Mar 20, 2019

Butterfly numbers down by two thirds

Hominy Blue (Polyommatus icarus).
Meadows adjacent to high-intensity agricultural areas are home to less than half the number of butterfly species than areas in nature preserves. The number of individuals is even down to one-third of that number. These are results of a research team led by Jan Christian Habel at the Technical University of Munich (TUM) and Thomas Schmitt at the Senckenberg Nature Research Society.

Germany is home to roughly 33,500 species of insects -- but their numbers are decreasing dramatically. Of the 189 species of butterflies currently known from Germany, 99 species are on the Red List, 5 have already become extinct, and 12 additional species are threatened with extinction.

Now a team led by Prof. Jan-Christian Habel of the Department of Terrestrial Ecology of the Technical University of Munich and Prof. Thomas Schmitt, Director of the Senckenberg German Entomological Institute in Muencheberg in Brandenburg, has examined the specific effects of the intensity of agricultural use on the butterfly fauna.

Reduced biodiversity also on areas around intensively cultivated fields

The research team recorded the occurrence of butterfly species in 21 meadow sites east of Munich. Of these study sites, 17 are surrounded by agriculturally used areas, and four are in nature preserves with near-natural cultivation.

They recorded a total of 24 butterfly species and 864 individuals in all study sites. Specialists among the butterflies were particularly dependent on near-natural habitats, while the more adaptable "generalists" were also found in other grassland sites.

"In the meadows that are surrounded by agriculturally used areas we encountered an average of 2.7 butterfly species per visit; in the four study sites within the protected areas 'Dietersheimer Brenne' and 'Garchinger Heide' near Munich we found an average of 6.6 species," adds Prof. Werner Ulrich of the Copernicus University in Thorn, Poland.

Negative impact of the industrialized agriculture demands rethinking

"Our results show an obvious trend: in the vicinity of intensively cultivated fields that are regularly sprayed with pesticides, the diversity and numbers of butterflies are significantly lower than in meadows near less used or unused areas," explains the study's lead author, Prof. Jan Christian Habel.

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Tiny song bird makes record migration

Blackpoll warbler wearing tiny 'backpack.'
It's an epic journey for a tiny bird.

For the first time, University of Guelph biologists have tracked an annual migration of up to 20,000 kilometres made by the 12-gram blackpoll warbler, one of the fastest declining songbirds in North America.

The bird's trek between its breeding grounds in the central and western boreal forest of North America and its winter home in the Amazon Basin -- one of the longest songbird migrations recorded -- is the topic of a new paper by a research team headed by U of G biologist Ryan Norris.

The paper was published today in the journal Ecology.

Describing a "great circle route" arcing across North America and including a transoceanic flight to South America, the study confirms an epic migration journey that scientists had long suspected but not yet proved.

In 2015, Norris and other biologists were the first to show that blackpolls breeding in the Maritimes and New England complete a non-stop transoceanic flight of up to three days and about 2,700 km along the eastern coast of the United States.

For this new study, they looked at the full migration of birds from central and western breeding populations.

"It's amazing," said Norris, who worked on the study with Hilary Cooke, associate conservation scientist with Wildlife Conservation Society Canada. "A bird weighing a couple of loonies travels from the western edge of North America all the way to the Amazon basin -- and, in between, traverses the Atlantic Ocean."

Other co-authors were integrative biology professor Amy Newman and U of G grad students Bradley Woodworth, Nikole Freeman and Alex Sutton, as well as researchers from other universities, conservation groups and national parks in Canada, the U.S. and Australia.

For the study, researchers tracked birds outfitted with tiny geolocators from four boreal forest sites across northern Canada and Alaska.

Total southward migration took about 60 days on average over distances ranging from 6,900 km for birds breeding in Churchill, Manitoba, to 10,700 km for populations on the western edge of the continent in Nome, Alaska.

Blackpolls from Nome took 18 days to fly across North America to the Atlantic coast of the Carolinas. There, the birds spent almost a month fattening up to double their body weight before a non-stop, 2 ½-day flight across open water to overwintering grounds in northern Colombia, Venezuela and Brazil.

They covered between 2,250 and 3,400 km for that transoceanic hop.

Norris said scientists had long believed that blackpolls followed the great circle route. Few of the birds have ever been found in the central or western States during fall migration.

