Researchers crack the peanut genome

Soroya Bertioli inspects peanut plants at the UGA Institute for Plant Breeding, Genetics and Genomics greenhouse.

Working to understand the genetics of peanut disease resistance and yield, researchers led by scientists at the University of Georgia have uncovered the peanut's unlikely and complicated evolution.

Researchers working as part of the International Peanut Genome Initiative have previously pinpointed one of the peanut's two wild ancestors and shown that the peanut is a living legacy of some of the earliest human agricultural societies in South America. Since then the team has mapped the entire peanut genome and identified the crop's second wild ancestor and the novel mechanism by which the shy, seed-hoarding plant generated the diversity we see today.

"Because of its complex genetic structure sequencing peanut was only possible using very recent developments in sequencing technology. The result is of unprecedented quality, and provides a reference framework for breeding and improvement of the peanut crop, and a whole new set of insights into the extraordinary genetic structure of peanut," said David Bertioli, Georgia Research Alliance Distinguished Investigator and peanut researcher at the College of Agricultural and Environmental Sciences.

Bertioli conducts his research through the CAES Institute for Plant Breeding, Genetics and Genomics, which is home to some of the world's foremost experts in this area of crop science and has been prolific in providing new genomic tools and information to help plant breeders around the world develop more sustainable, productive crop varieties.

The team's most recent paper was published in the journal Nature Genetics and is available online.

According to the USDA, farmers around the world grow 44.9 million metric tons of peanuts on more than 64 million acres. The crop is a staple food in many parts of Africa and Asia and is a source of peanut butter, snacks and cooking oil in the United States. In Georgia alone farmers grow $825 million in peanuts each year.

Despite their importance as a crop, plant researchers haven't had many of the genetic tools needed to speed the introduction of more sustainable and productive peanut varieties. That was because, until recently, scientists had been unable to map the peanuts' hypercomplex tetraploid genome. The Peanut Genome Initiative's international collaboration and advancements in technologies and data processing yielded the breakthroughs.

Peanut genome sequenced

The bedrock of the team's discoveries was the sequencing of the genome. Because the peanut originated from the hybridization of two wild ancestral species thousands of years ago, the initial phases of the project involved researchers developing genome sequences for those ancestors. Together, the ancestral genomes made a prototype for the genetic structure of cultivated peanuts. This was published in 2016.

This month, the Peanut Genome Initiative discusses the entire genome sequence for the modern cultivated peanut in a paper published in Nature Genetics on May 1.

The researchers used new advances in DNA-sequencing technologies to produce a complete genome sequence of unprecedented quality. The sequence consists of more than 2.5 billion base pairs of DNA arranged in 20 pairs of chromosomes, 10 pairs from each of the ancestral species.

The information in the sequence sheds light on parts of the plant's genetic code that control traits like seed size and disease resistance, which are important to plant breeders. But the sequence also revealed more about the origin of peanut during the dawn of agriculture in South America and on the genetic mechanisms that have generated diversity and allowed adaptation to environments around the globe.

The mother of peanut

Using the new genome sequence as a framework, the team was able to analyze the variations in more than 200 of the most diverse peanuts from all of over the world. Researchers found characteristic genetic fingerprints shared by all the peanut plants tested, providing new evidence that all modern peanut varieties stem from the same original hybrid.

"The new study underlines how peanut's origin was due to very special circumstances thousands of years ago. Ancient farmers transported one species into the range of another, allowing their hybridization and the formation of a new crop species," said Soraya Leal-Bertioli, a senior research scientist with the UGA Institute of Plant Breeding, Genetics and Genomics and the CAES department of plant pathology.

Scientists with the initiative had previously found the male donor of the original hybrid and origin of peanut's "B" subgenome. In this new study they identified the female donor, tracking the population of wild ancestral peanut that contributed the peanut "A" subgenome in Rio Seco, Argentina. These individuals form the "mother" population of peanut.

But the evidence that all modern peanuts can be traced to a single original hybrid sets up another mystery, Leal-Bertioli said. How does a plant with such a narrow genetic base develop so many variations and varieties?

"Shuffling, shuffling"

Most flowering plant species rely on animals or weather to spread their pollen or seeds to other plants to generate genetic diversity. Pollen and seeds can travel for miles, spreading newly occurring traits to new populations.

But peanuts, which produce their seeds underground, don't do that. It took early human farmers and their long-distance transport of seeds to get the first two ancestral peanut parents together.

Since then, however, the plant has used a new mechanism for creating diversity.

The peanut has two sets of chromosomes, one from each ancestor. By analyzing more than 200 cultivated peanuts from all over the world, it was shown that different landraces and cultivars have shuffled the genetic material of the ancestors and deleted some sections altogether. Over the past the 10,000 years, this shuffling has happened thousands of times -- allowing a much faster-paced generation of diversity than if the plants simply relied on mutation.

In a greenhouse on the UGA campus, the Bertiolis have worked with hybrids that re-create the original ancestral peanut and observed the shuffling in real time. They documented its effects in the spontaneous appearance of different flower colors. These same genetic mechanisms generate other types of variation as well, said David Bertioli.

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Giant panda's bamboo diet still looks surprisingly carnivorous

This photograph shows a wild panda feeding on bamboo leaves in the Foping Nature Reserve.

Giant pandas are unusual in being extremely specialized herbivores that feed almost exclusively on highly fibrous bamboo, despite belonging to a clade (Carnivora) of primarily flesh-eating carnivores. But a study reported in Current Biology on May 2 suggests that the switch to a restricted vegetarian diet wasn't, in some respects, as big an evolutionary leap as it seems.

The study finds that the protein and carbohydrate content of the panda's plant diet looks surprisingly like that of a hypercarnivore, animals that obtain more than 70 percent of their diet from other animals, they report. About 50 percent of the panda's energy intake comes in the form of protein, placing them right alongside feral cats and wolves.

"As we know, the giant panda is a Carnivora species, yet extremely specialized on a plant food, the bamboo," said Fuwen Wei of Chinese Academy of Sciences, Beijing. "Based on what they eat, they absolutely belong to the herbivores, but considering the macronutrient composition of the ingested and absorbed diets, they belong to the carnivores."

The pandas do have traits in common with herbivores, including a skull, jaw musculature, and dentition that are adapted for fibrous diets, and a specialized "pseudo-thumb" used for handling bamboo. They've also lost the ability to taste umami, which is often associated with meat eating. On the other hand, giant pandas have a digestive tract, digestive enzymes, and gut microbes that resemble that of carnivores and not herbivores.

In the new study, Wei teamed up with nutritional ecologist David Raubenheimer from the University of Sydney and colleagues to explore the macronutrient composition of their diet, including what the pandas ingest and what they absorb. Using an approach called nutritional geometry, the team showed that the macronutrient mix that giant pandas both eat and absorb is similar to carnivores, and unlike herbivores. The macronutrient composition of the panda's milk also places it squarely among other carnivores.

The researchers say the findings can help resolve long-standing questions concerning the evolution of the giant panda, including the unusual transition to extreme specialized herbivory by a member of a carnivorous clade. "In fact," they write, "the transition was likely more superficial than assumed, combining substantial adaptation to new food types with relatively smaller changes in macronutrient handling."

The herbivorous diet led to evolutionary adaptations in their teeth, skull, and pseudo-thumb needed to process bamboo. But their gut and digestive system changed little, suggesting minimal evolutionary modification from their ancestral state was needed to deal with the macronutritional properties of bamboo. Their short gut, together with the abundance of bamboo, allows the panda to consume and process large amounts of bamboo, compensating for the low digestive efficiency of such a fibrous diet.

"There is also a broader message from this study," says Raubenheimer. "It demonstrates the importance of considering both foods and nutrients in understanding the evolutionary ecology of animals. This is what nutritional geometry is designed to do."

Read more at Science Daily

A genomic tour-de-force reveals the last 5,000 years of horse history

This image shows a herd of Kazakh horses in the Pavlodar region of Kazakhstan in August 2016.

Each year on the first Saturday in May, Thoroughbred horses reach speeds of over 40 miles per hour as they compete to win the Kentucky Derby. But the domestic horse wasn't always bred for speed. In fact, an international team now has evidence to suggest that the modern horse is genetically quite different from the horses of even just a few hundred years ago.

Their work, appearing May 2 in the journal Cell, constructs the genetic history of the domestic horse across the world over the last 5,000 years by using the largest genome collection ever generated for a non-human organism. The findings identify two new horse lineages that are now extinct and suggest that familiar traits such as speed were only selected for more recently in their history.

