A species of chameleon small enough to easily perch on a match head has been discovered on a tiny island off Madagascar. Brookesia micra may represent the limit of miniaturization possible for a vertebrate with complex eyes
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The heart didn't beat for the baboon, but it did overcome the risk of organ rejection.
By breeding piglets with a few choice human genes, scientists were able to create sort-of-pig hearts that seem to be compatible with primate hosts. The organ wasn't used as a heart, but was instead grafted into the abdomen of an otherwise healthy baboon. After over a year, the best of the hearts are still living, viable organs. Next stop, the chest cavity!
Researchers at the National Heart, Lung and Blood Institute (NHLBI) of the National Institutes of Health will publish their results in the September issue of The Journal of Thoracic and Cardiovascular Surgery, though their findings were discussed several months ago at a conference. According to the study, the researchers experimented with different degrees of genetic modification in the pigs. They prevented all of the piglets from producing certain enzymes known to cause organ rejection in baboons (and, by extension, humans) but were given different gene alterations to keep blood from clotting, which is another common issue.
The most successful group had the human thrombomodulin gene added to their genomes. The expression of this gene prevented clotting, lead investigator Muhammad M. Mohiuddin said in a statement. While the average survival of the other groups were 70 days, 21 days and 80 days, the thrombomodulin group survived an average of 200 days in the baboon abdomen. And three of the five grafts in the group were still alive at 200 to 500 days since their grafting, when the study was submitted for review.
By understanding the secret of how lizards regenerate their tails, researchers may be able to develop ways to stimulate the regeneration of limbs in humans. Now, a team of researchers from Arizona State University is one step closer to solving that mystery. The scientists have discovered the genetic “recipe” for lizard tail regeneration, which may come down to using genetic ingredients in just the right mixture and amounts.
Other animals, such as salamanders, frog tadpoles and fish, can also regenerate their tails, with growth mostly at the tip. During tail regeneration, they all turn on genes in what is called the 'Wnt pathway’ – a process that is required to control stem cells in many organs, such as the brain, hair follicles and blood vessels. However, lizards have a unique pattern of tissue growth that is distributed throughout the tail.
"Regeneration is not an instant process," said Elizabeth Hutchins, a graduate student in ASU's molecular and cellular biology program and co-author of the paper. "In fact, it takes lizards more than 60 days to regenerate a functional tail. Lizards form a complex regenerating structure with cells growing into tissues at a number of sites along the tail.”
"We have identified one type of cell that is important for tissue regeneration," said Jeanne Wilson-Rawls, co-author and associate professor with ASU’s School of Life Sciences. "Just like in mice and humans, lizards have satellite cells that can grow and develop into skeletal muscle and other tissues."
"Using next-generation technologies to sequence all the genes expressed during regeneration, we have unlocked the mystery of what genes are needed to regrow the lizard tail," said Kusumi. "By following the genetic recipe for regeneration that is found in lizards, and then harnessing those same genes in human cells, it may be possible to regrow new cartilage, muscle or even spinal cord in the future."
The findings are published today in the journal PLOS ONE.
An MRI-guided laser system that allows surgeons to perform brain surgery on tumors and epileptic lesions in the brain is expected to become widely available to patients in need now that the technology has been acquired from Visualase Inc. by the global medical device company Medtronic, Inc., says a biomedical engineering professor from Texas A&M University who co-founded the company responsible for the technology.
The technology, says Gerard Coté, professor in the university’s Department of Biomedical Engineering and director of the Center for Remote Healthcare Technology, enables surgeons to pinpoint and destroy brain tumors and lesions with extreme precision and is a much less-invasive alternative to conventional surgery.
The advantage of this approach over other approaches for brain surgery, Coté explains, is that it can be performed while the patient is awake, requires no radiation and no skull flap (the large opening in traditional craniotomies), and is often performed in otherwise inoperable areas of the brain.
Traditional brain surgery, he explains, is usually a daylong operation that involves removing part of the skull, cutting through healthy brain matter and physically removing the problematic tissue. That procedure, he adds, can be followed by a weeklong hospital stay and prolonged recovery period.
