Jul 30, 2015

Plants Release Animal-like Substance When Stressed

Although plants do not have nervous systems, they respond to stress with chemical and electrical signals that are remarkably similar to those of animals, a new study has found.

The findings, published in the journal Nature Communications, could help to explain why certain plant-derived drugs work so well in humans.

At the center of it all is the neurotransmitter GABA (gamma-aminobutyric acid), which humans and animals, as well as plants, release when they are stressed out.

“We’ve known for a long time that the animal neurotransmitter GABA is produced by plants under stress, for example, when they encounter drought, salinity, viruses, acidic soils or extreme temperatures, but it was not known whether GABA was a signal in plants,” senior author Matthew Gilliham of the University of Adelaide’s School of Agriculture, Food and Wine said in a press release.

He continued, “We’ve discovered that plants bind GABA in a similar way to animals, resulting in electrical signals that ultimately regulate plant growth when a plant is exposed to a stressful environment.”

Co-author Stephen Tyerman is optimistic that the discovery could lead to new ways of modifying how plants respond to stress. He explained that most yield losses from agricultural crops come from “major stresses” like pathogens and poor environmental conditions. If the plants succumb to these threats, food shortages may result.

Tyerman further explained that by “identifying how plants use GABA as a stress signal, we have a new tool to help in the global effort to breed more stress-resilient crops to fight food insecurity.”

The researchers suspect that GABA and its interaction with neurotransmitters evolved independently in the plant and animal kingdoms. This is because, while the proteins share many characteristics in common, some aspects of these same proteins are different between plants and animals.

Nevertheless, since the basic GABA signaling system exists within both groups, particular plant-derived drugs and other plant-based products often match well with our health needs. For example, chamomile is thought to bind to GABA receptors, acting as an inhibitory neurotransmitter. As a probable result, this natural ingredient tends to provide a gentle, natural feeling of calmness when consumed.

Read more at Discovery News

Everglades Python May Be Second-Largest Ever in Florida

A python researcher working in Everglades National Park has captured what may be the second-largest Burmese python in the state of Florida, CBS Miami reports.

The snake was captured on July 9 in the park's Shark Valley and was documented at 18 feet 3 inches long. It's just 4 inches shy of the state's record 18 foot 7 inch python caught in Miami-Dade, CBS notes. Whether it's indeed the second-largest, officially, remains unclear, due to differences in record-keeping in and outside of the park.

Florida has struggled to contain the pythons, which lack a natural predator and wreak havoc with small mammal populations in the park.

The snake, a female, was euthanized, park officials said.

There could be more than 100,000 Burmese pythons in South Florida. Native to Asia, it exists in Florida thanks to an international pet trade that started decades ago, according to CBS.

From Discovery News

2000-Year-Old Cat Paw Prints Discovered on Tile

Paw prints made by a cat 2,000 years ago have been found on a Roman roof tile kept at a museum in south west England.

Dug up in Gloucester in 1969, the tile fragment had long lain unnoticed at Gloucester City Museum.

Only recently, a researcher spotted the cat’s paw on the tile while going through the finds from the 1969 archaeological excavation.

“At that time the archaeologists seem to have been more interested in digging things up than looking at what they found,” David Rice, curator at Gloucester City Museum, told Discovery News.

The cat is thought to have run across the wet clay tile when it was left out to dry in about AD100.

Despite the feline footprints, the Romans fired the tile, a type called tegula, and used it on the roof of a building in what became the Berkeley Street area of modern Gloucester.

It is possible the cat was a Roman army cat, the pet of a Roman soldier who stationed at the site.

The tile is now on display at the Gloucester City Museum and Art Gallery.

“The marks are the only example for Roman domestic cats that visitors can see in the museum,” Rice said.

“I believe there are more cat paw prints found on ancient Roman tiles in Britain than anywhere else in the Roman Empire including Italy. Roman Britons must have had a special liking for cats,” he added.

From Discovery News

Fossil Fuels May Be Screwing Up Carbon Dating

Radiocarbon dating has been helping put the planet’s history in the right order since it was first invented in the 1940s, giving scientists a key way to determine the age of artifacts like the Dead Sea Scrolls and the Shroud of Turin.

Thanks to fossil fuel emissions, though, the method used to date these famous artifacts may be in for a change.

