Astronomers discover dizzying spin of the Milky Way galaxy's 'halo'

Astronomers at the University of Michigan's College of Literature, Science, and the Arts (LSA) discovered for the first time that the hot gas in the halo of the Milky Way galaxy is spinning in the same direction and at comparable speed as the galaxy's disk, which contains our stars, planets, gas, and dust. This new knowledge sheds light on how individual atoms have assembled into stars, planets, and galaxies like our own, and what the future holds for these galaxies.

"This flies in the face of expectations," says Edmund Hodges-Kluck, assistant research scientist. "People just assumed that the disk of the Milky Way spins while this enormous reservoir of hot gas is stationary -- but that is wrong. This hot gas reservoir is rotating as well, just not quite as fast as the disk."

The new NASA-funded research using the archival data obtained by XMM-Newton, a European Space Agency telescope, was recently published in theAstrophysical Journal. The study focuses on our galaxy's hot gaseous halo, which is several times larger than the Milky Way disk and composed of ionized plasma.

Because motion produces a shift in the wavelength of light, the U-M researchers measured such shifts around the sky using lines of very hot oxygen. What they found was groundbreaking: The line shifts measured by the researchers show that the galaxy's halo spins in the same direction as the disk of the Milky Way and at a similar speed -- about 400,000 mph for the halo versus 540,000 mph for the disk.

"The rotation of the hot halo is an incredible clue to how the Milky Way formed," said Hodges Kluck. "It tells us that this hot atmosphere is the original source of a lot of the matter in the disk."

Scientists have long puzzled over why almost all galaxies, including the Milky Way, seem to lack most of the matter that they otherwise would expect to find. Astronomers believe that about 80% of the matter in the universe is the mysterious "dark matter" that, so far, can only be detected by its gravitational pull. But even most of the remaining 20% of "normal" matter is missing from galaxy disks. More recently, some of the "missing" matter has been discovered in the halo. The U-M researchers say that learning about the direction and speed of the spinning halo can help us learn both how the material got there in the first place, and the rate at which we expect the matter to settle into the galaxy.

"Now that we know about the rotation, theorists will begin to use this to learn how our Milky Way galaxy formed -- and its eventual destiny," says Joel Bregman, a U-M LSA professor of astronomy.

"We can use this discovery to learn so much more -- the rotation of this hot halo will be a big topic of future X-ray spectrographs," Bregman says.

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New remote-controlled microrobots for medical operations

For the past few years, scientists around the world have been studying ways to use miniature robots to better treat a variety of diseases. The robots are designed to enter the human body, where they can deliver drugs at specific locations or perform precise operations like clearing clogged-up arteries. By replacing invasive, often complicated surgery, they could optimize medicine.

EPFL scientist Selman Sakar teamed up with Hen-Wei Huang and Bradley Nelson at ETHZ to develop a simple and versatile method for building such bio-inspired robots and equipping them with advanced features. They also created a platform for testing several robot designs and studying different modes of locomotion. Their work, published in Nature Communications, produced complex reconfigurable microrobots that can be manufactured with high throughput. They built an integrated manipulation platform that can remotely control the robots' mobility with electromagnetic fields, and cause them to shape-shift using heat.

A robot that looks and moves like a bacterium

Unlike conventional robots, these microrobots are soft, flexible, and motor-less. They are made of a biocompatible hydrogel and magnetic nanoparticles. These nanoparticles have two functions. They give the microrobots their shape during the manufacturing process, and make them move and swim when an electromagnetic field is applied.

Building one of these microrobots involves several steps. First, the nanoparticles are placed inside layers of a biocompatible hydrogel. Then an electromagnetic field is applied to orientate the nanoparticles at different parts of the robot, followed by a polymerization step to "solidify" the hydrogel. After this, the robot is placed in water where it folds in specific ways depending on the orientation of the nanoparticles inside the gel, to form the final overall 3D architecture of the microrobot.

Once the final shape is achieved, an electromagnetic field is used to make the robot swim. Then, when heated, the robot changes shape and "unfolds." This fabrication approach allowed the researchers to build microrobots that mimic the bacterium that causes African trypanosomiasis, otherwise known as sleeping sickness. This particular bacterium uses a flagellum for propulsion, but hides it away once inside a person's bloodstream as a survival mechanism.

The researchers tested different microrobot designs to come up with one that imitates this behavior. The prototype robot presented in this work has a bacterium-like flagellum that enables it to swim. When heated with a laser, the flagellum wraps around the robot's body and is "hidden."

A better understanding of how bacteria behave

"We show that both a bacterium's body and its flagellum play an important role in its movement," said Sakar. "Our new production method lets us test an array of shapes and combinations to obtain the best motion capability for a given task. Our research also provides valuable insight into how bacteria move inside the human body and adapt to changes in their microenvironment."

For now, the microrobots are still in development. "There are still many factors we have to take into account," says Sakar. "For instance, we have to make sure that the microrobots won't cause any side-effects in patients."

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Scientists program cells to remember and respond to series of stimuli

Synthetic biology allows researchers to program cells to perform novel functions such as fluorescing in response to a particular chemical or producing drugs in response to disease markers. In a step toward devising much more complex cellular circuits, MIT engineers have now programmed cells to remember and respond to a series of events.

