Amazing Science
573.3K views | +234 today
Amazing Science
Amazing science facts - 3D_printing • aging • AI • anthropology • art • astronomy • bigdata • bioinformatics • biology • biotech • chemistry • computers • cosmology • education • environment • evolution • future • genetics • genomics • geosciences • green_energy • history • language • map • material_science • math • med • medicine • microscopy • nanotech • neuroscience • paleontology • photography • photonics • physics • postings • robotics • science • technology • video
Your new post is loading...
Scooped by Dr. Stefan Gruenwald!

Crystallographic elucidation of CRISPR-Cas9 endonuclease complex reveals RNA-mediated conformational changes

Crystallographic elucidation of CRISPR-Cas9 endonuclease complex reveals RNA-mediated conformational changes | Amazing Science |

The potential is there for bacteria and other microbes to be genetically engineered to perform a cornucopia of valuable goods and services, from the production of safer, more effective medicines and clean, green, sustainable fuels, to the clean-up and restoration of our air, water and land. Cells from eukaryotic organisms can also be modified for research or to fight disease. To achieve these and other worthy goals, the ability to precisely edit the instructions contained within a target's genome is a must. A powerful new tool for genome editing and gene regulation has emerged in the form of a family of enzymes known as Cas9, which plays a critical role in the bacterial immune system. Cas9 should become an even more valuable tool with the creation of the first detailed picture of its three-dimensional shape by researchers with the Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California (UC) Berkeley.

Biochemist Jennifer Doudna and biophysicist Eva Nogales, both of whom hold appointments with Berkeley Lab, UC Berkeley, and the Howard Hughes Medical Institute (HHMI), led an international collaboration that used x-ray crystallography to produce 2.6 and 2.2 angstrom (Å) resolution crystal structure images of two major types of Cas9 enzymes. The collaboration then used single-particle electron microscopy to reveal how Cas9 partners with its guide RNA to interact with target DNA. The results point the way to the rational design of new and improved versions of Cas9 enzymes for basic research and genetic engineering.

Cas9 is a family of RNA-guided bacterial endonucleases employed by Type II CRISPR systems to recognize and cleave double-stranded DNA at site-specific sequences. Genetic engineers have begun harnessing Cas9 for genome editing and gene regulation in many eukaryotic organisms. However, despite the successes to date, the technology has yet to reach its full potential because until now the structural basis for guide RNA recognition and DNA targeting by Cas9 has been unknown.

What has been a major puzzle in the CRISPR–Cas field is how Cas9 and similar RNA-guided complexes locate and recognize matching DNA targets in the context of an entire genome, the classic needle in a haystack problem," says Samuel Sternberg, lead author of the Nature paper and a member of Doudna's research group. "All of the scientists who are developing RNA-programmable Cas9 for genome engineering are relying on its ability to target unique 20-base-pair long sequences inside the cell. However, if Cas9 were to just blindly bind DNA at random sites across a genome until colliding with its target, the process would be incredibly time-consuming and probably too inefficient to be effective for bacterial immunity, or as a tool for genome engineers. Our study shows that Cas9 confines its search by first looking for PAM sequences. This accelerates the rate at which the target can be located, and minimizes the time spent interrogating non-target DNA sites."

Now, several scientists addressed this lack of detailed knowledge about Cas9 by first solving the three-dimensional crystal structures of two Cas9 proteins, representing large and small versions, from Streptococcus pyogenes (SpyCas) and Actinomyces naeslundii (AnaCas9) respectively. Using protein crystallography beamlines at Berkeley Lab's Advanced Light Source and the Paul Scherer Institute's Swiss Light Source, the collaboration discovered that despite significant differences outside of their catalytic domains, all members of the Cas9 family share the same structural core. The high resolution images showed this core to feature a clam-shaped architecture with two major lobes - a nuclease domain lobe and an alpha-helical lobe. Both lobes contained conserved clefts that become functional in nucleic acid binding.

"Our understanding of Cas9's structure was not complete with only the x-ray data because the protein in the crystals had been trapped in a state without its associated guide RNA," says Sam Sternberg, a member of Doudna's research group and a co-author of the Science paper. "Understanding how RNA-guided Cas9 targets matching DNA sequences for genome engineering and how this reaction and its specificity might be improved required an understanding of how the shape of Cas9 changes when it interacts with guide RNA, and when a matching DNA target sequence is bound."

The collaboration employed negative-staining electron microscopy to visualize the Cas9 protein bound to either guide RNA, or both RNA and target DNA. The structures revealed that the guide RNA binding structurally activates Cas9 by creating a channel between the two main lobes of the protein that functions as the DNA-binding interface.

"Our single particle electron microscopy analysis reveals the importance of guide-RNA for the conversion of Cas9 into a structurally-activated state," says David Taylor, a joint member of Doudna's and Nogales's research groups and another co-author of the Science paper. "The results underline that, in addition to sequence complementarity, other features of the guide-RNA must be considered when employing this technology."

No comment yet.
Scooped by Dr. Stefan Gruenwald!

ADARs, key facilitators of mRNA editing uncovered

ADARs, key facilitators of mRNA editing uncovered | Amazing Science |

Molecular biologists from Indiana University are part of a team that has identified a protein that regulates the information present in a large number of messenger ribonucleic acid molecules that are important for carrying genetic information from DNA to protein synthesis.

The new work, published in Cell Reports, finds that the protein ADR-1 binds to messenger ribonucleic acid, or mRNA, and then enhances RNA editing, a process that allows a gene to be present as multiple mRNAs that can then each affect gene expression differently.

Organisms ranging from sea anemone to humans utilize RNA editing to express different mRNAs at various times in development. Decreased mRNA editing has been reported in patients with neuropathological diseases like epilepsy, schizophrenia, amyotrophic lateral sclerosis and several types of cancer, including glioblastomas (brain tumors).

C. elegans is a microscopic worm that like humans highly expresses a family of proteins in the nervous system called ADARs—adenosine deaminases that act on RNA. ADARs change specific nucleotides (molecular building blocks for DNA and RNA) in RNA, in a process called adenosine-to-inosine editing, or A-to-I editing, that diversifies genetic information to specify different amino acids, splice sites and structures. Scientists currently estimate there are between 400,000 and 1 million A-to-I editing events in noncoding regions of the human transcriptome.

While newly synthesized RNA encodes the exact information found in DNA, it's when later RNA editing occurs that RNA gets altered, a change most often catalyzed by ADARs.

"One thing we also know is that ADAR protein levels are not altered in disease, implying that other mechanisms are also at work regulating ADAR-mediated RNA editing," Hundley said. "By identifying this major regulator of noncoding editing in C. elegans we can now focus on dissecting the regulatory mechanism and determining the conservation of this regulatory protein in human cells."

No comment yet.
Scooped by Dr. Stefan Gruenwald!