The technology developed by former Texas A&M students Ashok Gowda and the late Roger McNichols, conversely, can be completed in about four hours, and most patients can return home the following day, Coté says.
Known as “Visualase,” the technology is already used in more than 45 hospitals, nationwide, including 15 pediatric hospitals. Before the surgical procedure, computer software first helps identify the targeted tissue so that it may be treated and the surrounding healthy tissue can be avoided, Coté explains. During the procedure, a small entry is made in the skull that allows a laser applicator (about the size of a pencil lead) to be inserted into the tissue. The patient is placed in the MRI, and a physician receives and reviews images to verify proper positioning of the laser applicator in the skull. The clinician then uses a laser to heat and destroy the problematic tissue while imaging the tissue being damaged in real time to ensure destruction of the problematic tissue and to avoid damaging healthy tissue. The laser applicator is then removed, and the scalp is closed with one stitch, Coté notes.
This could be a classic win-win solution: A system proposed by researchers at MIT recycles materials from discarded car batteries — a potential source of lead pollution — into new, long-lasting solar panels that provide emissions-free power. The system is described in a paper in the journal Energy and Environmental Science,co-authored by professors Angela M. Belcher and Paula T. Hammond, graduate student Po-Yen Chen, and three others. It is based on a recent development in solar cells that makes use of a compound called perovskite — specifically, organolead halide perovskite — a technology that has rapidly progressed from initial experiments to a point where its efficiency is nearly competitive with that of other types of solar cells.
“It went from initial demonstrations to good efficiency in less than two years,” says Belcher, the W.M. Keck Professor of Energy at MIT. Already, perovskite-based photovoltaic cells have achieved power-conversion efficiency of more than 19 percent, which is close to that of many commercial silicon-based solar cells. Initial descriptions of the perovskite technology identified its use of lead, whose production from raw ores can produce toxic residues, as a drawback. But by using recycled lead from old car batteries, the manufacturing process can instead be used to divert toxic material from landfills and reuse it in photovoltaic panels that could go on producing power for decades.
Amazingly, because the perovskite photovoltaic material takes the form of a thin film just half a micrometer thick, the team’s analysis shows that the lead from a single car battery could produce enough solar panels to provide power for 30 households.
Researchers at Johns Hopkins have mapped a new technique for watching auditory processing in the brains of mice as brain cells lit up when the mice listened to tones and one another’s calls. The results, which represent a step toward better understanding how our own brains process language, appear online July 31 in the journal Neuron.
In the past, researchers often studied sound processing in various animal brains by poking tiny electrodes into the auditory cortex, the part of the brain that processes sound. They then played tones and observed the response of nearby neurons, laboriously repeating the process over a grid-like pattern to figure out where the active neurons were.
More recently, a technique called two-photon microscopy has allowed researchers to focus in on minute slices of the live mouse brain, observing activity in unprecedented detail. This newer approach has suggested that the precise arrangement of bands might be an illusion.
However, “you could lose your way within the zoomed-in views afforded by two-photon microscopy and not know exactly where you are in the brain,” says David Yue, M.D., Ph.D., a professor of biomedical engineering andneuroscience at the Johns Hopkins University School of Medicine. Yue led the study along with Eric Young, Ph.D., also a professor of biomedical engineering and a researcher in Johns Hopkins’ Institute for Basic Biomedical Sciences.
To get the bigger picture, John Issa, a graduate student in Yue’s lab, used a mouse genetically engineered to produce a molecule that glows green in the presence of calcium. Since calcium levels rise in neurons when they become active, neurons in the mouse’s auditory cortex glow green when activated by various sounds.
Issa used a two-photon microscope to peer into the brains of live mice as they listened to sounds and saw which neurons lit up in response, piecing together a global map of a given mouse’s auditory cortex.
“With these mice, we were able to both monitor the activity of individual populations of neurons and zoom out to see how those populations fit into a larger organizational picture,” he says.
The universe has so many black holes that it's impossible to count them all. There may be 100 million of these intriguing astral objects in our galaxy alone. Nearly all black holes fall into one of two classes: big, and colossal. Astronomers know that black holes ranging from about 10 times to 100 times the mass of our sun are the remnants of dying stars, and that supermassive black holes, more than a million times the mass of the sun, inhabit the centers of most galaxies.