He said population numbers have fallen in recent years, perhaps caused by habitat loss and declines in insect prey related to climate change.

"To understand what's causing the decline, we need to know their full annual cycle," he said.

In their paper, the researchers say climate change may make extreme coastal weather events more frequent and more extreme, with unknown impacts on long-distance migratory birds.

"As a conservation scientist, what strikes me most is that in a single year a blackpoll warbler has to navigate 20,000 kilometres across land and ocean, facing risks of cat predation, storms and collisions with buildings and vehicles, all while trying to find islands of habitat to rest and refuel in our human-dominated landscapes,"said Cooke. "In comparison, the boreal region of northern Canada provides safe and high-quality breeding habitat for this declining species. Protecting Canada's boreal forest is critical to saving this amazing songbird."

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Water-bearing minerals on asteroid Bennu

This mosaic image of the asteroid Bennu is composed of 12 PolyCam images collected by the OSIRIS-REx spacecraft from 15 miles away. An SwRI-led team is looking at the spectral data from the surface to better understand the composition of the asteroid.
A Southwest Research Institute-led team discovered evidence of abundant water-bearing minerals on the surface of the near-Earth asteroid (101955) Bennu. Using early spectral data from NASA's OSIRIS-REx spacecraft orbiting the asteroid, the team identified infrared properties similar to those in a type of meteorite called carbonaceous chondrites.

"Scientists are interested in the composition of Bennu because similar objects may have seeded the Earth with water and organic materials," said SwRI's Dr. Victoria Hamilton, a mission co-investigator and lead author of a paper outlining the discovery published March 19 in Nature Astronomy. "OSIRIS-REx data confirm previous ground-based observations pointing to aqueously altered, hydrated minerals on the surface of the asteroid."

Typical planetary models show that around 4.6 billion years ago, the solar system formed from the gravitational collapse of a giant nebular cloud. The Sun, planets and other objects such as asteroids and comets formed as materials within the collapsing cloud clumped together in a process known as accretion. Carbonaceous chondrites, which come from asteroids, show evidence for post-accretion interactions with water and/or ice that led to chemical reactions that produce hydrated minerals. Because these meteorites and their parent bodies formed close to the beginning of the solar system, they may provide clues to the distribution, abundance and movements of water in the solar disk at these times.

"During planetary formation, scientists believe that water was one of many chemical components that accreted to form Earth; however, most scientists think additional water was delivered in part by comets and pieces of asteroids, including water-bearing carbonaceous meteorites," Hamilton said. "Many of these meteorites also contain prebiotic organic chemicals and amino acids, which are precursors to the origin of life. The details of water delivery to Earth as well as the larger issue of the different inventories of water ice in the early solar system affect how we view solar system formation."

Two types of carbonaceous chondrites called CI and CM chondrites contain several percent by weight of organic compounds and some also contain water in abundances of 10-15 percent and as much as 20 percent in rare cases. The presence of volatile organic chemicals and water indicates that they have not undergone substantial heating.

"Because asteroids with hydrated minerals are found throughout the main asteroid belt, significant ice must have been present in the disk during and shortly after the time of carbonaceous asteroid accretion," Hamilton said.

In summer of 2020, OSIRIS-REx will touch Bennu's surface to collect a sample the surface regolith for return to Earth. The spectral measurements used in this study will be confirmed by lab experiments when a sample of Bennu's surface materials arrives back at Earth in 2023.

The geological characteristics of Bennu's surface indicate that it is an old rubble pile of gravitationally bound, unconsolidated fragments, left over from an ancient collision in the asteroid belt. These and future, higher-resolution spectral observations from OSIRIS-REx will provide vital context for analyzing the returned sample to evaluate the aqueous alteration experienced by Bennu's parent body based on details of mineral distribution, abundance and composition.

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The rise and fall of Ziggy star formation and the rich dust from ancient stars

Based on the observations with ALMA and HST, researchers assume that this galaxy contains stellar clusters with a mix of old and young stars. The clouds of gas and dust are illuminated by stellar light.
Researchers have detected a radio signal from abundant interstellar dust in MACS0416_Y1, a galaxy 13.2 billion light-years away in the constellation Eridanus. Standard models can't explain this much dust in a galaxy this young, forcing us to rethink the history of star formation. Researchers now think MACS0416_Y1 experienced staggered star formation with two intense starburst periods 300 million and 600 million years after the Big Bang with a quiet phase in between.