Hypnotically beautiful real-time wind map of Earth created by supercomputers

Hypnotically beautiful real-time wind map of Earth created by supercomputers | Amazing Science |

The wind has never been this beautiful! This interactive visualization of wind patterns all around the world is created by a script that downloads weather data from the Global Forecast System at the National Centers for Environmental Prediction, part of NOAA/the National Weather Service. This raw data is then rendered in your browser in the form of a globe that can be moved (drag with the mouse) and zoomed in and out of (use your mouse scroll wheel).

The data is updated every 3 hours, so it is pretty close to real-time considering that this isn't just a small local dataset but covers the whole planet. You can access it here: Earth Wind Map.

It reminds a little of this beautiful interactive animated wind map of the U.S., but  it's even more beautiful, and it covers the whole planet.

No comment yet.
Scooped by Dr. Stefan Gruenwald!

Dynamic urea bonds for inexpensive self-healing polymer

Dynamic urea bonds for inexpensive self-healing polymer | Amazing Science |

Stretchy, self-healing paints and other coatings recently took a step closer to common use, thanks to research being conducted at the University of Illinois. Scientists there have used "off-the-shelf" components to create a polymer that melds back together after being cut in half, without the addition of catalysts or other chemicals.

The material is made from a proprietary mixture of inexpensive commercially-available compounds, including a polyurea elastomer – polyurea is commonly found in a wide variety of products such as paints and plastics. The researchers reportedly "tweaked" the structure of its molecules, making the bonds between them longer. As a result, the molecules are easier to pull apart from one another, but they're also better able to bond back together.

When samples of what is being called "dynamic polyurea" are cut and then left for a day with the severed ends touching, they will heal back together with almost the same strength that they had before cutting. The process works at room temperature, although raising the ambient temperature to 37ºC (98.6ºF) will speed it up.

Some other experimental self-healing materials incorporate liquid-filled micro-capsules that break open when the material is cut or cracked. This means that they will only heal as long as there are unruptured capsules present. By contrast, dynamic polyurea can reportedly heal over and over again, as it relies solely on its molecular structure.

No comment yet.
Scooped by Dr. Stefan Gruenwald!

Nanoribbons of graphene conduct electricity ten times better than theory predicted

Nanoribbons of graphene conduct electricity ten times better than theory predicted | Amazing Science |

Physicists have produced nanoribbons of graphene — the single-atom-thick carbon — that conduct electrons better than theory predicted even for the most idealized form of the material. The finding could help graphene realize its promise in high-end electronics, where researchers have long hoped it could outperform traditional materials such as silicon.Carbon layers grown on silicon carbide conduct electricity even better than theory predicted.

In graphene, electrons can move faster than in any other material at room temperature. But techniques that cut sheets of graphene into the narrow ribbons needed to form wires of a nano-scale circuit leave ragged edges, which disrupt the electron flow (further reading: Graphene: The quest for supercarbon').

Now a team led by physicist Walt de Heer at the Georgia Institute of Technology in Atlanta has made ribbons that conduct electric charges for more than 10 micrometres without meeting resistance — 1,000 times farther than in typical graphene nanoribbons1. The ribbons made by de Heer's team in fact conduct electrons ten times better than standard theories of electron transport they should, say the authors. This unimpeded motion means that circuits could transmit signals faster and without the overheating issues that hamper typical semiconductor chips.

No comment yet.
Scooped by Dr. Stefan Gruenwald!

Salmons use Earth's magnetic field to migrate accurately comparing it to an inherited map

Salmons use Earth's magnetic field to migrate accurately comparing it to an inherited map | Amazing Science |

Diverse animals detect the Earth's magnetic field and use it as a cue in orientation and navigation. Most research on magnetoreception has focused on the directional or `compass' information that can be extracted from the Earth's field. Because the field varies predictably across the surface of the globe, however, it also provides a potential source of positional or `map' information, which some animals use to steer themselves along migratory pathways or to navigate toward specific target areas. The use of magnetic positional information has been demonstrated in several diverse animals including sea turtles, spiny lobsters, newts and birds, suggesting that such systems are phylogenetically widespread and can function over a wide range of spatial scales. These `magnetic maps' have not yet been fully characterized. They may be organized in several fundamentally different ways, some of which bear little resemblance to human maps, and they may also be used in conjunction with unconventional navigational strategies.

Salmons, for example, use Earth’s magnetic field to create a large-scale mental map which they follow to find suitable feeding grounds, a study published today in Current Biology has found. The salmons are born in rivers and live out the early part of their lives in freshwater before travelling hundreds or thousands of kilometres out into the open ocean, where they spend most of their adulthood.

It has long been suspected that salmon use Earth’s magnetic field to navigate during this long migration. But until now, the way that young salmon swim from their streambed out into the open ocean with no previous knowledge of the sea, nor any parents or experienced fish to follow, has been a mystery.  Previous work has suggested they might be guided, in part, by taking cues from regional magnetic fields to determine the best course – termed the “inherited magnetic map”. Because this map is inherited the salmon do not require any previous knowledge of their migration path or location.

The idea of an inherited magnetic map has long been speculated, but until now there has been no empirical evidence to suggest that salmon can determine their geographic position using the geomagnetic field. Nathan Putman from Oregon State University has now shown that salmon do navigate using an inherited magnetic map.

Dr. Putman and colleagues tested young Chinook salmon against different magnetic fields, either north or south of their typical ocean range, and found that the fish orientate themselves back towards their home range. If a fish was exposed to a north magnetic field, for instance, it would change its swimming direction back south.

Putman and colleagues also examined magnetic field components (magnetic intensity and the inclination angle) to determine which feature the fish use as a cue and found that neither of the features alone elicited the complete turn-around response, indicating that salmon rely on a combination of the two.

The results of the study also suggest this trait is inherited, as salmon are able to navigate without requiring any previous learning.

No comment yet.
Scooped by Dr. Stefan Gruenwald!

Shivering unlocks new way of fighting obesity

Shivering unlocks new way of fighting obesity | Amazing Science |

Shivering is not an activity many of us enjoy. We do it because we are cold and uncomfortable. But perhaps the news that it could have some of the same benefits as moderate bouts of exercise will stop us running in from the cold so quickly. Researchers have found that the act of shivering can stimulate the conversion of energy-storing “white fat” into energy-burning “brown fat”.

The findings, published in Cell Metabolism, show that when humans shiver their levels of hormones irisin (produced by muscle) and FGF21 (produced by brown fat) increase. Specifically, around 10-15 minutes of shivering by volunteers placed in temperatures of less than 15°C resulted in equivalent rises in irisin as an hour of moderate exercise.

Irisin, identified just two years ago in animals, converts white fat into brown fat. Unlike white fat, brown fat is designed to produce heat by burning calories. For example, around 50g of white fat retains more than 300 kilocalories of energy in the body. The same amount of brown fat could burn up to 300 kilocalories a day.

