New type of photosynthesis discovered

Colony of Chroococcidiopsis-like cells where the different colours represent photosynthesis driven by chlorophyll-a (magenta) and chlorophyll-f (yellow).

The discovery changes our understanding of the basic mechanism of photosynthesis and should rewrite the textbooks.

It will also tailor the way we hunt for alien life and provide insights into how we could engineer more efficient crops that take advantage of longer wavelengths of light.

The discovery, published today in Science, was led by Imperial College London, supported by the BBSRC, and involved groups from the ANU in Canberra, the CNRS in Paris and Saclay and the CNR in Milan.

The vast majority of life on Earth uses visible red light in the process of photosynthesis, but the new type uses near-infrared light instead. It was detected in a wide range of cyanobacteria (blue-green algae) when they grow in near-infrared light, found in shaded conditions like bacterial mats in Yellowstone and in beach rock in Australia.

As scientists have now discovered, it also occurs in a cupboard fitted with infrared LEDs in Imperial College London.

Photosynthesis beyond the red limit

The standard, near-universal type of photosynthesis uses the green pigment, chlorophyll-a, both to collect light and use its energy to make useful biochemicals and oxygen. The way chlorophyll-a absorbs light means only the energy from red light can be used for photosynthesis.

Since chlorophyll-a is present in all plants, algae and cyanobacteria that we know of, it was considered that the energy of red light set the 'red limit' for photosynthesis; that is, the minimum amount of energy needed to do the demanding chemistry that produces oxygen. The red limit is used in astrobiology to judge whether complex life could have evolved on planets in other solar systems.

However, when some cyanobacteria are grown under near-infrared light, the standard chlorophyll-a-containing systems shut down and different systems containing a different kind of chlorophyll, chlorophyll-f, takes over.

Until now, it was thought that chlorophyll-f just harvested the light. The new research shows that instead chlorophyll-f plays the key role in photosynthesis under shaded conditions, using lower-energy infrared light to do the complex chemistry. This is photosynthesis 'beyond the red limit'.

Lead researcher Professor Bill Rutherford, from the Department of Life Sciences at Imperial, said: "The new form of photosynthesis made us rethink what we thought was possible. It also changes how we understand the key events at the heart of standard photosynthesis. This is textbook changing stuff."

Preventing damage by light

Another cyanobacterium, Acaryochloris, is already known to do photosynthesis beyond the red limit. However, because it occurs in just this one species, with a very specific habitat, it had been considered a 'one-off'. Acaryochloris lives underneath a green sea-squirt that shades out most of the visible light leaving just the near-infrared.

The chlorophyll-f based photosynthesis reported today represents a third type of photosynthesis that is widespread. However, it is only used in special infrared-rich shaded conditions; in normal light conditions, the standard red form of photosynthesis is used.

It was thought that light damage would be more severe beyond the red limit, but the new study shows that it is not a problem in stable, shaded environments.

Co-author Dr Andrea Fantuzzi, from the Department of Life Sciences at Imperial, said: "Finding a type of photosynthesis that works beyond the red limit changes our understanding of the energy requirements of photosynthesis. This provides insights into light energy use and into mechanisms that protect the systems against damage by light."

These insights could be useful for researchers trying to engineer crops to perform more efficient photosynthesis by using a wider range of light. How these cyanobacteria protect themselves from damage caused by variations in the brightness of light could help researchers discover what is feasible to engineer into crop plants.

Textbook-changing insights

More detail could be seen in the new systems than has ever been seen before in the standard chlorophyll-a systems. The chlorophylls often termed 'accessory' chlorophylls were actually performing the crucial chemical step, rather than the textbook 'special pair' of chlorophylls in the centre of the complex.

This indicates that this pattern holds for the other types of photosynthesis, which would change the textbook view of how the dominant form of photosynthesis works.

Dr Dennis Nürnberg, the first author and initiator of the study, said: "I did not expect that my interest in cyanobacteria and their diverse lifestyles would snowball into a major change in how we understand photosynthesis. It is amazing what is still out there in nature waiting to be discovered."

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Mammals going nocturnal to avoid humans

Deer silhouette on forest path.

Human activity is causing the planet's mammals to flee daylight for the protection of night, according to a new study from the University of California, Berkeley.

The study, published today in the journal Science, and supported in part by the National Science Foundation, represents the first effort to quantify the global effects of human activity on the daily activity patterns of wildlife. Its results highlight the powerful and widespread process by which animals alter their behavior alongside people: human disturbance is creating a more nocturnal natural world.

"Catastrophic losses in wildlife populations and habitats as a result of human activity are well documented, but the subtler ways in which we affect animal behavior are more difficult to detect and quantify," said Berkeley PhD candidate and study lead author Kaitlyn Gaynor.

Gaynor, along with co-authors Justin Brashares and Cheryl Hojnowski of UC Berkeley, and Neil Carter of Boise State University, applied a meta-analysis approach, using data for 62 species across six continents to look for global shifts in the timing of daily activity of mammals in response to humans. These data were collected by various approaches, including remotely triggered cameras, GPS and radio collars, and direct observation. For each species in each study site, the authors quantified the difference in animal nocturnality under low and high human disturbance.

On average, mammals were 1.36 times more nocturnal in response to human disturbance. This means that an animal that naturally split its activity evenly between the day and night increased its nighttime activity to 68% around people. This finding was consistent across carnivore and herbivore species of all body sizes greater than 1 kg (small mammals were not included in the study). The pattern also held across different types of human disturbance, including activities such as hunting, hiking, mountain biking, and infrastructure such as roads, residential settlement, and agriculture.

"While we expected to find a trend towards increased wildlife nocturnality around people, we were surprised by the consistency of the results around the world," said Gaynor. "Animals responded strongly to all types of human disturbance, regardless of whether people actually posed a direct threat, suggesting that our presence alone is enough to disrupt their natural patterns of behavior."

According to Brashares, a professor in the Department of Environmental Science, Policy, and Management and the study's senior author, the consequences of the behavioral shift in wildlife can be seen through contrasting lenses.

"On the positive side, the fact that wildlife is adapting to avoid humans temporally could be viewed as a path for coexistence of humans and wild animals on an increasingly crowded planet," said Brashares. "However, animal activity patterns reflect millions of years of adaptation--it's hard to believe we can simply squeeze nature into the dark half of each day and expect it to function and thrive."

The authors describe a range of potential negative consequences of the shifts they report in wildlife, including mismatches between the environment and an animal's traits, disruption of normal foraging behavior, increased vulnerability to non-human predators, and heightened competition.

They point out, however, that while many of the studies included in their analysis documented a clear increase in nocturnal activity, few examined the consequences for individual animals, populations, or ecosystems.

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Scientists have captured the elusive cell that can regenerate an entire flatworm

Planarian flatworm adult stem cells known as neoblasts can be clustered based on their gene expression profiles (left panel). A neoblast subpopulation termed Nb2 expresses the cell membrane protein TSPAN-1 (center panel, a representative Nb2 cell with TSPAN-1 protein shown in green and DNA in blue). Nb2 neoblasts can repopulate stem cell-depleted animals (right panel, representative animals at different time points after Nb2 single-cell transplants).

Researchers at the Stowers Institute for Medical Research have captured the one cell that is capable of regenerating an entire organism. For over a century, scientists have witnessed the effects of this cellular marvel, which enables creatures such as the planarian flatworm to perform death-defying feats like regrowing a severed head. But until recently, they lacked the tools necessary to target and track this cell, so they could watch it in action and discover its secrets.

Now, by pioneering a technique that combines genomics, single-cell analysis, flow cytometry and imaging, scientists have isolated this amazing regenerative cell -- a subtype of the long-studied adult pluripotent stem cell -- before it performs its remarkable act. The findings, published in the June 14, 2018, issue of the journal Cell, will likely propel biological studies on highly regenerative organisms like planarians and also inform regenerative medicine efforts for other organisms like humans that have less regenerative capacity.

"This is the first time that an adult pluripotent stem cell has been isolated prospectively," says Alejandro Sánchez Alvarado, Ph.D., an investigator at the Stowers Institute and Howard Hughes Medical Institute and senior author of the study. "Our finding essentially says that this is no longer an abstraction, that there truly is a cellular entity that can restore regenerative capacities to animals that have lost it and that such entity can now be purified alive and studied in detail."

Every multicellular organism is built from a single cell, which divides into two identical cells, then four, and so on. Each of these cells contains the exact same twisted strands of DNA, and is considered pluripotent -- meaning it can give rise to all possible cell types in the body. But somewhere along the way, those starter cells -- known as embryonic stem cells -- resign themselves to a different fate and become skin cells, heart cells, muscle cells, or another cell type. In humans, no known pluripotent stem cells remain after birth. In planarians, they stick around into adulthood, where they become known as adult pluripotent stem cells or neoblasts. Scientists believe these neoblasts hold the secret to regeneration.

Though neoblasts have been the subject of scientific inquiry since the late 1800's, only in the last couple of decades have scientists been able to characterize this powerful cell population using functional assays and molecular techniques. Their efforts showed that this seemingly homogenous cell population was actually a conglomeration of different subtypes, with different properties and different patterns of gene expression.

"We might have to transplant over a hundred individual cells into as many worms to find one that is truly pluripotent and can regenerate the organism," says Sánchez Alvarado. "That's a lot of work, just to find the one cell that fits the functional definition of a true neoblast. And if we want to define it molecularly by identifying the genes that cell is expressing, we have to destroy the cell for processing. There was no way to do that and keep the cell alive to track it during regeneration."