"The horse has impacted human history like no other animal," says Ludovic Orlando, a research director with CNRS and the University of Toulouse and a Professor of Molecular Archaeology at the University of Copenhagen. "If you look at the historical record from the Bronze Age onward, horses are always part of the equation up until very recent times, connecting civilizations and impacting transportation, warfare, and agriculture. Our goal was to understand how humans and their activities transformed the horse throughout history to fit their purposes -- and how these changes in biology influenced human history."

The team responsible for this project consisted of 121 collaborators, including geneticists, archaeologists, and evolutionary biologists from 85 institutions around the world, and examined genome-scale data from 278 horse specimens from across Eurasia over the last 42,000 years.

"Such a large collection of data means that we can build a much more precise understanding of horse domestication and management through space and time," Orlando says. "But it was truly an interdisciplinary effort because of course it takes a lot more than just DNA to understand such a story. We had to integrate all these social, historical, and geographical aspects."

Overall, the team's findings suggest that equine history was much more complex than was previously realized. Today, there are only two known lineages of horses, the domestic horse and the Przewalski's horse. But the researchers here identified two additional now-extinct lineages of horses, one from the Iberian Peninsula and one from Siberia, both of which still existed 4,000-4,500 years ago. "We found two lineages of horses at the far ends of Eurasia that are not related to what we call the domestic horse today, nor to the Przewalski's horse. They are a sort of horse equivalent of what Neanderthals are to modern humans," Orlando says.

The researchers also found a major shift in the genetic makeup of horses in Europe and Central Asia in the 7th to 9th centuries and say this shift probably corresponds to Islamic expansions. The horses common in Europe before that time are now only found in regions such as Iceland; the new European horses after that time were much more similar to horses found in Persia during the Sassanid Empire. When the team performed a scan to identify genes that had been selected for in these Persian horses, they found evidence of selection in genes associated with body shape.

"It was a moment in history that reshaped the landscape of horses in Europe. If you look at what we today call Arabian horses, you know that they have a different shape -- and we know how popular this anatomy has been throughout history, including in racing horses. Based on the genomic evidence, we propose that this horse was so successful and influential because it brought a new anatomy and perhaps other favorable traits," he says.

The researchers found that there have been additional significant and recent changes in the domestic horse. Similar selection scans indicate that only in the last 1,500 years did traits such as ambling and speed over short distances become more actively sought. And when they looked at the overall genetic diversity of the domestic horse, the researchers found a sharp decline in the last 200 to 300 years. They believe this decline corresponds with new breeding practices that were introduced with the rise of the concept of "pure" breeds.

"What we picture as a horse today and what we picture as a horse from a thousand years ago or two thousand years ago was likely actually very different. Some of those traits that we are most familiar with are only a modern invention, and in the last few hundred years, we have actually impacted the horse genome a lot more than in the previous 4,000 years of domestication," says Orlando.

He believes that this research can tell us a lot about both the past and the present. "Our findings show that the past is a lot more diverse than we thought it was and that it cannot be imagined or inferred through modern-day variation. But ancient DNA tells us a lot about today as well, because it teaches us about the consequences of some shifts in breeding practices," he says. And that, he believes, can also affect the way we think about conservation and modern agricultural practices.

Of course, our understanding of the domestic horse's history is far from complete. Orlando acknowledges that there are geographic and temporal gaps in his story. Perhaps mostly glaringly, we still don't know when and or where the horse was domesticated. "Horse domestication is central to human history, and in 2019, we still don't understand where it started. That's mind-blowing," he says.

Read more at Science Daily

Two neutron stars collided near the solar system billions of years ago

If a comparable event happened today at a similar distance from the solar system, the ensuing radiation would outshine the entire night sky.

Astrophysicists Szabolcs Marka at Columbia University and Imre Bartos at the University of Florida, have identified a violent collision of two neutron stars 4.6 billion years ago as the likely source of some of the most coveted matter on Earth.

This single cosmic event, close to our solar system, gave birth to 0.3 percent of the Earth's heaviest elements, including gold, platinum and uranium, according to a new paper appearing in the May 2 issue of Nature.

"This means that in each of us we would find an eyelash worth of these elements, mostly in the form of iodine, which is essential to life," Bartos said. "A wedding ring, which expresses a deep human connection, is also a connection to our cosmic past predating humanity and the formation of Earth itself, with about 10 milligrams of it likely having formed 4.6 billion years ago."

"Meteorites forged in the early solar system carry the traces of radioactive isotopes," said Bartos, who received his Ph.D. at Columbia.

"As these isotopes decay they act as clocks that can be used to reconstruct the time they were created," Marka said.

To arrive at their conclusion, Bartos and Marka compared the composition of meteorites to numerical simulations of the Milky Way. They found that a single neutron-star collision could have occurred about 100 million years before the formation of Earth, in our own neighborhood, about 1000 light years from the gas cloud that eventually formed the Solar System.

The Milky Way galaxy itself is 100,000 light years in diameter, or 100 times the distance of this cosmic event from the cradle of Earth. "If a comparable event happened today at a similar distance from the Solar System, the ensuing radiation could outshine the entire night sky," Marka said.

The researchers believe that their study provides insight into a uniquely consequential event in our history. "It sheds bright light on the processes involved in the origin and composition of our solar system, and will initiate a new type of quest within disciplines, such as chemistry, biology and geology, to solve the cosmic puzzle," Bartos said.

"Our results address a fundamental quest of humanity: Where did we come from and where are we going? It is very difficult to describe the tremendous emotions we felt when realized what we had found and what it means for the future as we search for an explanation of our place in the universe, " Marka said.

From Science Daily

Chewing versus sex in duck-billed dinosaurs

The skulls of three hadrosaur dinosaurs, Lambeosaurus lambei (top left), Gryposaurus notabilis (top right), Parasaurolophus walkeri (lower).

The duck-billed hadrosaurs walked the Earth over 90-million years ago and were one of the most successful groups of dinosaurs. But why were these 2-3 tonne giants so successful? A new study, published in Paleobiology, shows that their special adaptations in teeth and jaws and in their head crests were crucial, and provides new insights into how these innovations evolved.

Called the 'sheep of the Mesozoic'as they filled the landscape in the Late Cretaceous period, hadrosaurs walked on their hind legs and were known for their powerful jaws with multiple rows of extremely effective teeth. They also had hugely varied head display crests that signalled which species each belonged to and were used to attract mates. Some even trumpeted and tooted their special call, using nasal passages through the head crests.

Researchers from the Universities of Bristol and the Catalan Institute of Paleontology in Barcelona used a large database describing morphological variety in hadrosaur fossils and computational methods that quantify morphological variety and the pace of evolution.

Dr Tom Stubbs, lead author of the study and a researcher from Bristol's School of Earth Sciences, said: "Our study shows that the unique hadrosaur feeding apparatus evolved fast in a single burst, and once established, showed very little change. In comparison, the elaborate display crests kept diversifying in several bursts of evolution, giving rise to the many weird and wonderful shapes."

Professor Mike Benton, the study's co-author from Bristol's School of Earth Sciences, added, "Variation in anatomy can arise in many ways. We wanted to compare the two famous hadrosaur innovations, and by doing so, provide new insights into the evolution of this important dinosaur group. New numerical methods allow us to test these kinds of complex evolutionary hypotheses."

"Our methods allowed us to identify branches on the hadrosaur evolutionary tree that showed rapid evolution in different parts of the skeleton," said co-author Dr Armin Elsler. "When we looked at the jaws and teeth, we only saw fast evolution on a single branch at the base of the group. On the other hand, the bones that form the display crests showed multiple fast rate branches."

Dr Albert Prieto-Márquez, co-author and world-leading expert on hadrosaurs from the Catalan Institute of Paleontology in Barcelona, added: "Our results suggest that evolution can be driven in different ways by natural selection and sexual selection. Hadrosaurs apparently fixed on a feeding apparatus that was successful and did not require massive modification to process their food. On the other hand, sexual selection drove the evolution of more complex crest shapes, and this is reflected by multiple evolutionary bursts."

From Science Daily

Embryo stem cells created from skin cells

These are 4-cell stage mouse embryos.

Researchers at the Hebrew University of Jerusalem (HU) have found a way to transform skin cells into the three major stem cell types that comprise early-stage embryos. The work (in mouse cells) has significant implications for modelling embryonic disease and placental dysfunctions, as well as paving the way to create whole embryos from skin cells.

As published in Cell Stem Cell, Dr. Yossi Buganim of HU's Department of Developmental Biology and Cancer Research and his team discovered a set of genes capable of transforming murine skin cells into all three of the cell types that comprise the early embryo: the embryo itself, the placenta and the extra-embryonic tissues, such as the umbilical cord. In the future, it may be possible to create entire human embryos out of human skin cells, without the need for sperm or eggs. This discovery also has vast implications for modelling embryonic defects and shedding light on placental dysfunctions, as well as solving certain infertility problems by creating human embryos in a petri dish.