There has been a lot of excitement surrounding the discovery of irisin because the energy-burning nature of brown fat makes it a potential therapeutic tool for targeting obesity and diabetes. It appears to be a golden ticket to promoting a healthy metabolism: as well as burning calories, it drains the blood of glucose (useful for preventing the onset of type II diabetes) as well as draining blood of unhealthy fat like triglycerides.

Also through studies in the laboratory on animals, FGF21 has been found to be a powerful activator of this brown fat, energy burning process. It is a molecule that originates in the liver and in brown fat itself. Since brown fat was discovered in humans, researchers have been bent on working out how to stimulate more of it, which makes this new research particularly exciting.

The capacity of brown fat to burn calories in order to produce heat and maintain body temperature in cold environments has long been known in animals. We are all born with supplies of brown fat; it is nature’s way of preventing hypothermia in babies. But until recently, it was thought to vanish in early infancy, getting replaced by “bad” white fat that sits on our waistlines.

We now know that brown fat is present in most, if not all, adults. Those with more brown fat are slimmer than those without. Glucose levels are also lower in humans with more brown fat. Efforts are therefore being made into understanding how brown fat is stimulated in humans. Previous studies have shown how irisin activates it in rodents; this research is an important step in understanding how it is stimulated in humans.

No comment yet.
Scooped by Dr. Stefan Gruenwald!

Planck Star: A New Type of Star Emerges From Inside Black Holes

Planck Star: A New Type of Star Emerges From Inside Black Holes | Amazing Science |

Black holes have fascinated scientists and the public alike for decades. There is special appeal in the idea that the universe contains regions of space so dense that light itself cannot escape and so extreme that the laws of physics no longer apply. What secrets can these extraordinary objects hide?

Today, we get an answer thanks to the work of Carlo Rovelli at the University of Toulon in France, and Francesca Vidotto at Radboud University in the Netherlands. These guys say that inside every black hole is the ghostly, quantum remains of the star from which it formed. And that these stars can later emerge as the black hole evaporates.

Rovelli and Vidotto call these objects “Planck stars” and say they could solve one of the most important questions in astrophysics. What’s more, evidence for the existence of Planck stars may be readily available, simply by looking to the night sky.

Planck stars would be small— stellar-mass black hole would form a Planck star about 10^-10 centimetres in diameter. But that’s still some 30 orders of magnitude larger than the Planck length.

An interesting question is whether these Planck stars would be stable throughout the life of the black hole that surrounds them. Rovelli and Vidotto have a fascinating answer. They say that the lifetime of a Planck star is extremely short, about the length of time it takes for light to travel across it.

But to an outside observer, Planck stars would appear to exist much longer. That’s because time slows down near high-density masses. For such an observer, a Planck star would last just as long as its parent black hole.

It then becomes possible for the black hole to interact with the Planck star it contains. Rovelli and Vidotto point out that as the black hole evaporates and shrinks, its boundary will eventually meet that of the Planck star as it expands after the bounce. “At this point there is no horizon any more and all information trapped inside can escape,” they say.

That immediately solves the information paradox. The information isn’t lost or trapped inside an unimaginably small region of space but eventually re-emitted into the universe.

There’s yet another exciting consequence of these ideas. Rovelli and Vidotto say this release of information would generate radiation with a wavelength of about 10^-14 cm. In other words, gamma rays.

The universe is filled with a foggy background of gamma rays that astrophysicists have already observed in considerable detail with orbiting telescopes. Could it be that they have already detected the signature of Planck stars releasing their information into the cosmos?

No comment yet.
Scooped by Dr. Stefan Gruenwald!

MITRE-Harvard nanocomputer may point the way to future computer miniaturization

MITRE-Harvard nanocomputer may point the way to future computer miniaturization | Amazing Science |

An interdisciplinary team of scientists and engineers from The MITRE Corporation and Harvard University have taken key steps toward ultra-small electronic computer systems that push beyond the imminent end of Moore’s Law. They designed and assembled, from the bottom up, a functioning, ultra-tiny control computer (nanocontroller) that they say is the densest nanoelectronic system ever built.

The “nanoelectronic finite-state machine” (“nanoFSM”) or nanocomputer measures 0.3 x 0.03 millimeters. It is composed of hundreds of nanowire transistors, each an under-20 nanometers switch. The nanowire transistors use very little power because they are “nonvolatile” — the switches remember whether they are on or off, even when no power is supplied to them.

In the nanoFSM, these nanoswitches are assembled and organized into circuits on several “tiles” (modules). Together, the tiles route small electronic signals around the computer, enabling it to perform calculations and process signals that could be used to control tiny systems, such as miniscule medical therapeutic devices, other tiny sensors and actuators, or even insect-sized robots.

In 2011, the MITRE-Harvard team demonstrated a single such tiny tile capable of performing simple logic operations (ultra-tiny nanocircuits). In their recent collaboration they combined three tiles on a single chip to produce a first-of-its-kind complex programmable nanocomputer.

“It was a challenge to develop a system architecture and nanocircuit designs that would pack the control functions we wanted into such a very tiny system,” according to Shamik Das, chief architect of the nanocomputer, who is also principal engineer and group leader of MITRE’s Nanosystems Group. “Once we had those designs, though, our Harvard collaborators did a brilliant job innovating to be able to realize them.”

No comment yet.
Scooped by Dr. Stefan Gruenwald!

Optical data storage has virtually unlimited lifetime

Optical data storage has virtually unlimited lifetime | Amazing Science |

Data stored on today's CDs and DVDs has a lifetime of several decades before the physical material begins to significantly decay. Researchers are working on prolonging the lifetime of stored data, but so far reaching even 100 years has been challenging. Now in a new study, researchers have demonstrated a data storage technique that has a lifetime of about 3 x 10E20 years at room temperature—virtually unlimited—which could lead to a new era of eternal data archiving.

The researchers, Jingyu Zhang, Mindaugas Gecevičius, Martynas Beresna, and Peter G. Kazansky at the University of Southampton in the UK, have published a paper in a recent issue of Physical Review Letters on the new data storage technique.

"In the fifth decade after the invention of the Internet, more and more data is generated in this Information Age," Zhang told "How to store the data while considering the physical decay of storage materials and techniques has attracted much attention. Many individuals, companies and governments are interested in eternal data archiving to store data for military, science, and confidential purposes. Some applications can already be seen in the market; for example, M-disc and others are still under development. There is also a disc by Hitachi which lasts millions of years. We believe we are presenting the ultimate solution for eternal data archiving."

As the scientists explain, there is a general tradeoff in data storage between lifetime and capacity, so that media that store larger amounts of information tend to have shorter lifetimes. For example, physicists have demonstrated the possibility of storing vast amounts of data with individual atoms, yet the storage time is a mere 10 picoseconds at room temperature.

