Feb 17, 2018

New stem-cell based stroke treatment repairs damaged brain tissue

Exosomes, shown as small red punctate clusters, are taken up by neurons, shown as green cell extensions surrounding a blue nucleus.
A team of researchers at the University of Georgia's Regenerative Bioscience Center and ArunA Biomedical, a UGA startup company, have developed a new treatment for stroke that reduces brain damage and accelerates the brain's natural healing tendencies in animal models. They published their findings in the journal Translational Stroke Research.

The research team led by UGA professor Steven Stice and Nasrul Hoda of Augusta University created a treatment called AB126 using extracellular vesicles (EV), fluid-filled structures known as exosomes, which are generated from human neural stem cells.

Fully able to cloak itself within the bloodstream, this type of regenerative EV therapy appears to be the most promising in overcoming the limitations of many cell therapies-with the ability for exosomes to carry and deliver multiple doses-as well as the ability to store and administer treatment. Small in size, the tiny tubular shape of an exosome allows EV therapy to cross barriers that cells cannot.

"This is truly exciting evidence, because exosomes provide a stealth-like characteristic, invisible even to the body's own defenses," said Stice, Georgia Research Alliance Eminent Scholar and D.W. Brooks Distinguished Professor in the College of Agricultural and Environmental Sciences. "When packaged with therapeutics, these treatments can actually change cell progression and improve functional recovery."

Following the administration of AB126, the researchers used MRI scans to measure brain atrophy rates in preclinical, age-matched stroke models, which showed an approximately 35 percent decrease in the size of injury and 50 percent reduction in brain tissue loss -- something not observed acutely in previous studies of exosome treatment for stroke.

Outside of rodents, the results were replicated by Franklin West, associate professor of animal and dairy science, and fellow RBC members using a porcine model of stroke-the only one of its kind in the U.S.

Based on these pre-clinical results, ArunA Biomedical plans to begin human studies in 2019, said Stice, who is also chief scientific officer of ArunA Biomedical.

"Until now, we had very little evidence specific to neural exosome treatment and the ability to improve motor function," said Stice. "Just days after stroke, we saw better mobility, improved balance and measurable behavioral benefits in treated animal models."

Named as part of the 'stroke belt' region, Georgia continues to exceed the national average in stroke deaths, which is the third leading cause of death in the U.S., with more than 140,000 Americans dying each year, according to the Centers for Disease Control and Prevention.

ArunA recently unveiled advances to the company's proprietary neural cell platform for the production of exosome manufacturing. Today, ArunA's manufacturing process positions the company to produce AB126 exosomes at a scale to meet early clinical demand. The company has plans to expand this initiative beyond stroke for preclinical studies in epilepsy, traumatic brain and spinal cord injuries later this year.

Researchers also plan to leverage collaborations with other institutions through the National Science Foundation Engineering Research Center for Cell Manufacturing Technologies, based at the Georgia Institute of Technology and supported by $20 million in NSF funding.

Read more at Science Daily

Lizards Ran for Their Lives on Two Feet During the Dinosaur Era

Reconstruction of a lizard running bipedally while being chased by the pterosaur Pteraichnus koreanensis, based on the trackways found at the Hasandong Formation, South Korea.
While searching for dinosaur bones in August 2004, vertebrate paleontologist Yuong-Nam Lee found some ancient footprints for a pterosaur and other small animals. He was studying pterosaurs at the time, so the tracks left behind by the other species were not of much interest. Lee placed the mudstone slab containing the tracks in the Geological Museum of the Korea Institute of Geoscience and Mineral Resources, where it remained in storage for 12 years.

Lee returned to the slabs two years ago with fresh eyes and dated the four series of trackways to between 125–100 million years ago. Then came a eureka moment.

"I was very excited, because they represent the oldest lizard tracks in the world," Lee told Seeker, clarifying that the footprints are actually about 110 million years old.

He showed the tracks to some colleagues, including Anthony Fiorillo, chief curator and vice president of research and collections at the Perot Museum of Nature & Science.

"Initially we thought that these were indeed very interesting early lizard tracks, but then we realized that they provide evidence for lizards running on their hind feet," Fiorillo said. "That realization made the discovery even cooler."

The trackways, reported in the journal Scientific Reports, provide the first direct evidence for bipedal — or two-footed — running in fossil lizards. What's more, they suggest that the lizard could have been running away from a pterosaur during the Cretaceous Period (145.5–65.5 million years ago).

Prior studies on fossilized lizard skeletons indicated that early reptiles might have run on two feet, but no one was really sure.

"That's what is so important about trackways," Fiorillo said. "They actually record a behavior."

Photograph (left) and drawing (right) of the lizard trackways on the mudstone block
Lee, Fiorillo, lead author Hang-Jae Lee, and senior author Junchang Lü determined that the lizard was close to 2.5 inches long. They cannot tell exactly how fast it was running.

"However," Lee said, "modern lizards can run quite quickly. For example, the Costa Rican spiny-tailed iguana can attain a sprint speed of 34.6 kilometers per hour (21.5 miles per hour), which is about as fast as a charging grizzly bear." Basiliscus basiliscus, aka the "Jesus lizard," can even run on the surface of water.

Based on early skeletal material in the fossil record, the scientists suspect that the running lizard came from an extinct family of Iguania. They identified the prints as Sauripes hadongensis, which refers to the group of fossilized lizard tracks and not to the precise species, which remains unknown for now.

Since the fossils are very well preserved, the researchers were able to study the lizard's foot anatomy in detail. They identified 25 footprints showing typical lizard anatomy with curved digits increasing in length from the inside of the foot to the outside, and four shorter handprints with a longer third digit compared to the other four digits.

The authors found that the footprints were predominant, which is more consistent with a two-legged, rather than a four-legged, gait. Increasing stride length and other aspects of the tracks suggest that the prehistoric lizards were running on their toes.

Close-up images, as well as corresponding drawings, of two of the lizard trackways
Tracks for carnivorous non-avian dinosaurs were also found at the site, what is now the Hasandong Formation of South Gyeongsang Province, South Korea. The dinosaurs were, Lee said, "probably too big to worry about catching tiny lizards."

Nevertheless, being a small animal surrounded by much larger species — many of which were meat-loving — must have been a challenging existence. The pterosaur Pteraichnus koreanensis, which could have preyed upon the prehistoric iguana-like lizard, was a small and agile predator with sharp teeth and large eyes.

The pterosaurs "could have attacked prey from the air, like some birds do," Lee said.

The lizard, with its longer muscular hind limbs and shorter forelimbs, somewhat resembles a miniature Tyrannosaurus rex. But Lee said that there is no close common ancestor shared between lizards and dinosaurs. Any resemblance is therefore due to independent evolution.

Non-avian theropod dinosaurs like T. rex had fully erect legs, while lizards maintained a sprawled posture when they ran. Carnivorous dinosaurs exhibited obligate bipedality, meaning that their evolution restricted them to two-footed navigation. The ancient lizard's bipedality was more passive, such that it could likely switch from being four-legged to two-legged, depending on its needs.

The early iguana-like lizard probably evolved this unique way of moving so that it could move as fast as possible away from predators. The genetic structure of lizard ancestors did not allow them to evolve four more evenly-sized muscular limbs, as with many mammals that can run fast. Running on two-limbs could also have allowed the lizard to hold its head upward, keeping a closer eye on tall or aerial predators like pterosaurs.

Illustration showing the lizard's estimated size and how it ran
Bidedality in humans probably evolved more as a response to environmental changes. The primate ancestors of humans are thought to have lived in forested regions, where they spent much of their time in trees.

"The environment changed to more open areas that, among other things, changed the distribution of food," Lee said.

It is unclear how often the earliest bipedal primates ran. They were surely pursued by predators from time to time, and might have legged it for other reasons, such as escaping other natural threats or desiring to move quickly over long distances in non-threatening situations.

Read more at Seeker

Feb 16, 2018

Comes naturally? Using stick insects, scientists explore natural selection, predictability

A green morph of the Timema genus of stick insects.
Is evolution predictable? Are changes in a species random or do they happen because of natural selection?

"Evolution often appears random, even when driven by the deterministic process of natural selection, because we just aren't aware of all the environmental fluctuations and other factors taking place that drive change," says Utah State University biologist Zach Gompert. "If we had a better understanding of the mechanisms at play, we might have a better picture of evolutionary change and its predictability."

