Aug 27, 2014
Last summer, archaeologists discovered a rare time capsule of this ancient drinking culture: the world's oldest known wine cellar, found in the ruins of a sprawling palatial compound in Upper Galilee.
The mud-brick walls of the room seem to have crumbled suddenly, perhaps during an earthquake. Whatever happened, no one came to salvage the 40 wine jars inside after the collapse; luckily for archaeologists, the cellar was left untouched for centuries.
Excavators at the site took samples of the residue inside the jars. In a new study published today (Aug. 27) in the journal PLOS ONE, the researchers describe what their chemical analysis turned up: biomarkers of wine and herbal additives that were mixed into the drink, including mint, cinnamon and juniper.
Wild nights in Tel Kabri
Archaeologists unearthed the wine cellar in a palatial complex at a site called Tel Kabri in present-day northern Israel, near the borders of Syria and Lebanon. As far back as the Stone Age, the area's springs attracted settlers. During the second millennium B.C., a more centralized Canaanite community of thousands of people popped up around a palace, which likely housed a leader or ruling family who could redistribute wealth and commodities, said Andrew Koh, an archaeologist at Brandeis University, in Waltham, Massachusetts, and one of the excavators on the dig.
The compound was at its peak between 1900 B.C. and 1600 B.C. Artifacts and paintings found at the site suggest this community had contact with Egypt, Mesopotamian cultures to the north and east, and the Minoan civilization that arose in Crete.
In July, Koh and colleagues were excavating an area they thought was outside the palace when they found a 3-foot-tall (1 meter) jar they dubbed "Bessie." The team eventually turned up 39 more jars inside a room measuring about 16 feet by 26 feet (5 m by 8 m). All together, the vessels would have held around 528 gallons (2,000 liters) of wine, and the cellar was conveniently located next to a banquet hall.
"What we have is quite substantial — 40 jars — but it's not enough to redistribute to the whole countryside, so we're arguing that this is the personal or palatial wine cellar," Koh told Live Science. "It's for a nuclear kind of in-group, whether it's the family or clan, and it's for local, on-the-spot consumption. But it's still a lot of wine — they must have thrown large parties."
What's in the wine
The residue from all 32 jars sampled in the study contained tartaric acid, one of the main acids in wine. In all but three jars, the researchers found syringic acid, a marker of red wine. The absence of syringic acid in those three jars may indicate that they contained some of the earliest examples of white wine, which got its start later than red wine, Koh said.
The researchers found signatures of pine resin, which has powerful antibacterial properties and was likely added at the vineyard to help preserve the wine. Scientists also found traces of cedar, which may have come from wooden beams used during the wine-pressing process.
The researchers noticed that the cellar's simplest wines, those with only resin added, were typically found in the jars lined up in a row against the wall near the outdoor entrance to the room. But the wines with the more complex additives were generally found in jars near a platform in the middle of the cellar and two narrow rooms leading to the banquet hall next door. Koh and colleagues believe the wine would have been brought from the countryside into the cellar, where a wine master would have mixed in honey and herbs like juniper and mint before a meal.
As for the taste, Koh said the ancient booze may have resembled modern retsina, a somewhat divisive Greek wine flavored with pine resin — described by detractors as having a note of turpentine. (Koh said he and his colleagues usually hear two different kinds of remarks about the ancient wine: Some say, "I would love to drink this wine," while others say, "It must have just tasted like vinegar with twigs in it.")
While the wine wouldn't be what drinkers are used to today, the jars at Tel Kabri likely contained some the finest vintages of the day, Koh said.
"If the Egyptian kings and pharaohs wanted wine from this area, it must have been quite good," Koh said.
Recreating old wine from lost grapes
Based on the fabric of the clay jars, the researchers said the wine came from the local region, though they're still trying to pinpoint where the supplying vineyards may have been located. The scientists do know that one of the most famous vineyards of antiquity, the Bethanath estate, got its start about 1,000 years later, just 9 miles (15 km) away from Tel Kabri.
Koh and colleagues are also hoping DNA tests reveal what kind of grapes were used, which may interest not only archaeologists but also current wine producers.
The Islamic conquest of the 7th century put an end to much of the region's wine culture. It wasn't until the 19th century that Upper Galilee's vineyards experienced a revival, largely thanks to Baron Edmond de Rothschild, who imported grapes from Bordeaux, France, that still form the basis of much of Israel's wine culture today, Koh said. But these grapes are perhaps not the best varieties for the region's climate.
