Amazing Science
779.6K views | +36 today
Scooped by Dr. Stefan Gruenwald
onto Amazing Science!

Time reversal findings may open doors to the future

Time reversal findings may open doors to the future | Amazing Science |

Imagine a cell phone charger that recharges your phone remotely without even knowing where it is; a device that targets and destroys tumors, wherever they are in the body; or a security field that can disable electronics, even a listening device hiding in a prosthetic toe, without knowing where it is.

The figure shown demonstrates secure communication with nonlinear time-reversal of two different UMD images using electromagnetic waves (signals) each sent through a complicated wave scattering environment (brown box in the middle). The black boxes represent time-reversed signals that are not reconstructed after being scattered.

While these applications remain only dreams, researchers at the University of Maryland have come up with a sci-fi seeming technology that one day could make them real. Using a time-reversal technique, the team has discovered how to transmit power, sound or images to a nonlinear object without knowing the object's exact location and without affecting objects around it. 

"That's the magic of time reversal," says Steven Anlage, a university physics professor involved in the project. "When you reverse the waveform's direction in space and time, it follows the same path it took coming out and finds its way exactly back to the source."

The time-reversal process is less like living the last five minutes over and more like playing a record backwards, explains Matthew Frazier, a postdoctoral research fellow in the university's physics department. When a signal travels through the air, its waveforms scatter before an antenna picks it up. Recording the received signal and transmitting it backwards reverses the scatter and sends it back as a focused beam in space and time.

"If you go toward a secure building, they won't let you take cell phones," Frazier says, "So instead of checking everyone, they could detect the cell phone and send a lot of energy to to jam it." What differentiates this research from other time-reversal projects, such as underwater communication, is that it focuses on nonlinear objects such as a cellphone, diode or even a rusty piece of metal. When the altered, nonlinear frequency of nonlinear objects is recorded, time-reversed and retransmitted, it creates a private communication channel, because other objects cannot understand the signal.

No comment yet.
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!

20,000+ FREE Online Science and Technology Lectures from Top Universities

20,000+ FREE Online Science and Technology Lectures from Top Universities | Amazing Science |



Toll Free:1-800-605-8422  FREE
Regular Line:1-858-345-4817



NOTE: To subscribe to the RSS feed of Amazing Science, copy into the URL field of your browser and click "subscribe".


This newsletter is aggregated from over 1450 news sources:


All my Tweets and Scoop.It! posts sorted and searchable:



You can search through all the articles semantically on my

archived twitter feed


NOTE: All articles in the amazing-science newsletter can also be sorted by topic. To do so, click the FIND buntton (symbolized by the FUNNEL on the top right of the screen)  and display all the relevant postings SORTED by TOPICS.


You can also type your own query:


e.g., you are looking for articles involving "dna" as a keyword



CLICK on the little

FUNNEL symbol at the





• 3D-printing • aging • AI • anthropology • art • astronomy • bigdata • bioinformatics • biology • biotech • chemistry • computers • cosmology • education • environment • evolution • future • genetics • genomics • geosciencesgreen-energy • history • language • mapmaterial-science • math • med • medicine • microscopymost-reads • nanotech • neuroscience • paleontology • photography • photonics • physics • postings • robotics • science • technology • video 

Saberes Sin Fronteras OVS's curator insight, November 30, 2014 5:33 PM

Acceso gratuito a documentos de las mejores universidades del mundo

♥ princess leia ♥'s curator insight, December 28, 2014 11:58 AM

WoW  .. Expand  your mind!! It has room to grow!!! 

Scooped by Dr. Stefan Gruenwald!

The Resilience of Life to Astrophysical Events

The Resilience of Life to Astrophysical Events | Amazing Science |

Much attention has been given in the literature to the effects of astrophysical events on human and land-based life. However, little has been discussed on the resilience of life itself. A group of scientists now speculates about the statistics of events that completely sterilize an Earth-like planet with planet radii in the range 0.5–1.5R and temperatures of 300 K, eradicating all forms of life. They consider the relative likelihood of complete global sterilization events from three astrophysical sources – supernovae, gamma-ray bursts, large asteroid impacts, and passing-by stars. To assess such probabilities the researchers consider what cataclysmic event could lead to the annihilation of not just human life, but also extremophiles, through the boiling of all water in Earth’s oceans. Surprisingly, they find that although human life is somewhat fragile to nearby events, the resilience of Ecdysozoa such as Milnesium tardigradum renders global sterilization an unlikely event.

No comment yet.
Scooped by Dr. Stefan Gruenwald!

Extended Periodic Table

Extended Periodic Table | Amazing Science |

An extended periodic table theorizes about elements beyond oganesson (beyond period 7, or row 7). Currently seven periods in the periodic table of chemical elements are known and proven, culminating with atomic number 118, which completes the seventh row. If further elements with higher atomic numbers than this are discovered, they will be placed in additional periods, laid out (as with the existing periods) to illustrate periodically recurring trends in the properties of the elements concerned. Any additional periods are expected to contain a larger number of elements than the seventh period, as they are calculated to have an additional so-called g-block, containing at least 18 elements with partially filled g-orbitals in each period.


An eight-period table containing this block was suggested by Glenn T. Seaborg in 1969.[1][2] IUPAC defines an element to exist if its lifetime is longer than 10−14 seconds, which is the time it takes for the nucleus to form an electron cloud.[3] No elements in this region have been synthesized or discovered in nature.[4] The first element of the g-block may have atomic number 121, and thus would have the systematic name unbiunium. Elements in this region are likely to be highly unstable with respect to radioactive decay, and have extremely short half lives, although element 126 is hypothesized to be within an island of stability that is resistant to fission but not to alpha decay. It is not clear how many elements beyond the expected island of stability are physically possible, whether period 8 is complete, or if there is a period 9.


According to the orbital approximation in quantum mechanical descriptions of atomic structure, the g-block would correspond to elements with partially filled g-orbitals, but spin-orbit coupling effects reduce the validity of the orbital approximation substantially for elements of high atomic number. While Seaborg's version of the extended period had the heavier elements following the pattern set by lighter elements, as it did not take into account relativistic effects; models that take relativistic effects into account do not. Pekka Pyykkö and Burkhard Fricke used computer modeling to calculate the positions of elements up to Z = 172, and found that several were displaced from the Madelung rule.[5][6]


Richard Feynman noted[7] that a simplistic interpretation of the relativistic Dirac equation runs into problems with electron orbitals at Z > 1/α ≈ 137 as described in the sections below, suggesting that neutral atoms cannot exist beyond element 137, and that a periodic table of elements based on electron orbitals therefore breaks down at this point. On the other hand, a more rigorous analysis calculates the limit to be Z ≈ 173.