Sánchez Alvarado and his team began searching for a distinguishing characteristic that could identify this elusive cell ahead of time. One feature that had long been used to distinguish neoblasts from other cells is a stem cell marker known as piwi-1, so Postdoctoral Research Associate An Zeng, Ph.D., decided to start there. First, he separated the cells that expressed this marker from those that did not. Then he noticed the cells could be separated into two groups -- one that expressed high levels of piwi (aptly called piwi-high) and another that expressed low levels of piwi (called piwi-low). When Zeng studied the members of these two groups, he found only those that were piwi-high fit the molecular definition of neoblasts. So he discarded the rest.

"This kind of simultaneous quantitative analysis of gene expression and protein levels had never been done before in planarians," says Sánchez Alvarado. "We could not have done it without the amazing scientific support facilities here at Stowers, including molecular biology, flow cytometry, bioinformatics, and imaging groups. Many researchers had assumed that all cells expressing piwi-1 were true neoblasts, and it didn't matter how much of the marker they expressed. We showed it did matter."

Next, Zeng selected 8,000 or so of the piwi-high cells and analyzed their gene expression patterns. To his surprise, the cells fell not into just one or two, but 12 different subgroups. Through a process of elimination, Zeng excluded any subgroups with genetic signatures indicating that the cells were destined for a particular fate, like muscle or skin. That left him with two subgroups that could still be pluripotent, which he named Nb1 and Nb2.

Conveniently, the cells in subgroup Nb2 expressed a gene coding for a member of the tetraspanin protein family, a group of evolutionarily ancient and poorly understood proteins that sit on the surface of cells. Zeng made an antibody that could latch onto this protein, pulling the cells that carried it out of a mixture of other suspected neoblasts. He then transplanted the single purified cell into a planarian that had been subjected to lethal levels of radiation. Not only did these cells repopulate and rescue the irradiated animals, but they did so 14 times more consistently than cells purified by older methods.

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Microbe breaks 'universal' DNA rule by using two different translations

Scientists have discovered a microbe that uses two different translations of the DNA code at random.

DNA is often referred to as the blueprint for life, however scientists have for the first time discovered a microbe that uses two different translations of the DNA code at random. This unexpected finding breaks what was thought to be a universal rule, since the proteins from this microbe cannot be fully predicted from the DNA sequence.

Researchers from the Milner Centre for Evolution at the University of Bath and the Max-Planck Institute for Biophysical Chemistry in Göttingen, Germany have published their findings in the journal Current Biology.

All organisms receive genetic information from their parents which tell the cells how to make proteins -- the molecules that do the chemistry in our bodies. This genetic information comprises DNA molecules made up of a sequence of four chemical bases represented by the letters A, T, C and G; the genetic code dictates to the cell which sequence of amino acids to join together to form each protein given the underlying sequence in the DNA.

In a similar way that "dot dot dot" in morse code translates as S, so too the genetic code is read in blocks of three bases (codons) to translate to one amino acid.

It was originally thought that any given codon always results in the same amino acid -- just as dot dot dot always means S in morse code. GGA in the DNA for example translates as the amino acid glycine.

However a collaboration between Dr Stefanie Mühlhausen and Professor Laurence Hurst at the Milner Centre for Evolution at the University of Bath, and Martin Kollmar and colleagues at the Max-Planck Institute for Biophysical Chemistry in Göttingen, Germany have now described the first -- and unexpected -- exception to this rule in a natural code.

The group examined an unusual group of yeasts in which some species have evolved an unusual non-universal code. While humans (and just about everything else) translate the codon CTG as the amino acid leucine, some of the species of yeast instead translate this as the amino acid serine whilst others translate it as alanine.

This is odd enough in itself. But the team was even more surprised to find one species, Ascoidea asiatica, randomly translated this codon as serine or leucine. Every time this codon is translated the cell tosses a chemical coin: heads for leucine, tails it's serine.

Laurence Hurst, Professor of Evolutionary Genetics and Director of the Milner Centre for Evolution at the University of Bath, said: "This is the first time we've seen this in any species.

"We were surprised to find that about 50 per cent of the time that CTG is translated as serine, the remainder of the time it is leucine.

"The last rule of genetics codes, that translation is deterministic, has been broken. This makes this genome unique -- you cannot work out the proteins if you know the DNA."

To understand how this happens -- how this coin-toss mechanism is physically manifested -- the team investigated molecules called tRNAs -- which act as translators that recognise the codons and bring together the amino acids to make a protein chain.

Dr Martin Kollmar, from the Max-Planck Institute for Biophysical Chemistry in Göttingen said: "We found that Ascoidea asiatica, is unusual in having two sorts of tRNAs for CTG -- one which bridges with leucine and one which bridges with serine.

"So when CTG comes to be translated, it randomly picks one of the two tRNAs and hence randomly picks between serine and leucine."

Dr Stefanie Mühlhausen from The Milner Centre for Evolution at the University of Bath added: "Swapping a serine for leucine could cause serious problems in a protein as they have quite different properties -- serine is often found on the surface of the protein whereas leucine is hydrophobic and often buried inside the protein.

"We looked at how this strange yeast copes with this randomness and found that A. asiatica has evolved to use the CTG codon very rarely and especially avoids key parts of proteins."

The researchers estimate that the random encoding is 100 million years old, but other closely related species evolved to lose this potentially problematic trait.

Read more at Science Daily

Flying spiders sense meteorological conditions, use nanoscale fibers to float on the wind

The crab spider spins out tens of fine silk fibers for its aerial dispersal. A triangular sheet of fibers is observed at the moment of the takeoff.

Spiders take flight on the smallest of breezes by first sensing the wind, and then spinning out dozens of nanoscale fibers up to seven meters long, according to a study publishing June 14 in the open-access journal PLOS Biology by Moonsung Cho, Ingo Rechenberg, Peter Neubauer, and Christoph Fahrenson at the Technische Universität in Berlin. The study provides an unprecedentedly detailed look at the "ballooning" behavior that allows certain spiders to travel on the wind for hundreds of kilometers.

Many kinds of spiders engage in ballooning, either to disperse from their birth site, to search for food or mates, or to find new sites for colonization. While most ballooning spiders are juveniles or small adults, under 3 millimeters in length, some larger adults also balloon. Although the behavior has been studied before, these authors are the first to make detailed measurements of both the sensing behavior and the silk fibers that are used to catch the wind.

Through a combination of field observations and wind tunnel experiments, they found that large crab spiders (Xysticus species), about 5 mm long and weighing up to 25 milligrams, actively evaluated wind conditions by repeatedly raising one or both front legs and orienting to the wind direction. At wind speeds under 3.0 m/sec (7 mph), with relatively light updrafts, the spiders spun out multiple ballooning silks averaging 3 meters long, before releasing themselves from a separate silk line anchoring them to the blade of grass from which they launched. A single spider released up to 60 fibers, most of them as thin as 200 nanometers. These fibers differed from a drag line, which has been known as a ballooning line, and were produced by a separate silk gland.

The authors concluded that ballooning spiders actively sense wind characteristics and launch only when the wind speed and updraft are within relatively narrow ranges, increasing the odds of a productive flight. According to the fluid dynamic calculations the authors performed using their wind tunnel data, the spider relies on updrafts that form in the light winds into which they launch, further ensuring a successful flight.

"The pre-flight behaviors we observed suggest that crab spiders are evaluating meteorological conditions before their takeoff," Cho said. "Ballooning is likely not just a random launch into the wind, but one that occurs when conditions most favor a productive journey."

From Science Daily

Astronomers see distant eruption as black hole destroys star

Artist's conception of Tidal Disruption Event (TDE) in Arp 299. Powerful gravity of supermassive black hole shreds passing star, pulling material into disk rotating around the black hole, and launching jet of particles outward. Artist's conception in pullout -- background is Hubble Space Telescope image of Arp 299, a pair of colliding galaxies.

For the first time, astronomers have directly imaged the formation and expansion of a fast-moving jet of material ejected when the powerful gravity of a supermassive black hole ripped apart a star that wandered too close to the cosmic monster.

The scientists tracked the event with radio and infrared telescopes, including the National Science Foundation's Very Long Baseline Array (VLBA), in a pair of colliding galaxies called Arp 299, nearly 150 million light-years from Earth. At the core of one of the galaxies, a black hole 20 million times more massive than the Sun shredded a star more than twice the Sun's mass, setting off a chain of events that revealed important details of the violent encounter.

Only a small number of such stellar deaths, called tidal disruption events, or TDEs, have been detected, although scientists have hypothesized that they may be a more common occurrence. Theorists suggested that material pulled from the doomed star forms a rotating disk around the black hole, emitting intense X-rays and visible light, and also launches jets of material outward from the poles of the disk at nearly the speed of light.

"Never before have we been able to directly observe the formation and evolution of a jet from one of these events," said Miguel Perez-Torres, of the Astrophysical Institute of Andalusia in Granada, Spain.

The first indication came on January 30, 2005, when astronomers using the William Herschel Telescope in the Canary Islands discovered a bright burst of infrared emission coming from the nucleus of one of the colliding galaxies in Arp 299. On July 17, 2005, the VLBA revealed a new, distinct source of radio emission from the same location.

