HBO's popular television series "Game of Thrones" returns in April, but millions of fans continue to illegally download the program, giving it the dubious distinction of being the most pirated program.
Many may wonder why the TV network hasn't taken a more aggressive approach to combating illegal streaming services and downloaders. Perhaps it is because the benefits to the company outweigh the consequences. Research analysis by faculty in Indiana University's Kelley School of Business and two other schools found that a moderate level of piracy can have a positive impact on the bottom line for both the manufacturer and the retailer -- and not at the expense of consumers.
"When information goods are sold to consumers via a retailer, in certain situations, a moderate level of piracy seems to have a surprisingly positive impact on the profits of the manufacturer and the retailer while, at the same time, enhancing consumer welfare," wrote Antino Kim, assistant professor of operations and decision technologies at Kelley, and his co-authors.
"Such a win-win-win situation is not only good for the supply chain but is also beneficial for the overall economy."
While not condoning piracy, Kim and his colleagues were surprised to find that it can actually reduce, or completely eliminate at times, the adverse effect of double marginalization, an economic concept where both manufacturers and retailers in the same supply chain add to the price of a product, passing these markups along to consumers.
The professors found that, because piracy can affect the pricing power of both the manufacturer and the retailer, it injects "shadow" competition into an otherwise monopolistic market.
"From the manufacturer's point of view, the retailer getting squeezed is a good thing," Kim said. "It can't mark up the product as before, and the issue of double marginalization diminishes. Vice versa, if the manufacturer gets squeezed, the retailer is better off.
"What we found is, by both of them being squeezed together -- both at the upstream and the downstream levels -- they are able to get closer to the optimal retail price that a single, vertically integrated entity would charge."
In the example of "Game of Thrones," HBO is the upstream "manufacturer" in the supply chain, and cable and satellite TV operators are the downstream "retailers."
Kim and his co-authors -- Atanu Lahiri, associate professor of information systems at the University of Texas-Dallas, and Debabrata Dey, professor of information systems at the University of Washington -- presented their findings in the article, "The 'Invisible Hand' of Piracy: An Economic Analysis of the Information-Goods Supply Chain," published in the latest issue of MIS Quarterly.
They suggest that businesses, government and consumers rethink the value of anti-piracy enforcement, which can be quite costly, and consider taking a moderate approach. Australia, for instance, due to prohibitive costs, scrapped its three-strikes scheme to track down illegal downloaders and send them warning notices. Though the Australian Parliament passed a new anti-piracy law last year, its effectiveness remains unclear until after it is reviewed in two years.
As with other studies, Kim and his colleagues found that when enforcement is low and piracy is rampant, both manufacturers and retailers suffer. But they caution against becoming overzealous in prosecuting illegal downloaders or in lobbying for more enforcement.
"Our results do not imply that the legal channel should, all of a sudden, start actively encouraging piracy," they said. "The implication is simply that, situated in a real-world context, our manufacturer and retailer should recognize that a certain level of piracy or its threat might actually be beneficial and should, therefore, exercise some moderation in their anti-piracy efforts.
Read more at Science Daily
Jan 29, 2019
Engineering a cancer-fighting virus
 |
| This is a comparison of cancer cells and normal cells after being infected with the dl355 adenovirus. The top four cell types listed on the left (HeLa, C33A, A549, and H1299) are cancer cells, and the bottom two (BJ and WI38) are normal cells. As the amount of dl355 virus administered to the cancer cells increased (represented by MOI), more cancer cells died in 7 days, while the normal cells continued to live. |
Hokkaido University researchers have engineered a virus that selectively targets and kills cancer cells. The virus, called dl355, has an even stronger anticancer effect than another engineered virus currently used in clinical practice, according to a study published in the journal Oncology Reports.
Molecular oncologist Fumihiro Higashino and colleagues deleted a gene involved in viral replication, called E4orf6, from a type of adenovirus. The team previously discovered that E4orf6 stabilizes a type of mRNA called ARE-mRNAs in the infected cells enabling viral replication. ARE-mRNAs are known to be stable in stressed cells and cancer cells, but rapidly degrade in normal cells.
In laboratory tests, they found that their modified adenovirus, called dl355, replicated and increased its number significantly more in cancer cells than it did in normal cells. Higashino explains "The E4orf6-lacking virus relies on the stable ARE-mRNAs in cancer cells for its replication."