More on Periodic Tables

No comment yet.
Scooped by Dr. Stefan Gruenwald!

Praying Mantises Hunt Down Birds Worldwide

Praying Mantises Hunt Down Birds Worldwide | Amazing Science |
A study by zoologists from Switzerland and the US shows: praying mantises all over the globe also include birds in their diet. The Wilson Journal of Ornithology has just published the results.


Praying mantises are carnivorous insects with powerful raptorial front legs that usually depend on arthropods such as insects or spiders as their primary prey. Rather infrequently, they have also been witnessed eating small vertebrates such as frogs, lizards, salamanders or snakes. A new study by the zoologists Martin Nyffeler (University of Basel), Mike Maxwell (National University, La Jolla, California), and James Van Remsen (Louisiana State University) now shows that praying mantises all over the world also kill and eat small birds.


The researchers gathered and documented numerous examples of bird-eating mantises. In a systematic review, they were able to show that praying mantises from twelve species and nine genera have been observed preying on small birds in the wild. This remarkable feeding behavior has been documented in 13 different countries, on all continents except Antarctica. There is also great diversity in the victims: birds from 24 different species and 14 families were found to be the prey of mantises. "The fact that eating of birds is so widespread in praying mantises, both taxonomically as well as geographically speaking, is a spectacular discovery," comments Martin Nyffeler from the University of Basel and lead author of the study.


The researchers assembled 147 documented cases of this feeding behavior from all over the world. However, more than 70 percent were reported in the US, where praying mantises often capture birds at hummingbird feeders or plants pollinated by hummingbirds in house gardens. Consequently, hummingbirds make up the vast majority of birds killed by praying mantises, with the Ruby-throated Hummingbird (Archilochus colubris) being a particularly frequent victim.


Decades ago, several alien species of large mantises (e.g., Mantis religiosa and Tenodera sinensis) were released across North America as biological pest control agents. These imported species now constitute a new potential threat to hummingbirds and small passerine birds. However, there are also large native mantises that prey on birds. "Our study shows the threat mantises pose to some bird populations. Thus, great caution is advised when releasing mantises for pest control," says Nyffeler.

No comment yet.
Scooped by Dr. Stefan Gruenwald!

Surprise methanol detection in Enceladus’s plumes

Surprise methanol detection in Enceladus’s plumes | Amazing Science |

A serendipitous detection of the organic molecule methanol around an intriguing moon of Saturn suggests that material spewed from Enceladus undertakes a complex chemical journey once vented into space. This is the first time that a molecule from Enceladus has been detected with a ground-based telescope. Dr Emily Drabek-Maunder, of Cardiff University, will present the results on Tuesday 4th July at the National Astronomy Meeting at the University of Hull.


Enceladus's plumes are thought to originate in water escaping from a subsurface ocean through cracks in the moon's icy surface. Eventually these plumes feed into Saturn's second-outermost ring, the E-ring. Drabek-Maunder says: "Recent discoveries that icy moons in our outer Solar System could host oceans of liquid water and ingredients for life have sparked exciting possibilities for their habitability. But in this case, our findings suggest that that methanol is being created by further chemical reactions once the plume is ejected into space, making it unlikely it is an indication for life on Enceladus."


Past studies of Enceladus have involved the NASA/ESA Cassini spacecraft, which has detected molecules like methanol by directly flying into the plumes. Recent work has found similar amounts of methanol in Earth's oceans and Enceladus's plumes.


In this study, Dr Jane Greaves of Cardiff University and Dr Helen Fraser of the Open University detected the bright methanol signature using the IRAM 30-metre radio telescope in the Spanish Sierra Nevada. "This observation was very surprising since it was not the main molecule we were originally looking for in Enceladus's plumes," says Greaves.


The team suggests the unexpectedly large quantity of methanol may have two possible origins: either a cloud of gas expelled from Enceladus has been trapped by Saturn's magnetic field, or gas has spread further out into Saturn's E-ring. In either case, the methanol has been greatly enhanced compared to detections in the plumes. Team member Dr Dave Clements of Imperial College, points out: "Observations aren't always straightforward. To interpret our results, we needed the wealth of information Cassini gave us about Enceladus's environment. This study suggests a degree of caution needs to be taken when reporting on the presence of molecules that could be interpreted as evidence for life."


Cassini will end its journey later this year, leaving remote observations through ground- and space-based telescopes as the only possibility for exploring Saturn and its moons -- at least for now. Drabek-Maunder adds: "This finding shows that detections of molecules at Enceladus are possible using ground-based facilities. However, to understand the complex chemistry in these subsurface oceans, we will need further direct observations by future spacecraft flying through Enceladus's plumes."

No comment yet.
Scooped by Dr. Stefan Gruenwald!

Neutrons detect elusive Higgs amplitude mode in quantum material

Neutrons detect elusive Higgs amplitude mode in quantum material | Amazing Science |

A team led by the Department of Energy's Oak Ridge National Laboratory has used sophisticated neutron scattering techniques to detect an elusive quantum state known as the Higgs amplitude mode in a two-dimensional material.


The Higgs amplitude mode is a condensed matter cousin of the Higgs boson, the storied quantum particle theorized in the 1960s and proven experimentally in 2012. It is one of a number of quirky, collective modes of matter found in materials at the quantum level. By studying these modes, condensed matter researchers have recently uncovered new quantum states known as quasiparticles, including the Higgs mode.


These studies provide unique opportunities to explore quantum physics and apply its exotic effects in advanced technologies such as spin-based electronics, or spintronics, and quantum computing.


"To excite a material's quantum quasiparticles in a way that allows us to observe the Higgs amplitude mode is quite challenging," said Tao Hong, an instrument scientist with ORNL's Quantum Condensed Matter Division. Although the Higgs amplitude mode has been observed in various systems, "the Higgs mode would often become unstable and decay, shortening the opportunity to characterize it before losing sight of it," Hong said.


The ORNL-led team offered an alternative method. The researchers selected a crystal composed of copper bromide, because the copper ion is ideal for studying exotic quantum effects, Hong explained. They began the delicate task of "freezing" the material's agitating quantum-level particles by lowering its temperature to 1.4 Kelvin, which is about minus 457.15 degrees Fahrenheit.