"As time passed, the new object stayed bright at infrared and radio wavelengths, but not in visible light and X-rays," said Seppo Mattila, of the University of Turku in Finland. "The most likely explanation is that thick interstellar gas and dust near the galaxy's center absorbed the X-rays and visible light, then re-radiated it as infrared," he added. The researchers used the Nordic Optical Telescope on the Canary Islands and NASA's Spitzer space telescope to follow the object's infrared emission.

Continued observations with the VLBA, the European VLBI Network (EVN), and other radio telescopes, carried out over nearly a decade, showed the source of radio emission expanding in one direction, just as expected for a jet. The measured expansion indicated that the material in the jet moved at an average of one-fourth the speed of light. Fortunately, the radio waves are not absorbed in the core of the galaxy, but find their way through it to reach the Earth.

These observations used multiple radio-telescope antennas, separated by thousands of miles, to gain the resolving power, or ability to see fine detail, required to detect the expansion of an object so distant. The patient, years-long data collection rewarded the scientists with the evidence of a jet.

Most galaxies have supermassive black holes, containing millions to billions of times the mass of the Sun, at their cores. In a black hole, the mass is so concentrated that its gravitational pull is so strong that not even light can escape. When those supermassive black holes are actively drawing in material from their surroundings, that material forms a rotating disk around the black hole, and superfast jets of particles are launched outward. This is the phenomenon seen in radio galaxies and quasars.

"Much of the time, however, supermassive black holes are not actively devouring anything, so they are in a quiet state," Perez-Torres explained. "Tidal disruption events can provide us with a unique opportunity to advance our understanding of the formation and evolution of jets in the vicinities of these powerful objects," he added.

"Because of the dust that absorbed any visible light, this particular tidal disruption event may be just the tip of the iceberg of what until now has been a hidden population," Mattila said. "By looking for these events with infrared and radio telescopes, we may be able to discover many more, and learn from them," he said.

Such events may have been more common in the distant Universe, so studying them may help scientists understand the environment in which galaxies developed billions of years ago.

The discovery, the scientists said, came as a surprise. The initial infrared burst was discovered as part of a project that sought to detect supernova explosions in such colliding pairs of galaxies. Arp 299 has seen numerous stellar explosions, and has been dubbed a "supernova factory." This new object originally was considered to be a supernova explosion. Only in 2011, six years after discovery, the radio-emitting portion began to show an elongation. Subsequent monitoring showed the expansion growing, confirming that what the scientists are seeing is a jet, not a supernova.

Read more at Science Daily

Distant moons may harbor life

This is an artist's illustration of a potentially habitable exomoon orbiting a giant planet in a distant solar system.

We've all heard about the search for life on other planets, but what about looking on other moons?

In a paper published June 13 in The Astrophysical Journal, researchers at the University of California, Riverside and the University of Southern Queensland have identified more than 100 giant planets that potentially host moons capable of supporting life. Their work will guide the design of future telescopes that can detect these potential moons and look for tell-tale signs of life, called biosignatures, in their atmospheres.

Since the 2009 launch of NASA's Kepler telescope, scientists have identified thousands of planets outside our solar system, which are called exoplanets. A primary goal of the Kepler mission is to identify planets that are in the habitable zones of their stars, meaning it's neither too hot nor too cold for liquid water -- and potentially life -- to exist.

Terrestrial (rocky) planets are prime targets in the quest to find life because some of them might be geologically and atmospherically similar to Earth. Another place to look is the many gas giants identified during the Kepler mission. While not a candidate for life themselves, Jupiter-like planets in the habitable zone may harbor rocky moons, called exomoons, that could sustain life.

"There are currently 175 known moons orbiting the eight planets in our solar system. While most of these moons orbit Saturn and Jupiter, which are outside the Sun's habitable zone, that may not be the case in other solar systems," said Stephen Kane, an associate professor of planetary astrophysics and a member of the UCR's Alternative Earths Astrobiology Center. "Including rocky exomoons in our search for life in space will greatly expand the places we can look."

The researchers identified 121 giant planets that have orbits within the habitable zones of their stars. At more than three times the radii of the Earth, these gaseous planets are less common than terrestrial planets, but each is expected to host several large moons.

Scientists have speculated that exomoons might provide a favorable environment for life, perhaps even better than Earth. That's because they receive energy not only from their star, but also from radiation reflected from their planet. Until now, no exomoons have been confirmed.

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Ocean waves following sea ice loss trigger Antarctic ice shelf collapse

This is ice calving off an ice shelf in the Antarctic.

Storm-driven ocean swells have triggered the catastrophic disintegration of Antarctic ice shelves in recent decades, according to new research published in Nature today.

Lead author Dr Rob Massom, of the Australian Antarctic Division and the Antarctic Climate and Ecosystems Cooperative Research Centre, said that reduced sea ice coverage since the late 1980s led to increased exposure of ice shelves on the Antarctic Peninsula to ocean swells, causing them to flex and break.

"Sea ice acts as a protective buffer to ice shelves, by dampening destructive ocean swells before they reach the ice shelf edge," Dr Massom said.

"But where there is loss of sea ice, storm-generated ocean swells can easily reach the exposed ice shelf, causing the first few kilometres of its outer margin to flex."

"Over time, this flexing enlarges pre-existing fractures until long thin 'sliver' icebergs break away or 'calve' from the shelf front."

"This is like the 'straw that broke the camel's back', triggering the runaway collapse of large areas of ice shelves weakened by pre-existing fracturing and decades of surface flooding."

Study co-author Dr Luke Bennetts, from the University of Adelaide's School of Mathematical Sciences, said the finding highlights the need for sea ice and ocean waves to be included in ice sheet modelling.

This will allow scientists to more accurately forecast the fate of the remaining ice shelves and better predict the contribution of Antarctica's ice sheet to sea level rise, as climate changes.

"The contribution of the Antarctic Ice Sheet is currently the greatest source of uncertainty in projections of global mean sea level rise," Dr Bennetts said.

"Ice shelves fringe about three quarters of the Antarctic coast and they play a crucially important role in moderating sea level rise by buttressing and slowing the movement of glacial ice from the interior of the continent to the ocean."

"While ice shelf disintegration doesn't directly raise sea level because they are already floating, the resulting acceleration of the tributary glaciers behind the ice shelf, into the Southern Ocean, does."

Study co-author, Dr Phil Reid, from the Australian Bureau of Meteorology, said the research identifies a previously under-appreciated link between sea ice loss and ice shelf stability.

"Our study underlines the importance of understanding the mechanisms driving these sea ice trends, particularly in regions where sea ice acts as a protective buffer against ocean processes," he said.

The discovery comes after the international research team, from Australia, the United States and New Zealand, combined satellite images and surface and ocean wave data with modelling, to analyse five major ice shelf disintegrations, between 1995 and 2009.

These included the abrupt and rapid losses of 1600 square kilometres of ice from the Larsen A Ice Shelf in 1995, 3320 square kilometres from the Larsen B Ice Shelf in 2002, and 1450 square kilometres from the Wilkins Ice Shelf in 2009.

Each disintegration event occurred during periods when sea ice was significantly reduced or absent, and when ocean waves were large.

In only a matter of days, the collapse of the Larsen B Ice Shelf in 2002 removed an area of ice shelf that had been in place for the previous 11,500 years. Removal of the ice shelf buttressing effect also caused a 3- to 8-fold increase in the discharge of glacial ice, behind the shelf, into the ocean, in the year following disintegration.

DEFINITIONS OF TERMS USED

An ice sheet forms through the accumulation of snowfall, in this case on the Antarctic continent, when annual snowfall exceeds annual snowmelt. Over thousands of years the layers of snow build up and compact, forming a sheet of ice up to thousands of metres thick and thousands of kilometres across. As the ice thickens, the increasing height of snow and ice causes the ice sheet to flow.

The Antarctic Ice Sheet covers an area of about 14 million square kilometres; by comparison, the area of Australia is about 7.7 million square kilometres, and that of the USA is about 9.8 million square kilometres. It contains more than 90% of the world's ice -- enough to potentially raise global mean sea level by about 57 metres.

Grounded ice is that part of the ice sheet that is land-based and not floating on the ocean. Melting of grounded ice above sea level contributes to sea level rise.

Ice shelves are thick plates of ice, up to several hundred metres thick and fed by tributary glaciers. They are floating seaward extensions of the grounded ice sheet.

Sea ice is ice that originates from the freezing of seawater (unlike ice sheets, glaciers, icebergs and ice shelves). Sea ice typically forms a thin and highly-dynamic veneer up to a few metres thick that covers between about 3 million square kilometres (in winter) to 19-20 million square kilometres (in summer) of the Southern Ocean surrounding Antarctica. By comparison, the areas of the Antarctic continent, Australia and the USA are about 14, 7.7 and 9.8 million square kilometres, respectively.

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Amber fossils provide oldest evidence of frogs in wet, tropical forests

The best-preserved fossil of the group includes the skull, forelimbs, part of a backbone and a partial hind limb of a small, juvenile frog now known as Electrorana limoae. Next to its hindlimb is an unidentified beetle.

About 99 million years ago, a tiny juvenile frog in present-day Myanmar was suddenly trapped in sap with a beetle, perhaps its intended next meal.

Unlucky for the frog, but lucky for science.

An extinct species now named Electrorana limoae, it's one of four fossils that provide the earliest direct evidence of frogs living in wet, tropical forests and are the oldest-known examples of frogs preserved in amber.