The burning of fossil fuels is altering the ratio of carbon in the atmosphere, which may cause objects tested in the coming decades to seem hundreds or thousands of years older than they actually are, according a study published in the Proceedings of the National Academy of Sciences.

A cotton T-shirt manufactured and tested in 2050 may appear to be the same age as an artifact from the 11th century when dated using the radiocarbon method. A new shirt made in 2100, if emissions continue unabated, could appear to come from the year 100, alongside something worn by a Roman soldier.

In short, future human emissions may alter one of the most reliable methods for learning about the past.

Radiocarbon dating relies on the amount of radiocarbon, or carbon-14, remaining in an object to determine its approximate age. Radiocarbon is a radioactive form of carbon that’s created when nitrogen reacts with cosmic rays in the upper atmosphere. It occurs only in trace amounts, but it is present in every living thing.

Carbon-14 can combine with oxygen in the atmosphere to create carbon dioxide, which is then absorbed by plants and makes its way through the food chain. The amount of carbon-14 in living plants and animals matches the amount in the atmosphere, but when plants and animals die, they no longer absorb carbon-14.

Because radiocarbon has a known rate of decay, scientists can determine about how long it has been since the plant or animal was alive. The lower the amount of radiocarbon, the older the object.

But big changes in the atmosphere can throw off this method, like releasing tons of extra carbon dioxide into the air from burning fossil fuels. Because fossil fuels like coal and oil are so old, they have no radiocarbon left. When burned, they increase the amount of carbon dioxide, which dilutes the radiocarbon in the atmosphere and the amount that can be absorbed by organic material.

“Fossil fuels have lost all of their radiocarbon over millions of years of radioactive decay,” said Heather Graven, author of the study published last week. “This makes the atmosphere appear as though it has ‘aged.’”

Scientists are used to a bit of wiggle with carbon-14 dating; it can vary as much as 30 to 100 years from the actual age. But the changes from emissions will require some extra adjustment, even in the study’s best-case-scenario emissions projection.

Read more at Discovery News

Monstrous Aurora Detected Beyond our Solar System

For the first time, astronomers have detected an aurora erupting beyond the solar system, giving us a profound glimpse at the magnetism surrounding a brown dwarf, or “failed star.”

Until now, the only aurorae astronomers have witnessed have been located on planets within our own star system. The sun produces a steady stream of electrically charged particles, called ions, that wash throughout the solar system as the solar wind and intermittent coronal mass ejections. These ions go on to interact with planetary magnetic fields and atmospheres to generate beautiful lightshows.

In the case of Earth, powerful geomagnetic storms can be triggered when the sun’s magnetic field, loaded with ions, interacts with our global magnetosphere. Should this happen, ions from the sun are funneled into higher latitudes, which then interact with our atmosphere, generating Northern and Southern Lights — the Aurora Borealis and Aurora Australis, respectively.

Likewise, aurorae have been observed on Jupiter, Saturn and other planets in the solar system that possess a magnetic field and atmosphere.

Now astronomers have confirmed the first ever “exo”-aurora, an aurora erupting on a celestial object well beyond the confines of our solar system. But the most fascinating thing about this discovery is that this aurora wasn’t detected at an exoplanet, it was detected at a brown dwarf.

“All the magnetic activity we see on this object can be explained by powerful auroras,” said Gregg Hallinan, of the California Institute of Technology (Caltech), in a news release. “This indicates that auroral activity replaces solar-like coronal activity on brown dwarfs and smaller objects.”

Brown dwarfs are a mysterious class of object that forms a bridge between stars and planets. They possess characteristics of both, but cannot be clearly defined as either. As they are lower mass objects than stars that maintain nuclear fusion in their core, brown dwarfs are often referred to as “failed stars” — they are not massive enough to sustain fusion for long periods of time.

But what brown dwarfs lack in the fusion department, they certainly seem to make up for in the aurora department; the aurora detected on brown dwarf LSR J1835+3259 is 10,000 times more powerful than any planetary aurora we have detected previously.

LSR J1835+3259 is located 18 light-years from Earth and the radio signal generated by its aurora was detected by the Karl G. Jansky Very Large Array (VLA) in New Mexico. Optical measurements of the brown dwarf by the 5-meter Hale Telescope on Palomar Mountain, Calif., and the 10-meter Keck Telescope in Hawaii were also able to characterize the object. These observations have found that brown dwarfs support extremely powerful auroral activity, much stronger than planetary magnetic fields, but weaker than the coronal magnetic activity that can be found in more massive stars like our sun.