These cells can remember, in the correct order, up to three different inputs, but this approach should be scalable to incorporate many more stimuli, the researchers say. Using this system, scientists can track cellular events that occur in a particular order, create environmental sensors that store complex histories, or program cellular trajectories.

"You can build very complex computing systems if you integrate the element of memory together with computation," says Timothy Lu, an associate professor of electrical engineering and computer science and of biological engineering, and head of the Synthetic Biology Group at MIT's Research Laboratory of Electronics.

This approach allows scientists to create biological "state machines" -- devices that exist in different states depending on the identities and orders of inputs they receive. The researchers also created software that helps users design circuits that implement state machines with different behaviors, which can then be tested in cells.

Lu is the senior author of the new study, which appears in the 22 July issue ofScience. Nathaniel Roquet, an MIT and Harvard graduate student, is the paper's lead author. Other authors on the paper include Scott Aaronson, an associate professor of electrical engineering and computer science, recent MIT graduate Ava Soleimany, and recent Wellesley College graduate Alyssa Ferris.

Long-term memory

In 2013, Lu and colleagues designed cell circuits that could perform a logic function and then store a memory of the event by encoding it in their DNA.

The state machine circuits that they designed in the new paper rely on enzymes called recombinases. When activated by a specific input in the cell, such as a chemical signal, recombinases either delete or invert a particular stretch of DNA, depending on the orientation of two DNA target sequences known as recognition sites. The stretch of DNA between those sites may contain recognition sites for other recombinases that respond to different inputs. Flipping or deleting those sites alters what will happen to the DNA if a second or third recombinase is later activated. Therefore, a cell's history can be determined by sequencing its DNA.

In the simplest version of this system, with just two inputs, there are five possible states for the circuit: states corresponding to neither input, input A only, input B only, A followed by B, and B followed by A. The researchers also designed and built circuits that record three inputs, in which 16 states are possible.

For this study, the researchers programmed E. coli cells to respond to substances commonly used in lab experiments, including ATc (an analogue of the antibiotic tetracycline), a sugar called arabinose, and a chemical called DAPG. However, for medical or environmental applications, the recombinases could be re-engineered to respond to other conditions such as acidity or the presence of specific transcription factors (proteins that control gene expression).

Gene control

After creating circuits that could record events, the researchers then incorporated genes into the array of recombinase binding sites, along with genetic regulatory elements. In these circuits, when recombinases rearrange the DNA, the circuits not only record information but also control which genes get turned on or off.

The researchers tested this approach with three genes that code for different fluorescent proteins -- green, red, and blue, constructing a circuit that expressed a different combination of the fluorescent proteins for each identity and order of two inputs. For example, when cells carrying this circuit recieved input A followed by input B they fluoresced red and green, while cells that recieved B before A fluoresced red and blue.

Lu's lab now hopes to use this approach to study cellular processes that are controlled by a series of events, such as the appearance of cytokines or other signaling molecules, or the activation of certain genes.

"This idea that we can record and respond to not just combinations of biological events but also their orders opens up a lot of potential applications. A lot is known about what factors regulate differentiation of specific cell types or lead to the progression of certain diseases, but not much is known about the temporal organization of those factors. That's one of the areas we hope to dive into with our device," Roquet says.

For example, scientists could use this technique to follow the trajectory of stem cells or other immature cells into differentiated, mature cell types. They could also follow the progression of diseases such as cancer. A recent study has shown that the order in which cancer-causing mutations are acquired can determine the behavior of the disease, including how cancer cells respond to drugs and develop into tumors. Furthermore, engineers could use the state machine platform developed here to program cell functions and differentiation pathways.

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The above post is reprinted from materials provided by Massachusetts Institute of Technology. The original item was written by Anne Trafton.Note: Materials may be edited for content and length.

Historical records miss a fifth of global warming: NASA

A new NASA-led study finds that almost one-fifth of the global warming that has occurred in the past 150 years has been missed by historical records due to quirks in how global temperatures were recorded. The study explains why projections of future climate based solely on historical records estimate lower rates of warming than predictions from climate models.

The study applied the quirks in the historical records to climate model output and then performed the same calculations on both the models and the observations to make the first true apples-to-apples comparison of warming rates. With this modification, the models and observations largely agree on expected near-term global warming. The results were published in the journalNature Climate Change. Mark Richardson of NASA's Jet Propulsion Laboratory, Pasadena, California, is the lead author.

The Arctic is warming faster than the rest of Earth, but there are fewer historic temperature readings from there than from lower latitudes because it is so inaccessible. A data set with fewer Arctic temperature measurements naturally shows less warming than a climate model that fully represents the Arctic.

Because it isn't possible to add more measurements from the past, the researchers instead set up the climate models to mimic the limited coverage in the historical records.

The new study also accounted for two other issues. First, the historical data mix air and water temperatures, whereas model results refer to air temperatures only. This quirk also skews the historical record toward the cool side, because water warms less than air. The final issue is that there was considerably more Arctic sea ice when temperature records began in the 1860s, and early observers recorded air temperatures over nearby land areas for the sea-ice-covered regions. As the ice melted, later observers switched to water temperatures instead. That also pushed down the reported temperature change.

Scientists have known about these quirks for some time, but this is the first study to calculate their impact. "They're quite small on their own, but they add up in the same direction," Richardson said. "We were surprised that they added up to such a big effect."