The researchers fine-tuned the experiment until the particles reached the phase located near the desired quantum critical point -- the sweet spot where collective quantum effects spread across wide distances in the material, which creates the best conditions to observe a Higgs amplitude mode without decay.


With neutron scattering performed at ORNL's High Flux Isotope Reactor, the research team observed the Higgs mode with an infinite lifetime: no decay. "There's an ongoing debate in physics about the stability of these very delicate Higgs modes," said Alan Tennant, chief scientist of ORNL's Neutron Sciences Directorate. "This experiment is really hard to do, especially in a two-dimensional system. And, yet, here's a clear observation, and it's stabilized."

No comment yet.
Scooped by Dr. Stefan Gruenwald!

Milky Way could harbor 100 billion brown dwarfs

Milky Way could harbor 100 billion brown dwarfs | Amazing Science |

Our galaxy could have 100 billion brown dwarfs or more, according to work by an international team of astronomers, led by Koraljka Muzic from the University of Lisbon and Aleks Scholz from the University of St Andrews. On Thursday 6 July Scholz will present their survey of dense star clusters, where brown dwarfs are abundant, at the National Astronomy Meeting at the University of Hull.


Brown dwarfs are objects intermediate in mass between stars and planets, with masses too low to sustain stable hydrogen fusion in their core, the hallmark of stars like the Sun. After the initial discovery of brown dwarfs in 1995, scientists quickly realised that they are a natural by-product of processes that primarily lead to the formation of stars and planets.


All of the thousands of brown dwarfs found so far are relatively close to the Sun, the overwhelming majority within 1500 light years, simply because these objects are faint and therefore difficult to observe. Most of those detected are located in nearby star forming regions, which are all fairly small and have a low density of stars.


In 2006 the team began a new search for brown dwarfs, observing five nearby star forming regions. The Substellar Objects in Nearby Young Clusters (SONYC) survey included the star cluster NGC 1333, 1000 light years away in the constellation of Perseus. That object had about half as many brown dwarfs as stars, a higher proportion than seen before.


To establish whether NGC 1333 was unusual, in 2016 the team turned to another more distant star cluster,RCW 38, in the constellation of Vela. This has a high density of more massive stars, and very different conditions to other clusters.


RCW 38 is 5500 light years away, meaning that the brown dwarfs are both faint, and hard to pick out next to the brighter stars. To get a clear image, Scholz, Muzic and their collaborators used the NACO adaptive optics camera on the European Southern Observatory's Very Large Telescope, observing the cluster for a total of almost 3 hours, and combining this with earlier work.


The researchers found just as many brown dwarfs in RCW 38 – about half as many as there are stars- and realised that the environment where the stars form, whether stars are more or less massive, tightly packed or less crowded, has only a small effect on how brown dwarfs form.


Scholz says: "We've found a lot of brown dwarfs in these clusters. And whatever the cluster type, the brown dwarfs are really common. Brown dwarfs form alongside stars in clusters, so our work suggests there are a huge number of brown dwarfs out there."


From the SONYC survey, Scholz and team leader Koraljka Muzic, estimate that our galaxy, the Milky Way, has a minimum of between 25 and 100 billion brown dwarfs. There are many smaller, fainter brown dwarfs too, so this could be a significant underestimate, and the survey confirms these dim objects are ubiquitous.

No comment yet.
Rescooped by Dr. Stefan Gruenwald from Next-generation sequencing (NGS)!

Germans provide big boost for sequencing often ignored organisms

Germans provide big boost for sequencing often ignored organisms | Amazing Science |

One of Germany’s states has provided a big boost for biologists who want to decipher the genomes of organisms that don’t get much attention. This week, the state of Hessen, which includes Frankfurt, awarded its local institutions €17.6 million, the first half of a 7-year grant for sequencing plants, animals, and fungi. The award includes funding for the high-quality sequencing of about 700 organisms, and for the partial sequencing or resequencing of thousands more.


“German scientists are going to take a big step forward in understanding the genomic basis of life,” says W. John Kress, a researcher at the Smithsonian Institution in Washington, D.C., who helped conceive the Earth BioGenome Project, an ambitious effort to sequence much of life on Earth.


The grant will create the new LOEWE-Zentrum für Translationale Biodiversitätsgenomik (LOEWE-TBG)—loosely translated as the Translational Biodiversity Genomics Excellence Center. It is the brainchild of Axel Janke, Markus Pfenninger, and Steffen Pauls, genomics researchers at the Senckenberg Research Institute and Natural History Museum in Frankfurt. The center, scheduled to open in January 2018, will involve the museum, Goethe University Frankfurt, the Justus Liebig University Giessen, and the Fraunhofer Institute for Molecular Biology and Applied Ecology.  

Via Integrated DNA Technologies
No comment yet.
Scooped by Dr. Stefan Gruenwald!

From dry to wet: Rainfall might abruptly increase in Africa’s Sahel zone

From dry to wet: Rainfall might abruptly increase in Africa’s Sahel zone | Amazing Science |
Climate change could turn one of Africa's driest regions into a very wet one by suddenly switching on a Monsoon circulation. For the first time, scientists find evidence in computer simulations for a possible abrupt change to heavy seasonal rainfall in the Sahel, a region that so far has been characterized by extreme dryness. They detect a self-amplifying mechanism which might kick-in beyond 1.5-2 degrees Celsius of global warming – which happens to be the limit for global temperature rise set in the Paris Climate Agreement. Although crossing this new tipping point is potentially beneficial, the change could be so big, it would be a major adaptation challenge for an already troubled region. Further warming might enhance water availability for farming and grazing.

“More rain in a dry region can be good news,” says lead-author Jacob Schewe from the Potsdam Institute for Climate Impact Research (PIK). “Climate change due to greenhouse gases from burning fossil fuels really has the power to shake things up. It is driving risks for crop yields in many regions and generally increases dangerous weather extremes around the globe, yet in the dry Sahel there seems to be a chance that further warming might indeed enhance water availability for farming and grazing.”


Co-author Anders Levermann from PIK and Columbia University’s Lamont-Doherty Earth Observatory adds: “We don’t know what the impacts on the ground will be, this is beyond the scope of our study; but imagine the chance of a greening Sahel. Still, the sheer size of the possible change is mindboggling – this is one of the very few elements in the Earth system that we might witness tipping soon. Once the temperature approaches the threshold, the rainfall regime could shift within just a few years.”

No comment yet.
Scooped by Dr. Stefan Gruenwald!