Stars are the main players in the Universe, but they are supported by the unseen backstage stagehands: star dust and gas. Cosmic clouds of dust and gas are the sites of star formation and masterful storytellers of the cosmic history.

"Dust and relatively heavy elements such as oxygen are disseminated by the deaths of stars," said Yoichi Tamura, an associate professor at Nagoya University and the lead author of the research paper, "Therefore, a detection of dust at some point in time indicates that a number of stars have already formed and died well before that point."

Using ALMA (Atacama Large Millimeter/submillimeter Array), Tamura and his team observed the distant galaxy MACS0416_Y1. Because of the finite speed of light, the radio waves we observe from this galaxy today had to travel for 13.2 billion years to reach us. In other words they provide an image of what the galaxy looked like 13.2 billion years ago, which is only 600 million years after the Big Bang.

The astronomers detected a weak but telltale signal of radio emissions from dust particles in MACS0416_Y1 (Note 1). The Hubble Space Telescope, the Spitzer Space Telescope, and the European Southern Observatory's Very Large Telescope have observed the light from stars in the galaxy; and from its color they estimate the stellar age to be 4 million years.

"It ain't easy," said Tamura half-lost in a moonage daydream. "The dust is too abundant to have been formed in 4 million years. It is surprising, but we need to hang onto ourselves. Older stars might be hiding in the galaxy, or they may have died out and disappeared already."

"There have been several ideas proposed to overcome this 'dust budget crisis'," said Ken Mawatari, a researcher at the University of Tokyo. "However, no one is conclusive. We made a new model which doesn't need any extreme assumptions diverging far from our knowledge of the life of stars in today's Universe. The model well explains both the color of the galaxy and the amount of dust." In this model, the first burst of star formation started at 300 million years and lasted 100 million years. After that, the star formation activity went quiet for a time, and then restarted at 600 million years. The researchers think ALMA observed this galaxy at the beginning of its second generation of star formation.

Read more at Science Daily

It's spring already? Physics explains why time flies as we age

The 'endless days' of childhood.
A Duke University researcher has a new explanation for why those endless days of childhood seemed to last so much longer than they do now -- physics.

According to Adrian Bejan, the J.A. Jones Professor of Mechanical Engineering at Duke, this apparent temporal discrepancy can be blamed on the ever-slowing speed at which images are obtained and processed by the human brain as the body ages.

The theory was published online on March 18 in the journal European Review.

"People are often amazed at how much they remember from days that seemed to last forever in their youth," said Bejan. "It's not that their experiences were much deeper or more meaningful, it's just that they were being processed in rapid fire."

Bejan attributes this phenomenon to physical changes in the aging human body. As tangled webs of nerves and neurons mature, they grow in size and complexity, leading to longer paths for signals to traverse. As those paths then begin to age, they also degrade, giving more resistance to the flow of electrical signals.

These phenomena cause the rate at which new mental images are acquired and processed to decrease with age. This is evidenced by how often the eyes of infants move compared to adults, noted Bejan -- because infants process images faster than adults, their eyes move more often, acquiring and integrating more information.

The end result is that, because older people are viewing fewer new images in the same amount of actual time, it seems to them as though time is passing more quickly.

"The human mind senses time changing when the perceived images change," said Bejan. "The present is different from the past because the mental viewing has changed, not because somebody's clock rings. Days seemed to last longer in your youth because the young mind receives more images during one day than the same mind in old age."

From Science Daily

Mar 19, 2019

Mammals' unique arms started evolving before the dinosaurs existed

Photographs of the upper arm bones from seven kinds of early mammal relatives. The three bones on the left are from an early group called pelycosaurs, and the bones are all roughly the same shape. The four bones on the right are from therapsids, the group that includes today's mammals, and they show the greater variety of shapes and sizes that characterize therapsid limbs. The black scale bars represent 2cm.
Bats fly, whales swim, gibbons swing from tree to tree, horses gallop, and humans swipe on their phones -- the different habitats and lifestyles of mammals rely on our unique forelimbs. No other group of vertebrate animals has evolved so many different kinds of arms: in contrast, all birds have wings, and pretty much all lizards walk on all fours. Our forelimbs are a big part of what makes mammals special, and in a new study in the Proceedings of the National Academy of Sciences, scientists have discovered that our early relatives started evolving diverse forelimbs 270 million years ago -- a good 30 million years before the earliest dinosaurs existed.