These quirks hide around 19 percent of global air-temperature warming since the 1860s. That's enough that calculations generated from historical records alone were cooler than about 90 percent of the results from the climate models that the Intergovernmental Panel on Climate Change (IPCC) uses for its authoritative assessment reports. In the apples-to-apples comparison, the historical temperature calculation was close to the middle of the range of calculations from the IPCC's suite of models.

Any research that compares modeled and observed long-term temperature records could suffer from the same problems, Richardson said. "Researchers should be clear about how they use temperature records, to make sure that comparisons are fair. It had seemed like real-world data hinted that future global warming would be a bit less than models said. This mostly disappears in a fair comparison."

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On the path to controlled gene therapy

The ability to switch disease-causing genes on and off remains a dream for many physicians, research scientists and patients. Research teams from across the world are busy turning this dream into a reality, incuding a team of researchers from Charité -- Universitätsmedizin Berlin and the Max Planck Institute for Medical Research in Heidelberg. Led by Dr. Mazahir T. Hasan, and working under the auspices of the NeuroCure Cluster of Excellence, the team has successfully programmed a virus to transport the necessary genetic material to affected tissue and nerve cells inside the body.

A report on their new virus-based method, which delivers instructions to the host genome without becoming part of it, has been published in the journalMolecular Therapy Nucleic Acids.

From cancer to Alzheimer's disease, many life-threatening diseases can only be treated using drug-based treatment options, if at all. Many of these treatments are non-specific in nature, or even ineffective. In some cases, the undesirable side-effects may even outweigh the desirable ones. This is because indiscriminate treatments damage healthy cells, impairing their ability to communicate with other cells; as a result, it is hoped that genetically produced and modified mediators will be able to selectively target diseased cells, and improve the way treatment is delivered. "In the laboratory, we use attenuated, i.e. non-replicating,viruses that are known as recombinant adeno-associated viruses (rAAV). We use them to transport genetically encoded material into live organisms affected by disease," explains Dr. Hasan. "This approach opens up a whole range of options which, in the future, may allow us to treat and heal various diseases."

By successfully completing the initial step of testing this new method using an animal model, the researchers have laid the groundwork for future genetic treatments for use in humans. Before these can be used, however, they will need to be tested to ensure their safety. It is already known that rAAVs can transport genetically encoded material into any type of cell and tissue, including the brain, and that, once inside the cells, they are capable of repeatedly switching gene therapy applications on and off again. This on/off switch is controlled chemically, via either food intake or drinking water: "The fact that gene function can be switched on and off in this manner is of particular value, and renders the method a perfect candidate for use in controlled gene therapy," emphasizes Dr. Hasan

The fact that rAAV-infected cells do not trigger any form of measurable immune response and that their genetic material remains completely intact represents an additional benefit. While this does not mean that future gene therapy applications are guaranteed to be successful, the researchers are full of confidence for the future. "We are still at the laboratory stage," says Dr. Hasan, adding: "Once additional safety options are in place, this development could spearhead innovation, heralding in a time when the transfer of genetically encoded material will be used to heal severe diseases, including neurological ones such as Parkinson's disease, Alzheimer's disease and epilepsy."

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Role for enhancers in bursts of gene activity

A new study by researchers at Princeton University suggests that sporadic bursts of gene activity may be important features of genetic regulation rather than just occasional mishaps. The researchers found that snippets of DNA called enhancers can boost the frequency of bursts, suggesting that these bursts play a role in gene control.

The researchers analyzed videos of Drosophila fly embryos undergoing DNA transcription, the first step in the activation of genes to make proteins. In a study published in the journal Cell on July 14, the researchers found that placing enhancers in different positions relative to their target genes resulted in dramatic changes in the frequency of the bursts.

"The importance of transcriptional bursts is controversial," said Michael Levine, Princeton's Anthony B. Evnin '62 Professor in Genomics and director of the Lewis-Sigler Institute for Integrative Genomics. "While our study doesn't prove that all genes undergo transcriptional bursting, we did find that every gene we looked at showed bursting, and these are the critical genes that define what the embryo is going to become. If we see bursting here, the odds are we are going to see it elsewhere."

The transcription of DNA occurs when an enzyme known as RNA polymerase converts the DNA code into a corresponding RNA code, which is later translated into a protein. Researchers were puzzled to find about ten years ago that transcription can be sporadic and variable rather than smooth and continuous.

In the current study, Takashi Fukaya, a postdoctoral research fellow, and Bomyi Lim, a postdoctoral research associate, both working with Levine, explored the role of enhancers on transcriptional bursting. Enhancers are recognized by DNA-binding proteins to augment or diminish transcription rates, but the exact mechanisms are poorly understood.

Until recently, visualizing transcription in living embryos was impossible due to limits in the sensitivity and resolution of light microscopes. A new method developed three years ago has now made that possible. The technique, developed by two separate research groups, one at Princeton led by Thomas Gregor, associate professor of physics and the Lewis-Sigler Institute for Integrative Genomics, and the other led by Nathalie Dostatni at the Curie Institute in Paris, involves placing fluorescent tags on RNA molecules to make them visible under the microscope.

The researchers used this live-imaging technique to study fly embryos at a key stage in their development, approximately two hours after the onset of embryonic life where the genes undergo fast and furious transcription for about one hour. During this period, the researchers observed a significant ramping up of bursting, in which the RNA polymerase enzymes cranked out a newly transcribed segment of RNA every 10 or 15 seconds over a period of perhaps 4 or 5 minutes per burst. The genes then relaxed for a few minutes, followed by another episode of bursting.