Scientists recreate an extinct virus, a relative of smallpox

Scientists recreate an extinct virus, a relative of smallpox | Amazing Science |

Scientists at the University of Alberta have put together – from scratch – a relative of the smallpox virus, which serves as a reminder that the threat of deadly viruses created by humans is more than just theoretical.

The smallpox virus, which triggered brutal disease for centuries, was declared eradicated in 1980 after a successful global effort to end its reign of terror. But some scientists fear that it could be revived through what’s known as synthetic biology — the ability to make a virus by putting together by the recipe outlined in its genetic code.

The horsepox virus the Canadian team created is not a threat to human health — or even the health of horses — should it ever escape from a lab. And it’s not the first virus created by putting pieces of DNA together in the right sequence.

Still, the news that a team headed by David Evans, a professor of medical microbiology and immunology, had accomplished this feat — at a relatively low cost of about $100,000 plus labor — was a bit of a wakeup call. The news was first reported Thursday in Science Magazine.

“This is an example of what modern technologies can do,” noted Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases.

The warnings about the implications of synthetic biology have echoed since Eckard Wimmer of the State University of New York at Stony Brook reported in 2002 that he and his team had made a poliovirus from scratch.

Polioviruses are small in comparison with poxviruses, and a far less complex task. But scientists watching this field feared it was only a matter of time before the obstacles to creating other viruses were surmounted.

No comment yet.
Scooped by Dr. Stefan Gruenwald!

Transfer of atomic mass with a photon solves the momentum paradox of light

Transfer of atomic mass with a photon solves the momentum paradox of light | Amazing Science |

In a recent publication, Aalto University researchers show that in a transparent medium each photon is accompanied by an atomic mass density wave. The optical force of the photon sets the medium atoms in motion and makes them carry 92% of the total momentum of light, in the case of silicon.

The novel discovery solves the centennial momentum paradox of light. In the literature, there has existed two different values for the momentum of light in the transparent medium. Typically, these values differ by a factor of ten and this discrepancy is known as the momentum paradox of light. The difference between the momentum values is caused by neglecting the momentum of atoms moving with the light pulse.

To solve the momentum paradox the authors prove that the special theory of relativity requires an extra atomic density to travel with the photon. In related classical computer simulations, they use optical force field and Newton´s second law to show that a wave of increased atomic mass density is propagating through the medium with the light pulse.

The mass transfer leads to splitting of the total momentum of light into two components. The fields’ share of momentum is equal to the Abraham momentum while the total momentum, which includes also the momentum of atoms driven forward by the optical force, is equal to the Minkowski momentum.

”Since our work is theoretical and computational it must be still verified experimentally, before it can become a standard model of light in a transparent medium. Measuring the total momentum of a light pulse is not enough but one also has to measure the transferred atomic mass. This should be feasible using present interferometric and microscopic techniques and common photonic materials”, researcher Mikko Partanen says.


The researchers are working on potential optomechanical applications enabled by the optical shock wave of atoms predicted by the new theory. However, the theory applies not only to transparent liquids and solids but also to dilute interstellar gas. Using a simple kinematic consideration it can be shown that the energy loss caused by the mass transfer effect becomes for dilute interstellar gas proportional to the photon energy and distance travelled by light.

“This prompts for further simulations with realistic parameters for interstellar gas density, plasma properties and temperature. Presently the Hubble’s law is explained by Doppler shift being larger from distant stars. This effectively supports the hypothesis of expanding universe. In the mass polariton theory of light this hypothesis is not needed since redshift becomes automatically proportional to the distance from the star to the observer”, explains Professor Jukka Tulkki. Thus, an expanding universe scenario is no longer needed.


Research article: Mikko Partanen, Teppo Häyrynen, Jani Oksanen, and Jukka Tulkki. Photon mass drag and the momentum of light in a medium. Physical Review A 95. DOI: 10.1103/PhysRevA.95.063850

No comment yet.
Rescooped by Dr. Stefan Gruenwald from Limitless learning Universe!

Is the Yellowstone supervolcano about to blow? Global food supply would collapse for two years, causing a mass die-off of humans

Is the Yellowstone supervolcano about to blow? Global food supply would collapse for two years, causing a mass die-off of humans | Amazing Science |

One of the most beautiful places in the United States that every American should visit at least once in their life is Yellowstone National Park, a vast region of wildlife and geographical wonders that stretches through parts of Wyoming, Montana and Idaho.


Between the massive herds of bison that can be seen grazing out in the valleys, and the incredible geysers and hot springs that have been around for thousands of years, Yellowstone really does deserve to be one of the most popular tourist locations in the country. But despite its beauty, there is an ancient monster in Yellowstone that has remained dormant for 70,000 years… and it just might be getting ready to wake up.


Recently, there have been over 400 earthquakes recorded in Yellowstone, the latest being a magnitude 3 earthquake that struck on Monday, June 19. Just four days earlier, Yellowstone was hit with an even larger, magnitude 4.5 earthquake. “The epicenter of the shock was located in Yellowstone National Park, eight miles north-northeast of the town of West Yellowstone, Montana,” said scientists from the University of Utah in a statement. “The earthquake was reportedly felt in the towns of West Yellowstone and Gardiner, Montana, in Yellowstone National Park, and elsewhere in the surrounding region.” (Related: Scientists have been underestimating the threat of earthquakes.)


The earthquake that took place on June 15 was the largest to have hit Yellowstone since March 30, 2014, when the area of the Norris Geyser Basin experienced a magnitude 4.8 earthquake. This pattern of rather severe earthquakes in Yellowstone has led many to believe that avolcanic eruption is due to take place sometime in the near future, even though it is currently impossible to know when exactly that will happen. According to experts at the U.S. Geological Survey (USGS), the chances that the Yellowstone supervolcano will erupt is still significantly low. A USGS spokesperson recently told Newsweek that volcanic activity seems to be “slowly winding down” and that “no other geological activity has been detected.”


As of right now, the chances that Yellowstone’s supervolcano will erupt within the next year is one in 730,000.

But even though the chances of a massive volcanic eruption in Yellowstone are slim, what would happen if it did? Three years ago, the USGS published a report that modeled what would happen if Yellowstone’s supervolcano erupted. According to their findings, such an eruption would cover the majority of North America with a blanket of ash, with some areas of the country even being buried a meter deep.

Via CineversityTV
No comment yet.
Rescooped by Dr. Stefan Gruenwald from DNA and RNA research!