"Aside from fur, diverse forelimb shape is one of the most iconic characteristics of mammals," says the paper's lead author Jacqueline Lungmus, a research assistant at Chicago's Field Museum and a doctoral candidate at the University of Chicago. "We were trying to understand where that comes from, if it's a recent trait or if this has been something special about the group of animals that we belong to from the beginning."

To determine the origins of mammals' arms today, Lungmus and her co-author, Field Museum curator Ken Angielczyk, examined the fossils of mammals' ancient relatives. About 312 million years ago, land-dwelling vertebrates split into two groups -- the sauropsids, which went on to include dinosaurs, birds, crocodiles, and lizards, and the synapsids, the group that mammals are part of. A key difference between sauropsids and synapsids is the pattern of openings in the skull where jaw muscles attach. While the earliest synapsids, called pelycosaurs, were more closely related to humans than to dinosaurs, they looked like hulking reptiles. Angielczyk notes, "If you saw a pelycosaur walking down the street, you wouldn't think it looked like a mammal -- you'd say, 'That's a weird-looking crocodile.'"

About 270 million years ago, though, a more diverse (and sometimes furry) line of our family tree emerged: the therapsids. "Modern mammals are the only surviving therapsids -- this is the group that we're part of today," explains Lungmus. Therapsids were the first members of our family to really branch out -- instead of just croc-like pelycosaurs, the therapsids included lithe carnivores, burly-armed burrowers, and tree-dwelling plant-eaters.

Lungmus and Angielczyk set out to see if this explosion of diversity came with a corresponding explosion in different forelimb shapes. "This is the first study to quantify forelimb shape across a big sample of these animals," says Lungmus. The team examined the upper arm bones of hundreds of fossil specimens representing 73 kinds of pelycosaurs and therapsids, taking measurements near where the bones joined the shoulder and the elbow. They then analyzed the shapes of the bones using a technique called geometric morphometrics.

When they compared the shapes of arm bones, the researchers found a lot more variation in the bones of the therapsids than the pelycosaurs. They also noted that the upper part of the arm, near the shoulder, was especially varied in therapsids -- a feature that might have let them move more freely than the pelycosaurs, whose bulky and tightly-fitting shoulder bones likely gave them a more limited range of motion.

Lungmus and Angielczyk found that a wide variety of different forelimb shapes evolved within the therapsids 270 million years ago. "The therapsids are the first synapsids to increase the variability of their forelimbs -- this study dramatically pushes that trait back in time," says Lungmus. Prior to this study, the earliest that paleontologists had been able to definitively trace back mammals' diverse forelimbs was 160 million years ago. With Lungmus and Angielczyk's work, that's been pushed back by more than a hundred million years.

The researchers note that the study helps explain how mammals evolved traits that have made us what we are today. "So much of what we do every day is related to the way our forelimbs evolved -- even simple things like holding a phone," says Angielczyk.

Read more at Science Daily

Natural selection favors cheaters

Acmispon strigosus is an annual herb that is native to California.
Mutualisms, which are interactions between members of different species that benefit both parties, are found everywhere -- from exchanges between pollinators and the plants they pollinate, to symbiotic interactions between us and our beneficial microbes.

Natural selection -- the process whereby organisms better adapted to their environment tend to survive and produce more offspring -- predicts, however, that mutualisms should fall apart. Individuals that gain from the cooperation of others but do not reciprocate (so-called cheaters) should arise and destabilize mutualisms. Yet to date, surprisingly little evidence of such cheating or destabilization exists.

A team of biologists at the University of California, Riverside, has now found strong evidence of this cheating. Focusing on the interaction between nitrogen-fixing bacteria, or rhizobia, and their legume hosts spanning about 530 miles of California habitat, the researchers found that natural selection in their study populations favors cheating rhizobia.

The study, appearing in Ecology Letters, is the first to uncover cheater strains in natural populations and show how natural selection favors them.