Read more at Discovery News
This odd group has captured the first video footage of Death Valley's sailing stones creeping across Racetrack Playa. For a century, these eerie rocks and their long, graceful trails have stumped visitors and scientists. The boulders of black dolomite appear to move on their own, sliding uphill across the playa's flat lakebed. The trails are the only evidence the rocks move. No one has ever seen them set sail.
Lacking direct evidence, explanations for this geologic puzzle ran the gamut, from Earth's magnetic field to gale-force winds to slippery algae. Now, with video, time-lapse photographs and GPS tracking of Racetrack Playa's moving rocks, the mystery has finally been solved.
Jagged plates of thin ice, resembling panels of broken glass, bulldoze the rocks across the flooded playa, the scientists reveal today (Aug. 27) in the journal PLOS One. Driven by gentle winds, the rocks seem to hydroplane atop the fluffy, wet mud.
"It's a wonderful Goldilocks phenomenon," said lead study author Richard Norris. "Ponds like this are vanishingly rare in Death Valley, and it may be a decade between heavy enough rain or snowfall events to make a substantial pond," said Norris, a paleobiologist at the Scripps Institution of Oceanography in San Diego, California.
Leading theories had already narrowed in on wind, water and ice to propel the playa's rocks. But no one has come up with thin ice before. Models always targeted thick ice sheets, which could float the rocks across the playa like wind-driven icebergs. The ice seen during the study is too thin to pick up anything but pebbles.
"I have to confess I was surprised," said study co-author Ralph Lorenz, who has authored several studies suggesting thick ice carries the playa rocks. "I really expected buoyancy to be required, and it clearly wasn't. The ice was thinner than I thought would be needed. It was amazing to see the process actually happen," said Lorenz, a planetary scientist at the Applied Physics Laboratory at Johns Hopkins University in Baltimore.
A similar phenomenon is at work in colder climates, on a much more massive scale, the researchers said. When frozen lakes and rivers break up in the spring, the ice floes can dislodge big boulders, leaving grooves in the muddy sediment.
In a terrain known for its barren and bizarre geology, Racetrack Playa is one of the strangest. The dry lake is 3 miles long (4.5 kilometers), nearly flat as a tabletop and littered with a few hundred rocks. Some are as small as baseballs, but other boulders weigh as much as 700 lbs. (317 kilograms). Even the largest rocks trail long furrows behind them.
Some trails are short; some stretch twice the length of a football field. Other trails sharply zig and zag, suggesting quick changes in direction. Mysteriously, some trails are missing rocks.
The playa occasionally floods in winter, from rain or melted snow. Sitting at 3,608 feet (1,100 meters) above sea level and ringed by mountains, nighttime temperatures can drop below freezing, sheeting the temporary lake in thin ice or freezing it solid.
A rare combination of water and ice combines to move the rocks, the researchers said. The playa lake needs to be deep enough for floating ice, but shallow enough to leave the rocks exposed. The surface ice should be thin "windowpane" ice, but strong enough to break into big panels that can bully the rocks. Finally, the freezing nights need to be followed by sunny days with light winds, which drive the cracking ice across the lake.
A series of wet winter storms created the perfect conditions from December 2013 through February 2014. Hundreds of rocks scooted across Racetrack Playa five times in 10 weeks.
"Basically, the rocks move for about one minute in a million minutes," Lorenz told Live Science. "You have to be there at the right time, and the right time is generally one of the least hospitable times to be there."
Reaching Racetrack Playa requires a bone-jarring ride down a 28-mile gravel road. The remoteness has never deterred anyone obsessed with solving the riddle of the rocks. The first experiments here started in the 1940s and have never stopped.
A few years ago, two California cousins who grew up with a love of the desert decided to tackle the Racetrack Playa problem. Richard Norris is the biologist and Jim Norris is the engineer. They nabbed rare National Park Service permits to install equipment and sensors in Racetrack Playa.
"It's almost the purest form of doing science, for discovery's sake, rather than because your reputation is tied up in it," Richard Norris said.