"It's almost unheard of to get a fossil frog from this time period that is small, has preservation of small bones and is mostly three-dimensional. This is pretty special," said David Blackburn, study co-author and the associate curator of herpetology at the Florida Museum of Natural History. "But what's most exciting about this animal is its context. These frogs were part of a tropical ecosystem that, in some ways, might not have been that different to what we find today -- minus the dinosaurs."

The findings and species description were published today in Nature's Scientific Reports.

Frogs have been around for at least 200 million years, but glimpsing their early heyday is tough. Often small and lightly built, frogs don't tend to preserve well. The frog fossil record skews toward more robust species from arid, seasonal environments, although the bulk of frog diversity today lives in tropical forests.

"Ask any kid what lives in a rainforest, and frogs are on the list," Blackburn said. "But surprisingly, we have almost nothing from the fossil record to say that's a longstanding association."

The amber deposits of northern Myanmar in Southeast Asia provide a unique record of ancient forest ecosystems, with fossil evidence of mosses, bamboo-like plants, aquatic spiders and velvet worms. The discovery of Electrorana and the other fossils, the first frogs to be recovered from these deposits, help add to our understanding of frogs in the Cretaceous period, showing they have inhabited wet, tropical forests for at least 99 million years.

Frogs in amber are quite rare, with previous examples found in the Dominican Republic and Mexico and dating back only about 40 million and 25 million years, respectively.

Less than an inch long, Electrorana is the most well-preserved of the group. Clearly visible in the amber are the frog's skull, its forelimbs, part of its backbone, a partial hind limb and the unidentified beetle. The other amber fossils contain two hands and an imprint of a frog that likely decayed inside the resin.

But Electrorana raises more questions than it answers, Blackburn said.

Many characteristics herpetologists use to discern details of a frog's life history and determine how it's related to other frogs -- wrist bones, the pelvis, hip bones, the inner ear, the top of the backbone -- are either missing or were not yet fully developed in the juvenile frog.

The existing bones provide clues about Electrorana's possible living relatives, Blackburn said, but the results are puzzling: Species that have similar features include fire-bellied toads and midwife toads -- Eurasian species that live in temperate, not tropical, ecosystems.

Gathering CT skeletal data for both living and extinct frogs, one of Blackburn's long-term projects, could help illuminate ancient evolutionary relationships, possibly clarifying how Electrorana fits into the frog tree of life.

In the meantime, Blackburn nurtures the hope that other frogs in amber will be discovered, making Electrorana more than a one-hit wonder.

Read more at Science Daily

Long suspected theory about the moon holds water

Photograph of lunar meteorite NWA 2727.

A team of Japanese scientists led by Masahiro Kayama of Tohoku University's Frontier Research Institute for Interdisciplinary Sciences, has discovered a mineral known as moganite in a lunar meteorite found in a hot desert in northwest Africa.

This is significant because moganite is a mineral that requires water to form, reinforcing the belief that water exists on the Moon.

"Moganite is a crystal of silicon dioxide and is similar to quartz. It forms on Earth as a precipitate when alkaline water including SiO2 is evaporated under high pressure conditions," says Kayama. "The existence of moganite strongly implies that there is water activity on the Moon."

Kayama and his team analyzed 13 of the lunar meteorites using sophisticated methods to determine chemical compositions and structures of their minerals. These included electron microscopy for high-magnification, and micro-Raman spectroscopy to determine the structure of the minerals based on their atomic vibration.

Moganite was found in only one of those 13 samples, confirming the team's theory that it could not have formed in the African desert. "If terrestrial weathering had produced moganite in the lunar meteorite, there should be moganite present in all the samples that fell to Earth around the same time. But this was not the case," says Kayama.

He adds that part of the moganite had changed into the high-pressure SiO2 minerals stishovite and coesite, which he believes was most likely formed through heavy impact collisions on the Moon.

This is the first time that moganite has been detected in lunar rocks. The researchers say the meteorites probably came from an area of the Moon called Procellarum Terrane, and that the moganite was formed through the process of water evaporation in strong sunlight. Kayama's working theory is that deeper under the lunar surface, protected from the sun, crystals of water ice could be abundant.

In recent years, space missions have found evidence of lunar water or ice concentrated at the poles where sunlight appears at a very narrow angle, leading to pockets of cold traps. This is the first time, however, that the scientists have found evidence of abundant water ice in the lunar subsurface at mid and lower latitudes.

Kayama's team estimates that the accumulation of water in the lunar soil is about 0.6 weight percent. If they are right, future lunar explorers would have easier access to the resource, which would greatly enhance the chances of the Moon hosting human settlement and infrastructure, and supporting a variety of industries within the next few decades.

JAXA, the Japan Aerospace Exploration Agency, is said to be considering two future missions -- a lunar pole landing mission in five years to look for water resources and a sample return mission from the far-side of the Moon in ten years.

Read more at Science Daily

For 100 million years, amber freezes a tableau of tick's worst day ever

This silk-wrapped tick subsequently was entombed in amber that may have dripped from a nearby tree. Its fate, literally, was sealed.

One day in Myanmar during the Cretaceous period, a tick managed to ensnare itself in a spider web. Realizing its predicament, the tick struggled to get free. But the spider that built the web was having none of it. The spider popped over to the doomed tick and quickly wrapped it up in silk, immobilizing it for eternity.

We know the outline of this primordial worst-day-ever because the silk-wrapped tick subsequently was entombed in amber that may have dripped from a nearby tree. Its fate, literally, was sealed.

Fast-forward 100 million years or so, and that same tick was discovered by a German collector named Patrick Müller who was searching in Myanmar for Burmese amber pieces of scientific value. He passed the discovery on to scientist Jason Dunlop in at the Museum für Naturkunde in Berlin, who realized it was an important specimen.

"Dunlop brought in Lidia Chitimia-Dobler, who is a tick expert at the Bundeswehr Institute of Microbiology, and myself because we've worked together on Burmese amber things," said Paul Selden, distinguished professor of geology at the University of Kansas and director of the Paleontological Institute at the KU Biodiversity Institute and Natural History Museum.

Together with microscopy expert Timo Pfeffer, the team has just published a description of the tick in the journal Cretaceous Research.

"It's a show of behavior, really," said Selden. "Ticks already are known from the Burmese amber -- but it's unusual to find one wrapped in spider silk. We're not sure if the spider wrapped it in order to eat it later or if it was to get it out of the way and stop it from wriggling and destroying its web. That's something spiders do."

Selden said ticks are seldom found in Burmese amber, though the few that have been discovered were proved to be among the oldest tick specimens known to science.

"They're rare because ticks don't crawl around on tree trunks," he said. "Amber is tree resin, so it tends to capture things that crawl around on bark or the base of the tree. But ticks tend to be on long grass or bushes, waiting for passing animals to brush up against them, though some of them can be on birds or squirrels, or maybe a little crawling dinosaur."

The researchers took pains to ensure the ancient tick was indeed bound in spider silk, rather than fungal filaments that sometimes can grow around a dead tick.

"We think this was spider silk because of the angles that the threads make," Selden said. "Also, in the paper, we show a picture of a tick that started to decay -- and the fungus on that tick grows from its orifices -- from the inside to the outside. Whereas these threads are wrapped around externally and not concentrated at the orifices."

According to the research team, this is the first time this kind of interaction between ticks and spiders has been documented in the fossil record. Even though ticks aren't a typical staple of spider diets, spiders can occasionally prey on ticks in modern ecosystems.

"Just last year, I was on a field trip in Estonia and took a photo of a Steatoda spider wrapping up a red spider mite," said Selden. "That was serendipitous."

The KU researcher and his colleagues are unable to determine the species of spider that wrapped the tick because families of spiders known to catch ticks today lack a convincing Mesozoic fossil record. While it's difficult to identify the producer of the fossil silk with any certainty, it's safe to assume the spider's behavior was characteristic of most known spiders in the forest today.

"We don't know what kind of spider this was," Selden said. "A spider's web is stretched between twigs to catch prey that flies or bumps or crawls into it. As prey gets stuck, it adheres to the web and starts to struggle. Maybe some things can escape after some struggle, so the spider rushes to it out from hiding and wraps it in swaths of silk to immobilize it, to stop it escaping or destroying the web. This prevents prey from hitting back -- stinging or biting -- once it's wrapped in silk it can't move, and then the spider can bite it and inject gastric fluid to eat it or venom to subdue it as well."

The amber that preserved the small drama occurring between the spider and tick from 100 million years ago offers a thought-provoking peek into the natural past, according to Selden.

Read more at Science Daily

The true power of the solar wind

Particles from the sun are constantly hitting the surface of mercury.

The planets and moons of our solar system are continuously being bombarded by particles hurled away from the sun. On Earth this has hardly any effect, apart from the fascinating northern lights, because the dense atmosphere and the magnetic field of the Earth protect us from these solar wind particles. But on the Moon or on Mercury things are different: There, the uppermost layer of rock is gradually eroded by the impact of sun particles.

New results of the TU Wien now show that previous models of this process are incomplete. The effects of solar wind bombardment are in some cases much more drastic than previously thought. These findings are important for the ESA mission BepiColombo, Europe's first Mercury mission. The results have now been published in the planetology journal Icarus.