The researchers used a previously published database to quantify the landscape abundance of different rhizobial strains. They focused on naturally occurring populations of rhizobia in the genus Bradyrhizobium and the native annual plants, Acmispon strigosus, that these bacteria inhabit. Within these datasets they found that the fewer benefits the rhizobia provide to their host plants, the more common the rhizobia are.

"Our data show that natural selection favors cheating rhizobia, and support predictions that rhizobia can often subvert plant defenses and evolve to exploit hosts," said Joel Sachs, a professor of biology in the Department of Evolution, Ecology & Organismal Biology, who led the research team.

Sachs explained that beneficial bacteria are increasingly appreciated to be key for human health as well as the productivity of crops and livestock. Little is understood, however, about how much these bacterial services vary in natural systems and the forces that modulate them.

"In crop plants, in particular, agronomists have attempted -- and failed -- for several decades to design crop biofertilizers based on beneficial bacteria," he said. "Similar challenges have been faced in applying bacteria in other host systems -- probiotics, for example, which rarely affect host microbes. Our dataset suggests a potential flaw in these approaches; the bacteria, with their own evolutionary interests, can destabilize these interactions."

In their paper, the researchers show how benefits of bacterial symbionts vary over space and time, and how rapidly these systems can evolve.

"We often view the services of bacteria as fixed, but this is not at all true," Sachs said. "Just as each human varies a great deal in almost any trait we can measure, bacterial populations are even more highly variable. Understanding this variation and its drivers will be key to usefully harnessing these bacteria for our own purposes."

Already, his team is actively working to better understand how beneficial bacteria can be applied to improve plant growth. Preliminary data show that it is crucial to carefully select among bacterial variants to avoid using harmful strains.

"Simply applying beneficial bacteria to a crop is often not going to be sufficient since exploitative strains are expected to be lurking within these populations," Sachs said.

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Weird, wild gravity of asteroid Bennu

The asteroid Bennu as seen by the OSIRIS-REx spacecraft. The flying saucer-like shape of Bennu is generated, in part, by its spin.
Research led by the University of Colorado Boulder is revealing the Alice in Wonderland-like physics that govern gravity near the surface of the asteroid Bennu.

The new findings are part of a suite of papers published today by the team behind NASA's Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer (OSIRIS-REx) mission. And they come just three months after OSIRIS-REx first encountered Bennu on Dec. 3, 2018.

Since then, the spacecraft has completed a few dozen laps around the asteroid, which is about as tall as the Empire State Building, circling Bennu from a distance of about a mile. And those early circuits are giving scientists a whole new look at this mysterious rock, said CU Boulder's Daniel Scheeres, who leads the mission's radio science team.

In research appearing in Nature Astronomy, for example, his team reports the mass of that asteroid: a respectable 73 billion kilograms.

But Scheeres and his colleagues are also working to develop a map of the asteroid's gravitational pull. Their findings suggest that Bennu exists in a delicate balance between two competing forces, the result of the asteroid's wild spin. Bennu completes a full revolution about once every four hours.

And, Scheeres said, those forces could play an important role in the asteroid's long-term evolution -- and potential demise.

"When you spin this guy up, you create a competition between the gravity that's holding you down and the centrifugal acceleration, which is trying to throw you off," said Scheeres, distinguished professor in the Ann and H.J. Smead Department of Aerospace Engineering Sciences who leads the mission's radio science team.

To study those forces, Scheeres and his colleagues use OSIRIS-REx's navigational instruments to measure the minute tug that the asteroid exerts on the spacecraft.

And they dug up more than they expected. Based on the group's calculations, the region around Bennu's equator is trapped within a gravitational feature called a rotational Roche lobe -- something that scientists had not yet clearly observed on an asteroid.

In practice, that feature gets weird. If you were standing inside the boundaries of Bennu's Roche lobe and slipped on a banana peel, for example, not much would happen -- you'd be captured by the lobe and fall back to the surface.

"But if you were outside of the Roche lobe and slipped on a banana peel, you would roll toward the equator," Scheeres said. "And you could gain enough energy so that you'd roll off the equator and maybe up into orbit and then out into space."

It sounds like the sort of environment that Lewis Carroll could appreciate. But it also matters for the lifespan of Bennu, he added.

That's because radiation from the sun is causing Bennu to spin faster and faster over time. And as the asteroid's whirling builds up speed, its Roche lobe might also be shrinking, along with the forces that are holding Bennu together.