The team then looked at whether the location of the enhancer -- either upstream from the gene or downstream -- influenced the amount of bursting. In two different experiments, Fukaya placed the enhancer either upstream of the gene's promoter, or downstream of the gene and saw that the different enhancer positions resulted in distinct responses. When the researchers positioned the enhancer downstream of the gene, they observed periodic bursts of transcription. However when they positioned the enhancer upstream of the gene, the researchers saw some fluctuations but no discrete bursts. They found that the closer the enhancer is to the promoter, the more frequent the bursting.

To confirm their observations, Lim applied further data analysis methods to tally the amount of bursting that they saw in the videos. The team found that the frequency of the bursts was related to the strength of the enhancer in upregulating gene expression. Strong enhancers produced more bursts than weak enhancers. The team also showed that inserting a segment of DNA called an insulator reduced the number of bursts and dampened gene expression.

In a second series of experiments, Fukaya showed that a single enhancer can activate simultaneously two genes that are located some distance apart on the genome and have separate promoters. It was originally thought that such an enhancer would facilitate bursting at one promoter at a time -- that is, it would arrive at a promoter, linger, produce a burst, and come off. Then, it would randomly select one of the two genes for another round of bursting. However, what was instead observed was bursting occurring simultaneously at both genes.

"We were surprised by this result," Levine said. "Back to the drawing board! This means that traditional models for enhancer-promoter looping interactions are just not quite correct," Levine said. "It may be that the promoters can move to the enhancer due to the formation of chromosomal loops. That is the next area to explore in the future."

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Synthetic biology used to limit bacterial growth and coordinate drug release

Researchers at the University of California San Diego and the Massachusetts Institute of Technology (MIT) have come up with a strategy for using synthetic biology in therapeutics. The approach enables continual production and release of drugs at disease sites in mice while simultaneously limiting the size, over time, of the populations of bacteria engineered to produce the drugs. The findings are published in the July 20 online issue of Nature.

UC San Diego researchers led by Jeff Hasty, a professor of bioengineering and biology, engineered a clinically relevant bacterium to produce cancer drugs and then self-destruct and release the drugs at the site of tumors. The team then transferred the bacterial therapy to their MIT collaborators for testing in an animal model of colorectal metastasis. The design of the therapy represents a culmination of four previous Nature papers from the UC San Diego group that describe the systematic development of engineered genetic clocks and synchronization. Over the years, the researchers have employed a broad approach that spans the scales of synthetic biology.

The new study offers a therapeutic approach that minimizes damage to surrounding cells.

"In synthetic biology, one goal of therapeutics is to target disease sites and minimize damage," said UC San Diego bioengineering and biology professor Jeff Hasty. He wondered if a genetic "kill" circuit could be engineered to control a population of bacteria in vivo, thus minimizing their growth. "We also wanted to deliver a significant therapeutic payload to the disease site."

In order to achieve this, he and his team synchronized the bacteria to release bursts of known cancer drugs when a bacterial colony self-destructs within the tumor environment. The use of bacteria to deliver cancer drugs in vivo is enticing because conventional chemotherapy doesn't always reach the inner regions of a tumor, but bacteria can colonize there. Importantly, the researchers observed that the combination of chemotherapy and the gene products produced by the bacterial circuit consistently reduced tumor size.

"The new work by Jeff Hasty and team is a brilliant demonstration of how theory in synthetic biology can lead to clinically meaningful advances," said Jim Collins, a professor at MIT who is known as a founder of the field of synthetic biology. "Over a decade ago during the early days of the field, Jeff developed a theoretical framework for synchronizing cellular processes across a community of cells. Now his team has shown experimentally how one can harness such effects to create a novel, clinically viable therapeutic approach."

Limiting the bacterial population

In order to observe the bacterial population dynamics, the researchers designed custom microfluidic devices for careful testing before investigations in animal disease models. Consistent with the engineering design, they observed cycling of the bacterial population that successfully limits overall growth while simultaneously enabling production and release of encoded cargo. When the bacteria were equipped with a gene that drives production of a therapeutic, the synchronized lysis of the bacterial colony was shown to kill human cancer cells. It is the first engineered gene circuit in synthetic biology to achieve these objectives.

"In this paper, we describe a circuit that contains a gene that codes for a small molecule that can diffuse between cells and can turn on genes," said Omar Din, the paper's lead author and a UC San Diego Jacobs School of Engineering bioengineering Ph.D. student in Hasty's research group. "Once the population grows to a critical size -- a few thousand cells -- there's a high-enough concentration of that molecule present in the cells to cause mass transcription of the genes behind the promoter."

The molecule, AHL, is known to coordinate gene expression across a colony of bacterial cells. Once on, the genes driven by the promoter are also activated, including the AHL-producing gene itself. Thanks to this positive feedback loop, the more AHL accumulates, the more it is produced. Because AHL is small enough to diffuse between cells and turn on the promoter in neighboring cells, the genes activated by it would also be produced in high amounts, leading to a phenomenon known as quorum sensing. Bacteria use quorum sensing to communicate with each other about the size of their population, and regulate gene expression accordingly. Scientists have used this natural ability of bacteria extensively as a tool.

