Nov 24, 2016

Only half of a chromosome is DNA, 3-D imaging reveals

Rendering of a chromosome.
DNA makes up only half of the material inside chromosomes -- far less than was previously thought -- a study has revealed.

Up to 47 per cent of their structure is a mysterious sheath that surrounds the genetic material, researchers say.

While the precise function of this sheath is unknown, researchers suggest it may keep chromosomes isolated from one another during the key process of cell division.

Researchers say this so-called chromosome periphery could help to prevent errors from occurring when cells divide -- a hallmark of some forms of cancer and diseases associated with birth defects.

Using advanced imaging techniques, researchers have for the first time produced detailed 3D models of all 46 human chromosomes -- the structures inside cells that contain our genetic material.

Since their discovery in 1882, chromosomes have been the focus of intensive study. In spite of major technical advances, the complete structure and organisation of chromosomes has remained a mystery, researchers say.

Scientists at the University of Edinburgh developed a precise microscopy technique that allows them to study the structure of chromosomes in unprecedented detail. The method -- known as 3D-CLEM -- combines light and electron microscopy with computational modelling software to produce high-resolution 3D images of chromosomes.

Analysis of the images reveals that material containing DNA and supporting proteins -- known as chromatin -- accounts for between 53 and 70 per cent of the total contents of chromosomes. The remaining 30 to 47 per cent is composed of the chromosome periphery.

The study, published in the journal Molecular Cell, was funded by The Wellcome Trust. The research was carried out in collaboration with the Kazusa DNA Research Institute, Japan, National Cancer Institute, US, and the University of Liverpool.

Dr Daniel Booth, of the University of Edinburgh's School of Biological Sciences, who co-led the study, said: "The imaging technique we have developed to study chromosomes is truly groundbreaking. Defining the structure of all 46 human chromosomes for the first time has forced us to reconsider the idea that they are composed almost exclusively of chromatin, an assumption that has gone largely unchallenged for almost 100 years."

Read more at Science Daily

Endangered Australasian marsupials are ancient survivors of climate change

Lemdubuoryctes aruensis fossil teeth and jaws.
In a new paper, published in Scientific Reports, an international team of researchers has analysed fossils and DNA from living and recently extinct species to show that conservation sensitive Australasian marsupials are much older than previously thought.

"We used bandicoots as a model to examine the radiation of marsupials relative to climate change through time. Bandicoots are the marsupial equivalents of rodents and rabbits that today occupy a spectrum of desert through to rainforest habitats across Australia, New Guinea and surrounding islands. Alarmingly, however, most bandicoot species are under dire threat of extinction from introduced predators, habitat loss, and human hunting," says Dr Benjamin Kear from the Museum of Evolution at Uppsala University, and lead author on the study.

Bandicoot fossils are important for understanding how Australia's unique biodiversity has reacted to climate change in the past. They suggest that a shift towards drier conditions 5-10 million years ago drove ancient species into extinction, while simultaneously prompting the emergence of modern groups.

"The evolution of Australia's mammals has long been linked to aridity. Yet this hypothesis is based upon only a few distinguishing features found in the teeth and skulls of modern species," says Dr Ken Aplin of the Smithsonian National Museum of Natural History.

Dr Aplin recovered the remains of a remarkably archaic new fossil bandicoot, Lemdubuoryctes aruensis, from the Aru Islands of Eastern Indonesia.

The earliest bandicoot fossils are more than 25 million years old, but isolated teeth over 50 million years old hint at a deeper ancestry. In contrast, the first demonstrably modern bandicoots appeared less than 5 million years ago, while their most ancient relatives seemingly inhabited rainforests some 20 million years ago.

"The Aru Islands fossils are very primitive and resemble the most archaic extinct bandicoots, but amazingly are only 9,000 years old," says Dr Kear.

Lemdubuoryctes also did not live in a primordial rainforest, but rather a vast savannah plain that stretched between Australia and New Guinea during the last glacial maximum.

"While retreating rainforests and spreading grasslands did provide a backdrop for ecosystem change 5-10 million years ago. The Australian fauna likely adapted via changing its distribution rather than undergoing wholesale extinction and replacement," says Emeritus Prof. Michael Westerman from La Trobe University in Australia.

"This agrees with our results from DNA, which indicate that modern desert-living bandicoot groups pre-date the onset of aridity by as much as 40 million years," says Prof. Westerman.

Pointedly, such timeframes coincide with increasing seasonality and the proliferation of open Eucalyptus woodlands in the Australian continental interior.

Read more at Science Daily

Answering a longstanding question: Why is the surface of ice wet?

Figures illustrating the process in which a QLL, a thin layer of water on ice, transforms to a state of partial wetting. At the start (0.00 seconds), the surface of the ice is completely covered by the QLL. After six seconds, the layer has turned into droplets (Scale bar: 10 ?m).
A team of Hokkaido University scientists has unraveled a 150-year-old mystery surrounding the surface melting of ice crystals in subzero environments by using an advanced optical microscope.

"Ice is wet on its surface": Since this phenomenon, called surface melting, was mentioned by British scientist Michael Faraday more than 150 years ago, the question of why water on the surface of ice does not freeze in a subzero environment remained unanswered.

In their search for the underlying mechanism behind surface melting, the team used a special optical microscope jointly developed with Olympus Corp. to observe how thin water layers, or quasi-liquid layers (QLLs), are born and disappear at various temperatures and vapor pressure levels.

According to the researchers' findings, thin water layers do not homogeneously and completely wet the surface of ice -- a discovery that runs contrary to conventional wisdom. QLLs, therefore, are not able to stably exist at equilibrium, and thus vaporize.