Back in 2006, Japanese researchers discovered the capacity of skin cells to be "reprogrammed" into early embryonic cells that can generate an entire fetus, by expressing four central embryonic genes. These reprogrammed skin cells, termed "Induced Plutipotent Stem Cells" (iPSCs), are similar to cells that develop in the early days after fertilization and are essentially identical to their natural counterparts. These cells can develop into all fetal cell types, but not into extra-embryonic tissues, such as the placenta.

Now, the Hebrew University research team, headed by Dr. Yossi Buganim, Dr. Oren Ram from the HU's Institute of Life Science and Professor Tommy Kaplan from HU's School of Computer Science and Engineering, as well as doctoral students Hani Benchetrit and Mohammad Jaber, found a new combination of five genes that, when inserted into skin cells, reprogram the cells into each of three early embryonic cell types -- iPS cells which create fetuses, placental stem cells, and stem cells that develop into other extra-embryonic tissues, such as the umbilical cord. These transformations take about one month.

The HU team used new technology to scrutinize the molecular forces that govern cell fate decisions for skin cell reprogramming and the natural process of embryonic development. For example, the researchers discovered that the gene "Eomes" pushes the cell towards placental stem cell identity and placental development, while the "Esrrb" gene orchestrates fetus stem cells development through the temporary acquisition of an extrae-mbryonic stem cell identity.

To uncover the molecular mechanisms that are activated during the formation of these various cell types, the researchers analyzed changes to the genome structure and function inside the cells when the five genes are introduced into the cell. They discovered that during the first stage, skin cells lose their cellular identity and then slowly acquire a new identity of one of the three early embryonic cell types, and that this process is governed by the levels of two of the five genes.

Read more at Science Daily

Running may have made dinosaurs' wings flap before they evolved to fly

Caudipteryx robot for testing passive flapping flight.

Before they evolved the ability to fly, two-legged dinosaurs may have begun to flap their wings as a passive effect of running along the ground, according to new research by Jing-Shan Zhao of Tsinghua University, Beijing, and his colleagues.

The findings, published in PLOS Computational Biology, provide new insights into the origin of avian flight, which has been a point of debate since the 1861 discovery of Archaeopteryx. While a gliding type of flight appears to have matured earlier in evolutionary history, increasing evidence suggests that active flapping flight may have arisen without an intermediate gliding phase.

To examine this key point in evolutionary history, Zhao and his colleagues studied Caudipteryx, the most primitive, non-flying dinosaur known to have had feathered "proto-wings." This bipedal animal would have weighed around 5 kilograms and ran up to 8 meters per second.

First, the researchers used a mathematical approach called modal effective mass theory to analyze the mechanical effects of running on various parts of Caudipteryx's body. These calculations revealed that running speeds between about 2.5 to 5.8 meters per second would have created forced vibrations that caused the dinosaur's wings to flap.

Real-world experiments provided additional support for these calculations. The scientists built a life-size robot of Caudipteryx that could run at different speeds, and confirmed that running caused a flapping motion of the wings. They also fitted a young ostrich with artificial wings and found that running indeed caused the wings to flap, with longer and larger wings providing a greater lift force.

"Our work shows that the motion of flapping feathered wings was developed passively and naturally as the dinosaur ran on the ground," Zhao says. "Although this flapping motion could not lift the dinosaur into the air at that time, the motion of flapping wings may have developed earlier than gliding."

Zhao says that the next step for this research is to analyze the lift and thrust of Caudipteryx's feathered wings during the passive flapping process.

From Science Daily

Organ bioprinting gets a breath of fresh air

Bioprinting research from the lab of Rice University bioengineer Jordan Miller featured a visually stunning proof-of-principle -- a scale-model of a lung-mimicking air sac with airways and blood vessels that never touch yet still provide oxygen to red blood cells.

Bioengineers have cleared a major hurdle on the path to 3D printing replacement organs with a breakthrough technique for bioprinting tissues.

The new innovation allows scientists to create exquisitely entangled vascular networks that mimic the body's natural passageways for blood, air, lymph and other vital fluids.

The research is featured on the cover of this week's issue of Science. It includes a visually stunning proof-of-principle -- a hydrogel model of a lung-mimicking air sac in which airways deliver oxygen to surrounding blood vessels. Also reported are experiments to implant bioprinted constructs containing liver cells into mice.

The work was led by bioengineers Jordan Miller of Rice University and Kelly Stevens of the University of Washington (UW) and included 15 collaborators from Rice, UW, Duke University, Rowan University and Nervous System, a design firm in Somerville, Massachusetts.

"One of the biggest road blocks to generating functional tissue replacements has been our inability to print the complex vasculature that can supply nutrients to densely populated tissues," said Miller, assistant professor of bioengineering at Rice's Brown School of Engineering. "Further, our organs actually contain independent vascular networks -- like the airways and blood vessels of the lung or the bile ducts and blood vessels in the liver. These interpenetrating networks are physically and biochemically entangled, and the architecture itself is intimately related to tissue function. Ours is the first bioprinting technology that addresses the challenge of multivascularization in a direct and comprehensive way."

Stevens, assistant professor of bioengineering in the UW College of Engineering, assistant professor of pathology in the UW School of Medicine, and an investigator at the UW Medicine Institute for Stem Cell and Regenerative Medicine, said multivascularization is important because form and function often go hand in hand.

"Tissue engineering has struggled with this for a generation," Stevens said. "With this work we can now better ask, 'If we can print tissues that look and now even breathe more like the healthy tissues in our bodies, will they also then functionally behave more like those tissues?' This is an important question, because how well a bioprinted tissue functions will affect how successful it will be as a therapy."

The goal of bioprinting healthy, functional organs is driven by the need for organ transplants. More than 100,000 people are on transplant waiting lists in the United States alone, and those who do eventually receive donor organs still face a lifetime of immune-suppressing drugs to prevent organ rejection. Bioprinting has attracted intense interest over the past decade because it could theoretically address both problems by allowing doctors to print replacement organs from a patient's own cells. A ready supply of functional organs could one day be deployed to treat millions of patients worldwide.

"We envision bioprinting becoming a major component of medicine within the next two decades," Miller said.

"The liver is especially interesting because it performs a mind-boggling 500 functions, likely second only to the brain," Stevens said. "The liver's complexity means there is currently no machine or therapy that can replace all its functions when it fails. Bioprinted human organs might someday supply that therapy."

To address this challenge, the team created a new open-source bioprinting technology dubbed the "stereolithography apparatus for tissue engineering," or SLATE. The system uses additive manufacturing to make soft hydrogels one layer at a time.

Layers are printed from a liquid pre-hydrogel solution that becomes a solid when exposed to blue light. A digital light processing projector shines light from below, displaying sequential 2D slices of the structure at high resolution, with pixel sizes ranging from 10-50 microns. With each layer solidified in turn, an overhead arm raises the growing 3D gel just enough to expose liquid to the next image from the projector. The key insight by Miller and Bagrat Grigoryan, a Rice graduate student and lead co-author of the study, was the addition of food dyes that absorb blue light. These photoabsorbers confine the solidification to a very fine layer. In this way, the system can produce soft, water-based, biocompatible gels with intricate internal architecture in a matter of minutes.

Tests of the lung-mimicking structure showed that the tissues were sturdy enough to avoid bursting during blood flow and pulsatile "breathing," a rhythmic intake and outflow of air that simulated the pressures and frequencies of human breathing. Tests found that red blood cells could take up oxygen as they flowed through a network of blood vessels surrounding the "breathing" air sac. This movement of oxygen is similar to the gas exchange that occurs in the lung's alveolar air sacs.

To design the study's most complicated lung-mimicking structure, which is featured on the cover of Science, Miller collaborated with study co-authors Jessica Rosenkrantz and Jesse Louis-Rosenberg, co-founders of Nervous System.

"When we founded Nervous System it was with the goal of adapting algorithms from nature into new ways to design products," Rosenkrantz said. "We never imagined we'd have the opportunity to bring that back and design living tissues."

In the tests of therapeutic implants for liver disease, the team 3D printed tissues, loaded them with primary liver cells and implanted them into mice. The tissues had separate compartments for blood vessels and liver cells and were implanted in mice with chronic liver injury. Tests showed that the liver cells survived the implantation.

Miller said the new bioprinting system can also produce intravascular features, like bicuspid valves that allow fluid to flow in only one direction. In humans, intravascular valves are found in the heart, leg veins and complementary networks like the lymphatic system that have no pump to drive flow.