Some viruses can be used to treat cancers, as they replicate within the cells until they burst and die. The researchers infected several types of cultured cancer cells with 100 dl355 virus particles per cell and found that nearly all the cancer cells died within seven days. In contrast, most normal cells infected with the virus did not die, even after seven days. Several cancer cell lines managed to survive low doses of dl355, but all cancer cells were killed by the virus as the dose was increased. Tumour growth was also significantly suppressed when dl355 was administered to human tumour cells grown in mice.
Finally, the team compared the anticancer effects of dl355 with another anticancer adenovirus currently used in clinical practice, called dl1520. dl355 replication was higher in all cancer cell lines tested, including cervical and lung cancer cells, and was better at killing all but one type of cancer cell, compared to dl1520. Both viruses only killed very few normal cells.
The findings suggest that dl355 has potential to be an effective anticancer treatment, the team concludes. They suggest enhancing the stabilization of ARE-mRNAs in cancer cells could even further strengthen its effect, but Professor Higashino notes that further research is required. "While we think dl355 has the potential to be an effective treatment method in dealing with many types of cancers, much more research needs to be done. When we think of a timeline, at least five more years of further research may be required, possible more, on top of clinical trials," Professor Higashino noted.
From Science Daily
Missing-link in planet evolution found
 |
| This is an artist's impression of the newly discovered object. |
The Edgeworth-Kuiper Belt is a collection of small celestial bodies located beyond Neptune's orbit. The most famous Edgeworth-Kuiper Belt Object is Pluto. Edgeworth-Kuiper Belt Objects are believed to be remnants left over from the formation of the Solar System. While small bodies like asteroids in the inner Solar System have been altered by solar radiation, collisions, and the gravity of the planets over time; objects in the cold, dark, lonely Edgeworth-Kuiper Belt preserve the pristine conditions of the early Solar System. Thus astronomers study them to learn about the beginning of the planet formation process.
Edgeworth-Kuiper Belt Objects with radii from 1 kilometer to several kilometers have been predicted to exist, but they are too distant, small, and dim for even world-leading telescopes, like the Subaru Telescope, to observe directly. So a research team led by Ko Arimatsu at the National Astronomical Observatory of Japan used a technique known as occultation: monitoring a large number of stars and watching for the shadow of an object passing in front of one of the stars. The OASES (Organized Autotelescopes for Serendipitous Event Survey) team placed two small (28 cm) telescopes on the roof of the Miyako open-air school on Miyako Island, Miyakojima-shi, Okinawa Prefecture, Japan, and monitored approximately 2000 stars for a total of 60 hours.
Analyzing the data, the team found an event consistent with a star appearing to dim as it is occulted by a 1.3 km radius Edgeworth-Kuiper Belt Object. This detection indicates that kilometer sized Edgeworth-Kuiper Belt Objects are more numerous than previously thought. This supports models where planetesimals first grow slowly into kilometer sized objects before runaway growth causes them to merge into planets.
Arimatsu explains, "This is a real victory for little projects. Our team had less than 0.3% of the budget of large international projects. We didn't even have enough money to build a second dome to protect our second telescope! Yet we still managed to make a discovery that is impossible for the big projects. Now that we know our system works, we will investigate the Edgeworth-Kuiper Belt in more detail. We also have our sights set on the still undiscovered Oort Cloud out beyond that."
Read more at Science Daily
Fluid-inspired material self-heals before your eyes
 |
| The fluid-inspired material self-heals in seconds when scratched, scraped or cracked. |
A Northwestern University team has developed a new coating strategy for metal that self-heals within seconds when scratched, scraped or cracked. The novel material could prevent these tiny defects from turning into localized corrosion, which can cause major structures to fail.
"Localized corrosion is extremely dangerous," said Jiaxing Huang, who led the research. "It is hard to prevent, hard to predict and hard to detect, but it can lead to catastrophic failure."
When damaged by scratches and cracks, Huang's patent-pending system readily flows and reconnects to rapidly heal right before the eyes. The researchers demonstrated that the material can heal repeatedly -- even after scratching the exact same spot nearly 200 times in a row.