An Exosphere of Shattered Rock

"The solar wind consists of charged particles -- mainly hydrogen and helium ions, but heavier atoms up to iron also play a role," explains Prof. Friedrich Aumayr from the Institute of Applied Physics at TU Wien. These particles hit the surface rocks at a speed of 400 to 800 km per second and the impact can eject numerous other atoms. These particles can rise high before they fall back to the surface, creating an "exosphere" around the Moon or Mercury -- an extremely thin atmosphere of atoms sputtered from the surface rocks by solar wind bombardment.

This exosphere is of great interest for space research because its composition allows scientists to deduce the chemical composition of the rock surface -- and it is much easier to analyse the exosphere than to land a spacecraft on the surface. In October 2018, ESA will send the BepiColombo probe to Mercury, which is to obtain information about the geological and chemical properties of Mercury from the composition of the exosphere.

Charge matters

However, this requires a precise understanding of the effects of the solar wind on the rock surfaces, and this is precisely where decisive gaps in knowledge still exist. Therefore, the TU Wien investigated the effect of ion bombardment on wollastonite, a typical moon rock. "Up to now it was assumed that the kinetic energy of the fast particles is primarily responsible for atomization of the rock surface," says Paul Szabo, PhD student in Friedrich Aumayr's team and first author of the current publication. "But this is only half the truth: we were able to show that the high electrical charge of the particles plays a decisive role. It is the reason that the particles on the surface can do much more damage than previously thought."

When the particles of the solar wind are multiply charged, i.e. when they lack several electrons, they carry a large amount of energy which is released in a flash on impact. "If this is not taken into account, the effects of the solar wind on various rocks are misjudged," says Paul Szabo. Therefore, it is not possible to draw exact conclusions about the surface rocks with an incorrect model from the composition of the exosphere.

Read more at Science Daily

David vs Goliath: How a small molecule can defeat asthma attacks

Chemical structure of small molecule PM-43I.

An invisible particle enters your lungs. The next thing you know breathing becomes difficult. You are having as asthma attack. Asthma is one of the most common and difficult to endure chronic conditions. About 30 million Americans experience asthma attacks and 3 million have a severe, therapy-resistant form of the disease. In some cases, the condition can be fatal.

"Despite the prevalence of asthma around the world, therapy for this condition has not significantly changed, with a few exceptions, in the last 70 to 80 years," said Dr. David Corry, professor of medicine-immunology, allergy and rheumatology at Baylor College of Medicine. "For the most part, we are still treating the symptoms of the disease, not the underlying causes. In this work we present a novel new way to target a pathway we think is at the core of this allergic condition."

Current treatments attempt to relieve typical asthma symptoms, namely the constriction of the airways so patients can breathe easily. Treatments may also include steroids to shut down the inflammation that scientists have thought for many decades underlies airway constriction. Inflammation of the airway leads to shortness of breath, and that can make people panic and head to the emergency room. Corry's laboratory has been studying asthma for about 20 years. One of their interests is to better understand the molecular pathways that drive airway constriction.

The makings of an asthma attack

An asthma attack is anything but a simple event. It begins when environmental factors -- allergens -- enter the lungs and activate a chain reaction of molecular pathways that set off the development of the disease. Allergens activate immune cells, recruiting them to the lungs and leading some of them to produce a strong IgE antibody response and others to secrete immune mediators called cytokines. Cytokines IL-4 and IL-13 in particular are required for asthma to happen. These cytokines activate another molecule, transcription factor STAT6, that drives the expression of a number of genes ultimately leading to the exaggerated contraction of the airways that causes the much feared shortness of breath.

Mice that are genetically engineered to lack STAT6, also lack the responses triggered by the IL-4/IL-13/STAT6 interaction and are completely resistant to asthma attacks.

"STAT6 is at the epicenter of the immune responses that mediate asthma, so we looked for a means to block STAT6 activation," said Dr. J. Morgan Knight, post-doctoral fellow in the Corry lab. "To activate STAT6, IL-4 and IL-13 bind to their corresponding receptors on immune cells. These receptors share a critical subunit called IL4R-alpha that activates STAT6. However, additional research from our lab has shown that completely different receptors can also activate STAT6. So, we focused our efforts on developing a small-molecule that would bind to and inhibit STAT6 activity directly."

David defeats Goliath

Such efforts are no small feat. Corry, Knight and their colleagues had to design a small molecule capable of specifically targeting STAT6, which is inside the cells of the lungs, without also triggering unwanted side effects.

"After years of work, we succeeded," said Knight. "We chemically synthesized a small molecule called PM-43I that can inhibit STAT6-dependent allergic airway disease in mice. Moreover, PM-43I reversed preexisting allergic airway disease in mice with a minimum dose of 0.25 ?g/kg. Importantly, PM-43I was efficiently cleared through the kidneys and had no long-term toxicity. We concluded that PM-43I represents the first of a class of small molecules that may be suitable for further clinical development as a therapeutic drug against asthma."

One major advantage of developing PM-43I as an asthma drug that specifically targets a path that is required for the disease is that people probably would not need steroid treatments at the same time, which is what current asthma medications sometimes are paired with. Steroids shut down inflammation, but also other immune responses, such as the body's ability to fight an infection. The researchers' work shows that in fact treatment with their small molecule can control the asthma without impairing the mice's ability to fight pathogens. "This is important because there is a higher incidence of pneumonia in people with asthma, presumably because of the steroids they take," Corry said. "Steroids drive down all the immune system, but our small molecule specifically targets the pathway that leads to asthma, uncompromising the other pathways that allow the body to fight disease. We anticipate that patients treated with our small molecule would not need steroids as our treatment alone would be able to control the asthma. Consequently, these patients' ability to fight infections would not be affected."

Although other groups have developed monoclonal antibodies that effectively target IL4R-alpha and inhibit STAT6-dependent allergic disease, and these antibodies are close to be approved by the Food and Drug Administration, the researchers think that their small-molecule approach offers unique advantages when compared with the much larger antibodies.

"We think that our small molecule offers the option of being easier to make and less expensive than the monoclonal antibody approach," Corry said. "Also, people might develop sensitivity or tolerance to the monoclonal antibody treatment. On the other hand, our compound is a chemically synthesized very small molecule, so we think there is a smaller chance that people would develop a sensitivity to it. In addition, we think that our small molecule is better able to block STAT6 than the antibodies."

"I am most excited about the potential to really affect disease," Knight said. "I think that if our small molecule approach can help the lung resolve the chronic inflammation that is driving the asthma attacks, it might be possible to also resolve their condition."

Read more at Science Dialy

Researchers map brain of blind patient who can see motion

Researchers at the Brain and Mind Institute at Western University in London, Canada, have confirmed and detailed a rare case of a blind woman able to see objects -- but only if in motion. She can catch a ball rolled or thrown to her.

Neuroscientists at Western University's Brain and Mind Institute, have confirmed and detailed a rare case of a blind woman able to see objects -- but only if in motion.

A team led by neuropsychologist Jody Culham has conducted the most extensive analysis and brain mapping to date of a blind patient, to help understand the remarkable vision of a 48-year-old Scottish woman, Milena Canning.

Canning lost her sight 18 years ago after a respiratory infection and series of strokes. Months after emerging blind from an eight-week coma, she was surprised to see the glint of a sparkly gift bag, like a flash of green lightning.

Then she began to perceive, sporadically, other moving things: her daughter's ponytail bobbing when she walked, but not her daughter's face; rain dripping down a window, but nothing beyond the glass; and water swirling down a drain, but not a tub already full with water.

Glaswegian ophthalmologist Gordon Dutton referred Canning to the Brain and Mind Institute in London, Canada, where tests by Culham's team included functional Magnetic Resonance Imaging (fMRI) to examine the real-time structure and workings of her brain.

They determined Canning has a rare phenomenon called Riddoch syndrome -- in which a blind person can consciously see an object if moving but not if stationary.

"She is missing a piece of brain tissue about the size of an apple at the back of her brain -- almost her entire occipital lobes, which process vision," says Culham, a professor in the Department of Psychology and Graduate Program in Neuroscience.

"In Milena's case, we think the 'super-highway' for the visual system reached a dead end. But rather than shutting down her whole visual system, she developed some 'back roads' that could bypass the superhighway to bring some vision -- especially motion -- to other parts of the brain."

In essence, Canning's brain is taking unexpected, unconventional detours around damaged pathways.

During the study, Canning was able to recognize the motion, direction, size and speed of balls rolled towards her; and to command her hand to open, intercept and grab them at exactly the right time. She could navigate around chairs.

Yet she inconsistently identified an object's colour, and was able only half the time to detect whether someone's hand in front of her showed thumb-up or thumb-down.

"This work may be the richest characterization ever conducted of a single patient's visual system," says Culham. "She has shown this very profound recovery of vision, based on her perception of motion."

The research shows the remarkable plasticity of the human brain in finding work-arounds after catastrophic injuries. And it suggests conventional definitions of 'sight' and 'blindness' are fuzzier than previously believed.

"Patients like Milena give us a sense of what is possible and, even more importantly, they give us a sense of what visual and cognitive functions go together," Culham says.

For Canning, the research at BMI helps explain more about what she perceives and how her brain is continuing to change. She is able to navigate around chairs, can see a bright-shirted soccer goalie and can see steam rising from her morning cup of coffee, for example.

Read more at Science Daily

Trio of infant planets discovered around newborn star

Artist impression of protoplanets forming around a young star.