But scattered across the universe like oases in a desert are a few apparent black holes of a more mysterious type. Ranging from a hundred times to a few hundred thousand times the sun's mass, these intermediate-mass black holes are so hard to measure that even their existence is sometimes disputed. Little is known about how they form. And some astronomers question whether they behave like other black holes.
Now a team of astronomers has accurately measured—and thus confirmed the existence of—a black hole about 400 times the mass of our sun in a galaxy 12 million light years from Earth. The finding, by University of Maryland astronomy graduate student Dheeraj Pasham and two colleagues, was published online August 17 in the journal Nature.
Pasham focused on one object in Messier 82, a galaxy in the constellation Ursa Major. Messier 82 is our closest "starburst galaxy," where young stars are forming. Beginning in 1999 a NASA satellite telescope, the Chandra X-ray Observatory, detected X-rays in Messier 82 from a bright object prosaically dubbed M82 X-1. Astronomers, including Mushotzky and co-author Tod Strohmayer of NASA's Goddard Space Flight Center, suspected for about a decade that the object was an intermediate-mass black hole, but estimates of its mass were not definitive enough to confirm that.
Between 2004 and 2010 NASA's Rossi X-Ray Timing Explorer (RXTE) satellite telescope observed M82 X-1 about 800 times, recording individual x-ray particles emitted by the object. Pasham mapped the intensity and wavelength of x-rays in each sequence, then stitched the sequences together and analyzed the result
Among the material circling the suspected black hole, he spotted two repeating flares of light. The flares showed a rhythmic pattern of light pulses, one occurring 5.1 times per second and the other 3.3 times per second – or a ratio of 3:2.
Chemists led by Nobel laureate K. Barry Sharpless at The Scripps Research Institute (TSRI) have used his click chemistry to uncover unprecedented, powerful reactivity for making new drugs, diagnostics, plastics, smart materials and many other products.
The new SuFEx—Sulfur Fluoride Exchange—reactions enable chemists to link molecules of their choice together using derivatives of a common commercial chemical considered essentially inert. The Sharpless team made this chemical reliably and predictably reactive. Astonishingly, acid-base constraints are rarely a concern, though they are central to nature's chemistry and an enormous hurdle for chemists. The stabile linkers are also non-polar and can enter cells, so have potential for crossing the blood-brain barrier.
Consequently, SuFEx gives easy access to an entire, unexplored galaxy within the chemical universe. “This is a new, emergent phenomenon,” said Sharpless, the W.M. Keck Professor of Chemistry and member of the Skaggs Institute for Chemical Biology at TSRI.
Click chemistry, conceived in the mid-90s as a method for discovering new and improving existing chemical reactivity, became universally used in the chemical sciences after the 2002 discovery of copper-catalyzed azide-alkyne cycloaddition (CuAAC). Now SuFEx is the second “perfect” click reaction to be discovered at TSRI.
Sharpless shared the 2001 Nobel Prize in Chemistry for his discovery and development during the 80s of asymmetric catalytic reactions. Nature routinely makes “handed” molecules like DNA, which is like a spiral staircase you enter on the left, but chemists could not reliably make left- or right-handed molecules. The Sharpless asymmetric reactions gave chemists that gift with general reactions that made either left- or right-handed products at will.
Tvashtar Catena is one of the most interesting features on Jupiter’s moon Io. It is an active volcanic region located near the moon’s north pole. This ever-changing, extremely active volcanic field consists of a chain of giant volcanic paterae, caldera-like depressions.
This chain has exhibited highly variable volcanic activity in a series of observations. Tvashtar was studied by the Galileo spacecraft over several years, from late 1999 until early 2002. In December 2000, the Cassini spacecraft had a distant and brief encounter with the Jupiter system en route to Saturn, allowing for joint observations with Galileo.