The study was published today (Jan. 28) in Research, the first Science Partner Journal recently launched by the American Association for the Advancement of Science (AAAS) in collaboration with the China Association for Science and Technology (CAST). Huang is a professor of materials science and engineering in Northwestern's McCormick School of Engineering.
While a few self-healing coatings already exist, those systems typically work for nanometer- to micron-sized damages. To develop a coating that can heal larger scratches in the millimeter-scale, Huang and his team looked to fluid.
"When a boat cuts through water, the water goes right back together," Huang said. "The 'cut' quickly heals because water flows readily. We were inspired to realize that fluids, such as oils, are the ultimate self-healing system."
But common oils flows too readily, Huang noted. So he and his team needed to develop a system with contradicting properties: fluidic enough to flow automatically but not so fluidic that it drips off the metal's surface.
The team met the challenge by creating a network of lightweight particles -- in this case graphene capsules -- to thicken the oil. The network fixes the oil coating, keeping it from dripping. But when the network is damaged by a crack or scratch, it releases the oil to flow readily and reconnect. Huang said the material can be made with any hollow, lightweight particle -- not just graphene.
"The particles essentially immobilize the oil film," Huang said. "So it stays in place."
Read more at Science Daily
Jan 28, 2019
To catch a wave, rocket launches from top of world
 |
| Earth's magnetosphere, showing the northern and southern polar cusps (illustration). |
CAPER-2, short for Cusp Alfvén and Plasma Electrodynamics Rocket-2, is a sounding rocket mission -- a type of spacecraft that carries scientific instruments on short, targeted trips to space before falling back to Earth. In addition to their relatively low price tags and quick development time, sounding rockets are ideally suited for launching into transient events -- like the sudden formation of the aurora borealis, or northern lights.
For CAPER-2 scientists, flying through an aurora provides a peek into a process as fundamental as it is complex: How do particles get accelerated throughout space? NASA studies this phenomenon in an effort to better understand not only the space environment surrounding Earth -- and thus protect our technology in space from radiation -- but also to help understand the very nature of stars and atmospheres throughout the solar system and beyond.
"Throughout the universe you have charged particles getting accelerated -- in the Sun's atmosphere, in the solar wind, in the atmospheres of other planets, and in astrophysical objects," said Jim LaBelle, space physicist at Dartmouth College in Hanover, New Hampshire, and principal investigator for the CAPER-2 mission. "An aurora presents us with a local laboratory where we can observe these acceleration processes close at hand."
Technically, the CAPER-2 team is interested in what happens just before an aurora starts glowing. Electrons, pouring into our atmosphere from space, collide with atmospheric gases and trigger the aurora's glow. Somehow, they pick up speed along the way.
"By the time they crash into our atmosphere, these electrons are traveling over 10 times faster than they were before," said Doug Rowland, space physicist at NASA's Goddard Space Flight Center in Greenbelt, Maryland, who also studies particle acceleration. "We still don't understand the fundamental physics of how that happens."
The CAPER-2 team focused on a special kind of aurora that forms during the day. Unlike the nighttime aurora, the daytime aurora is triggered by electrons that stream in directly from the Sun -- and we know far less about them.
"There's been a huge amount of research done on the regular nighttime aurora, but the daytime aurora is much less studied," said Craig Kletzing, space physicist at the University of Iowa in Iowa City and coinvestigator for the mission. "There are good indications that there are some similarities and there are also some differences."
The team is focusing on how the electrons that create daytime auroras are jostled around by waves, in ways that may or may not differ from nighttime auroras. Two kinds of waves are of special interest, and have opposite effects. Alfvén waves, named after Swedish Nobel laureate Hannes Alfvén who first predicted their existence in 1942, are thought to accelerate the electrons. These huge waves -- measuring tens to hundreds of miles long from peak to peak -- propagate along Earth's magnetic field lines, whipping electrons to and fro.
On the other side are Langmuir waves, which are generated by the electrons themselves -- a process that steals some of the electrons' energy and slows them down. CAPER-2 will carry a high-resolution wave-particle correlator to measure them, the first sounding rocket mission to do so for the daytime aurora.
"This is very data-intensive," said LaBelle. "It's unique to sounding rockets to be able to look at this mechanism in this level of detail."
For the launch, the CAPER-2 team traveled to northern Norway, one of the few places that can put a rocket within range of the daytime aurora. Every day, northern Norway rotates under an opening in Earth's magnetic field known as the northern polar cusp, where particles from the Sun can funnel into our upper atmosphere.