Gompert, with colleagues Patrick Nosil, Romain Villoutreix, Clarissa de Carvalho and Victor Soria-Carracso of England's University of Sheffield, along with Timothy Farkas of the University of Connecticut, Jeffrey Feder of the University of Notre Dame and Bernard Crespi of Canada's Simon Fraser University, explored these questions and report findings in the Feb. 16, 2018, issue of the journal Science.

The research was supported by a European Research Council grant and a Canadian Natural Sciences and Engineering Research Council grant, along with computational resources from the University of Utah Center for High?Performance Computing.

Gompert and colleagues used data from the past to test their ideas of evolutionary predictability.

"We used a rare and unique data set of 25 years of field data documenting the evolution of cryptic body coloration in terms of frequencies of three 'morphs' -- flavors, if you will -- of stick insects," says Gompert, assistant professor in USU's Department of Biology and the USU Ecology Center. "Using the first 10?15 years of the data, we tried predicting, or forecasting, the changes that would occur in the subsequent years of the data."

The three morphs are green, green with a white stripe and 'melanistic' or dark brown.

"These insects are cryptic, meaning they visually blend into their surroundings to hide from hungry predators," Gompert says.

Both types of the green stick insects live on green foliage, while the brown insects live on brown stems.

How close did the team's predictions match up to the collected data? Really close for the green versus green?striped morphs, but rather poorly for the melanistic morph, he says.

Using genomic analysis, the scientists were able to show, in both cases, the deterministic process of selection was the likely cause of evolutionary change.

"With the green versus green?striped morphs, the cause of selection was simple and well understood facilitation of predictability," Gompert says. "In contrast, with the melanistic morph, natural selection was more complex and tied to variation in weather and climate, making it harder to predict from past patterns of change."

The scientists compared their results to better known studies, including Darwin's finches and the scarlet tiger moth, both of which were also not very predictable.

"Our findings support previous discoveries and suggest evolution of morph frequencies in these stick insects is indeed a result of selection," Gompert says. "They also suggest poor predictability of environmental variation and how it affects selection, rather than random evolutionary processes, might be the main limits on predicting evolution."

Read more at Science Daily

Soft tissue fossil clues could help search for ancient life on Earth and other planets

The fossil Waptia from the Burgess Shale, Canada. New Oxford University research suggests that the mineralogy of the surrounding earth is key to conserving soft parts of organisms, and finding more exceptional fossils like the Waptia.
Fossils that preserve entire organisms (including both hard and soft body parts) are critical to our understanding of evolution and ancient life on Earth. However, these exceptional deposits are extremely rare. The fossil record is heavily biased towards the preservation of harder parts of organisms, such as shells, teeth and bones, as soft parts such as internal organs, eyes, or even completely soft organisms, like worms, tend to decay before they can be fossilised. Little is known about the environmental conditions which stop this process soon enough for the organism to be fossilised.

New Oxford University research suggests that the mineralogy of the surrounding earth is key to conserving soft parts of organisms, and finding more exceptional fossils. Part-funded by NASA, the work could potentially support the Mars Rover Curiosity in its sample analysis, and speed up the search for traces of life on other planets.

Perhaps the most iconic of all exceptional fossil deposits is the Burgess Shale of Canada, popularised by Stephen J. Gould's Wonderful Life. Dating to around 500 million years ago, the deposit preserves exceptional fossils from the Cambrian Explosion, an event which saw the rapid diversification of early animal life from simpler single-celled ancestors. Burgess Shale-type fossil localities are now known across the globe and without them roughly 80% of Cambrian organisms (those that have no hard skeleton or shell) would be unknown, distorting our picture of early animal evolution.

Published in Geology, the study, conducted by researchers from Oxford's Department of Earth Sciences, Yale University, and Pomona College, builds on their previous research which revealed that certain clay minerals are toxic to bacteria that decay marine animals. This time around, the team set out to find geological evidence that rocks composed of the same clay minerals are the hosts of Burgess Shale-type fossils.

The team examined more than 200 Cambrian rock samples using powder X-ray diffraction analysis to determine their mineralogical composition, comparing rocks with Burgess Shale-type fossils with those with only fossilised shells and bones. Nicholas Tosca, Associate Professor of Sedimentary Geology at Oxford, said: 'The number of samples required for this study was made possible because the diffractometer at Oxford collects mineralogical data 250 times faster than a conventional instrument.'

The findings reveals that soft tissue fossils are generally found in rocks rich in the mineral berthierine, one of the main clay minerals identified by the previous study as being toxic to decay bacteria. Ross Anderson, lead author and fellow at All Souls College, Oxford, explains: 'Berthierine is an interesting mineral because it forms in tropical settings when the sediments contain elevated concentrations of iron. This means that Burgess Shale-type fossils are likely confined to rocks which were formed at tropical latitudes and which come from locations or time periods that have enhanced iron. This observation is exciting because it means for the first time we can more accurately interpret the geographic and temporal distribution of these iconic fossils, crucial if we want to understand their biology and ecology.'

The study provides a mineralogical signature which can be used to find the more elusive sites that are home to these extraordinary fossils. 'The mineralogical associations we identified mean that for a given Cambrian sedimentary mudrock we can predict with around 80% accuracy whether it is likely to contain Burgess Shale-type fossils,' explains Anderson.

Of the project's wider applications, potentially supporting the search for life beyond our own planet, Anderson adds: 'For the vast majority of Earth's history, life has not possessed hard shells or skeletons. This means that if we want to look for fossil evidence of life on other planets like Mars, the chances are we probably need to find fossils of entirely soft organisms, and Burgess Shale-type fossilisation provides a way. NASA's Curiosity rover has the ability to record mineralogy on the Martian surface, so it could potentially look for the types of rocks which might be most conducive to preserving these fossils.'

Read more at Science Daily

Women who clean at home or work face increased lung function decline

The accelerated lung function decline in the women working as cleaners was "comparable to smoking somewhat less than 20 pack- years."
Women who work as cleaners or regularly use cleaning sprays or other cleaning products at home appear to experience a greater decline in lung function over time than women who do not clean, according to new research published online in the American Thoracic Society's American Journal of Respiratory and Critical Care Medicine.

In "Cleaning at Home and at Work in Relation to Lung Function Decline and Airway Obstruction," researchers at the University of Bergen in Norway analyzed data from 6,235 participants in the European Community Respiratory Health Survey. The participants, whose average age was 34 when they enrolled, were followed for more than 20 years.

"While the short-term effects of cleaning chemicals on asthma are becoming increasingly well documented, we lack knowledge of the long-term impact," said senior study author Cecile Svanes, MD, PhD, a professor at the university's Centre for International Health. "We feared that such chemicals, by steadily causing a little damage to the airways day after day, year after year, might accelerate the rate of lung function decline that occurs with age."

The study found that compared to women not engaged in cleaning:

  • Forced expiratory volume in one second (FEV1), or the amount of air a person can forcibly exhale in one second, declined 3.6 milliliters (ml)/year faster in women who cleaned at home and 3.9 ml/year faster in women who worked as cleaners.
  • Forced vital capacity (FVC), or the total amount of air a person can forcibly exhale, declined 4.3 ml/year faster in women who cleaned at home and 7.1 ml/year faster in women who worked as cleaners.

The authors found that the accelerated lung function decline in the women working as cleaners was "comparable to smoking somewhat less than 20 pack- years."

That level of lung impairment was surprising at first, said lead study author Øistein Svanes, a doctoral student also at the Department for Clinical Science. "However, when you think of inhaling small particles from cleaning agents that are meant for cleaning the floor and not your lungs, maybe it is not so surprising after all."

The authors speculate that the decline in lung function is attributable to the irritation that most cleaning chemicals cause on the mucous membranes lining the airways, which over time results in persistent changes in the airways and airway remodeling.

The study did not find that the ratio of FEV1 to FVC declined more rapidly in women who cleaned than in those who did not. The metric is used when diagnosing and monitoring patients with chronic obstructive pulmonary disease, or COPD. The study did find that asthma was more prevalent in women who cleaned at home (12.3 percent) or at work (13.7 percent) compared to those who did not clean (9.6 percent).

The study also did not find that men who cleaned, either at home or at work, experienced greater decline in FEV1 or FVC than men who did not.

The researchers took into account factors that might have biased the results, including smoking history, body mass index and education.

Study limitations include the fact that the study population included very few women who did not clean at home or work. These women, the authors wrote, might "constitute a selected socioeconomic group." The number of men who worked as occupational cleaners was also small, and their exposure to cleaning agents was likely different from that of women working as cleaning professionals.