Two independent teams of astronomers have uncovered convincing evidence that three young planets are in orbit around an infant star known as HD 163296. Using a new planet-finding strategy, the astronomers identified three discrete disturbances in a young star's gas-filled disk: the strongest evidence yet that newly formed planets are in orbit there.

Over the past several years, the Atacama Large Millimeter/submillimeter Array (ALMA) has transformed our understanding of protoplanetary disks -- the gas- and dust-filled planet factories that encircle young stars. The rings and gaps in these disks provide intriguing circumstantial evidence for the presence of planets. Other phenomena, however, could account for these tantalizing features.

Using a new planet-hunting technique that identifies unusual patterns in the flow of gas within a protoplanetary disk, two teams of astronomers have confirmed the distinct, telltale hallmarks of newly formed planets orbiting an infant star in our galaxy. These results are presented in a pair of papers appearing in the Astrophysical Journal Letters.

"We looked at the localized, small-scale motion of gas in a star's protoplanetary disk. This entirely new approach could uncover some of the youngest planets in our galaxy, all thanks to the high-resolution images coming from ALMA," said Richard Teague, an astronomer at the University of Michigan and principal author on one of the papers.

To make their respective discoveries, each team analyzed the data from various ALMA observations of the young star HD 163296. HD 163296 is about 4 million years old and located about 330 light-years from Earth in the direction of the constellation Sagittarius.

Rather than focusing on the dust within the disk, which was clearly imaged in earlier ALMA observation, the astronomers instead studied the distribution and motion of carbon monoxide (CO) gas throughout the disk. Molecules of CO naturally emit a very distinctive millimeter-wavelength light that ALMA can observe. Subtle changes in the wavelength of this light due to the Doppler effect provide a glimpse into the kinematics -- or motion -- of the gas in the disk.

If there were no planets, gas would move around a star in a very simple, predictable pattern known as Keplerian rotation.

"It would take a relatively massive object, like a planet, to create localized disturbances in this otherwise orderly motion," said Christophe Pinte of Monash University in Australia and lead author on one of the two papers. "Our new technique applies this principle to help us understand how planetary systems form."

The team led by Teague identified two distinctive planet-like patterns in the disk, one at approximately 80 astronomical units (AU) from the star and the other at 140 AU. (An astronomical unit is the average distance from the Earth to the Sun, or about 150 million kilometers.) The other team, led by Pinte, identified the third at about 260 AU from the star. The astronomers calculate that all three planets are similar in mass to Jupiter.

The two teams used variations on the same technique, which looked at anomalies in the flow of the gas -- as seen in the shifting wavelengths of the CO emission -- that would indicate it was interacting with a massive object.

Teague and his team measured variations in the gas's velocity. This revealed the impact of multiple planets on the gas motion nearer to the star.

Pinte and his team more directly measured the gas's actual velocity, which is better for studying the outer portion of the disk and can more accurately pinpoint the location of a potential planet.

Detecting protoplanets

"Though thousands of exoplanets have been discovered in the last few decades, detecting protoplanets is at the frontier of science," said Pinte. The techniques currently used for finding exoplanets in fully formed planetary systems -- such as measuring the wobble of a star or how a transiting planet dims starlight -- don't lend themselves to detecting protoplanets.

ALMA's stunning images of HD 163296 and other similar systems have revealed intriguing patterns of concentric rings and gaps within protoplanetary disks. These gaps may be evidence that protoplanets are plowing the dust and gas away from their orbits, incorporating some of it into their own atmospheres. A previous study of this particular star's disk shows that the dust and gas gaps overlap, suggesting that at least two planets have formed there.

These initial observations, however, merely provided circumstantial evidence and could not be used to accurately estimate the masses of the planets, noted Teague. "Since other mechanisms can also produce ringed gaps in a protoplanetary disk, it is impossible to say conclusively that planets are there by merely looking at the overall structure of the disk," he said.

Latest innovation

The key to a more conclusive detection, note the astronomers, lies in teasing out the fine-scale velocity signatures from the carbon monoxide gas.

"Although dust plays an important role in planet formation and provides invaluable information, gas accounts for 99 percent of a protoplanetary disks' mass," said coauthor Jaehan Bae of the Carnegie Institute for Science. "It is therefore crucial to study kinematics of the gas."

Light that a gas emits from a protoplanetary disk changes its wavelengths depending on the gas's relative motion to Earth due to the Doppler effect. "This is analogous to the Doppler technique used for finding fully formed planets," said coauthor Dan Foreman-Mackey of the Flatiron Institute. "Though rather than looking at the changes in wavelength from the wobble of the star, we're diving deep into the disk to see how the fine-scale changes are happening."

ALMA's fantastic resolution enabled the researchers to measure carbon monoxide's velocity patterns throughout the disk.

"The precision is mind boggling," said coauthor Til Birnstiel of the University Observatory of Munich. In a system where gas rotates at about 5 kilometers per second, ALMA detected velocity changes as small as a few meters per second. "This allows us to find very small deviations from the expected normal rotation in a disk," Teague said. Planets change the density of the gas near their orbits, which changes the gas's pressure, inducing these corresponding changes in velocity.

"We compared the observations with computer models to show that the observed flows fit beautifully with predictions for the flow pattern around a newborn planet a few times the mass of Jupiter," said coauthor Daniel Price of Monash University.

This new technique allows astronomers to more precisely estimate protoplanetary masses and is less likely to produce false positives. "We are now bringing ALMA front and center into the realm of planet detection," said coauthor Ted Bergin of the University of Michigan.

"Oftentimes in science, ideas turn out not to work or assumptions turn out to be wrong. This is one of the cases where the results are much more exciting than what I had imagined," Birnstiel said.

"These studies will also help us to understand how planets like those in our solar system were born," said coauthor Francois Menard from Grenoble University in France.

Read more at Science Daily

New method can quickly and accurately detect infections

New electrochemical method developed at UTSA to test the presence of a bacterial infection is faster and more accurate than methods currently on the market.

A new study by Waldemar Gorski, professor and chair of the UTSA Department of Chemistry, and Stanton McHardy, associate professor of research in chemistry and director of the UTSA Center for Innovative Drug Discovery, describes a method that could show quickly and accurately whether a person has been infected with harmful bacteria or other pathogens. Additionally, this new method shows the exact severity of infection in a person.

The most common method of testing for infection in medical facilities is currently a strip that turns a certain color when infected fluids come into contact with it.

"The problem with this method is that it's imprecise," Gorski said. "The human eye is forced to judge the level of infection based on the hue and deepness of a color. It's difficult to make an accurate call based on that." Furthermore, roughly a third of samples cannot be tested because the fluids contain blood or are too opaque.

Other methods include microbiology or examining body fluid samples under a microscope and counting white blood cells, also known as leukocytes, which are an indicator of an infection. However, these can be slow processes and require more highly trained personnel.

Gorski, seeing a need for an easier and more rapid method of testing for infection, resolved to test an electrochemical approach, and sought out McHardy, a medicinal chemist. Together, they created molecules that bind to leukocyte enzymes and produce an electrical current to signal the presence of an infection.

Their new molecules are housed on a testing strip. After being contacted with infected bodily fluids, the strip is connected to a computer monitor that displays a clear range of electrochemical responses demonstrating the severity of an infection.

"The signs and symptoms people demonstrate aren't always reflective of the level of the infection they have," McHardy said. "This device could very easily show just how serious an infection is and make diagnosis a much quicker process, possibly preventing a more serious illness."

Gorski believes the method could be especially useful to people who have just undergone surgery, as it could determine definitively whether they have an infection from the procedure before it worsens.

Read more at Science Daily

Making mistakes while studying actually helps you learn better

When learning something new, there are instances where trial and error helps rather than hinders, according to recent findings by Baycrest researchers.

Contrary to popular belief, when a person makes a mistake while learning, it improves their memory for the right information, but only if the error is close to the correct answer, according to a study published in the journal, Memory.

"Our research found evidence that mistakes that are a 'near miss' can help a person learn the information better than if no errors were made at all," says Dr. Nicole Anderson, senior author on the paper and senior scientist at Baycrest's Rotman Research Institute. "These types of errors can serve as stepping stones to remembering the right answer. But if the error made is a wild guess and out in left field, then a person does not learn the correct information as easily."

These findings could help with improving education for not only younger adults, but also late-life learners.

In one of the studies reported in the paper, researchers recruited 32 young adults with no Spanish background to guess the English definition of certain Spanish words. The Spanish words selected either resembled an English word with a similar meaning (such as careera, which means degree) or the word looked like an English word, but meant something different (such as carpeta, which resembles carpet, but means folder).

Participants were shown the Spanish words and asked to guess its meaning. Then, they were briefly shown the correct translation, before being shown another Spanish word. After repeating this process with 16 Spanish words, participants had a short break before their memory for the translations was tested.

Researchers found that people were better able to remember the correct translations for Spanish words that were similar to the English word. They had greater difficulty recalling the meaning for words that looked misleading.

"Based on these findings, someone studying for an exam should only take practice quizzes after reviewing the material," says Dr. Anderson, who is also an associate professor of psychology and psychiatry at the University of Toronto. "If a person takes a practice test and is unfamiliar with the content, they risk making guesses that are nowhere near the right answer. This could make it harder for them to learn the correct information later."

Even if a person makes a mistake while testing themselves, as long as their error is close to the right answer, they're more likely to remember the right information, adds Dr. Anderson.