Meeting the aurora right where they form is the best way to understand physical processes that are far too large to replicate in a lab.
Read more at Science Daily
Humans colonized diverse environments in Southeast Asia and Oceania during the Pleistocene
 |
| Cagayan, Northern Luzon, the Philippines -- Southeast Asia offers a particularly exciting region in regard of early hominin movements across the supposed "Movius Line" a boundary previously argued to separate populations. Records from the region can be linked to a variety of hominins throughout the Pleistocene, including Homo erectus, Homo floresiensis (or "the Hobbit"), and Homo sapiens. |
The paper, published by scientists from the Max Planck Institute for the Science of Human History focuses on hominin movements across the supposed 'Movius Line' a boundary previously argued to separate populations with different cultural and cognitive capacities. While such divisions and assumptions are now clearly outdated, the authors argue that focus on this part of the world may, instead, be used to study the different patterns of colonization of diverse tropical and maritime habitats by different members of our ancestral line. As Noel Amano, co-author on the study states, 'analysis of biogeochemical records, animal assemblages, and fossil plant records associated with hominin arrival can be used to reconstruct the degree to which novel or specialized adaptations were required at a given place and time'.
Southeast Asia offers a particularly exciting region in this regard as such records can be linked to a variety of hominins throughout the Pleistocene, including Homo erectus, Homo floresiensis (or 'the Hobbit'), and Homo sapiens. As Patrick Roberts, lead author of the study states the accumulated evidence shows, 'While earlier members of our genus appear to have followed riverine and lacustrine corridors, Homo sapiens specialized in adaptations to tropical rainforests, faunally depauperate island settings, montane environments, and deep-water marine habitats.' The authors hope that, in future, the growth of new methods and records for determining past hominin ecologies will enable similar comparisons to be undertaken in different parts of the world, further testing the unique capacities of our species during its global expansion.
From Science Daily
Climate change reshaping how heat moves around globe
 |
| The Antarctic. |
"The greenhouse effect and carbon dioxide aren't the only issues to consider as the planet grows warmer -- they are just one part of the equation. The way that the atmosphere and oceans move heat around is changing, too, and this could have significant effects on temperatures around the world," said Zhengyu Liu, co-lead author of the study and professor of climate dynamics in the Department of Geography at The Ohio State University.
Liu and Chengfei He, a graduate student in Ohio State's atmospheric science program, analyzed model simulations to illustrate how heat is expected to be transferred by the oceans and atmosphere in the near future. The researchers compared the models with historical temperature data from the oceans themselves to paint a clearer picture of how climate change is shifting and will continue to shift these patterns in this century. Their study appears online today (Jan. 28, 2019) in the journal Nature Climate Change.
Without heat transfer, the world's hottest spots would be sizzling and the coolest spots would be even more frigid. Conditions in both hot and cold climates are affected by the movement of heat from the equator toward the poles in the atmosphere and oceans, He said.
As scientists look for a better understanding of all the factors contributing to climate change -- and for ways to ameliorate the problem -- these heat-transfer patterns are important to watch, He said.
This is the first study to examine current changes in heat transfer and to conclude that warming temperatures are driving increased heat transfer in the atmosphere, which is compensated by a reduced heat transfer in the ocean. Additionally, the researchers concluded that the excess oceanic heat is trapped in the Southern Ocean around the Antarctic.
"The ocean stores a lot of heat and in the last 50 years that has increased. And we can correlate that directly with increases in atmospheric carbon dioxide caused by human activity," Liu said. "Most studies like this have looked at future changes, hundreds of years from now. We examined the near-term differences of a warming climate."
For now, that heat is not re-entering the atmosphere, but at some point it may. If that were to happen, changes in heat transfer could contribute to significant shifts in normal temperatures worldwide, he said.
"For instance, if we didn't have heat transfer, Ohio would be 20 or 30 degrees colder than we are right now," Liu said. "Therefore, it is important to predict how the heat transfer will be changed in the future."