During this time, a 25 kilometres (16 mi) long, 1 to 2 kilometres (0.62 to 1.2 mi) high curtain of lava was seen to erupt from one crater, a lake of superheated silicate lava erupted in the largest crater, and finally a plume of gas burst out, rising 385 kilometres (239 mi) above the moon and blanketing areas as far away as 700 kilometres (430 mi).
Therefore scientists expected that the lava flow margins or patera boundaries within Tvashtar would have changed drastically. However, the series of observations revealed little modification of this sort suggesting that the intense eruptions at Tvashtar are topographically confined.
Another eruption on Tvashtar on February 26 2007 was photographed by the New Horizons probe as it went past Jupiter en route to Pluto. The probe observed an enormous 330 kilometres (210 mi) high plume from the volcano, with an as-yet unexplained filamentary structure, made clearly visible by the background light from the sun.
In these images, taken by NASA’s Galileo spacecraft, we can see Tvashtar Catena just after an active volcanic eruption. The left one is taken on 26 Nov 1999 and the right one on 22 Feb 2000. The red and yellow lava flows we see are illustrations based upon imaging data.
The two small bright spots are sites where molten rock is exposed to the surface at the toes of lava flows. The larger orange and yellow ribbon is a cooling lava flow that is more than 60 kilometers (37 mi) long. Dark, diffuse deposits surrounding the active lava flow were not there during the November 1999 flyby of Io.
There are currently almost 2,000 extrasolar planets known to us, but most are inhospitable gas giants. Thanks to NASA's Kepler mission, a handful of smaller, rockier planets have been discovered within the habitable zones of their stars that could provide a niche for alien life.
In astronomy, a habitable zone is a region of space around a star where conditions are favorable for life as it may be found on Earth. Planets and moons in these regions are the likeliest candidates to be habitable. Our sun has a temperature of about 5800K. For stars cooler than our sun (M dwarfs, also known as red dwarfs, at 3000-4000K) the region is closer in. For hotter stars (A dwarfs at 10,000K) the region is much farther out.
The habitable zone of a star is typically defined as the range from a star where temperatures would allow liquid water to exist on the surface of a planet. At the inner edge of this zone, the star's blistering heat vaporizes the planet's water into the atmosphere in a runaway greenhouse effect. At the outer edge of the habitable zone, temperatures are so cold that clouds of carbon dioxide form and the little solar energy that does arrive bounces off the clouds, turning the planet into a frozen wasteland.
However, this concept is rather simple. In reality, many other factors come into play that could affect a planet's habitability. New research has revealed that the rate at which a planet spins is instrumental in its ability to support life. Not only does rotation control the length of day and night, it can also tug on the winds that blow through the atmosphere and ultimately influence cloud formation.
The radiation that the Earth receives from the Sun is strongest at the equator. The air in this region is heated until it rises up through the atmosphere and heads towards the poles of the planet where it subsequently cools. This cool air falls through the atmosphere and is ushered back towards the equator. This process of atmospheric circulation is known as a Hadley cell.
If a planet is rotating rapidly, the Hadley cells are confined to low latitudes and they are arranged into different bands that encircle the planet. Clouds become prominent at tropical regions, which are important for reflecting a proportion of the light back into space. However, for a planet in a tighter orbit around its star, the radiation received from the star is much more extreme.
This will decrease the temperature difference between the equator and the poles and ultimately weaken the Hadley cells. The result is fewer clouds at the tropical regions available to protect the planet from the intense heat, and the planet becomes uninhabitable.
If, on the other hand, the planet is a slow rotator, then the Hadley cells can expand to encompass the entire world. This is because the atmospheric circulation is enhanced due to the difference in temperature between the day and night side of the planet. The days and nights are very long, so that the half of the planet that is bathed in light from the star has plenty of time to soak up the Sun. In contrast, the night side of the planet is much cooler, as it has been shaded from the star for some time.
This difference in temperature is large enough to cause the warm air from the day side to flow to the night side, in a similar manner as opening a door on a cold day results in warm air fleeing from a room. The increased circulation causes more clouds to build up over the substellar point, which is the point on the planet where the star would be seen directly overhead, and where radiation is most intense. The clouds over the substellar point then create a shield for the ground below as most of the harmful radiation is reflected away.