Din used quorum sensing as an engineering tool to synchronize the cells and then added a kill gene that causes cells to break open (lyse) when a bacterial colony grows to a threshold. After the mass self-destruction event, a few cells remain to repopulate the colony and the resulting population dynamics are cyclical.

"The lysis circuit was originally conceived for use as an aquatic biosensor, but it subsequently became clear that an exciting application could be the coordinated release of drugs when bacteria lyse in vivo," Hasty said.

Watch a video showing the programmed cycles of bacterial drug delivery.

Finding the right drug combination

Next, the researchers needed to find the right drug for delivery by the bacteria. They tested three different therapeutic proteins that had been shown to shrink tumors. The tests showed that the proteins were most effective when combined. They placed the genes responsible for these proteins in the circuit along with the lysis gene. They then conducted experiments with HeLa cells that showed enough protein was produced to kill cancer cells.

The testing of the therapy in mice was carried out by UC San Diego bioengineering alumnus Tal Danino while he was a postdoctoral researcher in Sangeeta Bhatia's research group at MIT. Danino is now a professor at Columbia University.

The bacteria were first injected into mice with a grafted subcutaneous tumor. This mouse model was used to visualize the bacterial population in vivo and observe their dynamics. The result was a decrease in tumor size. Danino then used a more advanced mouse model with liver metastases, where bacteria were fed to the mice. After testing a combination of the engineered bacteria and chemotherapy with this model, the researchers found that the combined therapy prolonged survival of the mice over either therapy administered alone. The researchers note that this new approach has not yet cured any mice. They did find that the therapy led to around a 50 percent increase in life expectancy, but it's difficult to anticipate how this would translate to humans. Taken together, the experiments in mice establish a proof-of-principle for using the tools of synthetic biology to engineer 'tumor-targeting' bacteria to deliver therapeutic proteins in vivo.

Developing a strategy

The new Nature paper shows the use of quorum sensing to limit bacterial population growth and release drugs. In previous Nature papers, the Hasty lab has shown how engineered cellular oscillations can be coordinated within a bacterial colony and even between thousands of interacting colonies.

"This paper describes a highly innovative strategy employing synthetic biology to weaponize bacteria," said Bert Vogelstein, Director of the Ludwig Center at Johns Hopkins University and pioneer in the field of cancer genomics. "The authors show that these bacteria can be used to slow the growth of tumors growing in mice. Though much further work will be required to make this therapy applicable to humans, it's just the kind of new, forward-thinking approach that we desperately need if we are to more effectively combat cancer."

Next possible steps include investigating the natural presence of bacteria in tumors and then engineering these bacteria for use in vivo and using multiple strains of bacteria to form a therapeutic community.

"Additionally, we are currently investigating methods for maintaining the circuit inside bacteria," said Din. "Since the proteins produced by the circuit put a burden on the bacteria, the bacteria are prone to mutate these genes. Additionally, there is a selection pressure to get rid of the plasmids which harbor the genes comprising the circuit. Thus, one of our future research aims is to identify strategies for stabilizing the circuit components in bacteria and decreasing their susceptibility to mutations."

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First atmospheric study of Earth-sized exoplanets points to possible habitability

Using NASA's Hubble Space Telescope, astronomers have conducted the first search for atmospheres around temperate, Earth-sized planets beyond our solar system and found indications that increase the chances of habitability on two exoplanets.

Specifically, they discovered that the exoplanets TRAPPIST-1b and TRAPPIST-1c, approximately 40 light-years away, are unlikely to have puffy, hydrogen-dominated atmospheres usually found on gaseous worlds.

"The lack of a smothering hydrogen-helium envelope increases the chances for habitability on these planets," said team member Nikole Lewis of the Space Telescope Science Institute (STScI) in Baltimore. "If they had a significant hydrogen-helium envelope, there is no chance that either one of them could potentially support life because the dense atmosphere would act like a greenhouse."

Julien de Wit of the Massachusetts Institute of Technology in Cambridge, Massachusetts, led a team of scientists to observe the planets in near-infrared light using Hubble's Wide Field Camera 3. They used spectroscopy to decode the light and reveal clues to the chemical makeup of an atmosphere. While the content of the atmospheres is unknown and will have to await further observations, the low concentration of hydrogen and helium has scientists excited about the implications.

"These initial Hubble observations are a promising first step in learning more about these nearby worlds, whether they could be rocky like Earth, and whether they could sustain life," says Geoff Yoder, acting associate administrator for NASA's Science Mission Directorate in Washington. "This is an exciting time for NASA and exoplanet research."

The planets orbit a red dwarf star at least 500 million years old, in the constellation of Aquarius. They were discovered in late 2015 through a series of observations by the TRAnsiting Planets and PlanetesImals Small Telescope (TRAPPIST), a Belgian robotic telescope located at ESA's (European Space Agency's) La Silla Observatory in Chile.

TRAPPIST-1b completes a circuit around its red dwarf star in 1.5 days and TRAPPIST-1c in 2.4 days. The planets are between 20 and 100 times closer to their star than Earth is to the sun. Because their star is so much fainter than our sun, researchers think that at least one of the planets, TRAPPIST-1c, may be within the star's habitable zone, where moderate temperatures could allow for liquid water to pool.