The new optical data storage technique presented here provides both excellent lifetime and capacity. To record data, a femtosecond (fs) laser delivers ultrashort (280-fs, with 1 fs = 10-15 seconds) light pulses onto a piece of quartz. The light pulses create nanogratings—tiny dots—in the quartz, with each dot carrying three bits of information. This triple storage is possible because the laser performs multilevel encoding, so that the dots encode the intensity and polarization of the light in three layers of the quartz. Applying this technique, a disc the size of a CD or DVD with about 1000 layers has a data capacity of hundreds of terabytes, compared with hundreds of megabytes for today's commercial discs.

To determine the lifetime of the optical data storage system, the researchers subjected the information to accelerated aging to obtain the decay rate. The underlying mechanism of decay is the collapse of nanovoids that exist between the nanogratings; when the nanovoids collapse, the nanogratings become unstable and lose their stored data.

The researchers calculated that the decay time of the nanogratings, and thus the lifetime of the data storage system, is about 3 x 1020 years at room temperature, indicating unprecedented high stability. The lifetime decreases at elevated temperatures, but even at temperatures of 462 K (189° C, 372° F), the extrapolated decay time is 13.8 billion years, comparable to the age of the Universe.

Reference: Jingyu Zhang, et al. "Seemingly Unlimited Lifetime Data Storage in Nanostructured Glass." PRL 112, 033901 (2014). DOI: 10.1103/PhysRevLett.112.033901

No comment yet.
Scooped by Dr. Stefan Gruenwald!

WIRED: Astronauts Spot Mysterious Ice Circles in World's Deepest Lake

WIRED: Astronauts Spot Mysterious Ice Circles in World's Deepest Lake | Amazing Science |

Astronauts aboard the International Space Station noticed two mysterious dark circles in the ice of Russia’s Lake Baikal in April. Though the cause is more likely aqueous than alien, some aspects of the odd blemishes defy explanation.

The two circles are the focal points for ice break-up and may be caused by upwelling of warmer water in the lake. The dark color of the circles is due to thinning of the ice, which usually hangs around into June. Upwelling wouldn’t be strange in some relatively shallow areas of the lake where hydrothermal activity has been detected, such as where the circle near the center of the lake (pictured below) is located. Circles have been seen in that area before in 1985 and 1994, though they weren’t nearly as pronounced. But the location of the circle near the southern tip of the lake (pictured above) where water is relatively deep and cold is puzzling.

The lake itself is an oddity. It is the largest by volume and the deepest (5370 feet at its deepest point), as well as one of the oldest at around 25 million years. The photo above was taken by an astronaut from the ISS. The photo below was taken by NASA’s MODIS satellite instrument.

No comment yet.
Scooped by Dr. Stefan Gruenwald!

Capturing ten-color ultrasharp images of synthetic DNA structures resembling numerals 0 to 9

Capturing ten-color ultrasharp images of synthetic DNA structures resembling numerals 0 to 9 | Amazing Science |

A new microscopy method could enable scientists to generate snapshots of dozens of different biomolecules at once in a single human cell, a team from the Wyss Institute of Biologically Inspired Engineering at Harvard University reported Sunday in Nature Methods.

Such images could shed light on complex cellular pathways and potentially lead to new ways to diagnose disease, track its prognosis, or monitor the effectiveness of therapies at a cellular level.

Cells often employ dozens or even hundreds of different proteins and RNA molecules to get a complex job done. As a result, cellular job sites can resemble a busy construction site, with many different types of these tiny cellular workers coming and going. Today's methods typically only spot at most three or four types of these tiny workers simultaneously. But to truly understand complex cellular functions, it's important to be able to visualize most or all of those workers at once, said Peng Yin, Ph.D., a Core Faculty member at the Wyss Institute and Assistant Professor of Systems Biology at Harvard Medical School.

To capture ultrasharp images of biomolecules, they had to overcome laws of physics that stymied microscopists for most of the last century. When two objects are closer than about 200 nanometers apart — about one five-hundredth the width of a human hair — they cannot be distinguished using a traditional light microscope: the viewer sees one blurry blob where in reality there are two objects.

Since the mid-1990s, scientists have developed several ways to overcome this problem using combinations of specialized optics, special fluorescent proteins or dyes that tag cellular components.

Ralf Jungmann, Ph.D., now a Postdoctoral Fellow working with Yin at the Wyss Institute and Harvard Medical School, helped develop one of those super-resolution methods, called DNA-PAINT, as a graduate student. DNA-PAINT can create ultrasharp snapshots of up to three cellular workers at once by labeling them with different colored dyes.

To visualize cellular job sites with crews of dozens of cellular workers, Yin's team, including Jungmann, Maier Avendano, M.S., a graduate student at Harvard Medical School, and Johannes Woehrstein, a postgraduate research fellow at the Wyss Institute, modified DNA-PAINT to create a new method called Exchange-PAINT.

Exchange-PAINT relies on the fact that DNA strands with the correct sequence of letters, or nucleotides, bind specifically to partner strands with complementary sequences. The researchers label a biomolecule they want to visualize with a short DNA tag, then add to the solution a partner strand carrying a fluorescent dye that lights up only when the two strands pair up. When that partner strand binds the tagged biomolecule, it lights up, then lets go, causing the biomolecule to "blink" at a precise rate the researchers can control. The researchers use this blinking to obtain ultrasharp images.

To test Exchange-PAINT, the researchers created 10 unique pieces of folded DNA, or DNA origami, that resembled the numerals 0 through 9. These numerals could be resolved with less than 10 nanometers resolution, or one-twentieth of the diffraction limit.

The team was able to use Exchange-PAINT to capture clear images of the 10 different types of miniscule DNA origami structures in one image. They also used the method to capture detailed, ultrasharp images of fixed human cells, with each color tagging an important cellular component — microtubules, mitochondria, Golgi apparatus, or peroxisomes.

No comment yet.
Scooped by Dr. Stefan Gruenwald!

Retina cells 3D printed for the first time

Retina cells 3D printed for the first time | Amazing Science |

The ability to arrange cells into highly defined patterns and structures has recently elevated the use of 3D printing in the biomedical sciences to create cell-based structures for use in regenerative medicine.

A group of researchers from the UK have used 3-D biomedical printing to successfully print new eye cells, making it the first time the technology has been used successfully to print mature central nervous system cells. The breakthrough could lead to the production of artificial tissue grafts made from the variety of cells found in the human retina and may aid in the search to cure blindness.

Experts at the University of Cambridge printed two types of cells - ganglion cells and glial cells - derived from adult rat retinas. Ganglion cells transmit information from the eye to parts of the brain, while glial cells provide support and protection for neurons.

Co-authors of the study Professor Keith Martin and Dr Barbara Lorber, from the John van Geest Centre for Brain Repair, University of Cambridge, said: "The loss of nerve cells in the retina is a feature of many blinding eye diseases. The retina is an exquisitely organised structure where the precise arrangement of cells in relation to one another is critical for effective visual function".

