Superbright, fast X-rays image single layer of proteins

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In biology, a protein’s shape is key to understanding how it causes disease or toxicity. Researchers who use X-rays to take snapshots of proteins need a billion copies of the same protein stacked and packed into a neat crystal. Now, scientists using exceptionally bright and fast X-rays can take a picture that rivals conventional methods with a sheet of proteins just one protein molecule thick.Using a type of laser known as XFEL, the technique opens the door to learning the structural details of almost 25 percent of known proteins, many of which have been overlooked due to their inability to stack properly. The team of researchers led by the Department of Energy’s Pacific Northwest and Lawrence Livermore National Laboratories report their results with this unique form of X-ray diffraction in the March issue of the International Union of Crystallography Journal.”In this paper, we’re proving it’s possible to use an XFEL to study individual monolayers of protein,” said PNNL microscopist James Evans. “Just being able to see any diffraction is brand new.”Evans co-led the team of two dozen scientists with LLNL physicist Matthias Frank. The bright, fast X-rays were produced at the Linac Coherent Light Source at SLAC National Accelerator Laboratory in Menlo Park, Calif., the newest of DOE’s major X-ray light source facilities at the national laboratories. LCLS, currently the world’s most powerful X-ray laser, is an X-ray free-electron laser. It produces beams millions of times brighter than earlier X-ray light sources.Coming in at around 8 angstrom resolution (which can make out items a thousand times smaller than the width of a hair), the proteins appear slightly blurry but match the expected view based on previous research. Evans said this level of clarity would allow researchers, in some cases, to see how proteins change their shape as they interact with other proteins or molecules in their environment.To get a clearer view of protein monolayers using XFEL, the team will need to improve the resolution to 1 to 3 angstroms, as well as take images of the proteins at different angles, efforts that are currently underway.Not Your Family’s CrystalResearchers have been using X-ray crystallography for more than 60 years to determine the shape and form of proteins that form the widgets and gears of a living organism’s cells. The conventional method requires, however, that proteins stack into a large crystal, similar to how oranges stack in a crate. …


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First global geologic map of Jupiter"s largest moon Ganymede details an icy world

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More than 400 years after its discovery by Galileo, the largest moon in the solar system has finally claimed a spot on the map.A team of scientists led by Wes Patterson of the Johns Hopkins Applied Physics Laboratory (APL), Laurel, Md., and Geoffrey Collins of Wheaton College, Norton, Mass., has produced the first global geologic map of Ganymede, a Galilean moon of Jupiter. Published by the U.S. Geological Survey, the map technically illustrates the varied geologic character of Ganymede’s surface, and is the first complete global geologic map of an icy, outer-planet moon.Patterson, Collins and colleagues used images from NASA’s Voyager and Galileo missions to create the map. It’s only the fourth of its kind covering a planetary satellite; similar maps exist for Earth’s moon as well as Jupiter’s moons Io and Callisto.”By mapping all of Ganymede’s surface, we can more accurately address scientific questions regarding the formation and evolution of this truly unique moon,” says Patterson, a planetary scientist.Since its discovery in January 1610, Ganymede has been the focus of repeated observation, first by Earth-based telescopes, and later by flyby missions and spacecraft orbiting Jupiter. These studies depict a complex icy world whose surface is characterized by the striking contrast between its two major terrain types: the dark, very old, highly cratered regions; and the lighter, somewhat younger (but still ancient) regions marked with an extensive array of grooves and ridges.  With a diameter of 3,280 miles (5,262 kilometers), Ganymede is larger than both planet Mercury and dwarf planet Pluto. It’s also the only satellite in the solar system known to have its own magnetosphere. The map details geologic features of the moon that formed and evolved over much of our solar system’s history. These features record evidence of Ganymede’s internal evolution, its dynamical interactions with the other Galilean satellites, and the evolution of the small bodies that have impacted Ganymede’s surface.The new chart will be a valuable tool for researchers to compare the geologic characters of other icy moons, since almost any type of feature that is found on other icy satellites has a similar feature somewhere on Ganymede. And with a surface over half as large as all the land area on Earth, Ganymede offers a wide variety of locations to observe. …


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New pathway for fear discovered deep within brain

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Fear is primal. In the wild, it serves as a protective mechanism, allowing animals to avoid predators or other perceived threats. For humans, fear is much more complex. A normal amount keeps us safe from danger. But in extreme cases, like post-traumatic stress disorder (PTSD), too much fear can prevent people from living healthy, productive lives. Researchers are actively working to understand how the brain translates fear into action. Today, scientists at Cold Spring Harbor Laboratory (CSHL) announce the discovery of a new neural circuit in the brain that directly links the site of fear memory with an area of the brainstem that controls behavior.How does the brain convert an emotion into a behavioral response? For years, researchers have known that fear memories are learned and stored in a small structure in the brain known as the amygdala. Any disturbing event activates neurons in the lateral and then central portions of the amygdala. The signals are then communicated internally, passing from one group of neurons to the next. …


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How our brain networks: White matter "scaffold" of human brain revealed

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For the first time, neuroscientists have systematically identified the white matter “scaffold” of the human brain, the critical communications network that supports brain function.Their work, published Feb. 11 in the open-source journal Frontiers in Human Neuroscience, has major implications for understanding brain injury and disease. By detailing the connections that have the greatest influence over all other connections, the researchers offer not only a landmark first map of core white matter pathways, but also show which connections may be most vulnerable to damage.”We coined the term white matter ‘scaffold’ because this network defines the information architecture which supports brain function,” said senior author John Darrell Van Horn of the USC Institute for Neuroimaging and Informatics and the Laboratory of Neuro Imaging at USC.”While all connections in the brain have their importance, there are particular links which are the major players,” Van Horn said.Using MRI data from a large sample of 110 individuals, lead author Andrei Irimia, also of the USC Institute for Neuroimaging and Informatics, and Van Horn systematically simulated the effects of damaging each white matter pathway.They found that the most important areas of white and gray matter don’t always overlap. Gray matter is the outermost portion of the brain containing the neurons where information is processed and stored. Past research has identified the areas of gray matter that are disproportionately affected by injury.But the current study shows that the most vulnerable white matter pathways — the core “scaffolding” — are not necessarily just the connections among the most vulnerable areas of gray matter, helping explain why seemingly small brain injuries may have such devastating effects.”Sometimes people experience a head injury which seems severe but from which they are able to recover. On the other hand, some people have a seemingly small injury which has very serious clinical effects,” says Van Horn, associate professor of neurology at the Keck School of Medicine of USC. “This research helps us to better address clinical challenges such as traumatic brain injury and to determine what makes certain white matter pathways particularly vulnerable and important.”The researchers compare their brain imaging analysis to models used for understanding social networks. To get a sense of how the brain works, Irimia and Van Horn did not focus only on the most prominent gray matter nodes — which are akin to the individuals within a social network. Nor did they merely look at how connected those nodes are.Rather, they also examined the strength of these white matter connections, i.e. which connections seemed to be particularly sensitive or to cause the greatest repercussions across the network when removed. …


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