"With the addition of multivascular and intravascular structure, we're introducing an extensive set of design freedoms for engineering living tissue," Miller said. "We now have the freedom to build many of the intricate structures found in the body."

Miller and Grigoryan are commercializing key aspects of the research through a Houston-based startup company called Volumetric. The company, which Grigoryan has joined full time, is designing and manufacturing bioprinters and bioinks.

Miller, a longstanding champion of open-source 3D printing, said all source data from the experiments in the published Science study are freely available. In addition, all 3D printable files needed to build the stereolithography printing apparatus are available, as are the design files for printing each of the hydrogels used in the study.

"Making the hydrogel design files available will allow others to explore our efforts here, even if they utilize some future 3D printing technology that doesn't exist today," Miller said.

Miller said his lab is already using the new design and bioprinting techniques to explore even more complex structures.

"We are only at the beginning of our exploration of the architectures found in the human body," he said. "We still have so much more to learn."

Read more at Science Daily

Pinpointing Gaia to map the Milky Way

This image, a composite of several observations captured by ESO's VLT Survey Telescope (VST), shows the space observatory Gaia as a faint trail of dots across the lower half of the star-filled field of view. These observations were taken as part of an ongoing collaborative effort to measure Gaia's orbit and improve the accuracy of its unprecedented star map.

Gaia, operated by the European Space Agency (ESA, surveys the sky from orbit to create the largest, most precise, three-dimensional map of our Galaxy. One year ago, the Gaia mission produced its much-awaited second data release, which included high-precision measurements -- positions, distance and proper motions -- of more than one billion stars in our Milky Way galaxy. This catalogue has enabled transformational studies in many fields of astronomy, addressing the structure, origin and evolution the Milky Way and generating more than 1700 scientific publications since its launch in 2013.

In order to reach the accuracy necessary for Gaia's sky maps, it is crucial to pinpoint the position of the spacecraft from Earth. Therefore, while Gaia scans the sky, gathering data for its stellar census, astronomers regularly monitor its position using a global network of optical telescopes, including the VST at ESO's Paranal Observatory. The VST is currently the largest survey telescope observing the sky in visible light, and records Gaia's position in the sky every second night throughout the year.

"Gaia observations require a special observing procedure," explained Monika Petr-Gotzens, who has coordinated the execution of ESO's observations of Gaia since 2013. "The spacecraft is what we call a 'moving target', as it is moving quickly relative to background stars -- tracking Gaia is quite the challenge!"

"The VST is the perfect tool for picking out the motion of Gaia," elaborated Ferdinando Patat, head of the ESO's Observing Programmes Office. "Using one of ESO's first-rate ground-based facilities to bolster cutting-edge space observations is a fine example of scientific cooperation."

"This is an exciting ground-space collaboration, using one of ESO's world-class telescopes to anchor the trailblazing observations of ESA's billion star surveyor," commented Timo Prusti, Gaia project scientist at ESA.

The VST observations are used by ESA's flight dynamics experts to track Gaia and refine the knowledge of the spacecraft's orbit. Painstaking calibration is required to transform the observations, in which Gaia is just a speck of light among the bright stars, into meaningful orbital information. Data from Gaia's second release was used to identify each of the stars in the field of view, and allowed the position of the spacecraft to be calculated with astonishing precision -- up to 20 milliarcseconds.

"This is a challenging process: we are using Gaia's measurements of the stars to calibrate the position of the Gaia spacecraft and ultimately improve its measurements of the stars," explains Timo Prusti.

"After careful and lengthy data processing, we have now achieved the accuracy required for the ground-based observations of Gaia to be implemented as part of the orbit determination," says Martin Altmann, lead of the Ground Based Optical Tracking (GBOT) campaign at the Centre for Astronomy of Heidelberg University, Germany.

Read more at Science Daily

Hubble astronomers assemble wide view of the evolving universe

This graphic compares the dimensions of the Hubble Legacy Field on the sky with the angular size of the Moon. The Hubble Legacy Field is one of the widest views ever taken of the universe with Hubble. The new portrait, a mosaic of nearly 7,500 exposures, covers almost the width of the full Moon. The Moon and the Legacy Field each subtend about an angle of one-half a degree on the sky (or half the width of your forefinger held at arm's length).

Astronomers have put together the largest and most comprehensive "history book" of galaxies into one single image, using 16 years' worth of observations from NASA's Hubble Space Telescope.

The deep-sky mosaic, created from nearly 7,500 individual exposures, provides a wide portrait of the distant universe, containing 265,000 galaxies that stretch back through 13.3 billion years of time to just 500 million years after the big bang. The faintest and farthest galaxies are just one ten-billionth the brightness of what the human eye can see. The universe's evolutionary history is also chronicled in this one sweeping view. The portrait shows how galaxies change over time, building themselves up to become the giant galaxies seen in the nearby universe.

This ambitious endeavor, called the Hubble Legacy Field, also combines observations taken by several Hubble deep-field surveys, including the eXtreme Deep Field (XDF), the deepest view of the universe. The wavelength range stretches from ultraviolet to near-infrared light, capturing the key features of galaxy assembly over time.

"Now that we have gone wider than in previous surveys, we are harvesting many more distant galaxies in the largest such dataset ever produced by Hubble," said Garth Illingworth of the University of California, Santa Cruz, leader of the team that assembled the image. "This one image contains the full history of the growth of galaxies in the universe, from their time as 'infants' to when they grew into fully fledged 'adults.'"

No image will surpass this one until future space telescopes are launched. "We've put together this mosaic as a tool to be used by us and by other astronomers," Illingworth added. "The expectation is that this survey will lead to an even more coherent, in-depth and greater understanding of the universe's evolution in the coming years."

The image yields a huge catalog of distant galaxies. "Such exquisite high-resolution measurements of the numerous galaxies in this catalog enable a wide swath of extragalactic study," said catalog lead researcher Katherine Whitaker of the University of Connecticut, in Storrs. "Often, these kinds of surveys have yielded unanticipated discoveries which have had the greatest impact on our understanding of galaxy evolution."

Galaxies are the "markers of space," as astronomer Edwin Hubble once described them a century ago. Galaxies allow astronomers to trace the expansion of the universe, offer clues to the underlying physics of the cosmos, show when the chemical elements originated, and enable the conditions that eventually led to the appearance of our solar system and life.

This wider view contains about 30 times as many galaxies as in the previous deep fields. The new portrait, a mosaic of multiple snapshots, covers almost the width of the full Moon. The XDF, which penetrated deeper into space than this wider view, lies in this region, but it covers less than one-tenth of the full Moon's diameter. The Legacy Field also uncovers a zoo of unusual objects. Many of them are the remnants of galactic "train wrecks," a time in the early universe when small, young galaxies collided and merged with other galaxies.

Assembling all of the observations was an immense task. The image comprises the collective work of 31 Hubble programs by different teams of astronomers. Hubble has spent more time on this tiny area than on any other region of the sky, totaling more than 250 days, representing nearly three-quarters of a year.

"Our goal was to assemble all 16 years of exposures into a legacy image," explained Dan Magee, of the University of California, Santa Cruz, the team's data processing lead. "Previously, most of these exposures had not been put together in a consistent way that can be used by any researcher. Astronomers can select the data in the Legacy Field they want and work with it immediately, as opposed to having to perform a huge amount of data reduction before conducting scientific analysis."

The image, along with the individual exposures that make up the new view, is available to the worldwide astronomical community through the Mikulski Archive for Space Telescopes (MAST). MAST, an online database of astronomical data from Hubble and other NASA missions, is located at the Space Telescope Science Institute in Baltimore, Maryland.

The Hubble Space Telescope has come a long way in taking ever deeper "core samples" of the distant universe. After Hubble's launch in 1990, astronomers debated if it was worth spending a chunk of the telescope's time to go on a "fishing expedition" to take a very long exposure of a small, seemingly blank piece of sky. The resulting Hubble Deep Field image in 1995 captured several thousand unseen galaxies in one pointing. The bold effort was a landmark demonstration and a defining proof-of-concept that set the stage for future deep field images. In 2002, Hubble's Advanced Camera for Surveys went even deeper to uncover 10,000 galaxies in a single snapshot. Astronomers used exposures taken by Hubble's Wide Field Camera 3 (WFC3), installed in 2009, to assemble the eXtreme Deep Field snapshot in 2012. Unlike previous Hubble cameras, the telescope's WFC3 covers a broader wavelength range, from ultraviolet to near-infrared.