On May 4, astronomers took advantage of a rare simultaneous transit, when both planets crossed the face of their star within minutes of each other, to measure starlight as it filtered through any existing atmosphere. This double-transit, which occurs only every two years, provided a combined signal that offered simultaneous indicators of the atmospheric characters of the planets.

The researchers hope to use Hubble to conduct follow-up observations to search for thinner atmospheres, composed of elements heavier than hydrogen, like those of Earth and Venus.

"With more data, we could perhaps detect methane or see water features in the atmospheres, which would give us estimates of the depth of the atmospheres," said Hannah Wakeford, the paper's second author, at NASA's Goddard Space Flight Center in Greenbelt, Maryland.

Observations from future telescopes, including NASA's James Webb Space Telescope, will help determine the full composition of these atmospheres and hunt for potential biosignatures, such as carbon dioxide and ozone, in addition to water vapor and methane. Webb also will analyze a planet's temperature and surface pressure -- key factors in assessing its habitability.

"These Earth-sized planets are the first worlds that astronomers can study in detail with current and planned telescopes to determine whether they are suitable for life," said de Wit. "Hubble has the facility to play the central atmospheric pre-screening role to tell astronomers which of these Earth-sized planets are prime candidates for more detailed study with the Webb telescope."

The results of the study appear in the July 20 issue of the journal Nature.

The Hubble Space Telescope is a project of international cooperation between NASA and ESA. Goddard manages the telescope and STScI conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy in Washington.

For imaged and more information about Hubble, visit:

http://www.nasa.gov/hubble

http://hubblesite.org/news/2016/27

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Map provides detailed picture of how the brain is organized

The age of exploration has long passed, but there is at least one area still largely uncharted: the human brain. Now, a detailed new map by researchers at Washington University School of Medicine in St. Louis lays out the landscape of the cerebral cortex -- the outermost layer of the brain and the dominant structure involved in sensory perception and attention, as well as distinctly human functions such as language, tool use and abstract thinking.

With the features of a typical brain demarcated in painstaking detail, the new map will be a boon to researchers studying brain disorders such as autism, schizophrenia, dementia and epilepsy. Scientists will be able to use it to understand differences in the brains of patients with these diseases compared with adults who are healthy. It also will accelerate progress in deciphering the workings of the healthy brain and elucidating what makes us unique as a species.

The work will be published July 20 in Nature.

The researchers drew upon data and methods generated by the Human Connectome Project, a five-year, multimillion dollar study led by David Van Essen, PhD, the senior author on this paper, and involving a consortium that includes the University of Minnesota and Oxford University. The Human Connectome Project used a powerful, custom-built MRI machine to map the brains of 1,200 young adults. This study complements the Human Connectome Project by carefully delineating the brain regions so that their connections can be more accurately mapped.

The new map divides both the left and right cerebral hemispheres into 180 areas based on physical differences (such as the thickness of the cortex), functional distinctions (such as which areas respond to language stimuli), and differences in the connections of the areas. Brain cartography is not as simple as noting a "mountain" over here and a "river" over there, since much of the brain looks superficially the same. The map is more akin to a map showing state borders than topographic features; the most important divisions are invisible from the sky, but extremely important all the same.

"The brain is not like a computer that can support any operating system and run any software," said Van Essen, the Alumni Endowed Professor of Neuroscience. "Instead, the software -- how the brain works -- is intimately correlated with the brain's structure -- its hardware, so to speak. If you want to find out what the brain can do, you have to understand how it is organized and wired."

The researchers mapped the cortex, a layer of neural tissue that encases the rest of the brain like a crumpled sheet of paper. The cortex is important for sensation, attention, memory, perception, thought, language and consciousness.

A German neuroanatomist, Korbinian Brodmann, first mapped the human cortex in the first decade of the 20th century. He identified 50 regions, including areas later shown to be involved in visual, language and sensory processing.

When the new study's lead author Matthew Glasser, PhD, began studying the connections between language areas of the brain almost a century later, he quickly became frustrated with Brodmann's map and how it was typically being used in neuroimaging.

"My early work on language connectivity involved taking that 100-year-old map and trying to guess where Brodmann's areas were in relation to the pathways underneath them," said Glasser. "It quickly became obvious to me that we needed a better way to map the areas in the living brains that we were studying."

To make this map, Glasser, Van Essen, and colleagues pooled data from 210 healthy young adults of both sexes. The researchers combined measures of the thickness of the cortex and the amount of insulation around neuronal cables, with MRI scans of the resting brain and of the brain performing simple tasks, such as listening to a story.

"We ended up with 180 areas in each hemisphere, but we don't expect that to be the final number," Glasser said. "In some cases, we identified a patch of cortex that probably could be subdivided, but we couldn't confidently draw borders with our current data and techniques. In the future, researchers with better methods will subdivide that area. We focused on borders we are confident will stand the test of time."

Some of those areas are clearly involved in particular tasks, such as 55b, which lights up with activity when a person hears a story. Others contain a map of a person's field of vision, or are involved in controlling movement. Most areas probably will never be identified with a single function, because they don't do just one thing but instead coordinate information from many different signals.

In the century between Brodmann's map and Glasser and Van Essen's, many other maps of the cortex have been drawn, showing anywhere from 50 to 200 different areas. The researchers improved on previous maps by precisely aligning the brains to a common coordinate system before analysis, using an algorithm developed by colleagues at Oxford University, and incorporating the highest-quality MRI data available. The researchers also verified that their method could be applied to individuals by producing maps of the brains of a different set of 210 healthy young adults.