"The take home message of this study is that in the long run cleaning chemicals very likely cause rather substantial damage to your lungs," Øistein Svanes said. "These chemicals are usually unnecessary; microfiber cloths and water are more than enough for most purposes."

Read more at Science Daily

Physicists create new form of light

Scientists at MIT, Harvard University, and elsewhere have now demonstrated that photons can be made to interact — an accomplishment that could open a path toward using photons in quantum computing, if not in light sabers.
Try a quick experiment: Take two flashlights into a dark room and shine them so that their light beams cross. Notice anything peculiar? The rather anticlimactic answer is, probably not. That's because the individual photons that make up light do not interact. Instead, they simply pass each other by, like indifferent spirits in the night.

But what if light particles could be made to interact, attracting and repelling each other like atoms in ordinary matter? One tantalizing, albeit sci-fi possibility: light sabers -- beams of light that can pull and push on each other, making for dazzling, epic confrontations. Or, in a more likely scenario, two beams of light could meet and merge into one single, luminous stream.

It may seem like such optical behavior would require bending the rules of physics, but in fact, scientists at MIT, Harvard University, and elsewhere have now demonstrated that photons can indeed be made to interact -- an accomplishment that could open a path toward using photons in quantum computing, if not in light sabers.

In a paper published today in the journal Science, the team, led by Vladan Vuletic, the Lester Wolfe Professor of Physics at MIT, and Professor Mikhail Lukin from Harvard University, reports that it has observed groups of three photons interacting and, in effect, sticking together to form a completely new kind of photonic matter.

In controlled experiments, the researchers found that when they shone a very weak laser beam through a dense cloud of ultracold rubidium atoms, rather than exiting the cloud as single, randomly spaced photons, the photons bound together in pairs or triplets, suggesting some kind of interaction -- in this case, attraction -- taking place among them.

While photons normally have no mass and travel at 300,000 kilometers per second (the speed of light), the researchers found that the bound photons actually acquired a fraction of an electron's mass. These newly weighed-down light particles were also relatively sluggish, traveling about 100,000 times slower than normal noninteracting photons.

Vuletic says the results demonstrate that photons can indeed attract, or entangle each other. If they can be made to interact in other ways, photons may be harnessed to perform extremely fast, incredibly complex quantum computations.

"The interaction of individual photons has been a very long dream for decades," Vuletic says.

Vuletic's co-authors include Qi-Yung Liang, Sergio Cantu, and Travis Nicholson from MIT, Lukin and Aditya Venkatramani of Harvard, Michael Gullans and Alexey Gorshkov of the University of Maryland, Jeff Thompson from Princeton University, and Cheng Ching of the University of Chicago.

Biggering and biggering

Vuletic and Lukin lead the MIT-Harvard Center for Ultracold Atoms, and together they have been looking for ways, both theoretical and experimental, to encourage interactions between photons. In 2013, the effort paid off, as the team observed pairs of photons interacting and binding together for the first time, creating an entirely new state of matter.

In their new work, the researchers wondered whether interactions could take place between not only two photons, but more.

"For example, you can combine oxygen molecules to form O2 and O3 (ozone), but not O4, and for some molecules you can't form even a three-particle molecule," Vuletic says. "So it was an open question: Can you add more photons to a molecule to make bigger and bigger things?"

To find out, the team used the same experimental approach they used to observe two-photon interactions. The process begins with cooling a cloud of rubidium atoms to ultracold temperatures, just a millionth of a degree above absolute zero. Cooling the atoms slows them to a near standstill. Through this cloud of immobilized atoms, the researchers then shine a very weak laser beam -- so weak, in fact, that only a handful of photons travel through the cloud at any one time.

The researchers then measure the photons as they come out the other side of the atom cloud. In the new experiment, they found that the photons streamed out as pairs and triplets, rather than exiting the cloud at random intervals, as single photons having nothing to do with each other.

In addition to tracking the number and rate of photons, the team measured the phase of photons, before and after traveling through the atom cloud. A photon's phase indicates its frequency of oscillation.

"The phase tells you how strongly they're interacting, and the larger the phase, the stronger they are bound together," Venkatramani explains. The team observed that as three-photon particles exited the atom cloud simultaneously, their phase was shifted compared to what it was when the photons didn't interact at all, and was three times larger than the phase shift of two-photon molecules. "This means these photons are not just each of them independently interacting, but they're all together interacting strongly."

Memorable encounters

The researchers then developed a hypothesis to explain what might have caused the photons to interact in the first place. Their model, based on physical principles, puts forth the following scenario: As a single photon moves through the cloud of rubidium atoms, it briefly lands on a nearby atom before skipping to another atom, like a bee flitting between flowers, until it reaches the other end.

If another photon is simultaneously traveling through the cloud, it can also spend some time on a rubidium atom, forming a polariton -- a hybrid that is part photon, part atom. Then two polaritons can interact with each other via their atomic component. At the edge of the cloud, the atoms remain where they are, while the photons exit, still bound together. The researchers found that this same phenomenon can occur with three photons, forming an even stronger bond than the interactions between two photons.

"What was interesting was that these triplets formed at all," Vuletic says. "It was also not known whether they would be equally, less, or more strongly bound compared with photon pairs."

The entire interaction within the atom cloud occurs over a millionth of a second. And it is this interaction that triggers photons to remain bound together, even after they've left the cloud.

"What's neat about this is, when photons go through the medium, anything that happens in the medium, they 'remember' when they get out," Cantu says.

This means that photons that have interacted with each other, in this case through an attraction between them, can be thought of as strongly correlated, or entangled -- a key property for any quantum computing bit.

"Photons can travel very fast over long distances, and people have been using light to transmit information, such as in optical fibers," Vuletic says. "If photons can influence one another, then if you can entangle these photons, and we've done that, you can use them to distribute quantum information in an interesting and useful way."

Going forward, the team will look for ways to coerce other interactions such as repulsion, where photons may scatter off each other like billiard balls.

Read more at Science Daily

Feb 15, 2018

Birds and primates share brain cell types linked to intelligence

Neuronal cell types in the brains of birds linked to goal-directed behaviors and cognition are similar to cells in the mammalian neocortex, the large, layered structure on the outer surface of the brain where most higher-order processing takes place.

In a new study, published this week in the journal Current Biology, scientists from the University of Chicago show that some neurons in bird brains form the same kind of circuitry and have the same molecular signature as cells that enable connectivity between different areas of the mammalian neocortex. The researchers found that alligators share these cell types as well, suggesting that while mammal, bird and reptile brains have very different anatomical structures, they operate using the same shared set of brain cell types.

"Birds are more intelligent than you think, and they do clever things. So, the question is: What kind of brain circuitry are they using?" said Clifton Ragsdale, PhD, professor of neurobiology at UChicago and senior author of the study. "What this research shows is that they're using the same cell types with the same kinds of connections we see in the neocortex, but with a very different kind of organization."

Both the mammalian neocortex and a structure in the bird brain called the dorsal ventricular ridge (DVR) develop from an embryonic region called the telencephalon. However, the two regions mature into very different shapes. The neocortex is made up of six distinct layers while the DVR contains large clusters of neurons called nuclei.

Because of this different anatomy, many scientists proposed that the bird DVR does not correspond to the mammalian cortex but is instead analogous to another mammalian brain structure called the amygdala.

In 2012, Ragsdale and his team confirmed a 50-year-old hypothesis by University of California San Diego neuroscientist Harvey Karten that proposed the DVR performs a similar function to the neocortex, but with dramatically different anatomy. In that study, the UChicago researchers matched genetic markers of the "input" and "output" neurons of the mammalian neocortex with genes expressed in several bird DVR nuclei.

In the new study, led by graduate student Steven Briscoe, the team found that other populations of neurons in the bird DVR share molecular signatures with neocortical intratelencephalic cells, or IT neurons. These IT neurons form a critical link in the circuitry of the neocortex. They help communicate between different neocortical layers and across cortical areas from one side of the brain to the other. The team then extended their work from birds to reptiles and identified IT neurons in a similar place in the alligator DVR.

"The structure of the avian DVR looks nothing like the mammalian neocortex, and this has historically been a huge problem in comparative neuroscience," Briscoe said. "Anatomists have debated how to compare the DVR and neocortex for over a century, and our identification of IT neurons in the bird DVR helps to explain how such different brain structures can give rise to similar behaviors."

The research suggests an interesting possibility that birds and primates evolved intelligence independently, developing vastly different brain structures but starting with the same shared sets of cell types.