Furthermore, the team discovered that QLLs form only when the surface of ice is growing or sublimating, under supersaturated or unsaturated vapor conditions. This finding strongly suggests that QLLs are a metastable transient state formed through vapor growth and sublimation of ice, but are absent at equilibrium.

"Our results contradict the conventional understanding that supports QLL formation at equilibrium," says Ken-ichiro Murata, the study's lead author at Hokkaido University. "However, comparing the energy states between wet surfaces and dry surfaces, it is a corollary consequence that QLLs cannot be maintained at equilibrium. Surface melting plays important roles in various phenomena such as the lubrication on ice, formation of an ozone hole, and generation of electricity in thunderclouds, of which our findings may contribute towards the understanding."

The research is likely to provide a universal framework for understanding surface melting on other crystalline surfaces, too.

Read more at Science Daily

World of viruses uncovered

Schematic invertebrate illustration.
A groundbreaking study of the virosphere of the most populous animals -- those without backbones such as insects, spiders and worms and that live around our houses -- has uncovered 1445 viruses, revealing people have only scratched the surface of the world of viruses -- but it is likely that only a few cause disease.

The meta-genomics research, a collaboration between the University of Sydney and the Chinese Centre for Disease Control and Prevention in Beijing, was made possible by new technology that also provides a powerful new way to determine what pathogens cause human diseases.

Professor Edward Holmes, from the Marie Bashir Institute for Infectious Diseases & Biosecurity and the School of Life and Environmental Sciences, who led the Sydney component of the project said although the research revealed humans are surrounded by viruses in our daily lives, these did not transfer easily to humans.

"This groundbreaking study re-writes the virology text book by showing that invertebrates carry an extraordinary number of viruses -- far more than we ever thought," Professor Holmes said.

"We have discovered that most groups of viruses that infect vertebrates -- including humans, such as those that cause well-known diseases like influenza -- are in fact derived from those present in invertebrates," said Professor Holmes, who is also based at the University's multidisciplinary Charles Perkins Centre.

The study suggests these viruses have been associated with invertebrates for potentially billions of years, rather than millions of years as had been believed -- and that invertebrates are the true hosts for many types of virus.

The paper, "Redefining the invertebrate RNA virosphere," is published tonight in Nature.

"Viruses are the most common source of DNA and RNA on earth. It is all literally right under our feet," Professor Holmes said.

The findings suggest viruses from ribonucleic acid, known as RNA -- whose principal role is generally to carry instructions from DNA -- are likely to exist in every species of cellular life.

"It's remarkable that invertebrates like insects carry so very many viruses -- no one had thought to look before because most of them had not been associated with human-borne illnesses."

Although insects such mosquitoes are well-known for their potential to transmit viruses like zika and dengue, Professor Holmes stressed that insects should not generally be feared because most viruses were not transferable to humans and invertebrates played an important role in the ecosystem.

Importantly, the same techniques used to discover these invertebrate viruses could also be used to determine the cause of novel human diseases, such as the controversial 'Lyme-like disease' that is claimed to occur following tick bites.

Read more at Science Daily

Dino-Killing Crater Reveals Clues About Ice Age Sea Level

The massive underwater crater left by the asteroid that exterminated the dinosaurs has provided new evidence that sea levels were much lower during the last Ice Age, researchers said Wednesday.

Scientists worked on a platform off Mexico's east coast to dig for clues about the destruction of life 66 million years ago inside the 200-kilometer (125-mile) wide Chicxulub crater.

By chance, the researchers found evidence that the sea was much further away than the current coast line during the last Ice Age, which began 110,000 years ago and ended around 11,000 years ago, said mission leader Jaime Urrutia, president of the Mexican Academy of Science.

While a large part of the crater is now under the Gulf of Mexico, it was not submerged during the Ice Age.

"We discovered a circular structure at the bottom (of the sea)," Urrutia told a news conference.

"The only way that (such structures) are made is through the dissolution of carbonate and for carbonate to dissolve it must be exposed to air," he said.

This shows that the Yucatan peninsula was "literally much larger" between 18,000 and 23,000 years ago during the last Ice Age, the scientist said.

International geologists, paleontologists and microbiologists arrived on the Myrtle platform in the Gulf in April and worked there for two months, digging 1.5 kilometers (.93 mile) under the sea floor and extracting six tonnes of rock.

Some results of the studies have been published in the journal Science but the analysis continues at a laboratory in Bremen, Germany.

The 12-kilometer (7.4-mile) wide asteroid slammed the earth at a speed of 30 kilometers (18.6 miles) per second some 66 million years ago.

Its crater is unique on the planet because of its "peak ring" formation, a circular elevation as high as 500 meters with a 30-kilometer radius.

The platform was installed over one of the peaks to study the nature of the rocks below and how they took shape.

The scientists have yet to explain how the granite and molten rock petrified into peaks.

The first results show that the rocks moved up "like jelly," but while the rock was molten, the granite does not show signs of heating, Urrutia said.

The $15 million Expedition 364 was the first to peer into the undersea part of the Chicxulub crater.

From Discovery News

Nov 23, 2016

Poisonous amphibian defenses are linked to higher extinction risk

Poison Dart Frog.
Research published by a Swansea University scientist has found amphibians which have a toxic defense against predators -- such as the iconic poison dart frogs -- have a much higher risk of extinction than species which use other types of defense mechanisms.

The key finding of Dr Kevin Arbuckle's latest study, published in the journal Royal Society Open Science, is that poisonous species are 60% more likely to be threatened than species without chemical defenses.

Amphibians are usually considered the most threatened group of vertebrate animals and are experiencing population declines globally, raising conservation challenges.

The threats to amphibian biodiversity are numerous and include rapid habitat destruction, exploitation, and pollutants entering the environment.