The results are a precise map with unusually crisp borders and an algorithm capable of locating the areas in individual brains, even though each individual is unique in terms of the pattern of cortical folds and in the size and shape of areas on the cortical map.

"In the past, it was not always clear whether the results from two separate neuroimaging studies referred to the same area or not," Glasser said. By using the new map and alignment algorithm, results of separate studies could be more accurately compared.

Better individual maps of the brain could be very useful. Neurosurgeons at Washington University already use less detailed individual brain maps when preparing for surgery to avoid damaging the most important areas, such as those involved in language or motor function.

Individual brain maps also could guide treatment for neurological or psychiatric illnesses. Different types of dementia, for example, are characterized by degeneration in different areas of the brain. Clinicians could use the individual maps to personalize treatment, based on the areas affected, or to monitor response to treatment.

Like cartographers of old, brain cartographers primarily are providing a tool for others to use in exploration and discovery.

"We were able to persuade Nature to put online almost 200 extra pages of detailed information on each of the 180 regions as well as all of the algorithms we used to align the brains and create the map," Van Essen said. "We think it will serve the scientific community best if they can dive down and get these maps onto their computer screens and explore as they see fit."

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The above post is reprinted from materials provided by Washington University School of Medicine. The original item was written by Tamara Bhandari. Note: Materials may be edited for content and length.

Asteroid that formed moon's Imbrium Basin may have been protoplanet-sized

Around 3.8 billion years ago, an asteroid more than 150 miles across, roughly equal to the length of New Jersey, slammed into the Moon and created the Imbrium Basin -- the right eye of the fabled Man in the Moon. This new size estimate, published in the journal Nature, suggests an Imbrium impactor that was two times larger in diameter and 10 times more massive than previous estimates.

"We show that Imbrium was likely formed by an absolutely enormous object, large enough to be classified as a protoplanet," said Pete Schultz, professor of earth, environmental and planetary sciences at Brown University. "This is the first estimate for the Imbrium impactor's size that is based largely on the geological features we see on the Moon."

Previous estimates, Schultz said, were based solely on computer models and yielded a size estimate of only about 50 miles in diameter.

These new findings help to explain some of the puzzling geological features that surround the Imbrium Basin. The work also suggests -- based on the sizes of other impact basins in the Moon, Mars and Mercury -- that the early solar system was likely well stocked with protoplanet-sized asteroids.

Imbrium sculpture

The Imbrium Basin -- seen from Earth as a dark patch in the northwestern quadrant of the Moon's face -- measures about 750 miles across. The basin is surrounded by grooves and gashes, large enough to be seen with even small telescopes from Earth, created by rocks blasted  of the crater when it was formed. These features, known as the Imbrium Sculpture, radiate out from the center of the basin like spokes on a wheel, but are concentrated on the basin's southeast side. That suggests that the impactor traveled from the northwest, impacting at an oblique angle rather than straight on.

But in addition to features radiating from the basin's center, there is a second set of grooves with a different alignment. These appear to come from a region to the northwest, along the trajectory from which the impactor came.

"This second set of grooves was a real mystery," Schultz said. "No one was quite sure where they came from."

Through hypervelocity impact experiments performed using the Vertical Gun Range at the NASA Ames Research Center, Schultz was able to show that those grooves were likely formed by chunks of the impactor that sheared off on initial contact with the surface. The grooves created by those chunks enabled Schultz to estimate the size of the impactor.

Laboratory impacts

The Vertical Gun Range employs a 14-foot cannon that fires small projectiles at up to 16,000 miles per hour, while impact plates and high-speed cameras record the ballistic dynamics. During his experiments with low-angle impacts, Schultz noticed that impactors tend to start breaking apart when they first make contact with the surface. That point of initial contact is actually behind or "up-range" of the final crater, where the bulk of the impactor digs into the surface. The chunks that break off up-range of the final crater continue to travel at a high rate of speed, scouring and grooving the surface.

"The key point is that the grooves made by these chunks aren't radial to the crater," Schultz said. "They come from the region of first contact. We see the same thing in our experiments that we see on the Moon -- grooves pointing up-range, rather than the crater."

After seeing these features in the lab, Schultz worked with David Crawford of the Sandia National Laboratories to generate computer models showing that the same kind of physics would also happen at the colossal scales of a lunar impact.

With an understanding of how those grooves were created, Schultz could use them to find the Imbrium impact point. And because the fragments would have broken off from the either side of the impactor, the groove trajectories could be used to estimate the impactor's size.

Those calculations yielded an estimated diameter of 250 kilometers or 150 miles across, large enough for the object to be classified as a protoplanet.

"That's actually a low-end estimate," Schultz said. "It's possible that it could have been as large as 300 kilometers."

"Lost giants" and the Late Heavy Bombardment

Schultz and his colleagues used similar methods to estimate the sizes of impactors related to several other basins on the Moon created by oblique impacts. Those estimates -- for the Moscoviense and Orientale basins on the Moon's far side -- yielded impactor sizes of 100 and 110 kilometers across respectively, larger than some previous estimates.

Combining these new estimates with the fact that there are even larger impact basins on the Moon and other planets, Schultz concludes that protoplanet-sized asteroids may have been common in the early solar system.