In their study, the researchers used a single nozzle piezoelectric inkjet printer that ejected the cells through a sub-millimetre diameter nozzle when a specific electrical pulse was applied. The driving waveform was defined by a PC-driven generator. "We plan to extend this study to print other cells of the retina and to investigate if light-sensitive photoreceptors can be successfully printed using inkjet technology. In addition, we would like to further develop our printing process to be suitable for commercial, multi-nozzle print heads," Professor Martin concluded. His goal is to make living tissues using multiple nozzles so that different types of cells could be printed from different nozzles at the same time.

The study has been detailed in a paper published in Biofabrication.

No comment yet.
Scooped by Dr. Stefan Gruenwald!

Topological insulators could exist in six new types never seen before, theorists predict

Topological insulators could exist in six new types never seen before, theorists predict | Amazing Science |

Topological insulators—materials whose surfaces can freely conduct electrons even though their interiors are electrical insulators—have been of great interest to physicists in recent years because of unusual properties that may provide insights into quantum physics. But most analysis of such materials has had to rely on highly simplified models.

Now, a team of researchers at MIT has performed a more detailed analysis that hints at the existence of six new kinds of topological insulators. The work also predicts the materials' physical properties in sufficient detail that it should be possible to identify them unambiguously if they are produced in the lab, the scientists say.

The new findings are reported recently in Science by MIT professor of physics Senthil Todadri, graduate student Chong Wang, and Andrew Potter, a former MIT graduate student who is now a postdoc at the University of California at Berkeley.

"In contrast to conventional insulators, the surface of the topological insulators harbors exotic physics that are interesting both for fundamental physics, and possibly for applications," Senthil says. But attempts to study the properties of these materials have "relied on a highly simplified model in which the electrons inside the solid are treated as though they did not interact with each other." New analytical tools applied by the MIT team now reveal "that there are six, and only six, new kinds of topological insulators that require strong electron-electron interactions."

"The surface of a three-dimensional material is two-dimensional," Senthil says—which explains why the electrical behavior of the surface of a topological insulator is so different from that of the interior. But, he adds, "The kind of two-dimensional physics that emerges [on these surfaces] can never be in a two-dimensional material. There has to be something inside, otherwise this physics will never occur. That's what's exciting about these materials," which reveal processes that don't show up in other ways.

No comment yet.
Scooped by Dr. Stefan Gruenwald!

Tiny Sponges Seal A Gunshot Wound In 15 Seconds

Tiny Sponges Seal A Gunshot Wound In 15 Seconds | Amazing Science |
An Oregon startup has developed a pocket-size device that uses tiny sponges to stop bleeding fast.

When a soldier is shot on the battlefield, the emergency treatment can seem as brutal as the injury itself. A medic must pack gauze directly into the wound cavity, sometimes as deep as 5 inches into the body, to stop bleeding from an artery. It’s an agonizing process that doesn't always work--if bleeding hasn't stopped after three minutes of applying direct pressure, the medic must pull out all the gauze and start over again. It’s so painful, “you take the guy’s gun away first,” says former U.S. Army Special Operations medic John Steinbaugh.

Even with this emergency treatment, many soldiers still bleed to death; hemorrhage is a leading cause of death on the battlefield. "Gauze bandages just don't work for anything serious," says Steinbaugh, who tended to injured soldiers during more than a dozen deployments to Iraq and Afghanistan. When Steinbaugh retired in April 2012 after a head injury, he joined an Oregon-based startup called RevMedx, a small group of veterans, scientists, and engineers who were working on a better way to stop bleeding.

RevMedx recently asked the FDA to approve a pocket-size invention: a modified syringe that injects specially coated sponges into wounds. Called XStat, the device could boost survival and spare injured soldiers from additional pain by plugging wounds faster and more efficiently than gauze.

The team’s early efforts were inspired by Fix-a-Flat foam for repairing tires. “That’s what we pictured as the perfect solution: something you could spray in, it would expand, and bleeding stops,” says Steinbaugh. “But we found that blood pressure is so high, blood would wash the foam right out.”

So the team tried a new idea: sponges. They bought some ordinary sponges from a hardware store and cut them into 1-centimeter circles, a size and shape they chose on a whim but later would discover were ideal for filling wounds. Then, they injected the bits of sponge into an animal injury. “The bleeding stopped,” says Steinbaugh. “Our eyes lit up. We knew we were onto something.” After seeing early prototypes, the U.S. Army gave the team $5 million to develop a finished product.

No comment yet.
Scooped by Dr. Stefan Gruenwald!

Reserachers bring extensive world temperature records to Google Earth

Reserachers bring extensive world temperature records to Google Earth | Amazing Science |

Climate researchers from the University of East Anglia (UEA) in the UK have just given people a whole lot more to talk about. As part of an ongoing effort to increase the accessibility and transparency of data on past climate and climate change, they've made one of the most widely used records of Earth's climate accessible through Google Earth.

Established in 1971, the UEA's Climate Research Unit (CRU) has become one of the leading institutions involved in the study of natural and anthropogenic climate change. Drawing on monthly weather records from some 6,000 weather stations around the globe, some dating back over 150 years, the researchers are responsible for Climatic Research Unit Temperature Version 4 (CRUTEM4), a widely used dataset of land-surface air temperatures.

By making CRUTEM4 data available through Google Earth, users can zoom in on any of the 6,000 weather stations, drill down through some 20,000 graphs and view monthly, seasonal and annual temperature data, some of which dates back to 1850. The interface places a red and green checkerboard over areas for where data is available. Since some remote areas lack weather stations, there are gaps in the checkerboard.

"The data itself comes from the latest CRUTEM4 figures, which have been freely available on our website and via the Met Office," said Dr Tim Osborn from the CRU. "But we wanted to make this key temperature dataset as interactive and user-friendly as possible. The beauty of using Google Earth is that you can instantly see where the weather stations are, zoom in on specific countries, and see station datasets much more clearly."

There are already a number of climate datasets available for Google Earth, including those from the US National Oceanic and Atmospheric Administration (NOAA). Those wishing to view these and the CRUTEM4 dataset need only download Google Earth and open the KML format files. Due to the sheer volume of data, the CRU researchers expect there will be a few errors in their dataset and are encouraging users to alert them to any unusual figures.

No comment yet.
Scooped by Dr. Stefan Gruenwald!

CERN kicks off plans for LHC successor

CERN kicks off plans for LHC successor | Amazing Science |

The CERN particle-physics lab near Geneva is putting plans in place to build a successor to its Large Hadron Collider (LHC). At a meetingto be held at the University of Geneva next week, some 300 physicists and engineers – including current CERN boss Rolf-Dieter Heuer – will discuss a range of options for a possible future collider. This includes plans for a massive next-generation circular collider – with a circumference of 80–100 km – that would accelerate protons to energies of about 100 TeV.