Many characteristics of animals may be linked to contemporary extinction risk. For instance, certain traits are either known or suspected to influence factors such as mortality rates or the ability of populations to recover after declines, and are therefore potential predictors of extinction risk.

The work by Dr Arbuckle, Lecturer in Biosciences (Evolutionary Biology) in the University's College of Science, used amphibians as a model system and tested whether chemical antipredator defense is associated with contemporary extinction rates. This is possible by using conservation status (e.g. 'endangered', 'vulnerable') as a measure of extinction risk in species alive today.

Dr Arbuckle said: "The results of this new study suggest that while toxic defense can be great for avoiding predators, it might be bad news in the long-term for a species. It's another example of how evolution doesn't act 'for the good of the species', but instead for the good of the individual.

"The results also suggest that how a species defends itself might be part of the puzzle of working out which species are in need of conservation efforts.

"The study builds on my previous work, which found that toxic amphibians were also more likely to become extinct over their evolutionary history, and the next step is to figure out what mechanism is behind the link between defense and extinction.

Read more at Science Daily

The Real Reason for Viking Raids: A Lack of Eligible Women

For all their infamous raiding and plundering, the Vikings who attacked from Scandinavia might have been just a bunch of lonely-hearted bachelors, new researchsuggests.

During the Viking Age, which archaeological discoveries and written texts suggested lasted from about A.D. 750 to 1050, shipborne crews from Scandinavia went "viking" — that is, they started raiding. However, the causes of these invasions remain uncertain.

Previous research suggested a wide range of potential triggers for the Viking Age. One scenario hinted that warm climates led to better harvests and thus larger populations, and that such big groups felt compelled to raid. Another cited innovations in sailing technology, such as the additions of keels and sails to Scandinavian longships.

However, scientists have argued that such explanations are not especially convincing because they raised questions as to why Scandinavians did not respond in other ways to such triggers. For example, if the trigger for the raids was "innovations in sailing technology, why did Scandinavians elect to go raiding rather than focusing their efforts on peaceful trade?" said senior study author Mark Collard, a biological anthropologist at Simon Fraser University in Burnaby, British Columbia.

Now, researchers suggest a new twist on an ancient explanation: Scandinavian practices that led powerful men to monopolize women also might have led to significant pools of unwed men. Many of these single men, looking for marriage, might have gone on raids to gain status, wealth and captives, and thus go on to secure brides and concubines of their own.

Looking for love
The idea that an excess of single young men led to Viking raiding is one of the oldest explanations for the Viking Age, put forward about 1,000 years ago by historian Dudo of St. Quentin in his tome "History of the Normans."

"We were able to reinvigorate an explanation for Viking raiding that has been around for nearly 1,000 years," Collard told Live Science.

The new model links this older idea with the customs of polygyny, or having multiple wives, and concubinage, or the keeping of concubines, that ancient texts such as the "Sagas of Icelanders," medieval German chronicles, and reports by travelers such as the 10th-century Arab envoy Ahmad Ibn Fadlān suggested that Scandinavians once practiced, the researchers said.

Polygyny and concubinage would have limited the number of women eligible for single men to marry. Evolutionary biology suggests that such an imbalance would have then boosted competition for mates among unmarried men. Indeed, prior work has suggested that, on average, men die in warfare more often in polygynous societies than in monogamous ones, the researchers said.

This resulted in volatile societies in Scandinavia in which men were moved to engage in risky behavior, such as raiding expeditions to gain wealth and status to attract brides and to secure female slaves. One consequence of this was a surge in raiding that is linked with the start of the Viking Age, the researchers suggested.

Viking bachelors

Archaeological Viking finds discoveries and historical records suggest that loot and captives were main targets of raiders, and that most Vikings were men, although there is evidence that some raiders may have been women. For instance, the Irish text "War of the Gaedhil with the Gaill" recorded that one fleet belonged to a woman dubbed the Inghen Ruaidh, or "Red Girl," in Ireland during the 10th century A.D., the researchers said.

This model suggests that most Viking raiders would have been young men. Ancient mass graves and Icelandic sagas support this explanation, the researchers said. Other possibilities the model presents include that the Vikings were hypersensitive to insults, that they viewed risk taking positively and that there was intense competition among men. Icelandic sagas also revealed that these characteristics were common in Viking societies, the scientists added.

Read more at Discovery News

Ants in Ethiopia Are Poised to Launch a Global Invasion

Scientists performing a biodiversity survey in Ethiopia say they've come across an ant species that has all the earmarks of becoming a global invader.

Researchers from the North Carolina Museum of Natural Sciences spotted the species Lepisiota canescens in the ancient forests in the northern part of the country.

L. canescens, they say, is displaying signs of forming supercolonies – rare things in the ant world, typified by colonies that move beyond a single nest, sometimes over thousands of miles of terrain. Supercolony ants essentially expand their turf without constraints. They're a threat to structures, crops, and other species and are considered an enemy of biodiversity.

True to that description, the worrisome ant has now moved out of the forests and into farmlands, also closing in on roadways and more urban settings.

Ethiopia could just be the beginning, say the researchers, who have documented their findings about the ant in a study just published in the journal Insectes Sociaux.

"The species we found in Ethiopia may have a high potential of becoming a globally invasive species. Invasive species often travel with humans, so as tourism and global commerce to this region of Ethiopia continue to increase, so will the likelihood that the ants could hitch a ride, possibly in plant material or even in the luggage of tourists," said the study's lead author, D. Magdalena Sorger, in a statement.

Sorger and the other researchers observed several supercolonies of the ant, the largest of which encompassed 24 miles.

The ant's genus already has a nasty reputation. Another species of Lepisiota temporarily halted shipping out of Australia's Darwin Port in August 2015, when port authorities needed to be sure colonies found on nearby sites could not hitch rides to other ports of call.