"The large basins we see on the Moon and elsewhere are the record of lost giants," Schultz said.

The research has several other significant implications, he said. The surviving fragments from these impactors would have littered the ancient surface of the Moon, slowly becoming mixed with native soil and rock. That could help explain why samples returned from the Apollo missions had such a high meteoritic content. That is particularly true of Apollo 16, which landed downrange from the Imbrium impact.

Furthermore, Schultz's work suggests fragments from these giants could account for a many of the impacts that occurred during a period called the Late Heavy Bombardment, which occurred from about 3.8 billion years ago to around 4 billion years, when scientists think most of the craters we see on the Moon and Mercury were formed.

The impact models Schultz and Crawford developed suggest that thousands of the chunks that crumbled off of the Imbrium impactor and others would have broken and kept going, escaping the Moon's gravity and flying off into space. On subsequent orbits around the sun, those chunks would have crossed the Earth and Moon orbits again and again, creating a strong possibility of subsequent impacts. Some of those objects would have been a kilometer or two across, large enough to create 20-kilometer craters.

"These chips off the old blocks could have contributed significantly to the impact record we see on the Moon and other terrestrial planets," Schultz said.

Schultz also said he continues to be amazed by what we can learn just by looking up at the Moon.

"The Moon still holds clues that can affect our interpretation of the entire solar system," he said. "Its scarred face can tell us quite a lot about what was happening in our neighborhood 3.8 billion years ago."

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The above post is reprinted from materials provided by Brown University.Note: Materials may be edited for content and length.

Stem cells engineered to grow cartilage, fight inflammation

With a goal of treating worn, arthritic hips without extensive surgery to replace them, scientists have programmed stem cells to grow new cartilage on a 3-D template shaped like the ball of a hip joint. What's more, using gene therapy, they have activated the new cartilage to release anti-inflammatory molecules to fend off a return of arthritis.

The technique, demonstrated in a collaborative effort between Washington University School of Medicine in St. Louis and Cytex Therapeutics Inc. in Durham, N.C., is described July 18 in Proceedings of the National Academy of Sciences.

The discovery one day may provide an alternative to hip-replacement surgery, particularly in younger patients. Doctors are reluctant to perform such operations in patients under age 50 because prosthetic joints typically last for less than 20 years. A second joint-replacement surgery to remove a worn prosthetic can destroy bone and put patients at risk for infection.

"Replacing a failed prosthetic joint is a difficult surgery," said Farshid Guilak, PhD, a professor of orthopedic surgery at Washington University. "We've developed a way to resurface an arthritic joint using a patient's own stem cells to grow new cartilage, combined with gene therapy to release anti-inflammatory molecules to keep arthritis at bay. Our hope is to prevent, or at least delay, a standard metal and plastic prosthetic joint replacement."

The technique uses a 3-D, biodegradable synthetic scaffold that Guilak and his team developed. The scaffold, molded into the precise shape of a patient's joint, is covered with cartilage made from the patient's own stem cells taken from fat beneath the skin. The scaffold then can be implanted onto the surface of an arthritic hip, for example. Resurfacing the hip joint with "living" tissue is designed to ease arthritis pain, and delay or even eliminate the need for joint-replacement surgery in some patients.

Additionally, by inserting a gene into the newly grown cartilage and activating it with a drug, the gene can orchestrate the release of anti-inflammatory molecules to fight a return of arthritis, which usually is what triggers such joint problems in the first place.

"When there is inflammation, we can give a patient a simple drug, which activates the gene we've implanted, to lower inflammation in the joint," said Guilak, also a professor of developmental biology and of biomedical engineering. "We can stop giving the drug at any time, which turns off the gene."

That gene therapy is important, he explained, because when levels of inflammatory molecules rise in a joint, the cartilage is destroyed and pain increases. By adding gene therapy to the stem cell and scaffold technique, Guilak and his colleagues believe it will be possible to coax patients' joints to fend off arthritis and function better for a longer time.

The 3-D scaffold is built using a weaving pattern that gives the device the structure and properties of normal cartilage. Franklin Moutos, PhD, vice president of technology development at Cytex, explained that the unique structure is the result of approximately 600 biodegradable fiber bundles woven together to create a high-performance fabric that can function like normal cartilage.

"As evidence of this, the woven implants are strong enough to withstand loads up to 10 times a patient's body weight, which is typically what our joints must bear when we exercise," Moutos said.

Currently, there are about 30 million Americans who have diagnoses of osteoarthritis, and data suggest that the incidence of osteoarthritis is on the rise. That number includes many younger patients -- ages 40 to 65 -- who have limited treatment options because conservative approaches haven't worked and they are not yet candidates for total joint replacement because of their ages.

Bradley Estes, PhD, vice president of research and development at Cytex, noted, "We envision in the future that this population of younger patients may be ideal candidates for this type of biological joint replacement."

Guilak, who also is the director of research at Shriners Hospitals for Children -- St. Louis, and co-director of the Washington University Center of Regenerative Medicine, has been collaborating with Cytex on this research. The scientists have tested various aspects of the tissue engineering in cell culture, and some customized implants already are being tested in laboratory animals. He said if all goes well, such devices could be ready for safety testing in humans in three to five years.

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The above post is reprinted from materials provided by Washington University School of Medicine. The original item was written by Jim Dryden. Note: Materials may be edited for content and length.