Read more at Discovery News

Jul 29, 2015

NASA's Curiosity Rover Eyes Weird Rock on Mars

NASA’s Mars rover Curiosity went out of its way to investigate a rock the likes of which it has never seen before on the Red Planet.

Measurements by Curiosity’s rock-zapping ChemCam laser and another instrument revealed that the target, a chunk of bedrock dubbed Elk, contains high levels of silica and hydrogen, NASA officials said.

The abundance of silica — a silicon-oxygen compound commonly found here on Earth in the form of quartz — suggests that the bedrock may provide conditions conducive to the preservation of ancient carbon-containing organic molecules, if any exist in the area, the officials added. So Curiosity’s handlers sent the rover back 151 feet (46 meters) to check Elk out.

“One never knows what to expect on Mars, but the Elk target was interesting enough to go back and investigate,” ChemCam principal investigator Roger Wiens, of Los Alamos National Laboratory in New Mexico, said in a statement.

Elk lies near a spot on the lower reaches of the 3.4-mile-high (5.5 kilometers) Mount Sharp, called Marias Pass, whose rocks Curiosity had been studying. Marias Pass is a “geological contact zone” where dark sandstone meets lighter mudstone.

“We found an outcrop named Missoula where the two rock types came together, but it was quite small and close to the ground,” Curiosity project scientist Ashwin Vasavada, of NASA’s Jet Propulsion Laboratory in Pasadena, California, said in the same statement. “We used the robotic arm to capture a dog’s-eye view with the MAHLI [Mars Hand Lens Imager] camera, getting our nose right in there.”

ChemCam had fired at the Elk bedrock from the top of a small hill close to Marias Pass, which Curiosity had summitted before taking a look at the contact zone. After looking at the Missoula outcrop, the 1-ton rover began moving on, but an analysis of ChemCam’s data persuaded the team to turn Curiosity around for a closer look at Elk, mission team members said.

“ChemCam acts like eyes and ears of the rover for nearby objects,” Wiens said.

As Curiosity gathers data, mission engineers continue to investigate a short circuit that cropped up in the rover’s sample-collecting drill in February. No short circuits occurred during a July 18 engineering test, so the Curiosity team plans to conduct some drilling trials on rocks in the near future, NASA officials said.

Read more at Discovery News

X-Ray Reveals Mysterious Component of Human Hair

A new and surprising component of human hair has just been discovered, according to research that will be presented today at the annual meeting of the American Crystallographic Association, held in Philadelphia.

Human hair has been extensively studied for decades, but until now, a complete understanding of its structure had proven elusive.

"Hair traditionally has been constituted of three regions: medulla (central part of the hair), cortex (biggest volume fraction of the hair) and the cuticle (external part of the hair)," project leader Vesna Stanic, a scientist working at the Brazilian Synchrotron Light Source, told Discovery News.

"We discovered a new intermediate zone, which is in between the cuticle and cortex," she added.

Stanic and her team made the discovery by combining an ultra powerful submicron X-ray beam with cross-sectional geometry. The original goal was to just study materials used in hair treatments, and how they affect hair. While doing this, Stanic wondered about the diffraction patterns of hair.

Diffraction is the bending of waves around obstacles and openings. X-ray diffraction patterns of a given material can therefore reveal the local arrangement of both molecular and atomic structures.

Diffraction patterns of human hair have been documented before, but they usually involved pointing the X-ray beam perpendicular to the hair fiber axis. Stanic and her team decided to do something different.

"We performed a full diffraction map from a 30-micron-thick cross section of hair, with an incident beam parallel to the hair axis, and then compared it to the diffraction map with the beam perpendicular to the hair axis," she explained.

Before this study, human hair was thought to be composed only of a fibrous protein called alpha keratin, as well as certain minerals and lipids. The scientists were therefore extremely surprised to find that a key diffraction feature of alpha keratin was absent in the area between a hair strand's cuticle and cortex. The pattern instead corresponded to beta keratin.

Previously, beta-keratin was associated with reptiles and birds. It is what makes claws, scales, beaks and feathers strong, tough and, in the case of feathers, also flexible and elastic.

Alpha and beta keratin are similar molecules, but they have very different sizes and shapes.