Read more at Science Daily

Scientists discover almost 100 new exoplanets

After detecting the first exoplanets in the 1990s it has become clear that planets around other stars are the rule rather than the exception and there are likely hundreds of billions of exoplanets in the Milky Way alone. The search for these planets is now a large field of astronomy.
"We started out analyzing 275 candidates of which 149 were validated as real exoplanets. In turn 95 of these planets have proved to be new discoveries," said American PhD student Andrew Mayo at the National Space Institute (DTU Space) at the Technical University of Denmark.

"This research has been underway since the first K2 data release in 2014."

Mayo is the main author of the work being presented in the Astronomical Journal.

The research has been conducted partly as a senior project during his undergraduate studies at Harvard College. It has also involved a team of international colleagues from institutions such as NASA, Caltech, UC Berkeley, the University of Copenhagen, and the University of Tokyo.

The Kepler spacecraft was launched in 2009 to hunt for exoplanets in a single patch of sky, but in 2013 a mechanical failure crippled the telescope. However, astronomers and engineers devised a way to repurpose and save the space telescope by changing its field of view periodically. This solution paved the way for the follow up K2 mission, which is still ongoing as the spacecraft searches for exoplanet transits.

These transits can be found by registering dips in light caused by the shadow of an exoplanet as it crosses in front of its host star. These dips are indications of exoplanets which must then be examined much closer in order to validate the candidates that are actually exoplanets.

The field of exoplanets is relatively young. The first planet orbiting a star similar to our own Sun was detected only in 1995. Today some 3,600 exoplanets have been found, ranging from rocky Earth-sized planets to large gas giants like Jupiter.

It's difficult work to distinguish which signals are actually coming from exoplanets. Mayo and his colleagues analyzed hundreds of signals of potential exoplanets thoroughly to determine which signals were created by exoplanets and which were caused by other sources.

"We found that some of the signals were caused by multiple star systems or noise from the spacecraft. But we also detected planets that range from sub Earth-sized to the size of Jupiter and larger," said Mayo.

One of the planets detected was orbiting a very bright star.

"We validated a planet on a 10 day orbit around a star called HD 212657, which is now the brightest star found by either the Kepler or K2 missions to host a validated planet. Planets around bright stars are important because astronomers can learn a lot about them from ground-based observatories," said Mayo.

"Exoplanets are a very exciting field of space science. As more planets are discovered, astronomers will develop a much better picture of the nature of exoplanets which in turn will allow us to place our own solar system into a galactic context".

The Kepler space telescope has made huge contributions to the field of exoplanets both in its original mission and its successor K2 mission. So far these missions have provided over 5,100 exoplanet candidates that can now be examined more closely.

Read more at Science Daily

A Solar Storm Is Approaching Earth

If you live in the high latitudes, expect to see the Northern or Southern Lights shortly. A solar storm is on its way to Earth, as charged particles from the sun move towards our planet.

The solar particles are expected to hit as early as Thursday, February 15, but could arrive the following day. Auroras will shine in the sky as the charged particles hit gas molecules high in the atmosphere, causing molecules to glow. There's also a small chance that the storm will disrupt satellites or power grids.

"Aurora may be visible at high latitudes," the National Oceanic and Atmospheric Administration wrote in a statment. This could include the "northern tier" of the United States, with affected states including northern Michigan and Maine.

NOAA added that the forecast calls for a high probability of a G-1 or "minor" storm, which could strengthen to a G-2 or "moderate" storm depending on how the stream of particles hit Earth. Geomagnetic storms are ranked on a scale, with G at the bottom, R in the middle, and S as the most severe. Forecasts now say the particles will give our planet a glancing blow.

The particles, which originated from the sun after a moderate solar flare on February 12, could also affect power grids or spacecraft. NOAA stated that "weak power grid fluctuations" are possible, as well as a "minor impact on satellite operations."

NOAA and NASA monitor the sun using several telescopes; famous examples are the Solar Dynamics Observatory (SDO) and the Solar and Heliospheric Observatory (SOHO). These telescopes help generate weather forecasts by detecting when solar activity occurs. Scientists also study the sun to learn more about its internal structure and gather data to make better predictions about flares and particle ejections.

Solar flares and particle ejections are associated with sunspots — dark areas on the sun's surface — that host intense magnetic activity. As the magnetic fields in a sunspot cross, NASA stated, this can cause a sudden energy explosion, also known as a solar flare. This sends radiation out into space.

Sometimes these explosions can also send off charged particles, which are called coronal mass ejections or CMEs. "CMEs are huge bubbles of radiation and particles from the sun," NASA stated. "They explode into space at very high speed when the sun's magnetic field lines suddenly organize."

Many solar flares and CMEs blast harmlessly off into empty space. If they are directed towards Earth, however, space forecasters keep a close eye to see how severe the solar storm will be. If the storm looks bad, engineers can shut down non-essential systems on satellites or prepare for possible fluctuations in the power grid.

The sun has an 11-year cycle of sunspot activity. The last maximum in the cycle was in April 2014, with frequent and powerful solar flares and CMEs. The year 2018, by contrast, is expected to be quieter.

Read more at Seeker

Next-Gen RNA Sequencing Reveals Biological Patterns in Psychiatric Disorders

When forensic scientists examine the brains of individuals who died from advanced Alzheimer’s disease, the pathology is obvious. The diseased brain is choked with amyloid plaques and tangles of tau protein.

But when scientists look at the brains of people who suffered from serious psychiatric conditions like schizophrenia or bipolar disorder, there are no such obvious signs. If psychiatric disorders have biological roots, the clues may be hidden away deep within our DNA.

Over the last decade, there’s been an explosion in so-called genome-wide association studies. Armed with full maps of the human genome, researchers compare the entire DNA code of healthy people against individuals who suffer from diseases that are believed to have a genetic component. The hope is to identify the precise genetic variations — changes in just a few base pairs of A, G, C, and T — that may be responsible for disease, including mental illness.

Recently, genetic researchers have taken this a step further, sequencing and comparing the messenger RNA within cells that translates the DNA code into the proteins and enzymes that power human biology. If DNA codes for individual genes, messenger RNA is responsible for expressing those genes and at what levels.

Dr. Daniel Geschwind
Using this next-generation RNA sequencing, a team from UCLA believes that it’s identified some striking similarities between the patterns of gene expression found in the brains of people who suffered from five different psychiatric conditions: autism, schizophrenia, bipolar disorder, major depressive disorder, and alcohol abuse disorder.

The UCLA researchers sequenced messenger RNA from 700 postmortem brains of individuals diagnosed with one of the major psychiatric disorders and compared the expression levels of 10,000 genes against those found in healthy brains. The analysis revealed significant genetic overlap between the conditions and may point the way to more targeted treatments, according to a paper published in the journal Science.

Michael Gandal isan assistant professor of psychiatry and biobehavioral sciences at UCLA and lead author of the RNA sequencing paper. He told Seeker that the big question researchers are trying to answer is how genetic variations work from a biological standpoint. What are the underlying mechanisms that increase risk for disorders like autism or schizophrenia?

The answers may lie in the transcriptome, a term that describes the entire set of genes in an organism and their different expression levels. If the genome is the blueprint, the transcriptome is how those instructions are put into action.

In the study, Gandal and his colleague Daniel Geschwind, director of the UCLA Center for Autism Research and Treatment, were specifically analyzing the transcriptome of the brain. With RNA sequencing, they could see which specific genes in affected brains were expressed at higher levels (upregulated) and lower levels (downregulated) than healthy brains from the same population demographic.

When examined from a “10,000-foot view,” patterns and clusters began to emerge in the data, said Gandal. Genes associated with neuronal and synaptic processes, for example, were downregulated in the brains of people with autism, schizophrenia, and bipolar disorder.

“Our study was able to look in human brain tissue and show that there are reproducible patterns in the brain tissue itself that we think reflects the genetic risk for disease,” said Gandal. “This can give us a sense for what we think might be the primary pathology in these different disorders, at least in terms of how these genetic risk factors are playing out in the brain.”

While it’s too early to link patterns of gene expression to specific symptoms of psychiatric illnesses, Gandal said that his team is already using the RNA cluster data to explore potential targets for treatment.

For example, their RNA sequencing analysis showed that autism alone was associated with an upregulation of the genes that control for microglial cells, a cell that functions as a first responder in the brain’s immune system. Overexpression of microglia could lead to inflammation, which may contribute to some of the cognitive and behavioral impairments associated with autism.