Now the ant's exploding numbers in Ethiopia, combined with its known ecologically invasive ways, lead the scientists to fear a global invasion is possible.

"All it takes is one pregnant queen," Sorger said. "That's how fire ants started."

"It is good to have a record of what this species does in its native habitat," Sorger said of the team's research. "Rarely do we know anything about the biology of a species before it becomes invasive."

From Discovery News

Gorillas Have Been Caught Engaging in 'Mob Violence'

Notwithstanding Planet of the Apes characterizations of militaristic gorillas, smart chimpanzees and wise orangutans, the general perception of great apes has for a while now been that chimps, our closest relatives, are most inclined to display some of the disturbingly aggressive behavior toward each other that we once considered to be exclusively our forte, while gorillas are gentle, vegetarian, giants.

A recent study, however, has shaken up one of those assumptions. While chimp groups have long been known to engage in territory-expanding raids, violent intra-species behavior had rarely been observed or even suspected in gorillas. But the new paper documents three occasions on which mountain gorilla groups have ganged up on isolated individuals for no immediately obvious reason.

Writing in the journal Nature, Stacy Rosenbaum, a biological anthropologist at the University of Chicago, and colleagues devote particular detail to one such attack, in the Virunga National Forest in 2004, in which a solitary male named Inshuti approached a group known as the Beetsme group:

"Fifty minutes after initial contact, observers heard loud screams but were unable to identify the screamer(s) due to dense vegetation. Within seconds of the screaming, Inshuti ran away from Beetsme group's primary direction of travel, followed by three unidentified group males. The three males caught Inshuti and held his arms and legs to the ground. The rest of the group ran toward them from multiple directions... The alpha male's actions were the most violent of the behaviors visible to observers. While many gorillas were pulling out chunks of Inshuti's hair, biting, kicking, and hitting him, the alpha male repeatedly sank his teeth into his body and shook his head back and forth, similar to a canid shaking prey. Inshuti attempted to escape and moved ~20 meters before being dragged down and held under the group again... Approximately 3–4 minutes after the attack began, it abruptly stopped. It was unclear to observers why, but all attackers stopped within seconds of each other. Inshuti fled into nearby vegetation."

While Inshuti survived that attack — and another one, in 2013 — another male died of his injuries after being subjected to an 18-minute assault in 2010.

The Virunga mountain gorillas have been studied since the 1960s, but Rosenbaum and her colleagues note that such behavior had never been recorded until a major demographic shift began occurring in the the mid-1990s. During that time, instead of previously observed groups of one adult male and multiple females, groups increasingly contained several mature males. The presence of multiple males, Rosenbaum told Seeker, likely made such attacks a more attractive proposition, because it spread the risk of injury among multiple members of the group rather than heaping it all on the shoulders of one silverback.

It's unclear why such demographic changes — the result of young males simply electing not to leave the group in which they were born, rather than setting out to start their own — should have begun happening so dramatically over the last 20 or so years.

"That is the million-dollar question," Rosenbaum told Seeker. "We don't have a convincing explanation for that. We always want nice, clean answers to things like this. But at least so far, that's not the case here. One possibility, of course, is increased population density: the population has grown quite remarkably. It's really a remarkable conservation success story. And one of the side effects of that is that population density is higher. We don't actually believe this forest is anywhere near its carrying capacity, so we're somewhat skeptical that that would account for this, because it seems that there's plenty of food and space for males to disperse if they so choose. There used to be very, very few gorillas because they were being extensively hunted by humans. So in many ways this density is probably more representative of what it used to be.

"Another possibility is that human pressures are causing this in some way; there's obviously a lot of human presence in the forest, and people are always tempted to try and attribute it to that. But again, because of the timing of human pressures on the gorillas, it isn't a terrible convincing explanation. They were under the most pressure in the 1960s and 1970s, and we weren't seeing that kind of thing then."

Which raises the possibility that the previously-observed social group structure was the anomaly and that, as human pressures have decreased, the gorillas are reverting to type. But that doesn't wash, either; the extreme difference in size between females and mature males is a classic sign, replicated throughout the natural world, of a species that has evolved to live in a one-male, multiple-female social grouping.

"Obviously, the correlation is not perfect, and it could be that gorillas are just some bizarre outlier and that this does represent a return to the norm, or that throughout their history, there have always been fluctuations," added Rosenbaum. "We can't say, because the bottom line is we've only been studying them for 50 years, and gorillas have a very slow life history: They live a long time. So it takes an equally long time to be able to see enough generations of them that we can say anything meaningful about any changes."

Aside from the issue of how the demographic changes have taken place, what could be the possible motivation behind such attacks? Neither food nor space seem likely to be the issue: Mountain gorillas are non-territorial herbivores that eat at least 55 species of plant, many of which are available year-round. "There are," Rosenbaum and colleagues write, "probably few wild primate populations on Earth with less food resource stress than Virunga mountain gorillas and solitary males are in no way a threat to a group's food supply."

"I think there are probably many factors," Rosenbaum explained. "For some of the individuals that participate, particularly the adult males and the females and infants, there are very clear motivations for driving off outsiders. Females are presumably trying to protect the infants; males are presumably trying to keep the females from leaving, because when they interact with other males is when females may make the decision to leave their current group. Why something so extreme happened in these cases is harder to explain, because gorilla groups interact with each other all the time, and these cases are extreme outliers. We don't know why these are so exceptional."

Also hard to explain are why so many other members of the group — in two of the three cases, every single member (fully 42 gorillas in one instance), and in the other all but one — join in. It prompted Rosenbaum and her colleagues to draw a parallel, not with chimpanzees' planned-out territorial raids, but with a behavior witnessed in another great ape species: human mob violence.