The high albedo clouds can allow a planet to remain habitable even at levels of radiation that were previously thought to be too high, so that the inner edge of the habitable zone is pushed much closer to the star.
"Rotation can have a huge effect, and lots of planets that we previously thought were definitely not habitable now can be considered as candidates," says Dorian Abbot of the University of Chicago, and a co-author on the paper.
Researchers from the University of Washington’s Departments of Physics and Genome Sciences have developed a nanopore sequencing technique reaching read lengths of several thousand bases. The result is the latest in a series of advances in nanopore technology developed at the university.
The team, led by Jens Gundlach, published their findings in Nature Biotechnology as an advanced online publication on June 25, 2014 ("Decoding long nanopore sequencing reads of natural DNA").
“This is the first time anyone has shown that nanopores can be used to generate interpretable signatures corresponding to very long DNA sequences from real-world genomes,” said co-author Jay Shendure, an associate professor in Genome Sciences, “It’s a major step forward.
”The idea for nanopore sequencing originated in the 90s: a lipid membrane, similar to the material that makes up the cell wall, acts as a barrier separating two liquids. Inserted into the membrane is a tiny gap, just nanometers across, called a nanopore. By applying a voltage difference across the barrier, ions in the liquid try to move between the two sides of the barrier and the only way to do this is to flow through the nanopore. The movement of the charged molecules between the two liquids is a current, just like electrons moving along a wire in an electrical circuit, and can be recorded.
Any DNA in the system is also pulled towards the other side of the barrier by the voltage difference, since DNA is negatively charged, and just like the ions it has to pass through the nanopore. The difference is that the DNA is much bigger than the ions and partially blocks the nanopore, making it harder for the smaller molecules to pass through. As the ions are blocked by the DNA, there is a measurable difference in the current flowing across the membrane which is dependent on the DNA base passing through the nanopore. By measuring the changing current, information can be gained on the bases passing through.
The researchers created the nanopore by inserting a single protein called Mycobacterium smegmatis porin A, or MspA, in the membrane. MspA is normally found lining the membrane of a species of bacteria, controlling the intake of nutrients.
One challenge the researchers faced was the control of the DNA passing through the nanopore. Normally, the DNA would zip through the MspA nanopore too fast to detect the changes in the current. The researchers slowed the DNA movement through the pore using a second protein called phi29 DNA polymerase (DNAP), which captures DNA and slows its movement through the pore.
The shape of the protein MspA meant that several bases passed through the nanopore at one time and the current changes were the result of a combination of those bases. This presented another challenge. Since several bases passed through the nanopore at one time, the researchers needed a way to decipher what the current changes meant. To do this, they first made a library of DNA sequences that contains all possible combinations of 4 nucleotides (for the mathematically inclined, the library is 44 = 256 bases long – a string of 4 bases with 4 possible choices for each DNA base). The library, whose sequence was already known, was run though the nanopore first to find the current associated with each set of DNA base combinations. They combined the library measurements with known genome sequences to generate a set of expected current changes that could be compared to experimental measurements.
The researchers tested their approach by sequencing the entire genome of bacteriophage Phi X 174, a virus that infects bacteria and is used as a benchmark for evaluating new sequencing technologies. The impressive feat here is the length of the genome they sequenced – the Phi X 174 genome is 4,500 bases long. Other nanopore technologies have been limited to sequencing DNA fragments that were much shorter.
“Despite the remaining hurdles, our demonstration that a low-cost device can reliably read the sequences of naturally occurring DNA and can interpret DNA segments as long as 4,500 nucleotides in length represents a major advance in nanopore DNA sequencing,” explained Gundlach.
Many hands make light work, right? Well, MIT researchers have created a wrist-worn robot with a couple of extra digits.
There are several explanations for why the human hand developed the way it has. Some researchers link our opposable thumbs to our ancestors’ need to club and hurl objects at enemies or throw a punch, while others say that a unique gene enhancer (a group of proteins in DNA that activate certain genes) is what led to our anatomy. But most agree that bipedalism, enlarged brains and the need to use tools are what did the trick.