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Feb 14, 2018

Love and fear are visible across the brain instead of being restricted to any brain region

An emotional state mainly activates wide, overlapping neural networks. When comparing groups of emotions, positive emotions activate the anterior prefrontal cortex, negative basic emotions tend to activate the somatomotor and subcortical regions, and negative social emotions activate brain areas that process motor and social information.
The brain mechanisms of basic emotions such as anger and happiness are fairly similar across people. Differences are greater in social emotions, such as gratitude and contempt.

In the field of affective neuroscience, rivalling theories debate whether emotional states can be regarded as an activity of only certain brain regions. According to a new doctoral dissertation at Aalto University, an emotional state affects the operation of the entire brain instead of individual emotions being localised only in specific regions in the brain.

'From the biological point of view, an emotion is a state of the entire brain at a given moment. For example, the brain may interpret certain action models, memories and bodily changes altogether as anger,' explains Doctoral Candidate Heini Saarimäki.

Different emotional states of the participants were evoked with films, mental imagery or guided imagery based on narratives. After that, a classifier algorithm based on machine learning was trained to connect the specific emotions and the brain data related to them. The classifier algorithm was then tested by giving it new brain data and by measuring how successfully the algorithm recognised the correct emotion solely on the basis of the brain data. The method for measuring brain activity is based on measuring the changes in the blood oxygen content in the brain and it provides information on the activation of the brain with millimetre-accuracy.

The researchers were particularly interested in emotion-specific brain maps, that is, maps on the localisation of emotions in various areas across the entire brain. By analysing the activity of the entire brain, a machine learning algorithm may be able to determine the emotional state in question.

Saarimäki and her colleagues discovered that the brain maps of basic emotions such as anger, happiness, sadness, fear, surprise and disgust were to some extent similar across people. Basic emotions seem to be at least partially biologically determined, whereas social emotions -- gratitude, contempt, pride and shame -- are to a greater extent built on experience. In social emotions, the differences in brain activity between people are greater than in basic emotions.

From groups of similar emotions to the power of empathy

The classifier algorithm makes more mistakes with distinguishing emotions that have similar brain maps than with emotions whose brain maps have little in common. This information can be further compared to how people interpret certain emotions subjectively. Positive emotions, such as happiness, love, gratitude and pride, are more similar both as subjective experiences and at the level of brain activity. Negative emotions, such as fear, anger and sadness, on the other hand, have as a group a similar basis in brain activity. The brain activities during negative social emotions such as shame, guilt and contempt, in turn, resemble each other most but differ from the brain maps of basic negative emotions.

'We also discovered that the accuracy of emotion classification seems to be related to individual differences in emotional processing, such as in the ability to feel empathy. We want to examine in more detail how individual differences, for example in empathy, are linked to the functioning of the emotional systems of the brain. A separate research project investigating this is about to begin,' Saarimäki explains.

Read more at Science Daily

Rotating dusty gaseous donut around an active supermassive black hole

ALMA revealed the rotation of the torus very clearly for the first time.
Almost all galaxies hold concealed monstrous black holes in their centers. Researchers have known for a long time that the more massive the galaxy is, the more massive the central black hole is. This sounds reasonable at first, but host galaxies are 10 billion times bigger than the central black holes; it should be difficult for two objects of such vastly different scales to directly affect each other. So how could such a relation develop?

Aiming to solve this shadowy problem, a team of astronomers utilized the high resolution of ALMA to observe the center of spiral galaxy M77. The central region of M77 is an "active galactic nucleus," or AGN, which means that matter is vigorously falling toward the central supermassive black hole and emitting intense light. AGNs can strongly affect the surrounding environment, therefore they are important objects for solving the mystery of the co-evolution of galaxies and black holes.

The team imaged the area around the supermassive black hole in M77 and resolved a compact gaseous structure with a radius of 20 light-years. And, the astronomers found that the compact structure is rotating around the black hole, as expected.

"To interpret various observational features of AGNs, astronomers have assumed rotating donut-like structures of dusty gas around active supermassive black holes. This is called the 'unified model' of AGN," explained Masatoshi Imanishi?(National Astronomical Observatory of Japan), the lead author on a paper published in the Astrophysical Journal Letters. "However, the dusty gaseous donut is very tiny in appearance. With the high resolution of ALMA, now we can directly see the structure."

Many astronomers have observed the center of M77 before, but never has the rotation of the gas donut around the black hole been seen so clearly. Besides the superior resolution of ALMA, the selection of molecular emission lines to observe was key to revealing the structure. The team observed specific microwave emission from hydrogen cyanide molecules (HCN) and formyl ions (HCO+). These molecules emit microwaves only in dense gas, whereas the more frequently observed carbon monoxide (CO) emits microwaves under a variety of conditions . The torus around the AGN is assumed to be very dense, and the team's strategy was right on the mark.

"Previous observations have revealed the east-west elongation of the dusty gaseous torus. The dynamics revealed from our ALMA data agrees exactly with the expected rotational orientation of the torus," said Imanishi.

Interestingly, the distribution of gas around the supermassive black hole is much more complicated than what a simple unified model suggests. The torus seems to have an asymmetry and the rotation is not just following the gravity of the black hole but also contains highly random motion. These facts could indicate the AGN had a violent history, possibly including a merger with a small galaxy. Nevertheless, the identification of the rotating torus is an important step.

Read more at Science Daily

Alzheimer's disease reversed in mouse model

The brain of a 10-month-old mouse with Alzheimer's disease (left) is full of amyloid plaques (red) surrounded by activated microglial cells (green). But these hallmarks of Alzheimer's disease are reversed in animals that have gradually lost the BACE1 enzyme (right).
A team of researchers from the Cleveland Clinic Lerner Research Institute have found that gradually depleting an enzyme called BACE1 completely reverses the formation of amyloid plaques in the brains of mice with Alzheimer's disease, thereby improving the animals' cognitive function. The study, which will be published February 14 in the Journal of Experimental Medicine, raises hopes that drugs targeting this enzyme will be able to successfully treat Alzheimer's disease in humans.

One of the earliest events in Alzheimer's disease is an abnormal buildup of beta-amyloid peptide, which can form large, amyloid plaques in the brain and disrupt the function of neuronal synapses. Also known as beta-secretase, BACE1 helps produce beta-amyloid peptide by cleaving amyloid precursor protein (APP). Drugs that inhibit BACE1 are therefore being developed as potential Alzheimer's disease treatments but, because BACE1 controls many important processes by cleaving proteins other than APP, these drugs could have serious side effects.

Mice completely lacking BACE1 suffer severe neurodevelopmental defects. To investigate whether inhibiting BACE1 in adults might be less harmful, Riqiang Yan and colleagues generated mice that gradually lose this enzyme as they grow older. These mice developed normally and appeared to remain perfectly healthy over time.

The researchers then bred these rodents with mice that start to develop amyloid plaques and Alzheimer's disease when they are 75 days old. The resulting offspring also formed plaques at this age, even though their BACE1 levels were approximately 50% lower than normal. Remarkably, however, the plaques began to disappear as the mice continued to age and lose BACE1 activity, until, at 10 months old, the mice had no plaques in their brains at all.

"To our knowledge, this is the first observation of such a dramatic reversal of amyloid deposition in any study of Alzheimer's disease mouse models," says Yan, who will be moving to become chair of the department of neuroscience at the University of Connecticut this spring.

Decreasing BACE1 activity also resulted in lower beta-amyloid peptide levels and reversed other hallmarks of Alzheimer's disease, such as the activation of microglial cells and the formation of abnormal neuronal processes.

Loss of BACE1 also improved the learning and memory of mice with Alzheimer's disease. However, when the researchers made electrophysiological recordings of neurons from these animals, they found that depletion of BACE1 only partially restored synaptic function, suggesting that BACE1 may be required for optimal synaptic activity and cognition.

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Medical care for wounded ants

A Matabele ant treats the wounds of a mate whose limbs were bitten off during a fight with termite soldiers.
The African Matabele ants (Megaponera analis) tend to the wounds of their injured comrades. And they do so rather successfully: Without such attendance, 80 percent of the injured ants die; after receiving "medical" treatment, only 10 percent succumb to their injuries.

Erik T. Frank, Marten Wehrhan and Karl Eduard Linsenmair from Julius-Maximilians-Universität Würzburg (JMU) in Bavaria, Germany, made this astonishing discovery. Their results have been published in the journal Proceedings of the Royal Society B. No other insects are known to dress the wounds of their comrades. The JMU biologists even believe that such behaviour is unique in the entire animal kingdom.

Ants go on high-risk raids

Matabele ants have a high risk of getting injured every day: The insects, which are widely distributed in Sub-Saharan Africa, set out to raid termites two to four times a day. Proceeding in long files of 200 to 600 animals, they raid termites at their foraging sites, killing many workers and hauling the prey back to their nest where they are ultimately eaten.