This new image mosaic is the first in a series of Hubble Legacy Field images. The team is working on a second set of images, totaling more than 5,200 Hubble exposures, in another area of the sky. In the future, astronomers hope to broaden the multiwavelength range in the legacy images to include longer-wavelength infrared data and high-energy X-ray observations from two other NASA Great Observatories, the Spitzer Space Telescope and Chandra X-ray Observatory.

The vast number of galaxies in the Legacy Field image are also prime targets for future telescopes. "This will really set the stage for NASA's planned Wide Field Infrared Survey Telescope (WFIRST)," Illingworth said. "The Legacy Field is a pathfinder for WFIRST, which will capture an image that is 100 times larger than a typical Hubble photo. In just three weeks' worth of observations by WFIRST, astronomers will be able to assemble a field that is much deeper and more than twice as large as the Hubble Legacy Field."

In addition, NASA's upcoming James Webb Space Telescope will allow astronomers to push much deeper into the legacy field to reveal how the infant galaxies actually grew. Webb's infrared coverage will go beyond the limits of Hubble and Spitzer to help astronomers identify the first galaxies in the universe.

Read more at Science Daily

Water found in samples from asteroid Itokawa

The samples studied by Jin and Bose came from the feature called the Muses Sea, which is the smooth area in the middle of Itokawa.

Two cosmochemists at Arizona State University have made the first-ever measurements of water contained in samples from the surface of an asteroid. The samples came from asteroid Itokawa and were collected by the Japanese space probe Hayabusa.

The team's findings suggest that impacts early in Earth's history by similar asteroids could have delivered as much as half of our planet's ocean water.

"We found the samples we examined were enriched in water compared to the average for inner solar system objects," says Ziliang Jin. A postdoctoral scholar in ASU's School of Earth and Space Exploration, he is the lead author on the paper published May 1 in Science Advances reporting the results. His co-author is Maitrayee Bose, assistant professor in the School.

"It was a privilege that the Japanese space agency JAXA was willing to share five particles from Itokawa with a U.S. investigator," Bose says. "It also reflects well on our School."

The team's idea of looking for water in the Itokawa samples came as a surprise for the Hayabusa project.

"Until we proposed it, no one thought to look for water," says Bose. "I'm happy to report that our hunch paid off."

In two of the five particles, the team identified the mineral pyroxene. In terrestrial samples, pyroxenes have water in their crystal structure. Bose and Jin suspected that the Itokawa particles might also have traces of water, but they wanted to know exactly how much. Itokawa has had a rough history involving heating, multiple impacts, shocks, and fragmentation. These would raise the temperature of the minerals and drive off water.

To study the samples, each about half the thickness of a human hair, the team used ASU's Nanoscale Secondary Ion Mass Spectrometer (NanoSIMS), which can measure such tiny mineral grains with great sensitivity.

The NanoSIMS measurements revealed the samples were unexpectedly rich in water. They also suggest that even nominally dry asteroids such as Itokawa may in fact harbor more water than scientists have assumed.

Fragmented world

Itokawa is a peanut-shaped asteroid about 1,800 feet long and 700 to 1,000 feet wide. It circles the Sun every 18 months at an average distance of 1.3 times the Earth-Sun distance. Part of Itokawa's path brings it inside Earth's orbit and at farthest, it sweeps out a little beyond that of Mars.

Based on Itokawa's spectrum in Earth-based telescopes, planetary scientists place it in the S class. This links it with the stony meteorites, which are thought to be fragments from S-type asteroids broken off in collisions.

"S-type asteroids are one of the most common objects in the asteroid belt," says Bose. "They originally formed at a distance from the Sun of one-third to three times Earth's distance." She adds that although they are small, these asteroids have kept whatever water and other volatile materials they formed with.

In structure, Itokawa resembles a pair of rubble piles crunched together. It has two main lobes, each studded with boulders but having different overall densities, while between the lobes is a narrower section.

Jin and Bose point out that today's Itokawa is the remnant of a parent body at least 12 miles wide that at some point was heated between 1,000 and 1,500 degrees Fahrenheit. The parent body suffered several large shocks from impacts, with one final shattering event that broke it apart. In the aftermath two of the fragments merged and formed today's Itokawa, which reached its current size and shape about 8 million years ago.

"The particles we analyzed came from a part of Itokawa called the Muses Sea," says Bose. "It's an area on the asteroid that's smooth and dust-covered."

Jin adds, "Although the samples were collected at the surface, we don't know where these grains were in the original parent body. But our best guess is that they were buried more than 100 meters deep within it."

He adds that despite the catastrophic breakup of the parent body, and the sample grains being exposed to radiation and impacts by micrometeorites at the surface, the minerals still show evidence of water that has not been lost to space.

In addition, says Jin, "The minerals have hydrogen isotopic compositions that are indistinguishable from Earth."

Bose explains, "This means S-type asteroids and the parent bodies of ordinary chondrites are likely a critical source of water and several other elements for the terrestrial planets."

She adds, "And we can say this only because of in-situ isotopic measurements on returned samples of asteroid regolith -- their surface dust and rocks.

"That makes these asteroids high-priority targets for exploration."

Scouting for samples

Bose notes that she is building a clean-lab facility at ASU, which along with the NanoSIMS (partially funded by National Science Foundation) would be the first such facility at a public university capable of analyzing dust grains from other solar system bodies.

Another Japanese mission, Hayabusa 2, is currently at an asteroid named Ryugu, where it will collect samples, bringing them back to Earth in December 2020. The director of ASU's Center for Meteorite Studies, professor Meenakshi Wadhwa, is a member of the Initial Analysis team for Chemistry for the Hayabusa 2 mission.

ASU is also on board NASA's OSIRIS-REx sample-return mission, which is orbiting a near-Earth asteroid named Bennu. Among other instruments, the spacecraft carries the OSIRIS-REx Thermal Emission Spectrometer (OTES), designed by ASU Regents' Professor Philip Christensen and built at the School. OSIRIS-REx is scheduled to collect samples from Bennu in summer 2020 and bring them back to Earth in September 2023.

For planetary scientists and cosmochemists who are drawing a picture of how the solar system formed, asteroids are a great resource. As leftover building blocks for the planetary system, they vary greatly among themselves while preserving materials from early in solar system history.

Read more at Science Daily

First hominins on the Tibetan Plateau were Denisovans

The Xiahe mandible, only represented by its right half, was found in 1980 in Baishiya Karst Cave.

Denisovans -- an extinct sister group of Neandertals -- were discovered in 2010, when a research team led by Svante Pääbo from the Max Planck Institute for Evolutionary Anthropology (MPI-EVA) sequenced the genome of a fossil finger bone found at Denisova Cave in Russia and showed that it belonged to a hominin group that was genetically distinct from Neandertals. "Traces of Denisovan DNA are found in present-day Asian, Australian and Melanesian populations, suggesting that these ancient hominins may have once been widespread," says Jean-Jacques Hublin, director of the Department of Human Evolution at the MPI-EVA. "Yet so far the only fossils representing this ancient hominin group were identified at Denisova Cave."

Mandible from Baishiya Karst Cave

In their new study, the researchers now describe a hominin lower mandible that was found on the Tibetan Plateau in Baishiya Karst Cave in Xiahe, China. The fossil was originally discovered in 1980 by a local monk who donated it to the 6th Gung-Thang Living Buddha who then passed it on to Lanzhou University. Since 2010, researchers Fahu Chen and Dongju Zhang from Lanzhou University have been studying the area of the discovery and the cave site from where the mandible originated. In 2016, they initiated a collaboration with the Department of Human Evolution at the MPI-EVA and have since been jointly analysing the fossil.

While the researchers could not find any traces of DNA preserved in this fossil, they managed to extract proteins from one of the molars, which they then analysed applying ancient protein analysis. "The ancient proteins in the mandible are highly degraded and clearly distinguishable from modern proteins that may contaminate a sample," says Frido Welker of the MPI-EVA and the University of Copenhagen. "Our protein analysis shows that the Xiahe mandible belonged to a hominin population that was closely related to the Denisovans from Denisova Cave."

Primitive shape and large molars

The researchers found the mandible to be well-preserved. Its robust primitive shape and the very large molars still attached to it suggest that this mandible once belonged to a Middle Pleistocene hominin sharing anatomical features with Neandertals and specimens from the Denisova Cave. Attached to the mandible was a heavy carbonate crust, and by applying U-series dating to the crust the researchers found that the Xiahe mandible is at least 160,000 years old. Chuan-Chou Shen from the Department of Geosciences at National Taiwan University, who conducted the dating, says: "This minimum age equals that of the oldest specimens from the Denisova Cave."