Researchers Identify New Mechanism for Keeping DNA Protein in Line 

Researchers Identify New Mechanism for Keeping DNA Protein in Line  | Amazing Science |

Electrostatic forces known as phosphate steering help guide the actions of an enzyme called FEN1 that is critical in DNA replication and repair, finds a new study led by Berkeley Lab researchers. The findings help explain how FEN1 distinguishes which strands of DNA to target, revealing key details about a vital process in healthy cells as well as providing new directions for cancer treatment research.


The actions of a protein used for DNA replication and repair are guided by electrostatic forces known as phosphate steering, a finding that not only reveals key details about a vital process in healthy cells, but provides new directions for cancer treatment research.


Crystal structure of FEN1 protein bound to its target DNA. When shown with the protein surface, the gateway through which a single-stranded DNA flap can enter is visible. Without the surface, the metal catalyst, shown as a gray ball, can be seen. (Credit: Susan Tsutakawa/Berkeley Lab).


The findings,published this week in the journal Nature Communications, focus on an enzyme called flap endonuclease 1, or FEN1. Using a combination of crystallographic, biochemical, and genetic analyses, researchers at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) showed that phosphate steering kept FEN1 in line and working properly.

“FEN1, like many DNA replication and repair proteins, have paradoxical roles relevant to cancer,” said study lead author Susan Tsutakawa, a biochemist at Berkeley Lab’s Molecular Biophysics and Integrated Bioimaging Division. “A mistake by FEN1 could damage the DNA, leading to the development of cancer. On the other side, many cancers need replication and repair proteins to survive and to repair DNA damaged from cancer treatments. New evidence shows that phosphate steering helps ensure that FEN1 behaves as it should to prevent genome instability.”


During the process of replication, double-stranded DNA unzips to expose the nucleotides along its two separate strands. In that process, flaps of single-stranded DNA are created. The job of FEN1 is to remove those flaps by positioning metal catalysts so that they can break down the phosphodiester bonds that make up the backbone of nucleic acid strands. This cleavage action occurs in the duplex DNA near the junction with the single-stranded flap.

Via Integrated DNA Technologies
No comment yet.
Scooped by Dr. Stefan Gruenwald!

Projecting a visual image directly into the brain, bypassing the eyes

Projecting a visual image directly into the brain, bypassing the eyes | Amazing Science |
Imagine replacing a damaged eye with a window directly into the brain — one that communicates with the visual part of the cerebral cortex by reading from a million individual neurons and simultaneously stimulating 1,000 of them with single-cell accuracy, allowing someone to see again.

That’s the goal of a $21.6 million DARPA award to the University of California, Berkeley (UC Berkeley), one of six organizations funded by DARPA’s Neural Engineering System Design program announced this week to develop implantable, biocompatible neural interfaces that can compensate for visual or hearing deficits.*

The UCB researchers ultimately hope to build a device for use in humans. But the researchers’ goal during the four-year funding period is more modest: to create a prototype to read and write to the brains of model organisms — allowing for neural activity and behavior to be monitored and controlled simultaneously. These organisms include zebrafish larvae, which are transparent, and mice, via a transparent window in the skull.


“The ability to talk to the brain has the incredible potential to help compensate for neurological damage caused by degenerative diseases or injury,” said project leader Ehud Isacoff, a UC Berkeley professor of molecular and cell biology and director of the Helen Wills Neuroscience Institute. “By encoding perceptions into the human cortex, you could allow the blind to see or the paralyzed to feel touch.”


To communicate with the brain, the team will first insert a gene into neurons that makes fluorescent proteins, which flash when a cell fires an action potential. This will be accompanied by a second gene that makes a light-activated “optogenetic” protein, which stimulates neurons in response to a pulse of light.


To read, the team is developing a miniaturized “light field microscope.” Mounted on a small window in the skull, it peers through the surface of the brain to visualize up to a million neurons at a time at different depths and monitor their activity. This microscope is based on the revolutionary “light field camera,” which captures light through an array of lenses and reconstructs images computationally in any focus.


The combined read-write function will eventually be used to directly encode perceptions into the human cortex — inputting a visual scene to enable a blind person to see. The goal is to eventually enable physicians to monitor and activate thousands to millions of individual human neurons using light.


Isacoff, who specializes in using optogenetics to study the brain’s architecture, can already successfully read from thousands of neurons in the brain of a larval zebrafish, using a large microscope that peers through the transparent skin of an immobilized fish, and simultaneously write to a similar number.


The team will also develop computational methods that identify the brain activity patterns associated with different sensory experiences, hoping to learn the rules well enough to generate “synthetic percepts” — meaning visual images representing things being touched — by a person with a missing hand, for example. This technology has a lot of potential in the future.

Donald Schwartz's curator insight, July 18, 7:08 PM

Science fiction no more. Now this is what I call visualization.

Scooped by Dr. Stefan Gruenwald!

Why Do Corals Glow in the Dark? A new study suggests they use fluorescence for photosynthesis

Why Do Corals Glow in the Dark? A new study suggests they use fluorescence for photosynthesis | Amazing Science |

It’s one of the ocean’s most beautiful and striking mysteries: Why do corals fluoresce? In shallow waters, they glow a brilliant pink and purple. In deeper waters, corals turn red and green against a dim blue background. The view is most unforgettable at night with a flashlight and mask filter, when the fluorescent corals provide a “psychedelic adventure.”


Jörg Wiedenmann, a coral reef scientist at University of Southampton, had previously found that the pink and purple fluorescence in shallow waters act as a kind of sunscreen. The fluorescent pigments absorb damaging wavelengths of light and emit it as pink or purple light, protecting the single-celled organisms called zooxanthellae that live symbiotically inside coral. Zooxanthellae are photosynthetic and they provide the coral with food in exchange for shelter.


This “sunscreen” effect was interesting, but it didn’t explain why corals fluoresce in deeper water, where light was not intense enough to harm zooxanthellae. In fact, in those dim blue waters, the problem was more likely too little light. Wiedenmann and his colleagues now have a new study, in which they present a novel function for deep water fluorescence. And again, it has to do with the zooxanthellae: Coral may be converting blue light into orange-red light that penetrates deeper into the coral tissue, where photosynthetic zooxanthellae live. Fluorescence, by definition, is the absorption of light in one color and the emission in another.

No comment yet.
Scooped by Dr. Stefan Gruenwald!