Yet, for as dexterous as our hands make us, a team of researchers at the Massachusetts Institute of Technology think we can do better. Harry Asada, a professor of engineering, has developed a wrist-worn robot that will allow a person to peel a banana or open a bottle one-handed
Together with graduate student Faye Wu, Asada built a pair of robotic fingers that track, mimic and assist a person’s own five digits. The two extra appendages, which look like elongated plastic pointer fingers, attach to a wrist cuff and extend alongside the thumb and pinkie. The apparatus connects to a sensor-laden glove, which measures how a person’s fingers bend and move. An algorithm crunches that movement data and translates it into actions for each robotic finger.
The robot takes a lesson from the way our own five digits move. One control signal from the brain activates groups of muscles in the hand. This synergy, Wu explains in a video demonstration, is much more efficient than sending signals to individual muscles.
In order to map how the extra fingers would move, Wu attached the device to her wrist and began grabbing objects throughout the lab. With each test, she manually positioned the robot fingers onto an object in a way that would be most helpful—for example, steadying a soda bottle while she used her hand to untwist the top. In each instance, she recorded the angles of both her own fingers and those of her robot counterpart.
The discovery of the role of this gene, called Lhx1, provides scientists with a potential therapeutic target to help night-shift workers or jet lagged travelers adjust to time differences more quickly. The results, published in eLife, can point to treatment strategies for sleep problems caused by a variety of disorders.
“It’s possible that the severity of many dementias comes from sleep disturbances,” says Satchidananda Panda, a Salk associate professor who led the research team. “If we can restore normal sleep, we can address half of the problem.”
Every cell in the body has a “clock” – an abundance of proteins that dip or rise rhythmically over approximately 24 hours. The master clock responsible for establishing these cyclic circadian rhythms and keeping all the body’s cells in sync is the suprachiasmatic nucleus (SCN), a small, densely packed region of about 20,000 neurons housed in the brain’s hypothalamus.
More so than in other areas of the brain, the SCN’s neurons are in close and constant communication with one another. This close interaction, combined with exposure to light and darkness through vision circuits, keeps this master clock in sync and allows people to stay on essentially the same schedule every day. The tight coupling of these cells also helps make them collectively resistant to change. Exposure to light resets less than half of the SCN cells, resulting in long periods of jet lag.
In the new study, researchers disrupted the light-dark cycles in mice and compared changes in the expression of thousands of genes in the SCN with other mouse tissues. They identified 213 gene expression changes that were unique to the SCN and narrowed in on 13 of these that coded for molecules that turn on and off other genes. Of those, only one was suppressed in response to light: Lhx1.
“No one had ever imagined that Lhx1 might be so intricately involved in SCN function,” says Shubhroz Gill, a postdoctoral researcher and co-first author of the paper. Lhx1 is known for its role in neural development: it’s so important, that mice without the gene do not survive. But this is the first time it has been identified as a master regulator of light-dark cycle genes.
In a ground-breaking discovery released by the journal Science, researchers have revealed microhabitats of metabolically active, thriving microbes living in the world’s largest asphalt lake, Pitch Lake, on the island of Trinidad in the Caribbean. Asphalt lakes are large reservoirs of a sticky, black, viscous hydrocarbons (known as asphalt, bitumen or pitch) where no life was expected to be found.
The international team discovered the microbes in tiny water droplets recovered from the lake in 2011. Each sample, measuring only one to three microliters, has the equivalent volume of approximately 1/50 of a conventional “drop” of water.
The team’s only United States-based researcher, Dirk Schulze-Makuch, is a professor at Washington University School of the Environment. Using advanced sequencing technologies, the team extracted all the DNA of all organisms in each droplet simultaneously. Reading through 12 microdroplets, they found 21 species of bacteria and archaebacteria.
Professor Schulze-Makuch explained that each water droplet seems representative of an entire ecosystem because of the observed diversity in bacteria and archaea. Moreover, remarkably there was very little measurable ammonia or phosphates, both ingredients thought to be essential for life.
These microbes, the researchers report, are actively degrading oils in the lake, most likely to exploit it as a source of bioenergy. One bioengineering implication of this discovery is to use these active microbes to clean up oil spills with as little impact to the environment as possible.