In the winter of 2011, with the help of family and friends, the Norris clan lugged 15 imported rocks with motion-activated GPS units built by Jim Norris onto Racetrack Playa. (The Park Service didn't want the natural rocks disturbed.) They also installed a weather station to track wind gusts.
They waited for the rocks to move, but there was never any water.
Two years later, Lorenz, the planetary scientist, saw the weather station and tracked down the team at a research meeting held in Death Valley in November 2013. The Norris group was easy to find — they had matching T-shirts blazed with "Slithering Stones Research Initiative." Over beers, the researchers decided to join forces.
Lorenz has been investigating the sailing stones since 2006. He came to Death Valley to study the dust devils as an analog for conditions on Mars, but he also became fascinated by Racetrack Playa.
Right place, right time
In December 2013, the team hit the jackpot. They discovered the playa was slicked with water three inches (7 cm) deep. Overnight, the pond froze and when the sun rose the next morning and cracked the ice, the rocks set sail. It was all caught on camera.
Hundreds of rocks were in motion, Norris said. "The ice was just crackling and popping and making all these noises across the playa."
Some rocks moved in concert, even though they were hundreds of feet apart, while others creeped independently. The rocks inched along at gridlock speed, about 10 mph (16 km/h), which is equal to a few inches per second (2 to 6 meters per minute). The creeping could barely be detected at a distance.
Read more at Discovery News
The exploded star was found by accident eight months ago in the nearby galaxy M82 (pictured top), located about 11 million light-years from Earth. It turned out to be a particular type of supernovae, known as a “Ia”, which ramp up to maximum brightness in about three weeks and then slowly begin to dim.
At their peak, these types of exploded stars pump out as much energy as 4 billion times the energy of the sun, making them good yardsticks for measuring cosmic distances. It was by using these so-called “standard candles” that astrophysicists in 1998 discovered an unknown force, referred to as dark energy, was speeding up the universe’s expansion.
Scientists theorized that supernova Ia explosions are triggered by the sudden fusion of carbon and oxygen into heavier elements, such as nickel-56, inside a white dwarf star, making it unstable.
“Fusion happens in a flash,” astrophysicist Robert Kirshner, with the Harvard-Smithsonian Center for Astrophysics, writes in an article in this week’s Nature. “A thermonuclear flame rips through the white dwarf, fusing carbon into heavier elements with a sudden release of energy that tears the star apart. Fusion stops yielding energy at the element that has the most tightly bound nucleus — in the case of a white dwarf, nickel-56.”
When the exploded remains of the M82 star were found, astronomers moved quickly to find out if the theoretical predictions were right.
“The last type Ia in our galaxy was in 1604,” lead researcher Eugene Churazov, with Germany’s Max Planck Institute for Astrophysics, wrote in an email to Discovery News.
He and colleagues used the European Space Agency’s International Gamma-Ray Astrophysics Laboratory, nicknamed INTEGRAL, to observe the newly found supernova between 50 and 100 days after the explosion. They found a neat chain of chemistry caused by the decay of radioactive nickel isotopes into cobalt and iron. Calculations show the amount of radioactive nickel, the rate of the supernova expansion and the amount of mass produced in the explosion match predictions.
Read more at Discovery News
|A salamander relaxing in a fire, just minding its own business, is rudely prodded by a shirtless man. “A salamander lives in the fire, which imparts to it a most glorious hue,” reads the caption. Welcome to the wonderful world of alchemy.|
Yet that didn’t stop the legend of the fire-proof salamander (a name derived from the Persian meaning “fire within”) from persisting for 1,500 more years, from the Ancient Romans to the Middle Ages on up to the alchemists of the Renaissance. Some even believed it was born in fire, like the legendary Phoenix, only slimier and a bit less dramatic. And that its fur (huh?) could be used to weave fire-resistant garments.
Part of the problem, it seems, is that in addition to disproving the salamander’s powers, Pliny also wrote extensively that it had such powers—and then some. His Natural History, which has survived over the centuries as a towering catalog of everything from mining to zoology, describes the salamander as such: “It is so chilly that it puts out fire by its contact, in the same way as ice does. It vomits from its mouth a milky slaver [saliva], one touch of which on any part of the human body causes all the hair to drop off, and the portion touched changes its color and breaks out in a tetter,” a sort of itchy skin disease.
|Medieval bestiaries—encyclopedias that cataloged life on Earth—propagated the myth that salamanders love carrots. Are those carrots? Maybe they’re flames.|
So right away the salamander was mythologized as both a miraculous survivor and a menace. Indeed, later on in the 1200s, an English writer told of one laying waste to Alexander the Great’s army simply by swimming in a river they drank from. All told, 4,000 soldiers and 2,000 horses supposedly perished after consuming the salamander’s dirty bath water. Which would be pretty embarrassing, if only it were true.