Read more at Discovery News

Nov 22, 2016

New views of dwarf planet Ceres as Dawn moves higher

Occator Crater, home of Ceres' intriguing brightest areas, is prominently featured in this image from NASA's Dawn spacecraft.
The brightest area on Ceres stands out amid shadowy, cratered terrain in a dramatic new view from NASA's Dawn spacecraft, taken as it looked off to the side of the dwarf planet. Dawn snapped this image on Oct. 16, from its fifth science orbit, in which the angle of the sun was different from that in previous orbits. Dawn was about 920 miles (1,480 kilometers) above Ceres when this image was taken -- an altitude the spacecraft had reached in early October.

Occator Crater, with its central bright region and secondary, less-reflective areas, appears quite prominent near the limb, or edge, of Ceres. At 57 miles (92 kilometers) wide and 2.5 miles (4 kilometers) deep, Occator displays evidence of recent geologic activity. The latest research suggests that the bright material in this crater is composed of salts left behind after a briny liquid emerged from below, froze and then sublimated, meaning it turned from ice into vapor.

The impact that formed the crater millions of years ago unearthed material that blanketed the area outside the crater, and may have triggered the upwelling of salty liquid.

"This image captures the wonder of soaring above this fascinating, unique world that Dawn is the first to explore," said Marc Rayman, Dawn's chief engineer and mission director, based at NASA's Jet Propulsion Laboratory, Pasadena, California.

Dawn scientists also have released an image of Ceres that approximates how the dwarf planet's colors would appear to the human eye. This view, produced by the German Aerospace Center in Berlin, combines images taken from Dawn's first science orbit in 2015, using the framing camera's red, green and blue filters. The color was calculated based on the way Ceres reflects different wavelengths of light.

The spacecraft has gathered tens of thousands of images and other information from Ceres since arriving in orbit on March 6, 2015. After spending more than eight months studying Ceres at an altitude of about 240 miles (385 kilometers), closer than the International Space Station is to Earth, Dawn headed for a higher vantage point in August. In October, while the spacecraft was at its 920-mile altitude, it returned images and other valuable insights about Ceres.

On Nov. 4, Dawn began making its way to a sixth science orbit, which will be over 4,500 miles (7,200 kilometers) from Ceres. While Dawn needed to make several changes in its direction while spiraling between most previous orbits at Ceres, engineers have figured out a way for the spacecraft to arrive at this next orbit while the ion engine thrusts in the same direction that Dawn is already going. This uses less hydrazine and xenon fuel than Dawn's normal spiral maneuvers. Dawn should reach this next orbit in early December.

One goal of Dawn's sixth science orbit is to refine previously collected measurements. The spacecraft's gamma ray and neutron spectrometer, which has been investigating the composition of Ceres' surface, will characterize the radiation from cosmic rays unrelated to Ceres. This will allow scientists to subtract "noise" from measurements of Ceres, making the information more precise.

The spacecraft is healthy as it continues to operate in its extended mission phase, which began in July. During the primary mission, Dawn orbited and accomplished all of its original objectives at Ceres and protoplanet Vesta, which the spacecraft visited from July 2011 to September 2012.

Read more at Science Daily

Large number of dwarf galaxies discovered in the early universe

Massive cluster of galaxies Abell 1689 creates a strong gravitational effect on background and older galaxies, seen as arcs of light. Astronomers found the large population of distant dwarf galaxies from when the universe was between two to six billion years old. This cosmic time is critical as it is the most productive time for star formation in the universe.
A team of researchers, led by University of California, Riverside astronomers, found for the first time a large population of distant dwarf galaxies that could reveal important details about a productive period of star formation in the universe billions of years ago.

The findings, just published in The Astrophysical Journal, build on a growing body of knowledge about dwarf galaxies, the smallest and dimmest galaxies in the universe. Though diminutive, they are incredibly important for understanding the history of the universe.

It is believed that dwarf galaxies played a significant role during the reionization era in transforming the early universe from being dark, neutral and opaque to one that is bright, ionized and transparent.

Despite their importance, distant dwarf galaxies remain elusive, because they are extremely faint and beyond the reach of even the best telescopes. This means that the current picture of the early universe is not complete.

However, there is a way around this limitation. As predicted by Einstein's general theory of relativity, a massive object such as a galaxy located along the line of sight to another distant object, can act as a natural lens, magnifying the light coming from that background source.

This phenomenon, known as gravitational lensing, causes the background object to appear brighter and larger. Therefore, these natural telescopes can allow us to discover unseen distant dwarf galaxies.

As a proof of concept, in 2014, the UC Riverside team, including Brian Siana, an assistant professor in UC Riverside's Department of Physics and Astronomy who is the principal investigator of the observing programs, targeted one cluster of galaxies that produce the gravitational lensing effect and got a glimpse of what appeared to be a large population of distant dwarf galaxies.

The just-published paper, whose lead author was Anahita Alavi, a post-doctoral scholar working with Siana, builds on that work.

The team used the Wide Field Camera 3 on the Hubble Space Telescope to take deep images of three clusters of galaxies. They found the large population of distant dwarf galaxies from when the universe was between two to six billion years old. This cosmic time is critical as it is the most productive time for star formation in the universe.

In addition, the team took advantage of the spectroscopic data from Multi-Object Spectrograph for Infrared Exploration (MOSFIRE) on the W.M. Keck Observatory, to confirm that the galaxies belonged to this important cosmic period.

These dwarf galaxies are 10 to 100 times fainter than galaxies that have been previously observed during these periods of time. Though faint, these galaxies are far more numerous than their brighter counterparts.

This study demonstrates that the number of these dwarf galaxies evolves during this important time period such that they are even more abundant at earlier times. Therefore, the researchers unveiled a population of dwarf galaxies that are the most numerous galaxies in the universe during these time periods.