Switchable DNA mini-machines store information: They change shape in a cascade

Switchable DNA mini-machines store information: They change shape in a cascade | Amazing Science |
Biomedical engineers have built simple machines out of DNA, consisting of arrays whose units switch reversibly between two different shapes. The arrays' inventors say they could be harnessed to make nanotech sensors or amplifiers. Potentially, they could be combined to form logic gates, the parts of a molecular computer.


The arrays' inventors say they could be harnessed to make nanotech sensors or amplifiers. Potentially, they could be combined to form logic gates, the parts of a molecular computer.

The arrays' properties are scheduled for publication online by Science. The DNA machines can relay discrete bits of information through space or amplify a signal, says senior author Yonggang Ke, PhD, an assistant professor in the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory.


"In the field of DNA-based computing, the DNA contains the information, but the molecules are floating around in solution," Ke says. "What's new here is that we are linking the parts together in a physical machine."


Similarly, several laboratories have already made nanotech machines such as tweezers and walkers out of DNA. Ke says his team's work with DNA arrays sheds light on how to build structures with more complex, dynamic behaviors.


The arrays' structures look like accordion-style retractable security gates. Extending or contracting one unit pushes nearby units to change shape as well, working like a domino cascade whose tiles are connected. The arrays' units get their stability from the energy gained when DNA double helices stack up. To be stable, the units' four segments can align as pairs side by side in two different orientations. By leaving out one strand of the DNA at the edge of an array, the engineers create an external trigger. When that strand is added, it squeezes the edge unit into changing shape.


To visualize the DNA arrays, the engineers used atomic force microscopy. They built rectangular 11x4 and 11x7 arrays, added trigger strands and could observe the cascade propagate from the corner unit to the rest of the array. The arrays' cascades can be stopped or resumed at selected locations by designing break points into the arrays. The units' shape conversions are modulated by temperature or chemical denaturants.


For reference, the rectangular arrays are around 50 nanometers wide and a few hundred nanometers long -- slightly smaller than a HIV or influenza virion.

No comment yet.
Scooped by Dr. Stefan Gruenwald!

Solar paint offers endless energy from water vapor: Compound catalyses splitting of water molecules

Solar paint offers endless energy from water vapor: Compound catalyses splitting of water molecules | Amazing Science |
Researchers have developed a compound that draws moisture from the air and splits it into oxygen and hydrogen. The hydrogen can be captured as a clean fuel source.


The paint contains a newly developed compound that acts like silica gel, which is used in sachets to absorb moisture and keep food, medicines and electronics fresh and dry. But unlike silica gel, the new material, synthetic molybdenum-sulphide, also acts as a semi-conductor and catalyses the splitting of water molecules into hydrogen and oxygen.


Lead researcher Dr Torben Daeneke, from RMIT University in Melbourne, Australia, said: "We found that mixing the compound with titanium oxide particles leads to a sunlight-absorbing paint that produces hydrogen fuel from solar energy and moist air.


"Titanium oxide is the white pigment that is already commonly used in wall paint, meaning that the simple addition of the new material can convert a brick wall into energy harvesting and fuel production real estate. "Our new development has a big range of advantages," he said. "There's no need for clean or filtered water to feed the system. Any place that has water vapor in the air, even remote areas far from water, can produce fuel." Watch the video: colleague, Distinguished Professor Kourosh Kalantar-zadeh, said hydrogen was the cleanest source of energy and could be used in fuel cells as well as conventional combustion engines as an alternative to fossil fuels. "This system can also be used in very dry but hot climates near oceans. The sea water is evaporated by the hot sunlight and the vapor can then be absorbed to produce fuel.


"This is an extraordinary concept -- making fuel from the sun and water vapor in the air."

No comment yet.
Scooped by Dr. Stefan Gruenwald!

Astronomers Detect Orbital Motion in Pair of Supermassive Black Holes

Astronomers Detect Orbital Motion in Pair of Supermassive Black Holes | Amazing Science |
VLBA images detect orbital motion of two supermassive black holes as they circle each other at the center of a distant galaxy.


Using the supersharp radio "vision" of the National Science Foundation's Very Long Baseline Array (VLBA), astronomers have made the first detection of orbital motion in a pair of supermassive black holes in a galaxy some 750 million light-years from Earth. The two black holes, with a combined mass 15 billion times that of the Sun, are likely separated by only about 24 light-years, extremely close for such a system.


"This is the first pair of black holes to be seen as separate objects that are moving with respect to each other, and thus makes this the first black-hole 'visual binary,'" said Greg Taylor, of the University of New Mexico (UNM). Supermassive black holes, with millions or billions of times the mass of the Sun, reside at the cores of most galaxies. The presence of two such monsters at the center of a single galaxy means that the galaxy merged with another some time in the past. In such cases, the two black holes themselves may eventually merge in an event that would produce gravitational waves that ripple across the universe.


"We believe that the two supermassive black holes in this galaxy will merge," said Karishma Bansal, a graduate student at UNM, adding that the merger will come at least millions of years in the future. The galaxy, an elliptical galaxy called 0402+379, after its location in the sky, was first observed in 1995. It was studied in 2003 and 2005 with the VLBA. Based on finding two cores in the galaxy, instead of one, Taylor and his collaborators concluded in 2006 that it contained a pair of supermassive black holes.


The latest research, which Taylor and his colleagues are reporting in the Astrophysical Journal, incorporates new VLBA observations from 2009 and 2015, along with re-analysis of the earlier VLBA data. This work revealed motion of the two cores, confirming that the two black holes are orbiting each other. The scientists' initial calculations indicate that they complete a single orbit in about 30,000 years.

No comment yet.
Scooped by Dr. Stefan Gruenwald!

The multi-colored photons that might change quantum information science

The multi-colored photons that might change quantum information science | Amazing Science |

With leading corporations now investing in highly expensive and complex infrastructures to unleash the power of quantum technologies, INRS researchers have achieved a breakthrough in a light-weight photonic system created using on-chip devices and off-the-shelf telecommunications components. In their paper published in Nature, the team demonstrates that photons can become an accessible and powerful quantum resource when generated in the form of color-entangled quDits.


The system uses a small and cost-effective photonic chip fabricated through processes similar to those used for integrated electronics. With an on-chip micro-ring resonator excited by a laser, photons are emitted in pairs that share a complex quantum state. The photons are constructed in a state featuring a number of superimposed frequency components: The photons have several colors simultaneously, and the colors of each photon in a pair are linked (entangled), regardless of their separation distance.