Now, it was likely Europe’s fire salamander, with its vivid yellow-on-black coloration, that served as the inspiration for the legend, according to Nosson Slifkin in his book Sacred Monsters. As you might assume from its conspicuous colors, this species is in fact quite poisonous, secreting a neurotoxin to deter predators. And if it doesn’t feel like waiting to be attacked, it can actually fire this secretion at its approaching enemies. While the toxin can cause skin irritation in humans, it’s far from capable of poisoning 4,000 soldiers. But it’s likely this poisonous nature was simply scaled up for such myths.
|Europe’s glorious fire salamander has bright markings that warn predators that it’s poisonous, and dead eyes that say, “I’m going through a rough patch in my life right now.”|
Salamanders: The Furry Fire-Proof Heroes of the Working Man
It was a bit earlier, in the Middle Ages, when the legend of the fire-proof salamander picked up another facet: asbestos, a highly fire-resistant mineral with fibers we now know can absolutely devastate our lungs, leading to mesothelioma and other awful diseases. You see, before we foolishly packed our modern buildings with the stuff, in the ancient world it was woven into royal garments. According to Pliny, because it doesn’t burn, it was used to wrap the dead on funeral pyres, resulting in pure ash unsullied by charred fabric.
Curiously, Marco Polo noted “the real truth is that the Salamander is no beast, as they allege in our part of the world, but is a substance found in the earth.” He relates the experiences of a Turkish acquaintance in China, where the man dug up “Salamander,” or asbestos as we know it, and processed its fibers into napkins. “When first made these napkins are not very white, but by putting them into the fire for a while they come out as white as snow. And so again whenever they become dirty they are bleached by being put in the fire.”
Far from dismissing the salamander’s powers entirely, Browne goes on to break down its potential for surviving flames or even extinguishing coals, arguing that the critter’s moistness and mucus can indeed protect it from burning up, however briefly. “And therefore some truth we allow in the tradition: truth according unto Galen, that it may for a time resist a flame, or as Scaliger avers, extinguish or put out a coal: for thus much will many humid bodies perform: but that it perseveres and lives in that destructive element, is a fallacious enlargement.” (It’s safe to assume that salamanders do indeed fare somewhat better than creatures that actually have fur, but to my knowledge no modern experiments have been done to confirm this on account of, you know, ethics and all.)
Read more at Wired Science
Aug 26, 2014
To make this observation, the team also enlisted the help of a gravitational lens, a galaxy-size magnifying glass, to reveal otherwise invisible detail. These new studies of galaxy HATLAS J142935.3-002836 have shown that this complex and distant object looks surprisingly like the comparatively nearby pair of colliding galaxies collectively known as the Antennae.
"While astronomers are often limited by the power of their telescopes, in some cases our ability to see detail is hugely boosted by natural lenses created by the Universe," explains lead author Hugo Messias of the Universidad de Concepción in Chile and the Centro de Astronomia e Astrofísica da Universidade de Lisboa in Portugal. "Einstein predicted in his theory of General Relativity that, given enough mass, light does not travel in a straight line but will be bent in a similar way to a normal lens."
Cosmic lenses are created by massive structures like galaxies and galaxy clusters, which bend light from objects behind them due to their strong gravity -- an effect called gravitational lensing. The magnifying properties of this effect allow astronomers to study objects that would otherwise be invisible and to directly compare local galaxies with much more remote ones, when the Universe was significantly younger.
For these gravitational lenses to work, however, the foreground lensing galaxy and the one beyond need to be precisely aligned.
"These chance alignments are quite rare and tend to be hard to identify," adds Messias, "but, recent studies have shown that by observing at far-infrared and millimeter wavelengths we can find these cases much more efficiently."
HATLAS J142935.3-002836 (or H1429-0028 for short) is one of these sources and was found in the Herschel Astrophysical Terahertz Large Area Survey (HATLAS). It is among the brightest gravitationally lensed objects in the far-infrared regime found so far, even though we are seeing it at a time when the Universe was just half its current age.