The water droplets also had an unusually high salt content. By studying the isotope composition of droplets from Pitch Lake, the team was able to say that the microbes did not originate from surface waters that are part of the hydrologic cycle, but rather from much deeper, for example ancient underground seawater or another deep source of brine.
Professor Schulze-Makuch went on to explain that these microbes could mean life on other planets as well. One well-known example is Saturn’s moon, Titan. Its surface is characterized as being saturated with hydrocarbons, in liquid lakes on the ground and also in vapor form and liquid rain in the atmosphere. Schulze-Makuch explains that this discovery has implications for astrobiology, the study of life on other planets.
Researchers have developed a new type of solar concentrator that when placed over a window creates solar energy while allowing people to actually see through the window. It is called a transparent luminescent solar concentrator and can be used on buildings, cell phones and any other device that has a flat, clear surface.
Research in the production of energy from solar cells placed around luminescent plastic-like materials is not new. These past efforts, however, have yielded poor results -- the energy production was inefficient and the materials were highly colored.
"No one wants to sit behind colored glass," said Lunt, an assistant professor of chemical engineering and materials science. "It makes for a very colorful environment, like working in a disco. We take an approach where we actually make the luminescent active layer itself transparent."
The solar harvesting system uses small organic molecules developed by Lunt and his team to absorb specific nonvisible wavelengths of sunlight. "We can tune these materials to pick up just the ultraviolet and the near infrared wavelengths that then 'glow' at another wavelength in the infrared," he said.
The "glowing" infrared light is guided to the edge of the plastic where it is converted to electricity by thin strips of photovoltaic solar cells. "Because the materials do not absorb or emit light in the visible spectrum, they look exceptionally transparent to the human eye," Lunt said.
Injuries, birth defects (such as cleft palates) or surgery to remove a tumor can create gaps in bone that are too large to heal naturally. And when they occur in the head, face or jaw, these bone defects can dramatically alter a person's appearance. Researchers will report today that they have developed a "self-fitting" material that expands with warm salt water to precisely fill bone defects, and also acts as a scaffold for new bone growth.
Currently, the most common method for filling bone defects in the head, face or jaw (known as the cranio-maxillofacial area) is autografting. That is a process in which surgeons harvest bone from elsewhere in the body, such as the hip bone, and then try to shape it to fit the bone defect.
"The problem is that the autograft is a rigid material that is very difficult to shape into these irregular defects," says Melissa Grunlan, Ph.D., leader of the study. Also, harvesting bone for the autograft can itself create complications at the place where the bone was taken. Another approach is to use bone putty or cement to plug gaps. However, these materials aren't ideal. They become very brittle when they harden, and they lack pores, or small holes, that would allow new bone cells to move in and rebuild the damaged tissue.
To develop a better material, Grunlan and her colleagues at Texas A&M University made a shape-memory polymer (SMP) that molds itself precisely to the shape of the bone defect without being brittle. It also supports the growth of new bone tissue.
SMPs are materials whose geometry changes in response to heat. The team made a porous SMP foam by linking together molecules of poly(ε-caprolactone), an elastic, biodegradable substance that is already used in some medical implants. The resulting material resembled a stiff sponge, with many interconnected pores to allow bone cells to migrate in and grow. Upon heating to 140 degrees Fahrenheit, the SMP becomes very soft and malleable. So, during surgery to repair a bone defect, a surgeon could warm the SMP to that temperature and fill in the defect with the softened material. Then, as the SMP is cooled to body temperature (98.6 degrees Fahrenheit), it would resume its former stiff texture and "lock" into place.
The researchers also coated the SMPs with polydopamine, a sticky substance that helps lock the polymer into place by inducing formation of a mineral that is found in bone. It may also help osteoblasts, the cells that produce bone, to adhere and spread throughout the polymer. The SMP is biodegradable, so that eventually the scaffold will disappear, leaving only new bone tissue behind. To test whether the SMP scaffold could support bone cell growth, the researchers seeded the polymer with human osteoblasts. After three days, the polydopamine-coated SMPs had grown about five times more osteoblasts than those without a coating. Furthermore, the osteoblasts produced more of the two proteins, runX2 and osteopontin, that are critical for new bone formation.