Read more at Science Daily
'Metallic wood' has the strength of titanium and the density of water
 |
| A microscopic sample of the researchers' "metallic wood." Its porous structure is responsible for its high strength-to-weight ratio, and makes it more akin to natural materials, like wood. |
In a new study published in Nature Scientific Reports, researchers at the University of Pennsylvania's School of Engineering and Applied Science, the University of Illinois at Urbana-Champaign, and the University of Cambridge have done just that. They have built a sheet of nickel with nanoscale pores that make it as strong as titanium but four to five times lighter.
The empty space of the pores, and the self-assembly process in which they're made, make the porous metal akin to a natural material, such as wood.
And just as the porosity of wood grain serves the biological function of transporting energy, the empty space in the researchers' "metallic wood" could be infused with other materials. Infusing the scaffolding with anode and cathode materials would enable this metallic wood to serve double duty: a plane wing or prosthetic leg that's also a battery.
The study was led by James Pikul, Assistant Professor in the Department of Mechanical Engineering and Applied Mechanics at Penn Engineering. Bill King and Paul Braun at the University of Illinois at Urbana-Champaign, along with Vikram Deshpande at the University of Cambridge, contributed to the study.
Even the best natural metals have defects in their atomic arrangement that limit their strength. A block of titanium where every atom was perfectly aligned with its neighbors would be ten times stronger than what can currently be produced. Materials researchers have been trying to exploit this phenomenon by taking an architectural approach, designing structures with the geometric control necessary to unlock the mechanical properties that arise at the nanoscale, where defects have reduced impact.
Pikul and his colleagues owe their success to taking a cue from the natural world.
"The reason we call it metallic wood is not just its density, which is about that of wood, but its cellular nature," Pikul says. "Cellular materials are porous; if you look at wood grain, that's what you're seeing? -- ?parts that are thick and dense and made to hold the structure, and parts that are porous and made to support biological functions, like transport to and from cells."
"Our structure is similar," he says. "We have areas that are thick and dense with strong metal struts, and areas that are porous with air gaps. We're just operating at the length scales where the strength of struts approaches the theoretical maximum."
The struts in the researchers' metallic wood are around 10 nanometers wide, or about 100 nickel atoms across. Other approaches involve using 3D-printing-like techniques to make nanoscale scaffoldings with hundred-nanometer precision, but the slow and painstaking process is hard to scale to useful sizes.
"We've known that going smaller gets you stronger for some time," Pikul says, "but people haven't been able to make these structures with strong materials that are big enough that you'd be able to do something useful. Most examples made from strong materials have been about the size of a small flea, but with our approach, we can make metallic wood samples that are 400 times larger."
Pikul's method starts with tiny plastic spheres, a few hundred nanometers in diameter, suspended in water. When the water is slowly evaporated, the spheres settle and stack like cannonballs, providing an orderly, crystalline framework. Using electroplating, the same technique that adds a thin layer of chrome to a hubcap, the researchers then infiltrate the plastic spheres with nickel. Once the nickel is in place, the plastic spheres are dissolved with a solvent, leaving an open network of metallic struts.
"We've made foils of this metallic wood that are on the order of a square centimeter, or about the size of a playing die side," Pikul says. "To give you a sense of scale, there are about 1 billion nickel struts in a piece that size."
Because roughly 70 percent of the resulting material is empty space, this nickel-based metallic wood's density is extremely low in relation to its strength. With a density on par with water's, a brick of the material would float.
Replicating this production process at commercially relevant sizes is the team's next challenge. Unlike titanium, none of the materials involved are particularly rare or expensive on their own, but the infrastructure necessary for working with them on the nanoscale is currently limited. Once that infrastructure is developed, economies of scale should make producing meaningful quantities of metallic wood faster and less expensive.
Once the researchers can produce samples of their metallic wood in larger sizes, they can begin subjecting it to more macroscale tests. A better understanding of its tensile properties, for example, is critical.
"We don't know, for example, whether our metallic wood would dent like metal or shatter like glass." Pikul says. "Just like the random defects in titanium limit its overall strength, we need to get a better understand of how the defects in the struts of metallic wood influence its overall properties."
In the meantime, Pikul and his colleagues are exploring the ways other materials can be integrated into the pores in their metallic wood's scaffolding.