While the 27 km-circumference LHC has been colliding protons at energies of up to 7 TeV in the hunt for new particles since it first switch on in 2008, for more than 30 years physicists have been carrying out R&D on linear colliders that could one day be the LHC’s successor. One leading design effort is the International Linear Collider (ILC), which would accelerate electrons and positrons to about 250 GeV and smash them together at a rate of five times per second. Funding for the $8bn, 31 km-long collider has yet to be found, but Japanese particle physicists are already making moves to host this next-generation particle smasher.

Meanwhile, a design for a higher-energy machine – the Compact Linear Collider (CLIC) – that could operate at 3 TeV is being developed by a team at CERN. Construction of the ILC and CLICcould begin in the coming decade and they would, if built, study the Higgs boson in great detail through the "clean" collisions that can be made from colliding electron and positrons rather than smashing protons together.

Yet it remains unclear whether these machines will be built and physicists have recently been coming up with other proposals that involve circular colliders similar to the LHC. Such colliders do have some advantages, not least that physicists have a lot of experience in building them. In particular, from 1989 to 2000 CERN operated the Large Electron–Positron Collider (LEP), which was located in the same tunnel that now houses the LHC and was used to study the Z and W bosons in detail. "We need to keep our options open about what the next particle collider will be," says John Ellis of Kings College London, who has been involved in designs for particle colliders beyond the LHC and will be speaking at next week’s meeting. "A bigger, more ambitious machine could offer us more capabilities."

Delegates at next week’s Geneva meeting will discuss the technologies needed to create these future machines. One leading design for a next-generation circular collider is "TLEP", which would be housed in an enormous new 80–100 km-circumference tunnel that would most likely be built in Geneva. It could initially collide electrons and positrons (as would both the ILC and CLIC) at energies of about 350–500 GeV. Most of the cost of such a machine would be in excavating the tunnel, with the accelerator itself only accounting for about one-third of the total. Yet that same 100 km tunnel could then be used well into the future, eventually housing a proton–proton machine that could operate at an energy of up to 100 TeV, much in the same way as the LHC has used the LEP tunnel. This could then look for new particles – such as supersymmetric particles – that the LHC may yet discover. Researchers are planning to complete a conceptual design study for TLEP by 2017 as an input to the next review of the European strategy for particle physics.

No comment yet.
Scooped by Dr. Stefan Gruenwald!

Genome Sequencing Identifies 1,300 Microbe Species In Beijing Smog

Genome Sequencing Identifies 1,300 Microbe Species In Beijing Smog | Amazing Science |
Metagenomic survey reveals traces of pathogens and allergens in the city’s air.

Chinese researchers have now used genome sequencing to identify about 1,300 different microbial species in an exceptionally soupy smog that hit Beijing in January 2013 (ref. 1). Reassuringly, most of the microbes they found are benign — but a few are responsible for allergies and respiratory disease in humans. And on days with heavier pollution, the proportion of DNA from these allergens and pathogens increased, suggesting that they might present an additional health threat to vulnerable groups, such as older people or those with weakened immune systems.

Surveys of airborne microbes have long relied on culturing samples in the lab, a method that can easily miss key species. In the past few years, researchers have looked at the microbial genomes found in air to identify broad families or genera of bacteria — an approach called metagenomics. But this is the first time that a survey has drilled down to pinpoint particular species of microbes in air, which is important for assessing their pathogenic potential, says Ting Zhu, a biologist at Tsinghua University, Beijing, who was part of the team that performed the latest study. “It’s a proof of principle that one can extract and identify these microbes at the species level,” says Zhu. “It adds to our understanding of what we inhale every day.”

The scientists took 14 air samples over 7 consecutive days and filtered out two types of particles: those measuring less than 2.5 micrometres across, and those up to 10 micrometres across, known as PM2.5 and PM10, respectively. On some days during the experiment, Beijing’s PM2.5 levels topped 500 micrograms per cubic metre — some 20 times the World Health Organization’s guideline limits.

The scientists extracted and sequenced DNA from the samples, and compared the results with a large gene database. The most abundant species identified was Geodermatophilus obscurus, a common soil bacterium. But they also found Streptococcus pneumoniae, which can cause pneumonia; Aspergillus fumigatus, a fungal allergen; and a range of other bacteria typically found in faeces. The proportion of DNA from these species increased by 2–4 times on the smoggiest days, although the samples probably included material from dead cells too, “so we don’t know if they are still viable”, says Zhu. The researchers suggest that clinical studies could look for the same microbes in the sputum of patients with respiratory tract infections, to assess whether smoggier days lead to more infections.

Andrea Franzetti, a microbiologist at the University of Milan–Bicocca, Italy, says that the make-up of the microbial community in Beijing's air is broadly in line with a similar survey of airborne bacteria that his team conducted in Milan2. “What’s new is the high number of sequences,” he says. That helps to quickly pinpoint bacteria that might have worrying health effects, allowing microbiologists to target them for further study. “There is increasing evidence that bacteria could play an important role in the health effects of airborne particles,” says Franzetti.

No comment yet.
Scooped by Dr. Stefan Gruenwald!

Radar reveals ladybirds fly at altitudes of up to 1 km and at speeds of up to 60 km/h

Radar reveals ladybirds fly at altitudes of up to 1 km and at speeds of up to 60 km/h | Amazing Science |

The extraordinary heights and speeds of ladybird flight paths have been revealed for the first time. Scientists examining radar data have spotted the tiny creatures travelling at heights of up to 1100 metres, and at speeds of up to 60 kilometres per hour.

The discovery, published in the journal PLOS ONE, means that, in theory, ladybirds could travel from London to Birmingham in little more than two hours.

It could explain why invasive insects such as the harlequin ladybird have managed to spread so quickly from one part of the country to another.

The study also suggests that ladybirds are able to travel further when temperatures are warmer, a phenomenon that could exacerbate the problems posed by invaders as the climate warms. Dr. Lori Lawson Handley, from the University of Hull, led the research. 'These are the first recordings of ladybirds travelling at such extraordinarily high altitudes,' she says. 'Ladybirds are very capable flyers on their own, but this puts them up in the stronger winds where they can travel faster and further.'

'If you imagine a ladybird's shape, it's actually quite characteristic,' says Lawson Handley. 'They're more spherical compared to other insects, so between their weight, width and height, we can be pretty confident that we're identifying ladybirds in the radar data.'

Most of the ladybirds were found at heights between 150 and 500 metres above the ground, flying at an average speed of 30 kilometres an hour. But some were found at even higher altitudes, travelling even faster. In separate experiments, the team recorded the flight times of ladybirds in a Perspex box. The average flight lasted 36.5 minutes, with some going on for as long as 2 hours. This would mean that ladybirds could travel up to 120 kilometres in a single flight.

No comment yet.
Scooped by Dr. Stefan Gruenwald!

Diamond Defects Boost Quantum Technology

Diamond Defects Boost Quantum Technology | Amazing Science |

New research shows that a remarkable defect in synthetic diamond produced by chemical vapor deposition allows researchers to measure, witness, and potentially manipulate electrons in a manner that could lead to new “quantum technology” for information processing.