However, the ants meet fierce resistance from the well-armoured termite soldiers that are very adept at using their powerful jaws to fend off the attackers. Injury and mortality among the ants occur during such combats. For example, the ants frequently lose limbs that are bitten off by termite soldiers. When an ant is injured in a fight, it calls its mates for help by excreting a chemical substance which makes them carry their injured comrade back to the nest. Erik T. Frank already described this rescue service in 2017.

But the Würzburg biologists dug deeper: What happens once the injured ants are back in the nest? The ants treat the open wounds of their injured fellows by "licking" them intensively, often for several minutes. "We suppose that they do this to clean the wounds and maybe even apply antimicrobial substances with their saliva to reduce the risk of bacterial or fungal infection," Frank explains.

Severely injured ants are left behind on the battlefield

The team from the JMU Biocentre uncovered more exciting details about the emergency rescue service of the Matabele ants. Badly injured ants missing five of their six legs, for example, get no help on the battleground. The decision who is saved and who is left behind is made not by the rescuers but by the injured ants themselves.

Slightly injured ants keep still and even pull in their remaining limbs to facilitate transport. Their badly injured counterparts in contrast struggle and lash out wildly. "They simply don't cooperate with the helpers and are left behind as a result," Frank says. So the hopeless cases make sure that no energy is invested in rescuing them.

Slightly injured ants keep still

When Matabele ants are only slightly injured, they move much more slowly than normal once potential helpers are near. This behaviour probably increases their chances of being noticed by the other ants rushing back to the nest in a column. Or it may be that ants can localize the "save-me-substance" more easily in resting ants.

Read more at Science Daily

Feb 13, 2018

Ancient trail of Columbian mammoths uncovered in south-central Oregon

Footprints of mammoths, dated to 43,000 years ago, are seen in a portion of a trackway that was uncovered by researchers in 2017 in an ancient dry lake bed in Lake County, Oregon.
A fossilized trackway on public lands in Lake County, Oregon, may reveal clues about the ancient family dynamics of Columbian mammoths.

Recently excavated by a team from the University of Oregon Museum of Natural and Cultural History, the Bureau of Land Management and the University of Louisiana, the trackway includes 117 footprints thought to represent a number of adults as well as juvenile and infant mammoths.

Discovered by Museum of Natural and Cultural History paleontologist Greg Retallack during a 2014 class field trip on fossils at the UO, the Ice Age trackway is the focus of a new study appearing online ahead of print in the journal Palaeogeography, Palaeoclimatology, Palaeoecology.

Retallack returned to the site with the study's coauthors, including UO science librarian Dean Walton, in 2017. The team zeroed in on a 20-footprint track, dating to roughly 43,000 years ago, that exhibited some intriguing features.

"These prints were especially close together, and those on the right were more deeply impressed than those on the left-as if an adult mammoth had been limping," said Retallack, also a professor in the UO Department of Earth Sciences and the study's lead author.

But, as the study reveals, the limping animal wasn't alone: Two sets of smaller footprints appeared to be approaching and retreating from the limper's trackway.

"These juveniles may have been interacting with an injured adult female, returning to her repeatedly throughout the journey, possibly out of concern for her slow progress," Retallack said. "Such behavior has been observed with wounded adults in modern, matriarchal herds of African elephants."

The tracks were made in a layer of volcanic soil at Fossil Lake, a site first excavated by UO science professor Thomas Condon in 1876 and today administered by the Bureau of Land Management.

"America's public lands are some of the world's greatest outdoor laboratories. Localities such as this mammoth tracksite are unique parts of America's heritage and indicate that there are many special sites still to be discovered," said study co-author Brent Breithaupt, a paleontologist in the Wyoming State Office of the Bureau of Land Management.

Specimens from the 1876 Fossil Lake excavation-along with the rest of Condon's extensive assemblage of fossils and geologic specimens-were donated to UO in the early 1900s and form the core of the museum's Condon Fossil Collection, now under Retallack's direction and boasting upwards of 50,000 fossil specimens.

Last month a new state law went into effect, making the UO museum Oregon's default repository for fossils found on state lands. The museum is also a designated repository for artifacts and paleontological specimens collected from BLM-administered lands in Oregon, ensuring they are available to future generations for education and research.

As part of the 2017 study, Neffra Matthews of the BLM's National Operations Center in Denver, helped survey, map and document the trackway using photogrammetry, which helps scientists perform accurate measurements based on land-based or aerial photographs.

"There is a vast storehouse of natural history found on BLM-managed land, and it's exciting to work with researchers like Professor Retallack in capturing 3D data on fragile paleontological resources," she said.

Retallack said that trace fossils such as trackways can provide unique insights into natural history.

"Tracks sometimes tell more about ancient creatures than their bones, particularly when it comes to their behavior," he said. "It's amazing to see this kind of interaction preserved in the fossil record."

Read more at Science Daily

Rock art: Life-sized sculptures of dromedaries found in Saudi Arabia

High relief of standing dromedary on sandstone spur at center of image.
At a remarkable site in northwest Saudi Arabia, a CNRS archaeologist and colleagues from the Saudi Commission for Tourism and National Heritage (SCTH) have discovered camelid sculptures unlike any others in the region. They are thought to date back to the first centuries BC or AD. The find sheds new light on the evolution of rock art in the Arabian Peninsula and is the subject of an article published in Antiquity (February 2018).

Located in the province of Al Jawf in northwest Saudi Arabia, Camel Site, as it is known, was explored in 2016 and 2017 by a Franco-Saudi research team. The sculptures, some incomplete, were executed on three rocky spurs there. Though natural erosion has partly destroyed some of the works, as well as any traces of tools, the researchers were able to identify a dozen or so reliefs of varying depths representing camelids and equids. The life-sized sculpted animals are depicted without harnessing in a natural setting. One scene in particular is unprecedented: it features a dromedary meeting a donkey, an animal rarely represented in rock art. Some of the works are thus thematically very distinct from the representations often found in this region. Technically, they also differ from those discovered at other Saudi sites -- frequently simple engravings of dromedaries without relief -- or the sculpted facades of Al Ḩijr (Madâ'in Şâliḩ). In addition, certain Camel Site sculptures on upper rock faces demonstrate indisputable technical skills. Camel Site can now be considered a major showcase of Saudi rock art in a region especially propitious for archaeological discovery.

Though the site is hard to date, comparison with a relief at Petra (Jordan) leads the researchers to believe the sculptures were completed in the first centuries BC or AD. Its desert setting and proximity to caravan routes suggest Camel Site -- ill suited for permanent settlement -- was a stopover where travelers could rest or a site of worship.

From Science Daily

When it comes to extinction, body size matters

On a certain level, extinction is all about energy. Animals move over their surroundings like pacmen, chomping up resources to fuel their survival. If they gain a certain energy threshold, they reproduce, essentially earning an extra life. If they encounter too many empty patches, they starve, and by the end of the level it's game over.

Models for extinction risk are necessarily simple. Most reduce complex ecological systems to a linear relationship between resource density and population growth -- something that can be broadly applied to infer how much resource loss a species can survive.

This week in Nature Communications, an interdisciplinary team of scientists proposes a more nuanced model for extinction that also shows why animal species tend to evolve toward larger body sizes. The Nutritional State-structured Model (NSM) by ecologist Justin Yeakel (UC Merced), biologist Chris Kempes (Santa Fe Institute), and physicist Sidney Redner (Santa Fe Institute) incorporates body size and metabolic scaling into an extinction model where 'hungry' or 'full' animals, great and small, interact and procreate on a landscape with limited resources.

"Unlike many previous forager models, this one accounts for body size and metabolic scaling," Kempes explains. "It allows for predictions about extinction risk, and also gives us a systematic way of assessing how far populations are from their most stable states."

In the NSM, hungry animals are susceptible to mortality, and only full animals have the capacity to reproduce. Because animals' energetic needs change with body size, the researchers based their calculations for replenishment and reproduction on biological scaling laws that relate body size to metabolism.

They found that species of different sizes gravitate toward population states most stable against extinction. The states they derived in the model reproduce two oft-observed patterns in biology. The first, Damuth's law, is an inverse relationship between body size and population density: the bigger the species, the fewer of individuals cohabitate in a given area. Within the NSM, this fewer/larger more/smaller pattern emerges because large species are most stable against starvation in small numbers, while small species can afford to reach larger population densities.