"The Xiahe mandible likely represents the earliest hominin fossil on the Tibetan Plateau," says Fahu Chen, director of the Institute of Tibetan Research, CAS. These people had already adapted to living in this high-altitude low-oxygen environment long before Homo sapiens even arrived in the region. Previous genetic studies found present-day Himalayan populations to carry the EPAS1 allele in their genome, passed on to them by Denisovans, which helps them to adapt to their specific environment.

Read more at Science Daily

Ice feature on Saturn's giant moon, TItan

This figure shows 3 orientations of Titan's globe. Mapped in blue is the icy corridor.

Rain, seas and a surface of eroding organic material can be found both on Earth and on Saturn's largest moon, Titan. However, on Titan it is methane, not water, that fills the lakes with slushy raindrops.

While trying to find the source of Titan's methane, University of Arizona researcher Caitlin Griffith and her team discovered something unexoldpected -- a long ice feature that wraps nearly half way around Titan.

Griffith, a professor in the UA Lunar and Planetary Laboratory, is the lead author on the paper published today in Nature Astronomy.

On Titan, atmospheric methane molecules are continuously broken apart by sunlight. The resulting atmospheric haze settles to the surface and accumulates as organic sediments, rapidly depleting the atmospheric methane.

This organic veneer is made up of the material of past atmospheres.

There is no obvious source of methane, except from the evaporation of methane from the polar lakes. But Titan's lakes contain only one-third of the methane in Titan's atmosphere and will be exhausted soon by geological time scales.

One theory is that the methane could be supplied by subsurface reservoirs that vent methane into the atmosphere. Prior studies of Titan indicate the presence of a singular region called Sotra, which looks like cryo-volcano, with icy flow features.

Griffith's team set out to study the composition of Titan's surface, partly hoping to find subtle small cryo-volcanos candidates. They analyzed half of Titan's surface and none were detected, but Sotra was found to be exceptional in that it exhibits the strongest ice features.

Yet the major ice feature the researchers found was completely unexpected. It consists of a linear ice corridor that wraps around 40 percent of Titan's circumference.

"This icy corridor is puzzling, because it doesn't correlate with any surface features nor measurements of the subsurface," Griffith said. "Given that our study and past work indicate that Titan is currently not volcanically active, the trace of the corridor is likely a vestige of the past. We detect this feature on steep slopes, but not on all slopes. This suggests that the icy corridor is currently eroding, potentially unveiling presence of ice and organic strata."

The team's analysis also indicates a diversity of organic material in certain regions. These surface deposits are of interest because laboratory simulations of Titan's atmosphere produce biologically interesting compounds such as amino acids.

Griffith analyzed tens of thousands of spectral images taken of the topmost layer of the surface by Cassini's Visible and Infrared Mapping Spectrometer, using a method that enabled the detection of weak surface features.

This feat was accomplished by Griffith's application of the principal components analysis, or PCA. It allowed her to tease out subtle features caused by ice and organic sediments on Titan's surface from the ubiquitous haze and more obvious surface features. Instead of measuring the surface features individually for each pixel in an image, the PCA uses all of the pixels to recognize the main and more subtle signatures.

Griffith's team compared their results with past studies including the Huygens probe, which landed on Titan in 2005. The comparison validated both the technique and the results. Plans are underway to use the technique to explore the poles where methane seas reside.

"Both Titan and Earth followed different evolutionary paths, and both ended up with unique organic-rich atmospheres and surfaces," Griffth said. "But it is not clear whether Titan and Earth are common blueprints of the organic-rich of bodies or two among many possible organic-rich worlds."

Read more at Science Daily

What a dying star's ashes tell us about the birth of our solar system

Billions of years ago, before our solar system was born, a dead star known as a white dwarf in a nearby binary star system accumulated enough material from its companion to cause it to 'go nova.' The stellar explosion forged dust grains with exotic compositions not found in our solar system. A team of researchers led by the UA found such a grain (inset image), encased in a meteorite, that survived the formation of our solar system and analyzed it with instruments sensitive enough to ID single atoms in a sample. Measuring one 25,000th of an inch, the carbon-rich graphite grain (red) revealed an embedded speck of oxygen-rich material (blue), two types of stardust that were thought could not form in the same nova eruption.

A grain of dust forged in the death throes of a long-gone star was discovered by a team of researchers led by the University of Arizona.

The discovery challenges some of the current theories about how dying stars seed the universe with raw materials for the formation of planets and, ultimately, the precursor molecules of life.

Tucked inside a chondritic meteorite collected in Antarctica, the tiny speck represents actual stardust, most likely hurled into space by an exploding star before our own sun existed. Although such grains are believed to provide important raw materials contributing to the mix from which the sun and our planets formed, they rarely survive the turmoil that goes with the birth of a solar system.

"As actual dust from stars, such presolar grains give us insight into the building blocks from which our solar system formed," said Pierre Haenecour, lead author of the paper, which is scheduled for advance online publication on Nature Astronomy's website on Apr. 29. "They also provide us with a direct snapshot of the conditions in a star at the time when this grain was formed."

Dubbed LAP-149, the dust grain represents the only known assemblage of graphite and silicate grains that can be traced to a specific type of stellar explosion called a nova. Remarkably, it survived the journey through interstellar space and traveled to the region that would become our solar system some 4.5 billion years ago, perhaps earlier, where it became embedded in a primitive meteorite.

Novae are binary star systems in which a core remnant of a star, called a white dwarf, is on its way to fading out of the universe, while its companion is either a low-mass main sequence star or a red giant. The white dwarf then begins syphoning material off its bloated companion. Once it accretes enough new stellar material, the white dwarf re-ignites in periodic outbursts violent enough to forge new chemical elements from the stellar fuel and spew them deep into space, where they can travel to new stellar systems and become incorporated in their raw materials.

Since shortly after the Big Bang, when the universe consisted of only hydrogen, helium and traces of lithium, stellar explosions have contributed to the chemical enrichment of the cosmos, resulting in the plethora of elements we see today.

Taking advantage of sophisticated ion and electron microscopy facilities at the UA's Lunar and Planetary Laboratory, a research team led by Haenecour analyzed the microbe-sized dust grain down to the atomic level. The tiny messenger from outer space turned out to be truly alien -- highly enriched in a carbon isotope called 13C.

"The carbon isotopic compositions in anything we have ever sampled that came from any planet or body in our solar system varies typically by a factor on the order of 50," said Haenecour, who will join the Lunar and Planetary Laboratory as an assistant professor in the fall. "The 13C we found in LAP-149 is enriched more than 50,000-fold. These results provide further laboratory evidence that both carbon- and oxygen-rich grains from novae contributed to the building blocks of our solar system."

Although their parent stars no longer exist, the isotopic and chemical compositions and microstructure of individual stardust grains identified in meteorites provide unique constraints on dust formation and thermodynamic conditions in stellar outflows, the authors wrote.

Detailed analysis revealed even more unexpected secrets: Unlike similar dust grains thought to have been forged in dying stars, LAP-149 is the first known grain consisting of graphite that contains an oxygen-rich silicate inclusion.

"Our find provides us with a glimpse into a process we could never witness on Earth," Haenecour added. "It tells us about how dust grains form and move around inside as they are expelled by the nova. We now know that carbonaceous and silicate dust grains can form in the same nova ejecta, and they get transported across chemically distinct clumps of dust within the ejecta, something that was predicted by models of novae but never found in a specimen."

Unfortunately, LAP-149 does not contain enough atoms to determine its exact age, so researchers hope to find similar, larger specimens in the future.

"If we could date these objects someday, we could get a better idea of what our galaxy looked like in our region and what triggered the formation of the solar system," said Tom Zega, scientific director of the UA's Kuiper Materials Imaging and Characterization Facility and associate professor in the Lunar and Planetary Laboratory and UA Department of Materials Science and Engineering. "Perhaps we owe our existence to a nearby supernova explosion, compressing clouds of gas and dust with its shockwave, igniting stars and creating stellar nurseries, similar to what we see in Hubble's famous 'Pillars of Creation' picture."

The meteorite containing the speck of stardust is one of the most pristine meteorites in the Lunar and Planetary Laboratory's collection. Classified as a carbonaceous chondrite, it is believed to be analogous to the material on Bennu, the target asteroid of the UA-led OSIRIS-REx mission. By taking a sample of Bennu and bringing it back to Earth, the OSIRIS-REx mission team hopes to provide scientists with material that has seen little, if any, alteration since the formation of our solar system.

Until then, researchers depend on rare finds like LAP-149, which survived being blasted from an exploding star, caught in a collapsing cloud of gas and dust that would become our solar system and baked into an asteroid before falling to the earth.