Read more at Science Daily
Jan 27, 2019
Milky Way's neighbors pick up the pace
 |
| Taken with the European Southern Observatory's Gaia Satellite, the maps show the relative abundance of heavy elements (elements heavier than helium) in the stars. Yellow indicates fewer heavy elements and purple indicates more heavy elements. |
Named for explorer Ferdinand Magellan, who led the first European expedition to circumnavigate the globe, the Large and Small Magellanic Clouds are the Milky Way's nearest galactic neighbors -- companion galaxies that will someday merge with our galaxy. The two galaxies are visible only from the Southern Hemisphere, where they look like bright, wispy clouds.
A Map to Stellar History
Although humans have gazed at the Clouds for millennia, this is the first time astronomers have made a detailed map of the chemical compositions of the stars within them. The project, carried out by the Sloan Digital Sky Survey (SDSS), was led by NOAO astronomer David Nidever, who is also a research professor of physics at Montana State University.
"We mapped the positions, movements, and chemical make-up of thousands of stars in the Magellanic Clouds," said Nidever. "Reading these maps helps us reconstruct the history of when these galaxies formed their stars."
The maps are the first major discovery to come out of the new southern operations of SDSS's Apache Point Observatory Galaxy Evolution Experiment 2 (APOGEE-2) survey, which is being carried out on the Irénée du Pont Telescope at Las Campanas Observatory in Chile.
Making Maps from Stellar Spectra
To make the maps, the SDSS team collected spectra of as many stars as possible. Spectra, which spread out the light from a star in the form of a rainbow, encode the motions of stars, their temperature, the chemical elements they contain, and their stage in the stellar life cycle.
By measuring the chemical make-up of a galaxy's stars, astronomers are able to infer their "star formation history," a rough record of the rate at which stars formed over time. The reconstruction is possible because of the difference in the lifetimes of stars of different masses and the role more massive stars play in enriching galaxies with heavy elements.
As stars age, stars more massive than the Sun evolve and explode as supernovae, ejecting heavy elements out into the galaxy, while less massive stars live on. The ejected elements mix with the existing gas, enriching it. New generations of stars form from the enriched gas and inherit that chemical make-up. The process repeats, with the longer-lived lower mass stars surviving to record the enrichment history of the galaxy. By mapping the abundances of these stars, astronomers can "read" the star formation record of the galaxy.
Slow Start Followed by a Bang
The results show that the star formation history of the Large and Small Magellanic Clouds is completely different from that of our galaxy. "In the Milky Way, star formation began like gangbusters and later declined," explained team member Sten Hasselquist from the University of Utah. "In contrast, in the Magellanic Clouds, stars formed extremely slowly at early times, at a rate only 1/50th of the star formation rate in the Milky Way, but that rate has skyrocketed in the last 2 billion years."
Nidever thinks that the dramatic increase in the star formation rate is due to the interaction of the Magellanic Clouds with one another as they tumble toward the Milky Way. "The Clouds began their lives calmly in a relatively isolated part of the Universe, where there was no reason to form stars," said Nidever. "But in the last few billion years, the close interactions that the Clouds have had with each other and with the Milky Way is causing the gas in the Clouds to transform into stars."
Read more at Science Daily
The helix, of DNA fame, may have arisen with startling ease
 |
| A proto-nucleobase next to a nucleobase. Hard to tell the difference. |
In the lab, researchers at the Georgia Institute of Technology were surprised to see them do it under conditions thought to be common on Earth just before first life evolved: in plain water, with no catalysts, and at room temperature.
The neat spiraling also elegantly integrated another compound which today forms the backbone of RNA and DNA. The resulting structure had features that strongly resembled RNA.
Pivotal twists
The study has come a step closer to answering a chicken-egg question about the evolutionary path that led to RNA (from which DNA later evolved): Did the spiral come first, and did this structure influence which molecular components made it later into RNA because they fit well into the spiral?
"The spiraling could have had a reinforcing effect. It could have facilitated the molecules getting connected together that have the same chirality (curve) to connect into a common backbone that is compatible with the helical twist," said the study's principal investigator Nicholas Hud, a Regents Professor in Georgia Tech's School of Chemistry and Biochemistry.
The researchers published the new study in the journal Angewandte Chemie in December 2018. The research was funded by the National Science Foundation and the NASA Astrobiology Program under the Center for Chemical Evolution. The center is headquartered at Georgia Tech, and Hud is its principal investigator.