Stanic explained, "The basic difference between alpha and beta keratin is the molecule conformations. We can say that beta keratin is essentially stretched alpha keratin. Alpha keratin has a helical structure, while beta is typically arranged in sheets."

The discovery comes on the heels of other research helping to explain why humans from different parts of the world have distinctive hair types. The reason can be summed up in one word: Neanderthals.

Daven Presgraves, an associate professor in the Department of Biology at the University of Rochester, told Discovery News that people of non-African heritage today retain Neanderthal alleles (alternative gene types) at genes affecting keratin filaments.

"The implication is that these Neanderthal-derived alleles were particularly well adapted to Eurasian environments in which they'd evolved for several hundred thousands of years," Presgraves told Discovery News. "Modern humans who interbred with Neanderthals on their way out of Africa were, in effect, able to borrow these keratin-associated alleles, perhaps accelerating adaptation to a Eurasian environment that was new to them."

Read more at Discovery News

Cassini to Make Final Flybys of 2 Icy Saturn Moons

For the next six months, NASA’s Saturn-orbiting Cassini spacecraft will get its final look at two icy moons — one famous and one not so well-known. It will fly by the erupting moon Enceladus three times, checking out its plumes in the best detail to date. And it will take one last look at the moon Dione (pronounced die-OWN-ee), which may have eruptions as well.

Why are icy moons so interesting to astronomers? One reason is they represent some of the best chances of finding life in our solar system. Many of these icy moons are believed to host global oceans underneath. Warmed by gravitational interactions with massive Saturn, there could be microbes floating under the surface just waiting for us to examine.

The long last look at Dione will take place Aug. 17, when Cassini will do gravitational measurements to learn more about its interior and icy shell. “There are intriguing hints that perhaps there’s something similar going on on Dione that we might have on Enceladus, but we haven’t found the equivalent of a smoking gun,” Linda Spilker, the Cassini project scientist at NASA’s Jet Propulsion Laboratory, told Discovery News.

The plumes on Enceladus were first found from measurements by Cassini’s magnetometer, which recorded evidence that the magnetic field lines do not go down to the surface — as is what would be expected on an airless body.

But similar evidence is so far lacking at Dione. Perhaps it’s because the moon is bigger, Spilker says, meaning the plumes are pulled down by gravity and are harder to see. Scientists will also look at Dione from afar in 2017, when the moon passes in front of a background star. If there are plumes erupting from Dione, it would dim the starlight.

As for Enceladus itself, three final flybys are planned in 2015 to learn more about its environment: a view of the north pole on Oct. 14, a “plunge” into the known location of a plume Oct. 28, and an attempt to look at the thermal environment of the south pole Dec. 19.

It’s now winter time in the south pole of Enceladus, providing a unique opportunity to look at any heat coming from the “tiger stripes” in that region. These zones are associated with the icy plumes that are coming from Enceladus.

The north pole flyby will allow them to use a “high phase angle” to examine the plumes in more detail; it’s sort of the equivalent of driving into the sun with the dust on the windshield, Spilker said, because the sun reflects off the dust. This allows them to measure how the plumes have changed.

And the most spectacular of the trio of flybys will be going deep into a known plume region itself, to measure the gas and particles and learn more about their source. The working theory is that water from the sea floor of Enceladus goes through the cracks below the surface, interacts with the rocky core and heats up, then erupts back above the surface and interacts with colder water. Nanosilica particles have been detected in the plumes, which occur in the presence of hot water.

These regular flybys of moons are possible through interactions with the massive Titan, one of the larger moons in the solar system (almost as big as the planet Mercury) and also of interest because it has an ecosystem full of ethane and methane. Its liquid lakes make it unique in the solar system. So Cassini does observations of this intriguing world while taking advantage of its gravity to slingshot to other locations.

Read more at Discovery News

Stellar Mystery Solved: Exploding Star is a Lithium Factory

Lithium has been detected in stellar material blasting away from an exploding star, possibly revealing the source of the basic element in young stars, thereby solving a mystery that has perplexed astronomers for decades.

The event, known as a nova, occurred in southern skies in December 2013 near the bright star Beta Centauri. A nova is thought to occur in binary star systems where a white dwarf star pulls hydrogen from its binary partner. Once this material reaches a critical mass, the hydrogen undergoes a runaway fusion reaction, causing the white dwarf to erupt.