Read more at Science Daily

The space rock that hit the moon at 61,000 kilometers an hour

The flash from the impact of the meteorite on the eclipsed Moon, seen as the dot at top left (indicated by the arrow in the image), as recorded by two of the telescopes operating in the framework of the MIDAS Survey from Sevilla (Spain) on 2019 January 21.

Observers watching January's total eclipse of the Moon saw a rare event, a short-lived flash as a meteorite hit the lunar surface. Spanish astronomers now think the space rock collided with the Moon at 61,000 kilometres an hour, excavating a crater 10 to 15 metres across. Prof Jose Maria Madiedo of the University of Huelva, and Dr Jose L. Ortiz of the Institute of Astrophysics of Andalusia, publish their results in a new paper in Monthly Notices of the Royal Astronomical Society.

Total lunar eclipses take place when the Moon moves completely into the shadow of the Earth. The Moon takes on a red colour -- the result of scattered sunlight refracted through the Earth's atmosphere -- but is much darker than normal. These spectacular events are regularly observed by astronomers and the wider public alike.

The most recent lunar eclipse took place on 21 January 2019, with observers in North and South America and Western Europe enjoying the best view. At 0441 GMT, just after the total phase of the eclipse began, a flash was seen on the lunar surface. Widespread reports from amateur astronomers indicated the flash -- attributed to a meteorite impact -- was bright enough to be seen with the naked eye.

Madiedo and Ortiz operate the Moon Impacts Detection and Analysis System (MIDAS), using eight telescopes in south of Spain to monitor the lunar surface. The impact flash lasted 0.28 seconds and is the first ever filmed during a lunar eclipse, despite a number of earlier attempts.

"Something inside of me told me that this time would be the time," said Madiedo, who was impressed when he observed the event, as it was brighter than most of the events regularly detected by the survey.

Unlike the Earth, the Moon has no atmosphere to protect it and so even small rocks can hit its surface. Since these impacts take place at huge speeds, the rocks are instantaneously vaporised at the impact site, producing an expanding plume of debris whose glow can be detected from our planet as short-duration flashes.

MIDAS telescopes observed the impact flash at multiple wavelengths (different colours of light), improving the analysis of the event. Madiedo and Ortiz conclude that the incoming rock had a mass of 45kg, measured 30 to 60 centimetres across, and hit the surface at 61,000 kilometres an hour. The impact site is close to the crater Lagrange H, near the west-south-west portion of the lunar limb.

The two scientists assess the impact energy as equivalent to 1.5 tonnes of TNT, enough to create a crater up to 15 metres across, or about the size of two double decker buses side by side. The debris ejected is estimated to have reached a peak temperature of 5400 degrees Celsius, roughly the same as the surface of the Sun.

Madiedo comments: "It would be impossible to reproduce these high-speed collisions in a lab on Earth. Observing flashes is a great way to test our ideas on exactly what happens when a meteorite collides with the Moon."

Read more at Science Daily

Milky Way star with strange chemistry is from dwarf galaxy

The Subaru Telescope High Dispersion Spectrograph.

Astronomers have discovered a star in the Milky Way Galaxy with a chemical composition unlike any other star in our Galaxy. This chemical composition has been seen in a small number of stars in dwarf galaxies orbiting the Milky Way. This suggests that the star was part of a dwarf galaxy that merged into the Milky Way.

In the LAMOST (Large Sky Area Multi-Object Fiber Spectroscopic Telescope) survey data, researchers noticed the star J1124+4535 for its unusual chemical composition. Initial observations showed that J1124+4535, located in the constellation Ursa Major (Big Dipper), had low abundances of certain elements, such as magnesium. Follow-up observations with the High Dispersion Spectrograph on the Subaru Telescope confirmed the low levels of magnesium but found comparatively high levels of Europium. This is the first time an element ratio like this has been observed in a star in the Milky Way.

Stars form from clouds of interstellar gas. The element ratios of the parent cloud impart an observable chemical signature on stars formed in that cloud. So stars formed close together have similar element ratios. The composition of J1124+4535 doesn't match any other stars in the Milky Way, indicating that it must have formed elsewhere.

Chemical signatures similar to J1124+4535 have been observed in some stars in dwarf galaxies orbiting the Milky Way. Galaxy evolution models and simulations suggest that galaxies like the Milky Way grow by absorbing neighboring dwarf galaxies. Thus it makes sense that J1124+4535 was born in a now vanished dwarf galaxy which merged into the Milky Way.

From Science Daily

Astronomers discover 2,000-year-old remnant of a nova

Near the centre of the globular cluster Messier 22, the team of scientists discovered the remains of a nova.

For the first time, a European research team involving the University of Göttingen has discovered the remains of a nova in a galactic globular cluster. A nova is an explosion of hydrogen on the surface of a star which makes it much brighter. The remains have formed a glowing nebula. The remnant is located near the centre of the globular cluster Messier 22 and has recently been observed using modern instruments. The results will be published in the journal Astronomy & Astrophysics.

"The position and brightness of the remains match an entry from 48 BC in an ancient collection of observations by Chinese astronomers," says first author Fabian Göttgens of the Institute for Astrophysics at the University of Göttingen. This is research carried out for his PhD in the Stellar Astrophysics research group lead by Professor Dreizler. "They probably saw the original nova in the same place." This means modern measurements confirm one of the oldest observations of an event outside the solar system.

Globular clusters are large, spherical clusters of several hundreds of thousands of very old stars that orbit together around their home galaxy. There are 150 known globular clusters orbiting our galaxy, the Milky Way. Messier 22 is one of these star clusters, it lies in the constellation Sagittarius in the direction of the centre of the Milky Way. It was observed together with two dozen other globular clusters with the instrument MUSE at the Very Large Telescope of the ESO in Chile. The MUSE instrument was developed with the participation of the Institute for Astrophysics, which was funded by the BMBF. It does not only produce images, it also simultaneously splits starlight by colour, measuring the brightness of stars as a function of colour. This makes it particularly suitable for finding nebulae that often only glow in a certain colour -- usually red.

The newly discovered remains of the nova form a red shining nebula of hydrogen gas and other gases, which has a diameter of about 8,000 times the distance between Earth and Sun. Despite its size, the nebula is relatively light, with a mass about 30 times that of Earth, because the gas was dispersed by the explosion.

From Science Daily

Magma is the key to the moon's makeup

Snapshots of numerical modeling of the moon’s formation by a giant impact. The central part of the image is a proto-Earth; red points indicate materials from the ocean of magma in a proto-Earth; blue points indicate the impactor materials.

For more than a century, scientists have squabbled over how Earth's moon formed. But researchers at Yale and in Japan say they may have the answer.

Many theorists believe a Mars-sized object slammed into the early Earth, and material dislodged from that collision formed the basis of the moon. When this idea was tested in computer simulations, it turned out that the moon would be made primarily from the impacting object. Yet the opposite is true; we know from analyzing rocks brought back from Apollo missions that the moon consists mainly of material from Earth.

A new study published April 29 in Nature Geoscience, co-authored by Yale geophysicist Shun-ichiro Karato, offers an explanation.

The key, Karato says, is that the early, proto-Earth -- about 50 million years after the formation of the Sun -- was covered by a sea of hot magma, while the impacting object was likely made of solid material. Karato and his collaborators set out to test a new model, based on the collision of a proto-Earth covered with an ocean of magma and a solid impacting object.

The model showed that after the collision, the magma is heated much more than solids from the impacting object. The magma then expands in volume and goes into orbit to form the moon, the researchers say. This explains why there is much more Earth material in the moon's makeup. Previous models did not account for the different degree of heating between the proto-Earth silicate and the impactor.

"In our model, about 80% of the moon is made of proto-Earth materials," said Karato, who has conducted extensive research on the chemical properties of proto-Earth magma. "In most of the previous models, about 80% of the moon is made of the impactor. This is a big difference."

Karato said the new model confirms previous theories about how the moon formed, without the need to propose unconventional collision conditions -- something theorists have had to do until now.

For the study, Karato led the research into the compression of molten silicate. A group from the Tokyo Institute of Technology and the RIKEN Center for Computational Science developed a computational model to predict how material from the collision became the moon.

Read more at Science Daily

Giant planets and big data: What deep learning reveals about Saturn's storms

Cloud distribution as mapped by PlanetNet across six overlapping data sets. The stormy region feature (blue) occurs in the vicinity of dark storms (purple/green) in contrast to the unperturbed regions (red/orange). The area covered by the multiple storm system is equivalent to about 70% of the Earth's surface.

A "deep learning" approach to detecting storms on Saturn is set to transform our understanding of planetary atmospheres, according to University College London and University of Arizona researchers.