The second relationship, Cope's rule, holds that terrestrial mammals tend to evolve toward larger body sizes. This NSM shows that, overall, larger animals with slower metabolisms are the most stable against extinction by starvation. It even predicts an energetically "ideal" mammal, robust in the face of starvation, which would be 2.5 times the size of an African elephant.

"As we incorporated more realism into how quickly organisms gain or lose body fat as they find or don't find resources, the results of our model began aligning with large-scale ecological and evolutionary relationships. Most surprising was the observation that the NSM accurately predicts the maximum mammalian body size observed in the fossil record," explains Yeakel. Though the model doesn't account for predation, it does offer a dynamic and systematic framework for understanding how foragers survive on limited resources.

Read more at Science Daily

New models give insight into the heart of the Rosette Nebula

Rosette Nebula image is based on data obtained as part of the INT Photometric H-Alpha Survey of the Northern Galactic Plane.
A hole at the heart of a stunning rose-like interstellar cloud has puzzled astronomers for decades. But new research, led by the University of Leeds, offers an explanation for the discrepancy between the size and age of the Rosetta Nebula's central cavity and that of its central stars.

The Rosette Nebula is located in the Milky Way Galaxy roughly 5,000 light-years from Earth and is known for its rose-like shape and distinctive hole at its centre. The nebula is an interstellar cloud of dust, hydrogen, helium and other ionized gases with several massive stars found in a cluster at its heart.

Stellar winds and ionising radiation from these massive stars affect the shape of the giant molecular cloud. But the size and age of the cavity observed in the centre of Rosette Nebula is too small when compared to the age of its central stars.

Through computer simulations, astronomers at Leeds and at Keele University have found the formation of the Nebula is likely to be in a thin sheet-like molecular cloud rather than in a spherical or thick disc-like shape, as some photographs may suggest. A thin disc-like structure of the cloud focusing the stellar winds away from the cloud's centre would account for the comparatively small size of the central cavity.

Study lead author, Dr Christopher Wareing, from the School of Physics and Astronomy said: "The massive stars that make up the Rosette Nebula's central cluster are a few millions of years old and halfway through their lifecycle. For the length of time their stellar winds would have been flowing, you would expect a central cavity up to ten times bigger.

"We simulated the stellar wind feedback and formation of the nebula in various molecular cloud models including a clumpy sphere, a thick filamentary disc and a thin disc, all created from the same low density initial atomic cloud.

"It was the thin disc that reproduced the physical appearance -- cavity size, shape and magnetic field alignment -- of the Nebula, at an age compatible with the central stars and their wind strengths.

"To have a model that so accurately reproduces the physical appearance in line with the observational data, without setting out to do this, is rather extraordinary.

"We were also fortunate to be able to apply data to our models from the ongoing Gaia survey, as a number of the bright stars in the Rosette Nebula are part of the survey.

Applying this data to our models gave us new understanding of the roles individual stars play in the Rosette Nebula. Next we'll look at the many other similar objects in our Galaxy and see if we can figure out their shape as well."

The simulations, published today in the Monthly Notices of the Royal Astronomical Society, were run using the Advanced Research Computing centre at Leeds. The nine simulations required roughly half a million CPU hours -- the equivalent to 57 years on a standard desktop computer.

Read more at Science Daily

Sea level rise accelerating: acceleration in 25-year satellite sea level record

Jason-3 satellite mission helped detect an acceleration in sea level rise.
Global sea level rise is not cruising along at a steady 3 mm per year, it's accelerating a little every year, like a driver merging onto a highway, according to a powerful new assessment led by CIRES Fellow Steve Nerem. He and his colleagues harnessed 25 years of satellite data to calculate that the rate is increasing by about 0.08 mm/year every year -- which could mean an annual rate of sea level rise of 10 mm/year, or even more, by 2100.

"This acceleration, driven mainly by accelerated melting in Greenland and Antarctica, has the potential to double the total sea level rise by 2100 as compared to projections that assume a constant rate -- to more than 60 cm instead of about 30." said Nerem, who is also a professor of Aerospace Engineering Sciences at the University of Colorado Boulder. "And this is almost certainly a conservative estimate," he added. "Our extrapolation assumes that sea level continues to change in the future as it has over the last 25 years. Given the large changes we are seeing in the ice sheets today, that's not likely."

If the oceans continue to change at this pace, sea level will rise 65cm (26 inches) by 2100 -- enough to cause significant problems for coastal cities, according to the new assessment by Nerem and several colleagues from CU Boulder, the University of South Florida, NASA Goddard Space Flight Center, Old Dominion University, and the National Center for Atmospheric Research. The team, driven to understand and better predict Earth's response to a warming world, published their work today in the journal Proceedings of the National Academy of Sciences.

Rising concentrations of greenhouse gases in Earth's atmosphere increase the temperature of air and water, which causes sea level to rise in two ways. First, warmer water expands, and this "thermal expansion" of the oceans has contributed about half of the 7 cm of global mean sea level rise we've seen over the last 25 years, Nerem said. Second, melting land ice flows into the ocean, also increasing sea level across the globe.

These increases were measured using satellite altimeter measurements since 1992, including the U.S./European TOPEX/Poseidon, Jason-1, Jason-2, and Jason-3 satellite missions. But detecting acceleration is challenging, even in such a long record. Episodes like volcanic eruptions can create variability: the eruption of Mount Pinatubo in 1991 decreased global mean sea level just before the Topex/Poseidon satellite launch, for example. In addition, global sea level can fluctuate due to climate patterns such as El Niños and La Niñas (the opposing phases of the El Niño Southern Oscillation, or ENSO) which influence ocean temperature and global precipitation patterns.

So Nerem and his team used climate models to account for the volcanic effects and other datasets to determine the ENSO effects, ultimately uncovering the underlying sea-level rate and acceleration over the last quarter century. They also used data from the GRACE satellite gravity mission to determine that the acceleration is largely being driven by melting ice in Greenland and Antarctica.

The team also used tide gauge data to assess potential errors in the altimeter estimate. "The tide gauge measurements are essential for determining the uncertainty in the GMSL (global mean sea level) acceleration estimate," said co-author Gary Mitchum, USF College of Marine Science. "They provide the only assessments of the satellite instruments from the ground." Others have used tide gauge data to measure GMSL acceleration, but scientists have struggled to pull out other important details from tide-gauge data, such as changes in the last couple of decades due to more active ice sheet melt.

"This study highlights the important role that can be played by satellite records in validating climate model projections," said co-author John Fasullo, a climate scientist at the National Center for Atmospheric Research. "It also demonstrates the importance of climate models in interpreting satellite records, such as in our work where they allow us to estimate the background effects of the 1991 eruption of Mount Pinatubo on global sea level."

Although this research is impactful, the authors consider their findings to be just a first step. The 25-year record is just long enough to provide an initial detection of acceleration -- the results will become more robust as the Jason-3 and subsequent altimetry satellites lengthen the time series.

Read more at Science Daily

Feb 12, 2018

No sex for all-female fish species

The Amazon molly does not produce any male offspring. The females reproduce asexually through gynogenesis. Nevertheless they need sperm to trigger the cloning process.
Species that produce asexually are rare among vertebrates, making the Amazon molly (Poecilia formosa) the big exception. The small fish species, who is native to the border region of Texas and Mexico, does not produce any male offspring. The females reproduce asexually through gynogenesis, making their daughters identical clones of themselves.

This type of reproduction also means that they need sperm to trigger the cloning process. So the Amazon molly mates with closely related Molly fish to obtain this sperm. The sperm cells even penetrate the egg cell; however, none of the male's DNA is incorporated into the Molly's eggs. Rather, the egg completely destroys the male genes.

"According to established theories, this species should no longer exist. It should have long become extinct during the course of evolution," Manfred Schartl explains. The biochemist holds the Chair of Physiological Chemistry at the Biocenter of the University of Würzburg. Schartl with an international team of researchers explored how the Amazon molly has managed to survive in spite of this. For this purpose, the researchers sequenced the genome of the fish species and compared it with that of related species. The results of their research are published in the current issue of the journal Nature Ecology & Evolution.

Contradictory to established theories

There are two main reasons that argue against asexually reproducing species surviving in the long run: "Harmful changes occur in any genome at some point. In creatures whose offspring are pure clones, these defects would accumulate over generations until there are no more healthy individuals," Schartl explains. Species that reproduce sexually can easily eliminate such defects when the number of chromosomes is reduced by half during formation of egg and sperm cells to be recombined subsequently during fertilization from half of the maternal and paternal chromosomes, respectively.