Read more at Science Daily

Volcanic activity, declining ocean oxygen triggered mass extinction of ancient organisms

Postdoctoral Fellow Theodore Them (left, holding an extinct fossil sample) and Assistant Professor Jeremy Owens (right, holding a rock core sample). The researchers used the samples to study the global record of oxygenation.

Global climate change, fueled by skyrocketing levels of atmospheric carbon dioxide, is siphoning oxygen from today's oceans at an alarming pace -- so fast that scientists aren't entirely sure how the planet will respond.

Their only hint? Look to the past.

In a study to be published this week in the journal Proceedings of the National Academy of Sciences, researchers from Florida State University did just that -- and what they found brings into stark relief the disastrous effects a deoxygenated ocean could have on marine life.

Millions of years ago, scientists discovered, powerful volcanoes pumped Earth's atmosphere full of carbon dioxide, draining the oceans of oxygen and driving a mass extinction of marine organisms.

"We want to understand how volcanism, which can be related to modern anthropogenic carbon dioxide release, manifests itself in ocean chemistry and extinction events," said study co-author Jeremy Owens, an assistant professor in FSU's Department of Earth, Ocean and Atmospheric Science. "Could this be a precursor to what we're seeing today with oxygen loss in our oceans? Will we experience something as catastrophic as this mass extinction event?"

For this study, an international team of scientists set out to better understand today's oxygen-deprived oceans by investigating the Toarcian Oceanic Anoxic Event (T-OAE), an interval of global oceanic deoxygenation characterized by a mass extinction of marine organisms that occurred in the Early Jurassic Period.

"We wanted to reconstruct Early Jurassic ocean oxygen levels to better understand the mass extinction and the T-OAE," said Theodore Them, a postdoctoral researcher at FSU who led the study. "We used to think of ocean temperature and acidification as a one-two punch, but more recently we've learned this third variable, oxygen change, is equally important."

By analyzing the thallium isotope composition of ancient rocks from North America and Europe, the team found that ocean oxygen began to deplete well before the defined time interval traditionally ascribed to the T-OAE.

That initial deoxygenation, researchers say, was precipitated by massive episodes of volcanic activity -- a process not altogether unlike the industrial emission of carbon dioxide we're familiar with today.

"Over the past 50 years, we've seen that a significant amount of oxygen has been lost from our modern oceans," Them said. "While the timescales are different, past volcanism and carbon dioxide increases could very well be an analog for present events."

When the atmosphere is suffused with carbon dioxide, global temperatures climb, triggering a cascade of hydrological, biological and chemical events that conspire to sap the oceans of oxygen.

Scientists have found evidence that several hundred thousand years before the T-OAE, volcanoes flooded Earth's atmosphere with carbon dioxide, helping to set in motion the sequence of events that would ultimately result in oceanic deoxygenation and widespread marine life extinction.

While researchers have long surmised a link between volcanism, loss of oxygen and mass extinction, this study provides the first conclusive data.

"As a community, we've suggested that sediments deposited during the T-OAE were indicative of widespread oxygen loss in the oceans, but we've never had the data until now," Them said.

Prehistorical examples of carbon dioxide deluges and suffocating oceanic deoxygenation provide a lesson in how Earth systems respond to a variable climate.

This analysis of the T-OAE, and the onset of deoxygenation that preceded it, is another in a lineage of reports that presage a bleak future for oceans with diminishing levels of oxygen.

"It's extremely important to study these past events," Them said. "It seems that no matter what event we observe in Earth's history, when we see carbon dioxide concentrations increasing rapidly, the result tends to be very similar: a major or mass extinction event. This is another situation where we can unequivocally link widespread oceanic deoxygenation to a mass extinction."

Steps can still be taken to curb oxygen loss in the modern oceans. For example, conserving important wetlands and estuaries -- along with other environments that absorb and store large amounts of carbon dioxide -- could help to blunt the effects of harmful industrial emissions.

But should our oceans' oxygen contents continue to decline at their current rates, future marine organisms could be doomed to the same fate that befell their Jurassic ancestors.

"If you're an oxygen-consuming organism, you don't want to see major changes in marine oxygen levels," Them said. "You either adapt or go extinct."

Read more at Science Daily

Experiments trace interstellar dust back to solar system's formation

This cometary-type interplanetary dust particle was collected by a NASA stratospheric aircraft. Its porous aggregate structure is evident in this scanning electron microscope image.

Note: This press release was adapted from an original release by the University of Hawaii at Manoa in Honolulu.

Experiments conducted at the Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) helped to confirm that samples of interplanetary particles -- collected from Earth's upper atmosphere and believed to originate from comets -- contain dust leftover from the initial formation of the solar system.

An international team, led by Hope Ishii, a researcher at the University of Hawaii at Manoa (UH Manoa), studied the particles' chemical composition using infrared light at Berkeley Lab's Advanced Light Source (ALS). Scientists also explored their nanoscale chemical makeup using electron microscopes at the Lab's Molecular Foundry, which specializes in nanoscale R&D, and at the University of Hawaii's Advanced Electron Microscopy Center.

The study was published online June 11 in the journal Proceedings of the National Academy of Sciences.

The initial solids from which the solar system formed consisted almost entirely of carbon, ices, and disordered (amorphous) silicate, the team concluded. This dust was mostly destroyed and reworked by processes that led to the formation of planets. Surviving samples of pre-solar dust are most likely to be preserved in comets -- small, cold bodies that formed in the outer solar nebula.

In a relatively obscure class of these interplanetary dust particles believed to originate from comets, there are tiny glassy grains called GEMS (glass embedded with metal and sulfides) that are typically only tens to hundreds of nanometers in diameter, or less than a hundredth of the thickness of a human hair. Researchers embedded the sample grains in an epoxy that was cut into thin slices for the various experiments.

Using transmission electron microscopy at the Molecular Foundry, the research team made maps of the element distributions and discovered that these glassy grains are made up of subgrains that aggregated together in a different environment prior to the formation of the comet.

The nanoscale GEMS subgrains are bound together by dense organic carbon in clusters comprising the GEMS grains. These GEMS grains were later glued together with other components of the cometary dust by a distinct, lower-density organic carbon matrix.

The types of carbon that rim the subgrains and that form the matrix in these particles decompose with even weak heating, suggesting that the GEMS could not have formed in the hot inner solar nebula, and instead formed in a cold, radiation-rich environment, such as the outer solar nebula or pre-solar molecular cloud.

Jim Ciston, a staff scientist at the Molecular Foundry, said the particle-mapping process of the microscopy techniques provided key clues to their origins. "The presence of specific types of organic carbon in both the inner and outer regions of the particles suggests the formation process occurred entirely at low temperatures," he said.

"Therefore, these interplanetary dust particles survived from the time before formation of the planetary bodies in the solar system, and provide insight into the chemistry of those ancient building blocks."

He also noted that the "sticky" organics that covered the particles may be a clue to how these nanoscale particles could gather into larger bodies without the need for extreme heat and melting.

Ishii, who is based at the UH Manoa's Hawaii Institute of Geophysics and Planetology, said, "Our observations suggest that these exotic grains represent surviving pre-solar interstellar dust that formed the very building blocks of planets and stars. If we have at our fingertips the starting materials of planet formation from 4.6 billion years ago, that is thrilling and makes possible a deeper understanding of the processes that formed and have since altered them."

Hans Bechtel, a research scientist in the Scientific Support Group at Berkeley Lab's ALS, said that the research team also employed infrared spectroscopy at the ALS to confirm the presence of organic carbon and identify the coupling of carbon with nitrogen and oxygen, which corroborated the electron microscopy measurements.

The ALS measurements provided micron-scale (millionths of a meter) resolution that gave an average of measurements for entire samples, while the Molecular Foundry's measurements provided nanometer-scale (billionths of a meter) resolution that allowed scientists to explore tiny portions of individual grains.

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Genome-editing tool could increase cancer risk

Therapeutic use of gene editing with the so-called CRISPR-Cas9 technique may inadvertently increase the risk of cancer, according to a new study from Karolinska Institutet, Sweden, and the University of Helsinki, Finland, published in Nature Medicine. Researchers say that more studies are required in order to guarantee the safety of these 'molecular scissors' for gene-editing therapies.

CRISPR-Cas9 is a molecular machine first discovered in bacteria that can be programmed to go to an exact place in the genome, where it cuts the DNA. These precise 'molecular scissors' can be used to correct faulty pieces of DNA and are currently being used in clinical trials for cancer immunotherapy in the US and China. New trials are expected to be launched soon so as to treat inherited blood disorders such as sickle cell anemia.

Two independent articles published in the journal Nature Medicine now report that therapeutic application of the genome-editing tool may, in fact, increase the risk of cancer. In one of the studies, scientists from Karolinska Institutet and the University of Helsinki report that use of CRISPR-Cas9 in human cells in a laboratory setting can activate a protein known as p53, which acts as a cell's 'first aid kit' for DNA breaks. Once active, p53 reduces the efficiency of CRISPR-Cas9 gene editing. Thus, cells that do not have p53 or are unable to activate it show better gene editing. Unfortunately, however, lack of p53 is also known to contribute to making cells grow uncontrollably and become cancerous.