Normal computers process bits, the fundamental ones and zeros, one at a time. But in quantum computing, a “qubit” can be a one or a zero at the same time. This duplicitous state can allow multitasking at an astounding rate, which could exponentially increase the computing capacity of a tiny, tiny machine.

An “NV-“ center can be created within a diamond’s scaffold-like structure by replacing a missing carbon atom with a nitrogen atom (N)that has trapped an electron making the center negatively charged. Scientists can monitor the center’s behavior and thereby provide a window for understanding how electrons respond to different conditions. The center has the potential to serve as a qubit in future quantum computers.

Electrons occupy different orbits around their atom and, by analogy, spin like the Earth. For the first time, Struzhkin and his team, led by Marcus Doherty of the Australian National University, observed what happens to electrons in these NV- centers under high-pressure and normal temperatures. Coauthor of the study, Viktor Struzhkin at the Carnegie Institution for Science, explained: “Our technique offers a powerful new tool for analyzing and manipulating electrons to advance our understanding of high-pressure superconductivity, as well as magnetic and electrical properties.”

Struzhkin and team subjected single-crystal diamonds to pressures up to 600,000 times atmospheric pressure at sea level (60 gigapascals, GPa) in a diamond anvil cell and observed how electron spin and motion were affected. They optically excited the NV- centers with light and scanned microwave frequencies in a process called optically detected magnetic resonance to determine any changes. The NV- center is very sensitive to magnetic fields, electrical fields, and stress.

Until now, researchers thought that the orbits of the electrons that contribute to the defect’s electronic structure and spin dynamics were localized to the area immediately surrounding the vacancy. Doherty explained: "Our team found instead that the electrons also orbit more distant atoms and that the span of their orbits contract with increasing pressure."

In addition to overturning previous beliefs about the electron orbits, the researchers found a sensitive means to measure pressure. This method can detect changes in pressure of about 10 atmospheres in one second, even up to pressures of 500,000 atmospheres (50 GPa).

“This work demonstrates that defects in diamond have great potential as quantum sensors of high pressure phenomena and, conversely, that high pressure can be employed to study the quantum phenomena of the defects,” remarked Doherty.

No comment yet.
Scooped by Dr. Stefan Gruenwald!

Creation of the First Flexible Transparent Conductor of Electricity

Creation of the First Flexible Transparent Conductor of Electricity | Amazing Science |

University of Houston researchers have developed a new stretchable and transparent electrical conductor, bringing the potential for a fully foldable cell phone or a flat-screen television that can be folded and carried under your arm closer to reality.

hifeng Ren, a physicist at the University of Houston and principal investigator at the Texas Center for Superconductivity, said there long has been research on portable electronics that could be rolled up or otherwise easily transported. But a material that is transparent and has both the necessary flexibility and conductivity has proved elusive – some materials have two of the components, but until now, finding one with all three has remained difficult.

The researchers reported that gold nanomesh electrodes, produced by the novel grain boundary lithography, increase resistance only slightly, even at a strain of 160 percent, or after 1,000 cycles at a strain of 50 percent. The nanomesh, a network of fully interconnected gold nanowires, has good electrical conductivity and transparency, and has “ultrahigh stretchability,” according to the paper.

And unlike silver or copper, gold nanomesh does not easily oxidize, which Ren said causes a sharp drop in electrical conductivity in silver and copper nanowires.

Guo said the group is the first to create a material that is more stretchable and conductive at similar transparency, as well as the first to use grain boundary lithography in the quest to do so. More importantly, he said, it is the first to offer a clear mechanism to produce ultrahigh stretchability.

The grain boundary lithography involved a bilayer lift-off metallization process, which included an indium oxide mask layer and a silicon oxide sacrificial layer and offers good control over the dimensions of the mesh structure.

No comment yet.
Scooped by Dr. Stefan Gruenwald!

New Virtual Landgrab for Domain Names: Will It Change the Web?

New Virtual Landgrab for Domain Names: Will It Change the Web? | Amazing Science |

Up until now, the web has been organized using only a handful of generic top-level domains (gTLDs)— a fancy description of the words that come after the dot in a URL, such as .com, .net, .gov. But now, the Internet will face the biggest virtual land grab in its history. Starting today, 100 new top-level domains will be available through registrars like GoDaddy and Namecheap

This massive expansion is overseen by the Internet Corporation for Assigned Names and Numbers (ICANN), a non-profit organization charged with governing these new domains. New gTLDs fall into two categories: generic and brands. Generic TLDs include domains such as .photograpy, .bike, or .guru, whereas brand TLDs are reserved for the mega-corporations that can easily front the $185,000 price tag for a new domain. This means companies such as Google (who has registered for 101 TLDs) could brand websites with .google or .android. These domains will be controlled by the businesses themselves, who can use them however they want. 

So why did ICANN decide to add so many new TLDs, and why now? These new domain additions have been a long time coming. Eight years ago, the multilateral community which oversees Internet policies charged ICANN with developing new domains. After years of preparation, ICANN opened a six-month application period in January 2012. “The community and ICANN anticipated about 500 applicants,” says Cyrus Nazami, vice president of domain name services with ICANN. “We ended up with 1930 applicants. There was just a gold rush-type of interest of coming in and putting your stake in the ground.” 

Of the nearly 2000 applicants, 500 hundred were from major corporations such as Google, Apple, Microsoft, Ford, and BMW. Only 1300 were unique domains. This means some more common, potentially valuable domain names (.web, .book, .mail) were up for grabs. If multiple parties apply for the same domain, ICANN pushed for applicants to work out solution among themselves, but did hold what they call “an auction of last resort” when no solution was met. After another 18 months of processing applications, the first new domain names are ready to make their debut. 

Nazami sees many reasons why these new domains will improve the web, but one reason takes precedent—the internet just needed more space. In April 2013, 111 million URLs ended in .com, with .net coming in second with 15 million. ICANN says small businesses and individuals were having a tough time finding an available domain that would work for them. 

“Thirty or forty years ago, people basically had two, three, or four television stations, but today there are hundreds of them,” Nazami says. “They’re all specifically focused on a common interest, whether it be home and garden, automobiles, mechanics, or cooking. People identify with content specifically tailored.” Nazami also says that brand TLDs should give consumers peace of mind. When searching for say BMW, users can identify any website with the top-level domain .bmw as an official site. The new domains also bolster international web addresses as ICANN now allows a TLD to be made from one of dozens of different scripts, such as Chinese or Russian. 

No comment yet.
Scooped by Dr. Stefan Gruenwald!