There is another argument against the long survival of a species whose offspring are all clones of their mothers: "These species are usually not capable of adapting to environmental changes as quickly as their sexually producing counterparts," Schartl says. So within a few generations, they should be on the losing side of evolution which calls for the "survival of the fittest."

Unique genetic variability

To answer the question why this theory does not apply to the Amazon molly, the scientists studied their genome as well as that of two related fish species that reproduce sexually. The main insight: "We found little evidence of genetic degeneration in the Amazon molly, but rather a unique genetic variability and clear signs of an ongoing evolutionary process," Manfred Schartl says and he continues to explain that especially the genes relevant for the immune system exhibit a high level of genetic variability in the genome of P. formosa . From this the authors of the study conclude that this variability combined with a broad immune response essentially contributes to the fact that the Amazon molly does not share the fate of many other species that reproduce asexually, namely to fall victim to pathogens.

Read more at Science Daily

Global warming could cause key culinary crops to release seeds prematurely

This photograph shows oilseed rape pods that are opening and spreading the seeds.
Climate change is threatening crop yields worldwide, yet little is known about how global warming will confuse normal plant physiology. Researchers in the UK now show that higher temperatures accelerate seed dispersal in crop species belonging to the cabbage and mustard plant family, limiting reproductive success, and this effect is mediated by a gene called INDEHISCENT. The findings appear February 12 in the journal Molecular Plant.

"In many crops, such as oilseed rape, premature seed dispersal is one of the major causes of crop loss. In the context of climate change, this could become increasingly severe," says co-senior author Vinod Kumar, a plant developmental biologist at the John Innes Centre in Norwich, England. "This study exposes the potential vulnerabilities of crop production in the warming world and paves the way for addressing this problem."

Plants have an extraordinary ability to adjust their life cycle to suit a range of environmental conditions. For example, despite day-to-day changes in weather and temperature, the release of seeds stays in tune with prevailing seasonal conditions.

"Seed dispersal is also a key trait that must be controlled when domesticating plants for food production," says co-senior author Lars Østergaard, a plant geneticist at the John Innes Centre. "With the prospect of climate change affecting crop performance, we wanted to understand how environmental signals such as temperature affect seed dispersal."

One clue came from the observation that Arabidopsis plants, which belong to the Brassicaceae (mustard or cabbage) family, mature and open their seed pods faster when grown at elevated temperatures. Inspired by this observation, Xin-Ran Li, a postdoctoral researcher with Kumar and Østergaard and first author of the study, set out to investigate.

They found that a rise in temperature, from 22ºC to 27ºC, accelerated pod shattering and seed dispersal in Arabidopsis plants and important Brassicaceae crops such as oilseed rape, a key ingredient in vegetable oil. Moreover, elevated temperatures accelerated seed dispersal by enhancing the expression of the INDEHISCENT gene, which is known to regulate the development of seed pod tissue and promote fruit opening.

"We speculate that such mechanisms have evolved to facilitate proper seasonal timing of dispersal to ensure that seeds are released under conditions that are both timely and climatically optimal for germination," Li says. "There could perhaps be a selective advantage in early maturation and dispersal in the wild."

Beyond the evolutionary implications, the findings could have broad relevance for maintaining yields of important crops. Oilseed rape is one of the largest sources of vegetable oil in the world and is also used for biofuel and animal feed. More generally, the Brassicaceae family includes many economically valuable agricultural crops, including cabbage, mustard, broccoli, cauliflower, collard greens, Brussels sprouts, bok choy, kale, turnip, radish, and rutabaga.

"We were excited by the discovery that what we found in the model plant Arabidopsis also holds true for both crop plants, such as oilseed rape, as well as non-domesticated species from the Brassicaceae family," Kumar says. "This highlights the significance of our findings both in the wild as well as in the field."

Based on their study, the research team suggests new strategies for preparing crops for global warming. For example, plant breeding efforts could focus on developing temperature-resilient varieties capable of coping with climate change. In addition, gene-editing tools, such as the CRISPR/Cas system, could be used to reduce the expression of the INDEHISCENT gene, thereby delaying seed release and reducing crop loss.

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Mouse study adds to evidence linking gut bacteria and obesity

New research highlights the potential to prevent obesity and diabetes by manipulating levels and ratios of gut bacteria, and/or modifying the chemical and biological pathways for metabolism-activating genes.
A new Johns Hopkins study of mice with the rodent equivalent of metabolic syndrome has added to evidence that the intestinal microbiome -- a "garden" of bacterial, viral and fungal genes -- plays a substantial role in the development of obesity and insulin resistance in mammals, including humans.

A report of the findings, published Jan. 24 in Mucosal Immunology, highlights the potential to prevent obesity and diabetes by manipulating levels and ratios of gut bacteria, and/or modifying the chemical and biological pathways for metabolism-activating genes.

"This study adds to our understanding of how bacteria may cause obesity, and we found particular types of bacteria in mice that were strongly linked to metabolic syndrome," says David Hackam, M.D., Ph.D., surgeon-in-chief and co-director of Johns Hopkins Children's Center and the study's senior author. "With this new knowledge we can look for ways to control the responsible bacteria or related genes and hopefully prevent obesity in children and adults."

Metabolic syndrome, a cluster of conditions including obesity around the waist, high blood sugar and increased blood pressure, is a risk factor for heart disease, stroke and diabetes. While no precise cause for metabolic syndrome is known, previous studies of Toll-like receptor 4 (TLR4), a protein that receives chemical signals to activate inflammation, have suggested that TLR4 may be responsible in part for its development.

How and why TLR4 may be responsible for metabolic syndrome, however, has been unclear, says Hackam. Perhaps, the research team thought, TLR4 signaling in different cells and their association with the bacterial environment could result in different effects on the development of metabolic syndrome.

To first determine whether TLR4 specifically in the intestinal epithelium (layer of cells that line the small and large intestines) would cause the development of metabolic syndrome, the research team ran a series of experiments on both normal mice and mice genetically modified to lack TLR4 in their intestinal epithelium.

The researchers fed both groups of mice "standard chow," or food with 22 percent fat calories, for 21 weeks.

Compared to normal mice, those lacking TLR4 showed a series of symptoms consistent with metabolic syndrome, such as significant weight gain, increased body and liver fat, and insulin resistance.

The researchers then fed both groups of mice a high-fat diet composed of 60 percent fat calories for 21 weeks to find out whether diet would affect the development of metabolic syndrome. Again, the genetically modified mice gained significantly more in weight and had greater body and liver fat than the normal mice.

To confirm the role of TLR4 expression in the intestinal epithelium, the researchers genetically modified three more groups of mice: one group expressed TLR4 only in the intestinal epithelium, another group lacked TLR4 in all body cells and the third group lacked TLR4 only in white blood cells.

All groups ate standard chow, and all groups had similar body weight, body and liver fat, and glucose tolerance compared to normal mice. Compared with normal mice, belly and small intestine fat was higher in mice lacking TLR4 only in the intestinal epithelium. This, the researchers say, provides further evidence that deleting TLR4 specifically from the intestinal epithelium is required for developing metabolic syndrome.

To investigate the role the bacterial makeup of the gut had on the mice, Hackam and his team then administered antibiotics to the normal and TLR4 intestinal epithelium-deficient mice. Antibiotics significantly reduced the amount of bacteria in the intestinal tract and prevented all symptoms of metabolic syndrome in the mice that lacked TLR4 in their intestinal epitheliums.

This demonstrates, the researchers say, that bacterial levels can be manipulated to prevent the development of metabolic syndrome.

To further explore the role of intestinal epithelial TLR4 on the development of metabolic syndrome, the research team analyzed fecal samples from the TLR4 intestinal epithelium-deficient and normal mice. The team found that specific clusters of bacteria that contribute to the development of metabolic syndrome were expressed differently in the deficient mice than in normal mice. They also determined that the bacteria expressed genes that made them "less hungry" and thus less able to digest the nutrients present in the mouse chow. This resulted in a greater abundance of food for the mouse to absorb, which contributed to obesity.

The researchers then analyzed the genes expressed in the lining of the intestinal mucosa -- the site at which food absorption occurs -- in normal and TLR4 intestinal epithelium-deficient mice. Of note, the team determined that important genes in the perixisome proliferator-activated receptor (PPAR) metabolic pathway were significantly suppressed in the deficient mice. Administering antibiotics prevented the differences in gene regulation between the two groups of mice, as did administering drugs to activate the PPAR signaling pathway, further explaining the reasons for which obesity developed.

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