"By picking cells that have successfully repaired the damaged gene we intended to fix, we might inadvertently also pick cells without functional p53," says Dr Emma Haapaniemi, researcher at the Department of Medicine at Karolinska Institutet in Huddinge and co-first author of the study. "If transplanted into a patient, as in gene therapy for inherited diseases, such cells could give rise to cancer, raising concerns for the safety of CRISPR-based gene therapies."

"CRISPR-Cas9 is a powerful tool with staggering therapeutic potential," adds Dr Bernhard Schmierer, researcher at the Department of Medical Biochemistry and Biophysics at Karolinska Institutet, and Head of the High Throughput Genome Engineering Facility of Science for Life Laboratory (SciLifeLab), who co-supervised the study. "Like all medical treatments however, CRISPR-Cas9-based therapies might have side effects, which the patients and caregivers should be aware of. Our study suggests that future work on the mechanisms that trigger p53 in response to CRISPR-Cas9 will be critical in improving the safety of CRISPR-Cas9-based therapies."

From Science Daily

Discovery of the oldest mammal in Brazil pays tribute to David Bowie

Brasilestes stardusti existed more than 70 million years ago in what is now São Paulo State. Its description is based on a fossilized tooth.

Brasilestes stardusti is the name given to the oldest known mammal found in Brazil. It lived in what is now the northwest of São Paulo State at the end of the Mesozoic Era between 87 million and 70 million years ago. It is the only Brazilian mammal known to have coexisted with the dinosaurs.

The discovery of Brasilestes was announced on May 30, 2018, by a team led by Max Langer, a professor at the University of São Paulo's Ribeirão Preto School of Philosophy, Science & Letters (FFCLRP-USP). Langer's team included colleagues at the Federal University of Goiás and the University of Campinas in Brazil, La Plata Museum in Argentina, and the Massachusetts Institute of Technology (MIT) in the US.

Physically speaking, Brasilestes consists of a fossilized premolar tooth with a maximum crown length of 3.5 mm. "The tooth is small and incomplete: the roots are missing," said paleontologist Mariela Cordeiro de Castro, first author of the paper recently published in Royal Society Open Science.

"Small but not tiny," Castro continued. "Although it's only 3.5 mm, the Brasilestes tooth is three times bigger than all known Mesozoic mammal teeth. In the age of the dinosaurs, most mammals were the size of mice. Brasilestes was far larger, about the size of an opossum."

The name of the new species pays tribute to British rock star David Bowie, who died in January 2016, a month after the fossil was found. Brasilestes stardusti alludes to Ziggy Stardust, an extraterrestrial character created by Bowie for a 1972 album.

The research was supported by the São Paulo Research Foundation -- FAPESP as part of the thematic project "The origin and rise of dinosaurs in Gondwana (late Triassic-early Jurassic)" , for which Langer is principal investigator.

The fossilized tooth was found in a rocky outcrop of the Adamantina Formation in General Salgado, São Paulo State. The rocks are in a field on a ranch called Fazenda Buriti.

"We were visiting Mesozoic outcrops when Júlio Marsola [another member of the team], keen-sighted as a lynx, spotted a small tooth sticking up out of a rock," said Castro, a professor at the Federal University of Goiás (UFG).

"The General Salgado deposits are well-known. Several Mesozoic crocodiles have come from them. The particular outcrop where I found Brasilestes is interesting, with dozens of fragments of Mesozoic crocodile eggshells. I bent down to look more closely at a small part of the outcrop to see if there were any eggshells and spotted the tooth. If it had stayed out in the open like that for a few more days, the rain would have swept it away.

"When I noticed what appeared to resemble the base of the tooth's two roots [the roots themselves have broken off], I thought it must be a mammal. Laboratory analysis gave us the certainty that it is indeed from a mammal."

A placental mammal in the Botucatu Desert

While a mere 3.5 mm tooth, especially an incomplete one, may seem insufficient to describe a new species of mammal, in actual, fact extinct mammals are frequently described on the basis of a single fossilized tooth.

This is because teeth are the most durable part of the mammalian skeleton. After all, they have to withstand the wear and tear of chewing for an entire lifetime. In contrast, many fish species and reptiles, for example, grow new teeth continually throughout their lives. Indeed, mammalian teeth are often the only skeletal remains that stay intact long enough to become fossilized.

The fact that a single premolar is all that is left of Brasilestes and that it is incomplete prevented the researchers from distinguishing with absolute confidence the group of mammals to which the species belonged. They know the tooth belonged to a therian, a member of a large subclass of Mammalia that includes marsupials and placentals.

Although there is not enough evidence to support the inclusion of Brasilestes in either infraclass, the researchers believe (but cannot categorically conclude) it was a placental mammal. If so, the fossil is unique.

Today, there are three major groups of mammals, namely, placentals, marsupials and monotremes. All three evolved during the Mesozoic Era. At that time, however, they were by no means the only groups of mammals. There were also multituberculates, which were common in the northern hemisphere, as well as groups typical of the southern hemisphere such as meridiolestids and gondwanatherians -- named for Gondwana, the ancient southern supercontinent that gave rise to Africa, South America, Australia, Antarctica, and India.

The first Mesozoic mammal fossils were found in Argentinian Patagonia in the early 1980s, and some 30 species are now known. Until the Brasilestes announcement, these were the only ones found in South America. None remotely resembles the little tooth found in Brazil.

"When I showed the Brasilestes fossil to Edgardo Ortiz-Jaureguizar, a paleontologist at La Plata Museum, he was very surprised. He said he'd never seen anything like it, and at once showed it to another specialist at the same institution, Francisco Goin, who had the same reaction. Goin said Brasilestes resembled no other Mesozoic mammal found in Argentina, hence in South America," Castro recalled.

Among the 30-odd Argentinian species of Mesozoic mammals, there are meridiolestids, gondwanatherians, and even a few suspected multituberculates. There are no marsupials or placentals. The only fossils in these two groups found in South America date from after the mass extinction that wiped out the dinosaurs 66 million years ago in an event that marks the end of the Mesozoic and the onset of the current geological era, the Cenozoic.

Until the discovery of Brasilestes, the only traces of Mesozoic mammals in Brazil were hundreds of tracks and footprints left by unknown creatures 130 million years ago as they traversed the dunes of the Botucatu Desert in what is now São Paulo State. The solidified surface of those dunes has been preserved as sandstone slabs on which the footprints can be seen.

In 1993, Reinaldo José Bertini , a professor at São Paulo State University (UNESP) in Rio Claro, announced the discovery of a mammalian jawbone fragment with a single tooth far smaller than the Brasilestes premolar. However, Bertini did not publish a detailed study of the fossil and therefore could not name a new species.

"Brasilestes is not just the first Brazilian Mesozoic mammal to be described but also one of the few Mesozoic mammals found in more central regions of South America. The Argentinian fossils were found in geological formations in Patagonia, the southern tip of the continent," Langer said.

"Furthermore, Brasilestes is different from everything found before, suggesting that possibly placental mammals inhabited South America between 87.8 million and 70 million years ago," said the FAPESP thematic project coordinator.

New species possibly related to a mammal from India

Even more surprisingly, the Mesozoic mammal with premolars that most resemble the Brasilestes tooth lived on the other side of the world, in India, between 70 million and 66 million years ago. Its name is Deccanolestes. No other creature in the global fossil record is so similar to Brasilestes.

How could two members of the same lineage have lived so far apart in unconnected regions? Approximately 100 million years ago, when South America and Africa had only just been separated by the opening of the South Atlantic, India was breaking away from Gondwana and starting to wander through the Indian Ocean.

This implies that at least 100 million years ago, the ancestors of Brasilestes and Deccanolestes populated the Gondwana supercontinent. In other words, the lineage to which Brasilestes and Deccanolestes belong is far older than the ages of their fossils -- between 87 million and 70 million years ago for Brasilestes, and between 70 million and 66 million for Deccanolestes.

"The discovery of Brasilestes raises many more questions than answers about the biogeography of South American Mesozoic mammals," Langer said. "Thanks to Brasilestes, we've realized that the history of Gondwana's mammals is more complex than we thought."

Finding triggers speculation on xenarthrans' origins

This could give rise to new hypotheses and new lines of investigation. Who knows, for example, whether future research inspired by the discovery of Brasilestes will reveal the origin of a typical South American group, the xenarthrans, the order of armadillos, anteaters and sloths? Castro's main research interest, in fact, is the evolutionary history of the xenarthrans.

"An interesting feature of the Brasilestes premolar is its superthin enamel, which is only 20 micrometers thick. The Brasilestes enamel is the thinnest of any Cretaceous mammal in the fossil record. Most Mesozoic mammals have enamel in the range of 100 to 300 micrometers," Castro said.

"Tens of known species of xenarthrans are alive now. Hundreds are extinct. Only three have enamel. The microstructure of Brasilestes' premolar enamel is very similar to that of the nine-banded armadillo," said the FAPESP-supported researcher.

According to Castro, "molecular clock evidence suggests the xenarthran lineage started at least 85 million years ago. However, the oldest armadillo fossils, found in Rio de Janeiro, are about 50 million years old."

While it is intriguing to imagine Brasilestes as an ancient xenarthran, it is far too soon for any such affirmation.

"The age and provenance of Brasilestes do match molecular hypotheses for the origin of the xenarthrans, but it would be premature to infer taxonomic affinity in light of the morphological differences between the Brasilestes tooth and armadillo teeth," Castro said.

Langer agreed. "We have only one Brasilestes fossil. That's nowhere near enough to extract conclusions from the fossil record," he said.

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