Animal Pompeii: Exquisitely preserved feathered dinosaur fossils date back to a catastrophic event

Animal Pompeii: Exquisitely preserved feathered dinosaur fossils date back to a catastrophic event | Amazing Science |

A series of fossil discoveries in the 1990s changed our understanding of the lives of early birds and mammals, as well as the dinosaurs they shared an ecosystem with. All those discoveries had one thing in common: they came from a small region in northern China that preserved what is now called the Jehol Biota.

Until now, however, no one knew why so many well-preserved fossils were found in that region. In a new study published in Nature Communications, researchers discovered that this remarkable preservation might have been the result of a Pompeii-like event, where hot ash from a volcanic eruption entombed these animals.

According to Leicester University's Sarah Gabbott (who wasn’t involved in the study), “Unravelling the environments in which fossilization took place, as the authors do in this paper, is very important. It places the fossils within the context of their habitat and it allows us to determine what filters and biases may have played a part.” These biases may affect which organisms get preserved.

The fossils of the Jehol Biota are from the Early Cretaceous period, about 130 million years ago, and they comprise a wide variety of animals and plants. So far, about 60 species of plants, 1,000 species of invertebrates, and 140 species of vertebrates have been found in the Jehol Biota.

One of the most remarkable discoveries to arise from these fossils came in 2010, when Michael Benton of the University of Bristol found colour-banding preserved in dinosaur fossils. These stripes of light and dark are similar to stripes in modern birds, and they provided further evidence that dinosaurs evolved into birds. Benton also found that these fossils had intact mealnosomes—organelles that make pigments. This discovery allowed paleontologists to tell the colors of dinosaurs' feathers for the first time.

The area that supported the Jehol Biota is suspected to have been a wetland with many lakes. Most fossils are found in lakebeds, suggesting that either the fossils were washed into these lakes by floods or that the animals were in the lakes before fossilization took place.

Baoyu believes that if fossils don't separate bone joints, it means the animals must have been in the lake before dying. But that is not a convincing argument, Gabbott said. "A freshly dead carcass, buoyed by decay gases which collect in the stomach, can be transported for tens if not hundreds of kilometers without such disarticulation."

No other fossil location, let alone that which produced so many well-preserved samples, has ever been suggested to have undergone a similar event. However, a comparison can be made to what happened in Pompeii in 79 AD when Mount Vesuvius erupted. The ensuing destruction led to the preservation of the city’s architecture and objects but not of people or animals. The human and animal remains we see from Pompeii are plaster casts of the empty spaces their decomposed bodies left in the ash.

No comment yet.
Scooped by Dr. Stefan Gruenwald!

Black Death Left a Mark on Human Genome

Black Death Left a Mark on Human Genome | Amazing Science |

There have been multiple plagues throughout history around the world, but none have been so deadly as the Black Death, which killed an estimated one in every four Europeans, and so exerted very strong selection. The Black Death didn’t just wipe out millions of Europeans during the 14th century. It left a mark on the human genome, favoring those who carried certain immune system genes, according to a new study. Those changes may help explain why Europeans respond differently from other people to some diseases and have different susceptibilities to autoimmune disorders.

Geneticists know that human populations evolve in the face of disease. Certain versions of our genes help us fight infections better than others, and people who carry those genes tend to have more children than those who don’t. So the beneficial genetic versions persist, while other versions tend to disappear as those carrying them die. This weeding-out of all but the best genes is called positive selection. But researchers have trouble pinpointing positively selected genes in humans, as many genes vary from one individual to the next.

Genetically, the Rroma gypsies in Romania are still quite similar to the northwestern Indians, even though they have lived side by side with the Romanians for a millennium, the team found. But there were 20 genes in the Rroma and the Romanians that had changes that were not seen in the Indians’ versions of those genes, Netea and his colleagues report online today in the Proceedings of the National Academy of Sciences. These genes “were positively selected for in the Romanians and in the gypsies but not in the Indians,” Netea explains. “It’s a very strong signal.”

Those genes included one for skin pigmentation, one involved in inflammation, and one associated with susceptibility to autoimmune diseases such as rheumatoid arthritis. But the ones Netea and Bertranpetit were most excited about were a cluster of three immune system genes found on chromosome 4. These genes code for toll-like receptors, proteins which latch on to harmful bacteria in the body and launch a defensive response. “We knew they must be important for host defense,” Netea says.

What events in history might have favored these versions of the genes in gypsies and Romanians, but not in Indians? Netea and his colleagues tested the ability of the toll-like receptors to react to Yersinia pestis, the bacterium that caused the Black Death. They found that the strength of the immune response varied depending on the exact sequence of the toll-like receptor genes.

Netea and Bertranpetit propose that the Rroma and European Romanians came to have the same versions of these immune system genes because of the evolutionary pressure exerted by Y. pestis. Other Europeans, whose ancestors also faced and survived the Black Death, carried similar changes in the toll-like receptor genes. But people from China and Africa—two other places the Black Death did not reach—did not have these changes. The similarities in the other genes were likely caused by other conditions experienced by Rroma and Europeans, but not Indians.

No comment yet.
Scooped by Dr. Stefan Gruenwald!

World's Smallest Engine Runs On A Single Atom

World's Smallest Engine Runs On A Single Atom | Amazing Science |
Physicists are building a nano engine that runs on a single atom and will arguably be the most efficient ever made.

Like the one in your car, Johannes Roßnagel's engine is a four-stroke. In four steps it compresses and heats, then expands and cools. And as with any other engine, this cycle is repeated over and over again—transforming the changing temperature into mechanical energy. 

But Roßnagel's engine is no V-8. And it doesn't use internal combustion. Roßnagel, an experimental physicist at the University of Mainz in Germany, has conceived of and is in the process of building the world's tiniest engine, less than a micrometer in length. It is a machine so small it runs on a single atom. And in a recent paper in the journal Physical Review Letters, its inventors argue that, because of an interesting anomaly of quantum physics, this is also far and away the most efficient engine. 

The nano engine works like this: First, using tiny electrodes, the physicists trap a single atom in a cone of electromagnetic energy. "We're using a calcium-40 ion," Roßnagel says, "but in principle the engine could be built with just about any ion at all." This electromagnetic cone is essentially the engine's housing, and squeezes tightly over the atom. The physicists then focus two lasers on each end of the cone: one at the pointy end, which heats the atom, and another at the base of the cone, which uses a process called Doppler cooling to cool the atom back down. 

Because this heating and cooling slightly changes the size of the atom (more exactly, it alters the fuzzy smear of probability of where the atom exists), and the cone fits the atom so snuggly, the temperature change forces the atom to race back and forth along the length of the cone as the atom expands and contracts. For maximum efficiency, the physicists set the lasers to heat and cool at the same resonance at which the atom naturally vibrates from side to side. 

The result is that, like sound waves that build upon one other, the atom's oscillation between the two ends of the cone "gets accumulated, and becomes stronger and stronger," which can be harnessed, Roßnagel says. "If you imagine that you put a second ion by the cooler side, it could absorb the mechanical energy of our engine, much like a flywheel in a car engine." 

No comment yet.