"As that Roche lobe narrows further and further around the equator, it becomes easier and easier for this asteroid to lose material," Scheeres said. "So far, that material has been trapped by gravity, but at some point, if the asteroid keeps spinning faster, then you fall off the cliff."

In other words, Bennu could be in the process of spinning itself into oblivion.

Understanding those physics matters for advance OSIRIS-REx's scientific mission, too, said Jay McMahon, an assistant professor in aerospace engineering and a co-author of the new study.

He explained that in 2020, mission scientists will nudge OSIRIS-REx to within a few feet of Bennu, using the spacecraft's retractable arm to collect a sample of material from the surface. And to do that safely, they will need to know the rock's physics inside and out.

"You need to know the gravitational field for spacecraft operations, really to enable all the other science," McMahon said.

"When you're going to a new world, you have some idea of what it might look like," Scheeres said. "Then you actually go there, and you can start comparing what you thought it might look like versus reality."

The University of Arizona leads science operations for OSIRIS-REx, which was built by the Colorado-based Lockheed Martin Space. NASA's Goddard Space Flight Center in Maryland manages the overall mission.

Read more at Science Daily

Researchers create hydrogen fuel from seawater

A prototype device used solar energy to create hydrogen fuel from seawater.
Stanford researchers have devised a way to generate hydrogen fuel using solar power, electrodes and saltwater from San Francisco Bay.

The findings, published March 18 in Proceedings of the National Academy of Sciences, demonstrate a new way of separating hydrogen and oxygen gas from seawater via electricity. Existing water-splitting methods rely on highly purified water, which is a precious resource and costly to produce.

Theoretically, to power cities and cars, "you need so much hydrogen it is not conceivable to use purified water," said Hongjie Dai, J.G. Jackson and C.J. Wood professor in chemistry at Stanford and co-senior author on the paper. "We barely have enough water for our current needs in California."

Hydrogen is an appealing option for fuel because it doesn't emit carbon dioxide, Dai said. Burning hydrogen produces only water and should ease worsening climate change problems.

Dai said his lab showed proof-of-concept with a demo, but the researchers will leave it up to manufacturers to scale and mass produce the design.

Tackling corrosion

As a concept, splitting water into hydrogen and oxygen with electricity -- called electrolysis -- is a simple and old idea: a power source connects to two electrodes placed in water. When power turns on, hydrogen gas bubbles out of the negative end -- called the cathode -- and breathable oxygen emerges at the positive end -- the anode.

But negatively charged chloride in seawater salt can corrode the positive end, limiting the system's lifespan. Dai and his team wanted to find a way to stop those seawater components from breaking down the submerged anodes.

The researchers discovered that if they coated the anode with layers that were rich in negative charges, the layers repelled chloride and slowed down the decay of the underlying metal.

They layered nickel-iron hydroxide on top of nickel sulfide, which covers a nickel foam core. The nickel foam acts as a conductor -- transporting electricity from the power source -- and the nickel-iron hydroxide sparks the electrolysis, separating water into oxygen and hydrogen. During electrolysis, the nickel sulfide evolves into a negatively charged layer that protects the anode. Just as the negative ends of two magnets push against one another, the negatively charged layer repels chloride and prevents it from reaching the core metal.

Without the negatively charged coating, the anode only works for around 12 hours in seawater, according to Michael Kenney, a graduate student in the Dai lab and co-lead author on the paper. "The whole electrode falls apart into a crumble," Kenney said. "But with this layer, it is able to go more than a thousand hours."

Previous studies attempting to split seawater for hydrogen fuel had run low amounts of electric current, because corrosion occurs at higher currents. But Dai, Kenney and their colleagues were able to conduct up to 10 times more electricity through their multi-layer device, which helps it generate hydrogen from seawater at a faster rate.

"I think we set a record on the current to split seawater," Dai said.

The team members conducted most of their tests in controlled laboratory conditions, where they could regulate the amount of electricity entering the system. But they also designed a solar-powered demonstration machine that produced hydrogen and oxygen gas from seawater collected from San Francisco Bay.

And without the risk of corrosion from salts, the device matched current technologies that use purified water. "The impressive thing about this study was that we were able to operate at electrical currents that are the same as what is used in industry today," Kenney said.