Despite their faintness, these dwarf galaxies produce more than half of the ultraviolet light during this era. As ultraviolet radiation is produced by young hot stars, dwarf galaxies host a significant fraction of newly-formed stars at these cosmic times.

Read more at Science Daily

Huge, Mysterious Settlement Discovered Near Stonehenge

A vast, mysterious complex dating back more than 5,600 years has been unearthed just 1.5 miles from Stonehenge, British archaeologists have announced.

The finding in Wiltshire reinforces the theory that Stonehenge was a sacred monument and suggests the entire region was ritually active hundreds of years before the enigmatic stone circle was erected.

Found during excavations ahead of the construction of a new Army Service family accommodation, the 650-foot-diameter complex is known as a "causewayed enclosure." It consists of more than 3,100 feet of segmented ditches arranged in two concentric circles.

According to archaeologists at Wessex Archaeology, the remains date back to 3,650 B.C. — around 700 years before Stonehenge was known to be erected.

"These discoveries are changing the way we think about prehistoric Wiltshire and about the Stonehenge landscape in particular," Martin Brown, archaeologist for consultancy company WYG, which is leading the Larkhill housing development project, said in a statement.

"Causewayed enclosures," so-called because their ditches are crossed by multiple causeways, are some of the most puzzling prehistoric monuments.

About 70 of such enclosures are known across England. The newly found complex is the second that has been uncovered in the Stonehenge area.

It is believed these "causewayed enclosures" were used as temporary settlements, ceremonial gathering places, ritual activity and disposal of the dead.

At Larkhill, the ditches contained deliberately smashed pottery — evidence of ritualistic activities — dumps of worked flint and even a large stone hand mill used to ground grain into flour.

Human skull fragments also found at the site suggest ritual burials were performed in the sacred space.

"The Neolithic people whose monuments we are exploring shaped the world we inhabit," Brown said.

"They were the first farmers and the first people who settled down in this landscape, setting us on the path to the modern world," he added.

Read more at Discovery News

Glowing Geckos Light the Way to Improved Biodiversity

It turns out that if you sprinkle fluorescent dust on geckos, you can learn not only about the reptiles but also the biodiversity potential of farm land.

That's what researchers from Australian National University found, during a study on the sticky-footed creatures just published in the journal Agriculture, Ecosystems & Environment.

Geckos, the scientists found, use visual clues to move between separated habitat spaces, and changes to landscaping, they suggest, could go a long way toward improving, or harming, their lot and potentially that of other animals.

Old trees, for example, were shown to be important natural signage for the animals.

"Large, old, scattered trees have been shown to have immense ecological, social and economic value," said study lead Geoffrey Kay, in a statement. "Our work also shows that they are useful as visual flagpoles for native fauna navigating across the countryside."

The height of pastures and even the direction in which crops line up also influenced the geckos' movements, Kay and his team observed.

The insights were all thanks to a bit of dust and some travel-ready geckos. The reptiles, coated with the glow-in-the-dark dust, left behind trails that lit up the night, allowing Kay and his team to map in fine detail the tiniest gradations of movement made by the geckos.

The trails showed that geckos could identify habitat from 40 meters (131 feet) away but they could not do so from 80 meters (262 feet). That told the scientists that markers such as trees indiscriminately cut down could reduce and fragment habitats of geckos and other fauna and could also make less recognizable the paths used by migratory species.

A gecko trail shines brightly in this field.
Kay, citing habitat fragmentation and land clearing as the biggest global threats to biodiversity, offered suggestions for a way forward.

"It is important that financial incentives are put in place to encourage landholders to crop landscapes directionally between habitat patches to enhance the connectivity for reptiles, and potentially other fauna, which are a conservation priority given their rapid decline in agricultural landscapes globally," he said.

Meanwhile, Kay added, new regulations – regarding the removal of old, scattered trees, for example – might be considered to keep key habitat signposts from disappearing.

From Discovery News

Nov 21, 2016

Dressing up like a peacock: Bright colors by nanotechnology

The blue tarantula (Poecilotheria metallica) inspired researchers to produce non-iridescent structural colors.
Colors are produced in a variety of ways. The best known colors are pigments. However, the very bright colors of the blue tarantula or peacock feathers do not result from pigments, but from nanostructures that cause the reflected light waves to overlap. This produces extraordinarily dynamic color effects. Scientists from Karlsruhe Institute of Technology (KIT), in cooperation with international colleagues, have now succeeded in replicating nanostructures that generate the same color irrespective of the viewing angle.

In contrast to pigments, structural colors are non-toxic, more vibrant and durable. In industrial production, however, they have the drawback of being strongly iridescent, which means that the color perceived depends on the viewing angle. An example is the rear side of a CD. Hence, such colors cannot be used for all applications. Bright colors of animals, by contrast, are often independent of the angle of view. Feathers of the kingfisher always appear blue, no matter from which angle we look. The reason lies in the nanostructures: While regular structures are iridescent, amorphous or irregular structures always produce the same color. Yet, industry can only produce regular nanostructures in an economically efficient way.

Radwanul Hasan Siddique, researcher at KIT in collaboration with scientists from USA and Belgium has now discovered that the blue tarantula does not exhibit iridescence in spite of periodic structures on its hairs. First, their study revealed that the hairs are multi-layered, flower-like structure. Then, the researchers analyzed its reflection behavior with the help of computer simulations. In parallel, they built models of these structures using nano-3D printers and optimized the models with the help of the simulations. In the end, they produced a flower-like structure that generates the same color over a viewing angle of 160 degrees. This is the largest viewing angle of any synthetic structural color reached so far.

Apart from the multi-layered structure and rotational symmetry, it is the hierarchical structure from micro to nano that ensures homogeneous reflection intensity and prevents color changes.