The study's resulting polymers were not RNA but could be have been an important intermediate step in the early evolution of RNA. For building blocks, the researchers used base molecules referred to as "proto-nucleobases," highly suspected to be precursors of nucleobases, main components that transport genetic code in today's RNA.
Nucleobase paradox
The study had to work around a paradox in chemical evolution:
Making RNA or DNA using their actual nucleobases in the lab without the aid of the enzymes of living cells that usually do this job is more than a herculean task. Thus, although RNA and DNA are ubiquitous on Earth now, their evolution on pre-life Earth would appear to have been an anomaly requiring erratic convergences of extreme conditions.
By contrast, the Georgia Tech researchers' model of chemical evolution holds that precursor nucleobases self-assembled easily to into ancestral prototypes -- that were polymer-like and referred to as assemblies -- which later evolved into RNA.
"We would call these 'proto-nucleobases' or 'ancestral nucleobases,'" Hud said. "For our overall model of chemical evolution, we're saying that these proto-nucleobases, which self-assemble into these long strands, could have been part of a very early stage before modern nucleobases were incorporated."
One main suspected proto-nucleobase in this experiment -- and in previous experiments on the possible the evolution of RNA -- was triaminopyrimidine (TAP). Cyanuric acid (CA) was another. The researchers highly suspect TAP and CA were parts of a proto-RNA.
The chemical bonds that hold together assemblies of the two suspected proto-nucleobases were surprisingly strong but non-covalent, which is akin to connecting two magnets. In RNA the main bonds holding together modern nucleobases are covalent bonds, akin to welding, and enzymes make those bonds in cells today.
Helical biases
A helix can spiral two ways, left-handed or right-handed. In chemistry, a molecule can also be handed, or chiral, making for "L" or "D" forms of the molecule.
Incidentally, the building blocks of today's RNA and DNA are all the D form, which make a right-handed helix. Why they evolved like this is still a mystery.
Batches of TAP and CA the researchers started out with produced roughly equal amounts of right and left-handed helices, but something stood out: Whole regions of a batch were biased in one direction and were separate from other regions that spiraled mostly the other way.
"The propensity for the molecules to choose one helical direction was so strong that large regions of the batches were made up predominantly of assemblies that were unidirectionally twisted," Hud said.
This was surprising because the individual molecules of TAP and CA had no chirality of their own, neither L nor D. Still, the twists had a preferred direction.
'World record'
The researchers added two more experiments to test how strongly their RNA-like assemblies preferred making one-handed helices.
First, they introduced a smidgeon of compounds similar to TAP and CA, but which had L or D chirality, to nudge the spiraling direction. The whole batch conformed to the chirality of the respective additive, resulting in assemblies twisting in a unified direction as helices do in RNA and DNA today.
"It was the new world record for the smallest amount of a chiral dopant (additive) that would flip a whole solution," said Suneesh Karunakaran, the study's first author and a graduate researcher in Hud's lab. "This demonstrated how easy it would be in nature to get abundant amounts of unified helices."
Second, they put the sugar compound ribose-5-phosphate together with TAP to more closely emulate the current building blocks of RNA. The ribose fell into place, and the resulting assembly spiraled in a direction dictated by the ribose chirality.
"This molecule easily formed an RNA-like assembly that was surprisingly stable, even though the pieces were only held together by non-covalent bonds," Karunakaran said.
Evolution revolution
The study's results under such simple conditions represent a leap forward in experimental evidence for how the helical twist of biomolecules could have already been in place long before life emerged.
The research also expands a growing body of evidence supporting an unconventional hypothesis by the Center for Chemical Evolution, which dispenses with the need for a narrative that rare cataclysms and unlikely ingredients were necessary to produce life's early building blocks.
Instead, most biomolecules likely arose in several gradual steps, on quiet, rain-swept dirt flats or lakeshore rocks lapped by waves. Precursor molecules with the right reactivity enabled those steps readily and produced abundant materials for further evolutionary steps.
Basement engineer
In the lab, helix self-assemblage was so productive that it outstripped a detection device's capacity to examine the output. Regions a square millimeter or more in size were packed with unidirectionally spiraled polymer-like assemblies.
"To look at them I had to make adjustments to the equipment," said Karunakaran. "I punched holes in a foil and put it in front of the beam of our spectropolarimeter."
Read more at Science Daily
Subscribe to:
Posts (Atom)