With each frequency -- or color -- representing a dimension, the photons are generated on-chip as a high-dimensional quantum state (quDit). Thus far, quantum information science has largely focused on the exploitation of qubits, based on two-dimensional systems where two states are superimposed (for example, 0 AND 1 at the same time, in contrast to classical bits, which are 0 OR 1 at any time). Working in the frequency domain allows the superposition of many more states (for example, a high-dimensional photon can be red AND yellow AND green AND blue, although the photons used here were infrared for telecommunications compatibility), enhancing the amount of information in a single photon.


To date, Professor Roberto Morandotti, who leads the INRS research team, confirms the realization of a quantum system with at least one hundred dimensions using this approach, and the technology developed is readily extendable to create two-quDit systems with more than 9,000 dimensions (corresponding to 12 qubits and beyond, comparable to the state of the art in significantly more expensive/complex platforms). 


The use of the frequency domain for such quantum states enables their easy transmission and manipulation in optical fibre systems. "By merging the fields of quantum optics and ultrafast optical processing, we have shown that high-dimensional manipulation of these states is indeed possible using standard telecommunications elements like modulators and frequency filters," stresses telecommunications system expert Professor José Azaña, co-supervisor of the conducted research.

No comment yet.
Scooped by Dr. Stefan Gruenwald!

Genes change locations: Growing cells remix their genes

Genes change locations: Growing cells remix their genes | Amazing Science |

Moving genes about could help cells to respond to change according to scientists at the Babraham Institute in Cambridge, UK and the Weizmann Institute, Israel. Changing the location of a gene within a cell alters its activity. Like mixing music, different locations can make a gene ‘louder’ or ‘quieter’, with louder genes contributing more actively to the life of a cell.

Contrary to expectations, this latest study reveals that each gene doesn’t have an ideal location in the cell nucleus. Instead, genes are always on the move. Published in the journal Nature, researchers examined the organisation of genes in stem cells from mice. They revealed that these cells continually remix their genes, changing their positions as they progress though different stages. This work, which has also inspired a musical collaboration, suggests that moving genes about in this way could help cells to fine-tune the volume of each gene to suit the cell’s needs.

Scientists had believed that the location of genes in cells are relatively fixed with each gene having it’s rightful place. Different types of cells could organise their genes in different ways, but genes weren’t thought to move around much except when cells divide. This is the first time that gene organisation in individual cells has been studied in detail. The results provide snapshots of gene organisation, with each cell arranging genes in unique ways.

Co-first authors, Dr Takashi Nagano in the UK and Yaniv Lubling in Israel have collected and individually analysed information one-by-one from over 4000 cells for this study. Speaking about the work, Dr Nagano said: “We’ve never had access to this level of information about how genes are organised before. Being able to compare between thousands of individual cells is an extremely powerful tool and adds an important dimension to our understanding of how cells position their genes.”

No comment yet.
Scooped by Dr. Stefan Gruenwald!

Untreatable gonorrhoea on the rise worldwide

Untreatable gonorrhoea on the rise worldwide | Amazing Science |

Gonorrhoea is becoming as incurable as it was in the 1920s, before the first drugs to treat it were discovered. More than 60% of countries surveyed around the world have reported cases that resist last-resort antibiotics, according to an announcement by the World Health Organization (WHO) on 6 July, 2017. The announcement included information about a new gonorrhoea drug in development.


Since the 1930s, several classes of antibiotics have been used to kill the bacterium that causes gonorrhoea, Neisseria gonorrhoeae. Widespread use — and misuse — of these drugs, however, has led to a rise of antibiotic-resistant strains of the bacteria. “The best time to have had gonorrhoea was the eighties, since there were many drugs to treat it with,” says Ramanan Laxminarayan, director of the Center for Disease Dynamics, Economics and Policy in Washington DC. Increasingly, that's no longer the case, he says.


Health agencies in the United States, Europe and Canada have in recent years flagged drug-resistant gonorrhoea as an emerging threat. If left untreated, gonorrhoea can increase a woman’s risk of developing HIV infection, infertility or ectopic pregnancy — among other effects. When the WHO partnered with the Drugs for Neglected Diseases initiative (DNDi), a non-governmental organization in Geneva, Switzerland, in May 2016 to confront antimicrobial resistance, gonorrhoea was at the top of the list.

No comment yet.
Scooped by Dr. Stefan Gruenwald!

In a Lost Baby Tooth, Scientists Find Ancient Denisovan DNA

In a Lost Baby Tooth, Scientists Find Ancient Denisovan DNA | Amazing Science |

More than 100,000 years ago in a Siberian cave there lived a child with a loose tooth. One day her molar fell out, and fossilized over many millenniums, keeping it safe from the elements and the tooth fairy.


But she wasn’t just any child. Scientists say she belonged to a species of extinct cousins of Neanderthals and modern humans known today as the Denisovans. And in a paper published Friday in the journal Science Advances, a team of paleoanthropologists reported that she is only the fourth individual of this species ever discovered.


“We only have relatively little data from this archaic group, so having any additional individuals is something we’re very excited about,” saidViviane Slon, a doctoral candidate at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and lead author of the study.


The scant fossil record for these ancient hominins previously included only two adult molars and a finger bone. The Denisovans were only correctly identified in 2010 by a team of researchers led by Svante Paabo, who used the finger bone to sequence the species’ genome.

No comment yet.
Scooped by Dr. Stefan Gruenwald!

75 pictures of most bizarre sea creatures

75 pictures of most bizarre sea creatures | Amazing Science |

Flying squids and many more

Carlos Garcia Pando's comment, July 4, 5:38 AM
Thanks. I wonder why they say "bizarre" and "deep-sea" when most of them are pretty well-known and lovely ones, like dolphins, seals, or fishbowl creatures.
Asa Jomard's comment, July 4, 7:23 AM
There is a whole new exciting world down there for us to discover! Glad you liked it.
Scooped by Dr. Stefan Gruenwald!

New microscope can scan tumors during surgery and examine cancer biopsies in 3-D

New microscope can scan tumors during surgery and examine cancer biopsies in 3-D | Amazing Science |

When women undergo lumpectomies to remove breast cancer, doctors try to remove all the cancerous tissue while conserving as much of the healthy breast tissue as possible. But currently there’s no reliable way to determine during surgery whether the excised tissue is completely cancer-free at its margins — the proof that doctors need to be confident that they removed all of the tumor. It can take several days for pathologists using conventional methods to process and analyze the tissue.


That’s why between 20 and 40 percent of women have to undergo second, third or even fourth breast-conserving surgeries to remove cancerous cells that were missed during the initial procedure, according a recent study. 