To study this object in further detail, the astronomers started an extensive follow-up campaign using an impressive collection of incredibly powerful telescopes, including the Hubble Space Telescope, ALMA, the Keck Observatory, and the VLA, among others.
The Hubble and Keck images revealed a detailed gravitationally induced ring of light around the foreground galaxy. These high resolution images also showed that the lensing galaxy is an edge-on disc galaxy -- similar to our Milky Way -- which obscures parts of the background light due to the large dust clouds it contains.
But this obscuration is not a problem for ALMA and the VLA, since these two facilities observe the sky at longer wavelengths, which are unaffected by dust. Using the combined data, the team discovered that the background system was actually an ongoing collision between two galaxies. From this point on, ALMA and the VLA played a key role in further characterizing this object.
In particular, ALMA traced carbon monoxide, which allows detailed studies of star-formation mechanisms in galaxies. The ALMA observations also allowed the motion of the material in the galaxy to be measured. This was essential to show that the lensed object is indeed an ongoing galactic collision forming hundreds of new stars each year, and that one of the colliding galaxies still shows signs of rotation; an indication that it was a disc galaxy just before this encounter.
The system of these two colliding galaxies resembles a spectacular object that is much closer to us: the Antennae, which is the closest ongoing merger of two spiral galaxies. While the Antennae system is forming stars with a total rate of only a few ten times the mass of our Sun each year, H1429-0028 each year turns more than 400 solar masses of gas into new stars.
Read more at Science Daily
According to a new study, as many as 1 in 7 people may have this disorder, properly known as "confusional arousal," which can lead to confused or inappropriate behavior — such as answering the phone when an alarm goes off — or even violence.
The episodes usually happen when a person is woken suddenly, and people sometimes have no memory of these incidents, said Dr. Maurice Ohayon, a sleep psychiatrist at Stanford School of Medicine and co-author of the study, detailed today (Aug. 25) in the journal Neurology.
"It's like they are totally drunk — they don't know where they are or what they are doing," Ohayon told Live Science.
Confusional arousal is distinct from night terrors and sleepwalking, Ohayon said. It is often seen in children, but has not been well studied in adults.
In the study, the researchers interviewed a random sample of more than 19,000 American adults about their sleep habits and history of confusional arousal, as well as any mental illness and any medications they were taking.
About 15 percent of those surveyed said they had experienced at least one bout of this "sleep drunkenness" in the previous year, more than half of whom said they suffered at least one episode per week. Slightly fewer than 10 percent of those who had had an episode couldn't remember part or all of the experience, and 15 percent of them also had sleepwalking episodes.
Confusional arousal is different from the normal sleepiness that most people feel when they wake up, said Dr. Alan Manevitz, a clinical psychiatrist at Lenox Hill Hospital in New York who was not involved with the research. Most people with sleep grogginess generally remember their experience, but people with sleep drunkenness are not aware of their actions, and attempts to fully wake them usually fail, Manevitz told Live Science.
The unusual grogginess has many different causes, depending on the individual. The researchers found that among those who'd had an episode of sleep drunkenness, 70 percent also had a sleep disorder, and 37 percent had a mental illness. Only 31 percent were taking medication for these disorders, and these were mostly antidepressants.
People suffering from depression, bipolar disorder, alcoholism, panic or post-traumatic stress disorder and anxiety seemed more susceptible to the disorder, as did those with sleep apnea, a disorder in which a person briefly stops breathing during sleep, the researchers said.
Read more at Discovery News
The researchers discovered the microscopic oval object within the Nakhla Mars meteorite, which fell to Earth in Egypt in 1911. While the structure's appearance is intriguing, it most likely formed as a result of geological rather than biological processes, team members said.
"The consideration of possible biotic scenarios for the origin of the ovoid structure in Nakhla currently lacks any sort of compelling evidence," the scientists write in a new study published this month in the journal Astrobiology. "Therefore, based on the available data that we have obtained on the nature of this conspicuous ovoid structure in Nakhla, we conclude that the most reasonable explanation for its origin is that it formed through abiotic processes."