Via the size of the "flower," the resulting color can be adjusted, which makes this coloring method interesting for industry. "This could be a key first step towards a future where structural colorants replace the toxic pigments currently used in textile, packaging, and cosmetic industries," says Radwanul Hasan Siddique of KIT's Institute of Microstructure Technology, who now works at the California Institute of Technology. He considers short-term application in textile industry feasible.

Read more at Science Daily

Mysterious Items Found in 2000-Year-Old Cooking Pot

Swiss archaeologists have unearthed a mysterious pot filled with bronze coins and oil lamps, each decorated with images including gladiators and erotic scenes.

Found during construction work in Windisch, in the northern Swiss canton of Aargau, the cooking pot is believed to have been buried almost 2,000 years ago, when Aargau was home to the Roman legion camp Vindonissa.

According to the archaeologists, the pot is a typical cooking vessel known to have been used by the soldiers that stationed there.

What makes the finding unique, however, is the pot's contents. Inside the vessel there was a total of 22 oil lamps, each decorated with an image of the moon goddess Luna, a gladiator, a lion, a peacock and an erotic scene.

On each lamp, someone carefully placed a bronze coin. Most of the coins date from 66-67 AD, during the reign of the Roman emperor Nero. Each coin was of very low value, and was likely used in a symbolic gesture.

"What astonished us was the quantity and the combination of coins and lamps," Aargau cantonal archaeologist Georg Matter said in a statement.

The pot also contained charred bone pieces. Analysis showed they were animal bones, ruling out that the vessel was used as a urn for human remains.

Matter admitted the pot remains a mystery as no similar finding has been unearthed so far.

"We suspect that this is a ritual burial. But we can only puzzle about the thoughts and intentions behind it," Matter said.

From Discovery News

Blood from Human Babies, Teens Rejuvenates Old Mice

Aging is a killer. Incidence rates for heart disease, cancer, kidney disease and dementia all skyrocket as people reach their 70s and 80s. There's no cure for getting old, but there may be a surprising simple, albeit somewhat medieval, way to turn back the body's internal clock and reverse the deadly effects of degenerative diseases.

By injecting blood from human teens into old mice, researchers in California are reporting remarkable enhancements to the older rodents' memory and cognition. The blood, donated from human teenagers, appears to have kickstarted the creation of new neurons in the aged mice. The research echoes previous findings that transfusions of young blood can reverse the thickening of heart muscles, a major cause of heart failure.

Now scientists are hot on the trail of the specific proteins or other factors that are responsible for the "Fountain of Youth" effect of young blood. If those factors can be identified and isolated, we could be on the verge of new drug therapies that will redefine old age.

"It's sort of a bold question," said Joseph Castellano, a post-doctoral fellow at the Stanford School of Medicine. "Can we actually halt or even reverse certain aspects of aging? We think of the aging process as something that's fixed. Now we've seen that you can actually change the rate of aging phenotypes [physical characteristics]."

Castellano is a member of Tony Wyss-Coray's Neuro Immunology & Degeneration Lab, which published a landmark paper in 2014 proving that young mouse blood could significantly improve brain function in older mice.

More recently, Castellano and his colleagues repeated the mouse experiment using human blood donated from healthy newborn babies. The old mice, which had shown clear signs of cognitive decline, now breezed through spatial memory tests, and cellular analysis showed clear boosts of neural activity.

"We see that there's definitely something going on in the brain and specifically in the hippocampus, which is responsible for spatial memory," said Castellano, noting that the younger the blood, the more dramatic the rejuvenating effect.

The "creepy factor" is undeniably high with this kind of research, but no one is suggesting that old people should be hooked up to IVs filled with baby blood. Instead, researchers like Castellano are trying to identify the proteins responsible for young blood's anti-aging effects and turn those molecules into life-saving therapies.

"We're narrowing in on a couple of different factors present in human plasma that seem to be of interest," said Castellano, whose focus is on the blood-borne proteins that enhance brain function. "My suspicion is that there will be a lot of different factors coming out in the next several years that modify different processes in different tissues."

The Harvard University researchers who first reported the rejuvenating effects of young blood on heart tissue credited a protein called GDF11. The same protein, when injected into old mice, also seemed to spur neuron growth and stem cell regeneration. Attempts to replicate the results have met with mixed success, prompting doubts that GDF11 alone is the miracle molecule.

Read more at Discovery News

Some Sungrazing Comets May Be Different Beasts

We've been spoiled with comet science lately. The Rosetta spacecraft orbited Comet 67P/Churyumov-Gerasimenko for about 18 months and sent back daily updates on how the comet is behaving and changing.

That mission is now over, but luckily there is a long-running mission that looks at sungrazers, or comets that pass really close to the sun. The Solar and Heliospheric Observatory (SOHO) spacecraft is designed to look at our nearest star ind its thin atmosphere, but luckily it can also watch comets swing by. In the last 20 years, it's discovered more than 3,000 of these objects.

Here's the neat thing — a minority of these sungrazers may not be comets after all. An object called 322P/SOHO 1 appears to have some properties of asteroids or space rocks, not that loose mix of ice and dust that comets are known for. This and other properties of sungrazers are discussed in a new paper led by Karl Battams, an astrophysicist at the Naval Research Laboratory in Washington, D.C. The paper is on the prepublishing service arXiv and has been accepted in the journal Philosophical Transactions A.

"We found it kind of looks like an asteroid and it kinds of looks like a comet," Battams told Seeker. "There's a weird hybrid thing going on. The results were indeterminate, so we're not sure if this is something that was once a comet... or maybe an asteroid that got stuck. There's no definitive conclusion there."