Surprisingly simple

Looking back, Dai and Kenney can see the simplicity of their design. "If we had a crystal ball three years ago, it would have been done in a month," Dai said. But now that the basic recipe is figured out for electrolysis with seawater, the new method will open doors for increasing the availability of hydrogen fuel powered by solar or wind energy.

In the future, the technology could be used for purposes beyond generating energy. Since the process also produces breathable oxygen, divers or submarines could bring devices into the ocean and generate oxygen down below without having to surface for air.

Read more at Science Daily

Scientists hunt down the brain circuit responsible for alcohol cravings

Confocal analysis at 63x magnification, followed by the three-dimensional reconstruction of neuronal cell bodies and branches. The image shows an example of eYFP and CRF in the same neuron. This rendered isosurface analysis demonstrated the colocalization of CRF immunoreactivity within CeA neurons that also expressed Cre-dependent eYFP and validates the crh-Cre rat as a tool to gain more direct access to CRF neurons to study their functional neuroanatomy.
Scientists at Scripps Research have found that they can reverse the desire to drink in alcohol-dependent rats -- with the flip of a switch. The researchers were able to use lasers to temporarily inactivate a specific neuronal population, reversing alcohol-seeking behavior and even reducing the physical symptoms of withdrawal.

"This discovery is exciting -- it means we have another piece of the puzzle to explain the neural mechanism driving alcohol consumption," says Olivier George, PhD, an associate professor at Scripps Research and senior author of the new study, published March 18, 2019 in the journal Nature Communications.

Although the laser treatment is far from ready for human use, George believes identifying these neurons opens the door to developing drug therapies or even gene therapies for alcohol addiction.

"We need compounds that are specific to this neuronal circuitry," George says.

According to the National Institute on Alcohol Abuse and Alcoholism, more than 15.1 million adults in the United States suffer from alcohol use disorder. Previous work at Scripps Research has shown that transitioning from casual drinking to dependent drinking occurs alongside fundamental changes in how the brain sends signals. These signals drive the intense cravings that make it so difficult for many people to scale back their alcohol consumption.

George and his colleagues have been hunting for the brain cells that driving drinking in an alcohol-addicted rat model. In 2016, they reported that they had found a possible source: a neuronal "ensemble," or group of connected cells in a brain region called the central nucleus of the amygdala (CeA). This finding marked major progress in mapping the brain, but the researchers needed to characterize the identity of the neurons in this ensemble.

For the new study, they tested the role of a subset of neurons in the ensemble, called corticotropin-releasing factor (CRF) neurons. The George laboratory had found that these CRF neurons make up 80 percent of the ensemble. Were these neurons the masterminds driving alcohol cravings?

The researchers studied these neurons using optogenetics, a technique that involves the use of light to control cells in living tissue. Rats used in this study were surgically implanted with optic fibers aimed to shine light on the CRF neurons -- to inactivate them at the flip of a switch.

First, the scientists established a baseline for how much the rats would drink before they got addicted to alcohol. The rats drank little this point -- the equivalent of a glass of wine or one beer for a human. The scientists then spent several months increasing consumption in these rats to establish alcohol dependence.

The researchers then withdrew the alcohol, prompting withdrawal symptoms in the rats. When they offered alcohol again, the rats drank more than ever. The CeA neuronal ensemble was active, telling the rats to drink more.

Then the scientists flipped on the lasers to inactivate the CRF neurons -- and the results were dramatic. The rats immediately returned to their pre-dependent drinking levels. The intense motivation to drink had gone away. Inactivating these neurons also reduced the physical symptoms of withdrawal, such as abnormal gait and shaking.

"In this multidisciplinary study, we were able to characterize, target and manipulate a critical subset of neurons responsible for excessive drinking." says Giordano de Guglielmo, PhD, first author of the study and staff scientist at Scripps Research. "This was a team effort, and while we used challenging techniques, working with experts in the field and with the right tools, made everything easier and enjoyable."

The effect was even reversible. Turn off the lasers, and the rats returned to their dependent behavior.

From a basic science standpoint, this breakthrough is huge: It reveals wiring in the brain that drives a specific, destructive behavior. George says the next step in translating this work to humans is to find a way to selectively inhibit only these specific CRF neurons, perhaps using a novel or repurposed compound identified using high-throughput screening of large libraries of compounds.

Read more at Science Daily