A Cell-like Structure
The hollow ovoid is about 80 microns long by 60 microns wide, researchers said — far larger than most terrestrial bacteria but in the normal size range for eukaryotic Earth microbes (single-celled organisms that possess nuclei and other membrane-bound interior "organelles"). The study team is confident that the object is native to the sample and not the result of terrestrial contamination.
The scientists studied the structure using a number of different techniques, including electron microscopy, X-ray analysis and mass spectrometry. This work revealed that the ovoid is composed of iron-rich clay and contains a number of other minerals.
The researchers run through a number of possible formation scenarios in the new study, eventually concluding that the ovoid most likely formed when materials partially filled in a pre-existing vesicle — a vapor bubble, for example — in the rock.
But this supposition doesn't rule out the possibility that Martian lifeforms had something to do with the structure, team members said.
"Despite the extremely biomorphic overall shape of the ovoid, it is highly unlikely that it itself was an organism," said lead author Elias Chatzitheodoridis, of the National Technical University of Athens in Greece.
"However, it could have been formed directly by micro-organisms, or it could trap organic material that came from elsewhere," Chatzitheodoridis told Space.com via email. "That the ovoid is hollow means that there is enough space to accommodate colonies of microorganisms."
Making a firm link to Mars life would require further study and further discoveries, he added.
"We would be happy if we could have found more than one ovoid, with exactly the same texture both in the micro and the nanoscale," Chatzitheodoridis said. "However, we require to open up enough sample in a very careful way. Compelling evidence, though, would be if we could really find many of the same, clearly in a form of a colony, together with chemical and mineralogical biosignatures that are common for terrestrial microbes."
Nakhla is a well-studied meteorite — scientists have spotted possible signs of Mars life within it before —and previous research has mapped out its history in some detail. Nakhla's parent rock apparently crystallized about 1.3 billion years ago, Chatzitheodoridis and his colleagues write in the new study, then experienced two shock events that heated it up considerably.
The first of these shocks likely occurred around 910 million years ago and the second 620 million years ago. This latter event, which was triggered by a nearby meteorite strike on Mars, apparently included the flow of hot water through Nakhla's parent outcrop, the authors write. Finally, about 10 million years ago, another impact blasted Nakhla free of Mars, sending it on a looping trip through space that ended with its arrival at Earth in 1911.
Whether or not the Nakhla ovoid has some connection to Martian life, study of the meteorite can help researchers better understand the Red Planet's past (and, perhaps, present) potential to support life, Chatzitheodoridis said.
Read more at Discovery News
One of the more fascinating objects is the star in the center of the frame that appears to be sitting atop a column of smokey material. This is in fact a young stellar object (YSO) — basically a star’s embryo — that is slowly forming from the collapsing gas in its nebula. Called SSTC2D J033038.2+303212, this object has a disk of material seen edge-on that it continues to form from. The YSO seems to be generating its own hot jets of gas that light up the top of the dark nebulous column.
Below the YSO, however, there’s a huge, glowing ball of gas that brightens the scene. This is a reflection nebula — dust and gas that is lit up by numerous bright baby stars cocooned within — called [B77] 63.
Yet amongst the bright stellar birth is the pitch black object that seems to trail from [B77] 63. This dark nebula is called Dobashi 4173 and it blocks all light from any stars it may contain. The stars that overlay the nebula are actually foreground stars between us and Dobashi 4173.
This dramatic view was captured by the Hubble Space Telescope’s Advanced Camera for Surveys (ACS) that views the cosmos in ultraviolet, visible and near-infrared light.
From Discovery News
Aug 25, 2014
The findings, which suggest that the fungus "knows" its preferred host, provide new insights into the molecular mechanisms underlying this phenomenon, according to researchers.
"Fungi are well known for their ability to secrete chemicals that affect their environment," noted lead author Charissa de Bekker, a Marie Curie Fellow in Penn State's College of Agricultural Sciences, and Ludwig Maximilian of the University of Munich. "So we wanted to know what chemicals are employed to control so precisely the behavior of ants."
The research focused on a species from the genus Ophiocordyceps -- known as "zombie ant fungi" -- which control their ant hosts by inducing a biting behavior. Although these fungi infect many insects, the species that infect ants have evolved a mechanism that induces hosts to die attached by their mandibles to plant material, providing a platform from which the fungus can grow and shoot spores to infect other ants.