The new technique, called PlanetNet, identifies and maps the components and features in turbulent regions of Saturn's atmosphere, giving insights into the processes that drive them.

A study, published today in Nature Astronomy, provides results from the first demonstration of the PlanetNet algorithm. The results clearly show the vast regions affected by storms and that dark storm clouds contain material swept up from the lower atmosphere by strong vertical winds.

Developed by UA and UCL researchers, PlanetNet was trained and tested using infrared data from the Visible and Infrared Mapping Spectrometer instrument on Cassini, a joint mission between NASA, the European Space Agency and the Italian Space Agency.

A dataset containing multiple, adjacent storms observed at Saturn in February 2008 was chosen to provide a range of complex atmospheric features to challenge PlanetNet's capabilities.

"PlanetNet enables us to analyze much bigger volumes of data, and this gives insights into the large-scale dynamics of Saturn," said UA professor Caitlin Griffith, who co-authored the paper. "The results reveal atmospheric features that were previously undetected. PlanetNet can easily be adapted to other datasets and planets, making it an invaluable potential tool for many future missions."

Previous analysis of the dataset indicated a rare detection of ammonia in Saturn's atmosphere, in the form of an S-shaped cloud.

The map produced through PlanetNet shows that this feature is a prominent part of a much larger upwelling of ammonia ice clouds around a central dark storm. PlanetNet identifies similar upwelling around another small storm, suggesting such features are quite common.

The map also shows pronounced differences between the center of storms and the surrounding areas, indicating that the eye gives a clear view into the warmer, deep atmosphere.

"Missions like Cassini gather enormous amounts of data, but classical techniques for analysis have drawbacks, either in the accuracy of information that can be extracted or in the time they take to perform. Deep learning enables pattern recognition across diverse, multiple data sets," said Ingo Waldmann, lead author and deputy director of the UCL Centre for Space and Exoplanet Data.

"This gives us the potential to analyze atmospheric phenomena over large areas and from different viewing angles, and to make new associations between the shape of features and the chemical and physical properties that create them," he said.

Initially, PlanetNet searches the data for signs of clustering in the cloud structure and gas composition. For areas of interest, it trims the data to remove uncertainties at the edges and runs a parallel analysis of the spectral and spatial properties. Recombining the two data streams, PlanetNet creates a map that presents quickly and accurately the major components of Saturn's storms with unprecedented precision.

PlanetNet's accuracy has been validated on Cassini data not included in the training phase. The whole dataset has also been rotated and resampled to create synthetic data for further testing. PlanetNet has achieved over 90 percent classification accuracy in both test cases.

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Spinning black hole sprays light-speed plasma clouds into space

Artist's impression of jet ejections in V404 Cygni. With our radio telescopes, we see individual bright clouds of plasma that have been ejected from the innermost regions, and redirected by the puffed-up inner accretion disk.

Astronomers have discovered rapidly swinging jets coming from a black hole almost 8000 light-years from Earth.

Published today in the journal Nature, the research shows jets from V404 Cygni's black hole behaving in a way never seen before on such short timescales.

The jets appear to be rapidly rotating with high-speed clouds of plasma -- potentially just minutes apart -- shooting out of the black hole in different directions.

Lead author Associate Professor James Miller-Jones, from the Curtin University node of the International Centre for Radio Astronomy Research (ICRAR), said black holes are some of the most extreme objects in the Universe.

"This is one of the most extraordinary black hole systems I've ever come across," Associate Professor Miller-Jones said.

"Like many black holes, it's feeding on a nearby star, pulling gas away from the star and forming a disk of material that encircles the black hole and spirals towards it under gravity.

"What's different in V404 Cygni is that we think the disk of material and the black hole are misaligned. "This appears to be causing the inner part of the disk to wobble like a spinning top and fire jets out in different directions as it changes orientation."

V404 Cygni was first identified as a black hole in 1989 when it released a big outburst of jets and radiation.

Astronomers looking at archival photographic plates then found previous outbursts in observations from 1938 and 1956.

Associate Professor Miller-Jones said that when V404 Cygni experienced another very bright outburst in 2015, lasting for two weeks, telescopes around the world tuned in to study what was going on.

"Everybody jumped on the outburst with whatever telescopes they could throw at it," he said.

"So we have this amazing observational coverage."

When Associate Professor Miller-Jones and his team studied the black hole, they saw its jets behaving in a way never seen before.

Where jets are usually thought to shoot straight out from the poles of black holes, these jets were shooting out in different directions at different times.

And they were changing direction very quickly -- over no more than a couple of hours.

Associate Professor Miller-Jones said the change in the movement of the jets was because of the accretion disk -- the rotating disk of matter around a black hole.

He said V404 Cygni's accretion disk is 10 million kilometres wide, and the inner few thousand kilometres was puffed up and wobbling during the bright outburst.

"The inner part of the accretion disk was precessing and effectively pulling the jets around with it," Associate Professor Miller-Jones said.

"You can think of it like the wobble of a spinning top as it slows down -- only in this case, the wobble is caused by Einstein's theory of general relativity."

The research used observations from the Very Long Baseline Array, a continent-sized radio telescope made up of 10 dishes across the United States, from the Virgin Islands in the Caribbean to Hawaii.

Co-author Alex Tetarenko -- a recent PhD graduate from the University of Alberta and currently an East Asian Observatory Fellow working in Hawaii -- said the speed the jets were changing direction meant the scientists had to use a very different approach to most radio observations.

"Typically, radio telescopes produce a single image from several hours of observation," she said.

"But these jets were changing so fast that in a four-hour image we just saw a blur.

"It was like trying to take a picture of a waterfall with a one-second shutter speed." Instead, the researchers produced 103 individual images, each about 70 seconds long, and joined them together into a movie.

"It was only by doing this that we were able to see these changes over a very short time period," Dr Tetarenko said.

Study co-author Dr Gemma Anderson, who is also based at ICRAR's Curtin University node, said the wobble of the inner accretion disk could happen in other extreme events in the Universe too.

"Anytime you get a misalignment between the spin of a black hole and the material falling in, you would expect to see this when a black hole starts feeding very rapidly," Dr Anderson said.

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Chemists manipulate the quantum states of gold nanoclusters

Carnegie Mellon chemists created a 30-atom gold nanocluster with a hcp structure, which has a quantum lifetime of one nanosecond and a 38-atom gold nanocluster with a bcc structure, which has a quantum lifetime of 4.7 microseconds.

Researchers from Carnegie Mellon University's Department of Chemistry have found a way to control the lifetime of the quantum states of gold nanoclusters by three orders of magnitude, which could lead to improvements in solar cell and photocatalysis technologies. Their study is published in the April 18 issue of Science.

Excited quantum states occur when light is absorbed by a particle and the energy from that light is temporarily stored within the particle, making its energy higher than its ground state. The energy decays quickly and can be lost as heat in the span of a nanosecond, or one billionth of a second. Extending this quantum state could provide researchers with more time and opportunity to harness the stored energy.

Carnegie Mellon Chemistry Professor Rongchao Jin is known for developing precisely sized gold nanoparticles. In this extension of his work, post-doctoral researcher Meng Zhou and Ph.D. student Tatsuya Higaki, who are co-first authors of the paper, studied atomically precise gold nanoclusters containing between 30 and 38 atoms. They altered the structures of clusters by rearranging the atoms into exotic configurations and protecting them with a capping ligand.

The researchers measured the lifetimes of the nanoclusters' quantum states by using femtosecond and nanosecond time-resolved spectroscopy to take snapshots of the nanoclusters from the time when they absorbed energy from light, in this case a femtosecond laser pulse, until they released the energy. Collaborators at University of California, Riverside confirmed the results using density function theory calculations to analyze the molecular orbitals of the nanoclusters.

They found that a 30-atom gold nanocluster, with a hexagonal close-packed (hcp) structure, had a quantum lifetime of one nanosecond. But a 38-atom gold nanocluster with a body-centered cubic (bcc) structure had a much longer lifetime of 4.7 microseconds. Extending the lifetime by three magnitudes gives researchers ample time to extract the absorbed light energy from the nanoclusters -- a finding that has significant implications.

"The strategy of manipulating the excited-state lifetime from very short to very long is exciting. The exceptionally long quantum lifetime of 4.7 microseconds is comparable to that of bulk silicon, which is used for commercial solar cells," said Jin. "It should give us enough time to efficiently extract the energy into external circuits as an electronic current without losing too much energy to heat."

The tailored quantum lifetime can also be used to increase the efficiency of visible light-based photocatalysis used to convert solar energy storage into chemicals, such as converting methanol and ethanol from carbon dioxide.

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