The new light-sheet microscope — which is described in a new paper published June 26, 2017 in Nature Biomedical Engineering — offers other advantages over existing processes and microscope technologies. It conserves valuable tissue for genetic testing and diagnosis, quickly and accurately images the irregular surfaces of large clinical specimens, and allows pathologists to zoom in and “see” biopsy samples in three dimensions.


“The tools we use in pathology have changed little over the past century,” said co-author Nicholas Reder, chief resident and clinical research fellow in UW Medicine’s Department of Pathology. “This light-sheet microscope represents a major advance for pathology and cancer patients, allowing us to examine tissue in minutes rather than days and to view it in three dimensions instead of two — which will ultimately lead to improved clinical care.”

No comment yet.
Rescooped by Dr. Stefan Gruenwald from Fragments of Science!

Nil Communication: How to Send a Message without Sending Anything at All

Nil Communication: How to Send a Message without Sending Anything at All | Amazing Science |
Physicists have exploited the laws of quantum mechanics to send information without transmitting a signal. But have they, really?

Quantum mechanics is the consummate theory of particles, so it naturally describes measurements and interactions. During the past few decades, as computers have nudged the quantum, the theory has been reframed to encompass information, too. What quantum mechanics implies for measurements and interactions is notoriously bizarre. Its implications for information are stranger still.


One of the strangest of these implications refutes the material basis of communication as well as common sense. Some physicists believe that we may be able to communicate without transmitting particles. In 2013 an amateur physicist named Hatim Salih even devised a protocol, alongside professionals, in which information is obtained from a place where particles never travel. Information can be disembodied. Communication may not be so physical after all.


In April 2017, the early edition of a short article about Salih’s protocol appeared online in the Proceedings of the National Academy of Sciences. Most of the article’s 10 authors were members of the University of Science and Technology of China, at its branches in Shanghai and Hefei. The final author was Jian-Wei Pan, an eminent physicist who has also developed a constellation of satellites for communicating through quantum mechanics. He recently used this network for transmitting entangled particles over a distance of 1,200 kilometers.


Pan and his collaborators publish at a rate of more than one paper a month. But the paper that they published in April, co-written by Yuan Cao and Yu-Huai Li, was exceptional. They described an experiment in which they sent a black-and-white image of a Chinese knot to a computer, without transmitting any particles.


Extraordinary claims require extraordinary evidence—even the person whose work dug the original foundation for the team’s evidence, Lev Vaidman, doubts their claim. Vaidman and others have been arguing about how to interpret such results for a decade. And their communication is now changing how we understand the quantum theory.


Physicists strain to comprehend what quantum mechanics whispers about reality and what we can know about the material world. The theory, however, is starting to speak up. Physicists now question the uncertainty that the quantum theory has imposed, as even weak measurements reveal particulars that were once thought impossible. At stake are the very notions of measurements and interactions, and the foundations of the information technologies of the future.

Via Mariaschnee
No comment yet.
Rescooped by Dr. Stefan Gruenwald from DNA and RNA research!

Newly identified small RNA fragments defend the genome when it’s ‘naked’

Newly identified small RNA fragments defend the genome when it’s ‘naked’ | Amazing Science |

Our genomes are minefields, studded with potentially damaging DNA sequences over which hundreds of thousands of sentries stand guard. These sentries, called epigenetic marks, attach to the double helix at such spots and prevent the underlying DNA sequences from springing into destructive action.


A team from Cold Spring Harbor Laboratory (CSHL) describes now what might be considered emergency replacements for the sentries, shock troops pressed into service across the genome only during these curiously undefended moments. Specifically, these defenders are protecting the genome in mammalian embryos, at the very early point in their development before they are implanted in the wall of the maternal uterus.


The preimplantation embryo is one of two normal settings in which epigenetic marks are wiped clean before being reinscribed. The other setting is a step in the formation of germline cells—sperm and eggs—which have temporary defenders already known to biology, so-called piwi-interacting RNAs (piRNAs). The research published today, led by first author Andrea Schorn, a postdoctoral researcher in the lab of Rob Martienssen, demonstrates that another species of small RNA performs an analogous genome-defending role in preimplantation embryos during an interval of epigenetic reprogramming. Dr. Martienssen is a CSHL Professor and Howard Hughes Medical Institute investigator.


The newly identified defenders come in two varieties — RNA fragments consisting of 18 and 22 nucleotides. These RNA fragments, Dr. Schorn discovered, are perfect complements of sequences in retrotransposons that must be engaged in order for the genomic parasites to be activated.


This fact led to the discovery. Schorn scrutinized the contents of mouse embryonic stem cells and found many free-floating RNA fragments 18 nucleotides in length. Computer analysis revealed that their sequences perfectly matched sequences within transfer RNAs. tRNAs are ubiquitous, and are involved in the synthesis of proteins. It has been known for decades that tRNAs are hijacked by long terminal repeat (LTR)-retrotransposons, a portion of their sequence docking at a primer binding site (PBS) and initiating a process that activates the genomic parasite.


“Knowing that LTR retrotransposons need tRNAs to replicate, it was very tempting to believe that these 18-nucleotide tRNA fragments we were seeing in preimplantation embryonic stem cells could interfere with that process,” says Schorn. “We think the cell is deliberately chopping up full-length tRNAs into smaller fragments precisely because both tRNAs and the fragments cut from them recognize the PBS. This means the small, tRNA-derived fragments would be able to occupy that site and inhibit retrotransposon replication and mobility,” Martienssen explains.

The implications, Martienssen says, are potentially profound. This appears to tell us one way in which the genomes of mammals have tolerated vast numbers of transposons and other parasitic elements, even during periods when the genome is wiped clean of repressive epigenetic marks. “It’s plausible that this is a very ancient mechanism that cells have found to not only inhibit retrotransposons but help in protection against viruses as well,” Martienssen says.


The research discussed here was supported by NIH grant R01GM076396; a Bristol-Myers Squibb fellowship from the Watson School of Biological Sciences; the Howard Hughes Medical Institute; the Gordon and Betty Moore Foundation (GMBF3033); and CSHL Cancer Center Support Grant (5PP30CA045508).


“LTR-Retrotransposon Control by tRNA-Derived Small RNAs” appears online in Cell June 29, 2017. The authors are: Andrea J. Schorn, Michael J. Gutbrod, Chantal LeBlanc and Rob Martienssen. The paper can be accessed at:

Via Integrated DNA Technologies
No comment yet.