To study this mechanism, the researchers combined field research with a citizen-scientist in South Carolina, infection experiments under laboratory conditions and analysis using metabolomics, which is the study of the chemical processes associated with the molecular products of metabolism.
The scientists used a newly discovered fungal species from North America -- initially called Ophiocordyceps unilateralis sensu lato while it awaits a new name -- that normally controls an ant species in the genus Camponotus. To test whether a species of fungus that has evolved to control the behavior of one ant species can infect and control others, they infected nontarget hosts from the same ant genus and another genus (Formica).
They found that this obligate killer can infect and kill nontarget ants, but it cannot manipulate their behavior. "The brain of the target species was the key to understanding manipulation," de Bekker said.
The researchers next removed ant brains, keeping the organs alive in special media. The fungus then was grown in the presence of brains from different ant species to determine what chemicals it produced for each brain.
"This was 'brain-in-a-jar' science at its best," said co-author David Hughes, assistant professor of entomology and biology, Penn State. "It was necessary to reduce the complexity associated with the whole, living ant, and just ask what chemicals the fungus produces when it encounters the ant brain.
"You don't get to see a lot of behavior with fungi," he said. "You have to infer what they are doing by examining how they grow, where they grow and most important, what chemicals they secrete."
He explained that fungi are nourished via osmotrophy, by which they secrete compounds that degrade the bigger molecules in their environment into smaller ones that then can be taken up by the fungus. Using metabolomics, the researchers could determine precisely the chemical crosstalk between the fungus and the ant brain it grew alongside.
"We could see in the data that the fungus behaved differently in the presence of the ant brain it had co-evolved with," said de Bekker, whose Penn State co-authors also included Andrew Patterson, assistant professor of molecular toxicology, and Phil Smith, director of the Metabolomics Core Facility.
The researchers found thousands of unique chemicals, most of them completely unknown. This, according to Hughes, is not surprising, since little previous work has mined these fungi for the chemicals they produce.
But what did stand out were two known neuromodulators, guanobutyric acid (GBA) and sphingosine. These both have been reported to be involved in neurological disorders and were enriched when the fungus was grown in the presence of brains of its target species.
"There is no single compound that is produced that results in the exquisite control of ant behavior we observe," de Bekker said. "Rather, it is a mixture of different chemicals that we assume act in synergy.
"But whatever the precise blend and tempo of chemical secretion," she said, "it is impressive that these fungi seem to 'know' when they are beside the brain of their regular host and behave accordingly."
Noted Hughes, "This is one of the most complex examples of parasites controlling animal behavior because it is a microbe controlling an animal -- the one without the brain controls the one with the brain. By employing metabolomics and controlled laboratory infections, we can now begin to understand how the fungi pull off this impressive trick."
The research also is notable, the scientists contend, because it is the first extensive study of zombie ants in North America. Typically assumed to be a tropical phenomenon, they exist in temperate habitats but can be hard to find.
Read more at Science Daily
Taung Child's brain development not human-like? CT scan casts doubt on similarity to that of modern humans
The results have been published online in the Proceedings of the National Academy of Sciences (PNAS) on Aug. 25, in an article titled "New high resolution CT data of the Taung partial cranium and endocast and their bearing on metopism and hominin brain evolution."
The Taung Child has historical and scientific importance in the fossil record as the first and best example of early hominin brain evolution, and theories have been put forward that it exhibits key cranial adaptations found in modern human infants and toddlers.
To test the ancientness of this evolutionary adaptation, Dr Kristian J. Carlson, Senior Researcher from the Evolutionary Studies Institute at the University of the Witwatersrand, and colleagues, Professor Ralph L. Holloway from Columbia University and Douglas C. Broadfield from Florida Atlantic University, performed an in silico dissection of the Taung fossil using high-resolution computed tomography.
"A recent study has described the roughly 3 million-year-old fossil, thought to have belonged to a 3 to 4-year-old, as having a persistent metopic suture and open anterior fontanelle, two features that facilitate post-natal brain growth in human infants when their disappearance is delayed," said Carlson.
Comparisons with the existing hominin fossil record and chimpanzee variation do not support this evolutionary scenario.
Citing deficiencies in how the Taung fossil material has been recently assessed, the researchers suggest physical evidence does not incontrovertibly link features of the Taung skull, or its endocast, to early prefrontal lobe expansion, a brain region implicated in many human behaviors.
Read more at Science Daily