It has long been known that novae can produce an array of different chemical elements that enrich the interstellar medium with gases that go on to help form later generations of stars. However, though lithium is theorized to also be produced by these explosions, astronomers have not been able to detect any trace of the element in previous novae.

Lithium is one of the few elements that is thought to have been produced by the Big Bang, nearly 14 billion years ago. However, astronomers have observed a greater abundance of lithium in younger stars than older stars, indicating there must be another production mechanism in the modern universe.

So, in the 1970s, astronomers’ attention shifted to novae as being the culprit. Although rare, and much less powerful than their larger supernova cousins, it was thought that over the history of the Milky Way enough novae likely occurred to explain this abundance of lithium. But observations of novae seeking elusive lithium proved fruitless.

Then Nova Centauri 2013 (also known as V1369 Centauri) lit up our skies, an explosion that was easily visible to the naked eye and the brightest nova so far this century.

As reported in a new study published Wednesday in the Astrophysical Journal Letters, Luca Izzo, from Sapienza University of Rome and ICRANet, Pescara, Italy, and his team used the FEROS instrument on the MPG/ESO 2.2-meter telescope at the La Silla Observatory in Chile, and the PUCHEROS spectrograph on the ESO 0.5-meter telescope at the Observatory of the Pontificia Universidad Catolica de Chile near Santiago, to zoom in on V1369 Centauri.

These new data have revealed a “very clear signature” of lithium speeding away from the stellar explosion at a speed of 2 million kilometers (1.2 million miles) per hour, the first time lithium has ever been seen being produced by a nova.

Read more at Discovery News

LHC Keeps Bruising 'Difficult to Kill' Supersymmetry

In a new blow for the futuristic "supersymmetry" theory of the universe's basic anatomy, experts reported fresh evidence Monday of subatomic activity consistent with the mainstream Standard Model of particle physics.

New data from ultra high-speed proton collisions at Europe's Large Hadron Collider (LHC) showed an exotic particle dubbed the "beauty quark" behaves as predicted by the Standard Model, said a paper in the journal Nature Physics.

Previous attempts at measuring the beauty quark's rare transformation into a so-called "up quark" had yielded conflicting results. That prompted scientists to propose an explanation beyond the Standard Model -- possibly supersymmetry.

But the latest observations were "entirely consistent with the Standard Model and removes the need for this hypothesis" of an alternative theory, Guy Wilkinson, leader of LHC's "beauty experiment" told AFP.

"It would of course have been very exciting if we could show that there was something wrong with the Standard Model -- I cannot deny that would have been sensational," he said.

The Standard Model is the mainstream theory of all the fundamental particles that make up matter, and the forces that govern them.

But the model has weaknesses: it doesn't explain dark matter or dark energy, which jointly make up 95 percent of the universe. Nor is it compatible with Einstein's theory of general relativity -- the force of gravity as we know it does not seem to work at the subatomic quantum scale.

Supersymmetry, SUSY for short, is one of the alternatives proposed for explaining these inconsistencies, postulating the existence of a heavier "sibling" for every particle in the universe.

This may also explain dark matter and dark energy.

'Many-Headed Monster'

But no proof of supersymmetric twins has been found at the LHC, which has observed all the particles postulated by the Standard Model -- including the long-sought Higgs boson, which confers mass to matter.

Supersymmetry predicts the existence of at least five types of Higgs boson, but only one, believed to be the Standard Model Higgs, has so far been found.

Wilkinson said it was "too soon" to write off supersymmetry.

"It is very difficult to kill supersymmetry: it is a many-headed monster," he said.

But "if nothing is seen in the next couple of years, supersymmetry would be in a much harder situation. The number of true believers would drop."

Quarks are the most basic particles, building blocks of protons and neutrons, which in turn are found in atoms.

There are six types of quarks -- the most common are the "up" and "down" quarks, while the others are called "charm", "strange", "beauty" and "top."

The beauty quark, heavier than up and down quarks, can shift shape, and usually takes the form of a charm quark when it does.

Much more rarely, it morphs into an up quark. Wilkinson's team have now measured -- for the first time -- how often that happens.

"We are delighted because it is the sort of measurement nobody thought was possible at the LHC," he said. It had been thought that an even more powerful machine would be needed.

The revamped LHC, a facility of the European Organisation for Nuclear Research (CERN), was restarted in April after a two-year revamp to boost its power from eight to 13, potentially 14, teraelectronvolts (TeV).

Read more at Discovery News