Comet ISON, one of SOHO's most famous observations, is captured in a timelapse in 2013
Roughly 86% of the comets SOHO sees are definitely comets. They belong to a specific family called Kreutz comets, and includes the infamous Comet ISON that flew by the sun on Thanksgiving three years ago. The comet appeared to break up, then light up again before fading forever. It shows just how hard it is to make comet predictions; Battams himself remembers it as a crazy day.

The remaining 14% of sungrazers are more difficult to define, and are made up of four different groups known as the Meyer, Marsden, Kracht and Kracht II groups — as well as a "non-group" of objects that don't quite fit any of the other group's properties. Battams' paper suggests that most of these other sungrazers could be the cores of comets, or perhaps asteroids that somehow got close to the sun.

But more observations of sungrazers are needed. It's hard to predict their orbits because as they pass by the sun, the sun's gravity alters their path. For what it's worth, however, after a few passes by a short-term comet, scientists can make better predictions about where a comet is going. That is how a group led by Matthew Knight, from the University of Maryland, was able to observe 322P/SOHO 1 so far away from the sun, which was a first.

Read more at Discovery News

Nov 20, 2016

Archaeologist uses 'dinosaur crater' rocks, prehistoric teeth to track ancient humans

Rocks from the Chicxulub 'dinosaur crater' used to create a geological map for tracking humans and animals.
Where's the best place to start when retracing the life of a person who lived 4,000 years ago? Turns out, it's simple -- you start at the beginning.

Using a method known for helping forensic scientists solve cold cases, University of Florida doctoral student Ashley Sharpe created a map for determining the birthplace of ancient people and animals in Central America. Archaeologists will use the map to match lead found in bedrock from specific locations to a curious source: millennia-old teeth.

Pinpointing birth and death locations will help Sharpe and other archaeologists track the movement of prehistoric Maya and potentially solve mysteries surrounding the civilization's origins and eventual demise.

Sharpe sampled lead isotope values found in rocks, which act as local signatures, from the Chicxulub crater in the Yucatán Peninsula -- the site of the asteroid impact that wiped out the dinosaurs -- and places in Belize, Guatemala and Honduras. Details of the new study are described in the November issue of PLOS ONE.

"If I find an ancient Maya individual buried on the Yucatan in Mexico, I can do a chemical analysis of the lead in their teeth and discover a very different story," said Sharpe, who graduates from UF's department of anthropology and the environmental archaeology program at the Florida Museum of Natural History on the UF campus this fall. "Maybe they originally came from Guatemala. This can change our view of everything."

When our tooth enamel forms during childhood, it incorporates elements from the local environment, including the dust we breathe from rock layers beneath our feet. Bones, on the other hand, change every few years. And as we decompose, our bones soak up materials around the area we're buried like a sponge.

As the hardest substance in the human body, tooth enamel is different. It offers a window into life histories.

Tracing the movement of individuals via their teeth can offer clues about marriage alliances and slavery practices. Building knowledge of individual lives helps archaeologists figure out which villages were enemies, which were allies, and how the Maya communicated and traveled between cities. This could lead to a better understanding of how communication networks developed between Maya states, Sharpe said.

Previously, UF forensic anthropologists used lead analysis to trace the birthplace of unidentified homicide victims. UF archaeologists have also used lead to track ancient humans in the Indus Valley Civilization.

UF forensic anthropologists are using lead analysis to trace the birthplace of unidentified homicide victims, which can help police investigators narrow their search for missing persons to a particular state, country or region. Other archaeologists at UF have included lead analysis in research used to track ancient humans from the Indus Valley Civilization.

"The anthropology department here at UF is becoming a hub for lead-based research," Sharpe said. "In other words, we're the place to go if you need to track the origins an ancient or modern skeleton."

Researchers extract lead by first grinding up teeth, then inserting the particles into an inductively coupled plasma mass spectrometer. Temperatures inside the machine can be hotter than the sun, separating the lead.

Read more at Science Daily

First-ever study shows e-cigarettes cause damage to gum tissue

Electronic cigarette.
A University of Rochester Medical Center study suggests that electronic cigarettes are as equally damaging to gums and teeth as conventional cigarettes.

The study, published in Oncotarget, was led by Irfan Rahman, Ph.D. professor of Environmental Medicine at the UR School of Medicine and Dentistry, and is the first scientific study to address e-cigarettes and their detrimental effect on oral health on cellular and molecular levels.

Electronic cigarettes continue to grow in popularity among younger adults and current and former smokers because they are often perceived as a healthier alternative to conventional cigarettes. Previously, scientists thought that the chemicals found in cigarette smoke were the culprits behind adverse health effects, but a growing body of scientific data, including this study, suggests otherwise.

"We showed that when the vapors from an e-cigarette are burned, it causes cells to release inflammatory proteins, which in turn aggravate stress within cells, resulting in damage that could lead to various oral diseases," explained Rahman, who last year published a study about the damaging effects of e-cigarette vapors and flavorings on lung cells and an earlier study on the pollution effects. "How much and how often someone is smoking e-cigarettes will determine the extent of damage to the gums and oral cavity."

The study, which exposed 3-D human, non-smoker gum tissue to the vapors of e-cigarettes, also found that the flavoring chemicals play a role in damaging cells in the mouth.

"We learned that the flavorings-some more than others -- made the damage to the cells even worse," added Fawad Javed, a post-doctoral resident at Eastman Institute for Oral Health, part of the UR Medical Center, who contributed to the study. "It's important to remember that e-cigarettes contain nicotine, which is known to contribute to gum disease."

Most e-cigarettes contain a battery, a heating device, and a cartridge to hold liquid, which typically contains nicotine, flavorings, and other chemicals. The battery-powered device heats the liquid in the cartridge into an aerosol that the user inhales.

Read more at Science Daily