

"A [Maya] king without jade was no king at all," Canuto said.

By controlling Holmul in the east and La Corona in the west, the Kaanul dynasty was able to effectively access these riches without going through the capital city of its rival.

(See video of a Maya mural and calendar uncovered by National Geographic grantee Bill Saturno in Guatemala.)

Staying Put for Now

The frieze still lies buried in Holmul where it was initially discovered because it is too big to move, said lead archaeologist Estrada-Belli.

"We're going to try to preserve it and create a stable environment around it so people can eventually visit it," he said.



"We're very concerned about its present condition, so we had to re-bury the entrance tunnel to keep the humidity and climate around it stable."

—Ker Than

From: http://news.nationalgeographic.com/news/2013/08/pictures/130807-maya-frieze-discovered-holmul-guatemala-archaeology/

Thick Ice Sheet Covering Mars May Explain Mysterious Double-Layered Ejecta Craters

By Charles Poladianon August 05 2013 4:25 PM



Double-Layered Ejecta Craters may be the result of a thick layer of ice once covering mars. NASA

Researchers believe a mysterious type of crater was created as a result of mars having a thick sheet of ice covering its surface. Ejected material from the impact would later return to the surface, slide downward on the ice and create a secondary later at the bottom of the impact site.

According to geologists from Brown University, double-layered ejecta (DLE) craters were produced as a result of a sheet of ice covering the surface of mars. DLE craters have an impact site, a first layer of ejected debris and a smaller second layer of debris. The second layer may have been formed as ejected debris at the top of the crater rim slid off a sheet of ice that may have been 50 meters thick.

The DLE craters were first observed from data collected by NASA’s Viking missions in the 1970’s. While there was no explanation for these types of craters, the geologists believe, based on recent research indicating a period of mars’ history where ice was present, an object crashing into a layer of ice would have produced results similar to a DLE crater.

The new study of DLE craters was led by James W. Head, professor of geological science, and David Kutai Weiss, a graduate student at the university, and will be published in the journal Geophysical Research Letters. According to Head, in mars’ past the climate was cool enough to have ice present at the same location where DLE craters are located. “During these times, ice from the polar caps is redistributed into the mid-latitudes of mars as a layer about 50 meters thick, in the same place that we see that the DLEs have formed,” said Head in astatement.

As the geologists explain, the hypothesis of a sheet of ice causing a landslide of ejected material would explain several features of DLE craters. The inner layer of these craters have ridges flowing outward from the crater rim, called radial striations, that are commonly found in landslides that occur on glaciers on Earth.

Other DLE crater data supported the landslide on ice theory. According to Head, a steep crater rim was needed and larger craters, 25 kilometers, approximately 15 miles, or more in diameter, would not have a steep enough crater rim. Based on 600 known DLE craters, all of them were less than 25 kilometers in diameter. DLE craters did not have secondary impact areas, a trait common in other craters, and the researchers believe a sheet of ice could have protected mars’ surface from large chunks of ejected debris.

Understanding how DLE craters formed creates a clearer picture of mars’ history. “It could tell us a lot about the history of the martian climate on a global scale,” said Weiss.

From: http://www.ibtimes.com/thick-ice-sheet-covering-mars-may-explain-mysterious-double-layered-ejecta-craters-1372473

NASA’s Spitzer Space Telescope Observes A Stellar System That Has Its Own 'Hula Hoop' Dust Disk

By Charles Poladian

on August 01 2013 8:27 AM


NASA’s Spitzer Space Telescope discovered a stellar system in its infancy and observed some rather interesting phenomena. Of the three young stars that make up the system, two of them have a leftover dust disk surrounding them that resembles a "hula hoop."



An artist's representation of the YLW 16A stellar system. NASA/JPL-Caltech

The stellar system, YLW 16A, is located in the Rho Ophiuchi cloud complex, a star-forming region consisting of dense gas and dust, 407 light-years from earth. The dust disk is at a tilt due to the gravitational pull of the third star in the system.


The system goes through bright and dim periods, resembling a blink, every 93 days, NASA says. As the two stars orbit one another, they eventually appear above the dust disk, creating a period of brightness but will eventually be obscured by the surrounding dust. The observations of YLW 16A were made by NASA’s Spitzer Telescope in infrared light. Other observations came from the Two Micron All-Sky, or 2MASS, Survey at the Infrared Processing and Analysis Center at the California Institute of Technology and the European Southern Observatory’s Very Large Telescope in Chile.

Blinking stellar systems similar to YLW 16A were believed to be relatively rare but recent observations indicate these systems may be more common. NASA notes the discovery of four other blinking stellar systems. Lead author Peter Plavchan, from the NASA Exoplanet Science Institute and IPEC at Caltech, said, “These blinking systems offer natural probes of the binary and circumbinary planet formation process.” Binary planets are those that orbit a single star while circumbinary planets orbit two stars. Plavchan’s research will be published in the journal Astronomy & Astrophysics.

The dust disk surrounding the stars will eventually be the fuel for the formation of other stars and planets to form a new solar system, NASA says. Future observations of blinking stellar systems could provide new insight on planet formations as well as the dust and other material that make up the disks.

From: http://www.ibtimes.com/nasas-spitzer-space-telescope-observes-stellar-system-has-its-own-hula-hoop-dust-disk-1367085