Grunlan says that the next step will be to test the SMP's ability to heal cranio-maxillofacial bone defects in animals. "The work we've done in vitro is very encouraging," she says. "Now we'd like to move this into preclinical and, hopefully, clinical studies."
Men and women differ in plenty of obvious ways, and scientists have long known that genetic differences buried deep within our DNA underlie these distinctions. In the past, most research has focused on understanding how the genes that encode proteins act as sex determinants. But Cold Spring Harbor Laboratory (CSHL) scientists have found that a subset of very small genes encoding short RNA molecules, called microRNAs (miRNAs), also play a key role in differentiating male and female tissues in the fruit fly.
A miRNA is a short segment of RNA that fine-tunes the activation of one or several protein-coding genes. miRNAs are able to silence the genes they target and, in doing so, orchestrate complex genetic programs that are the basis of development.
In work published in Genetics, a team of CSHL researchers and colleagues describe how miRNAs contribute to sexual differences in fruit flies. You've probably never noticed, but male and female flies differ visibly, just like other animals. For example, females are 25% larger than males with lighter pigmentation and more abdominal segments.
The team of researchers, including Delphine Fagegaltier, PhD, lead author on the study, and CSHL Professor and Howard Hughes Medical Institute Investigator Greg Hannon, identified distinct miRNA populations in male and female flies. "We found that the differences in miRNAs are important in shaping the structures that distinguish the two sexes," says Fagegaltier. "In fact, miRNAs regulate the very proteins that act as sex determinants during development."
The team found that miRNAs are essential for sex determination even after an animal has grown to adulthood. "They send signals that allow germ cells, i.e., eggs and sperm, to develop, ensuring fertility," Fagegaltier explains. "Removing one miRNA from mature, adult flies causes infertility." More than that, these flies begin to produce both male and female sex-determinants. "In a sense, once they have lost this miRNA, the flies become male and female at the same time," according to Fagegaltier. "It is amazing that the very smallest genes can have such a big effect on sexual identity."
Some miRNAs examined in the study, such as let-7, have been preserved by evolution because of their utility; humans and many other animals carry versions of them. "This is probably just the tip of the iceberg," says Fagegaltier. "There are likely many more miRNAs regulating sexual identity at the cellular and tissue level, but we still have a lot to learn about these differences in humans, and how they could contribute to developmental defects and disease."
Japanese researchers have created an “artificial neural connection” (ANC) from the brain directly to the spinal locomotion center in the lower thoracic and lumbar regions of the spine, potentially one day allowing patients with spinal-cord damage, such as paraplegics, to walk.
The study led by Shusaku Sasada, research fellow, and Yukio Nishimura, associate professor, both of the National Institutes of Natural Sciences (NINS), was published online in The Journal of Neuroscience on August 13, 2014.
Neural networks called “central pattern generators” (see Ref. 2 and 3 below) in the locomotion center (lower than the lesion site) are capable of producing rhythmic movements, such as walking, even when isolated from the brain, the researchers suggest.
The researchers worked with neurologically intact subjects who are were asked to allow the computer to passively control their leg movements.
As a surrogate, the researchers used muscle signals normally generated by the arm movements associated with leg movements. These signals were used to control a computer-driven magnetic device that non-invasively (externally) stimulated neurons in the spinal locomotion center.
Additional simultaneous peripheral electrical stimulation to the foot via the ANC enhanced this walking-like behavior. Kinematics of the induced behaviors were identical to those observed in normal voluntary walking. The researchers said they are planning clinical studies in the near future.
A Virginia Tech scientist has discovered a potentially new form of plant communication, one that allows them to share an extraordinary amount of genetic information with one another.
The finding by Jim Westwood, a professor of plant pathology, physiology, and weed science in the College of Agriculture and Life Sciences, throws open the door to a new arena of science that explores how plants communicate with each other on a molecular level. It also gives scientists new insight into ways to fight parasitic weeds that wreak havoc on food crops in some of the poorest parts of the world. His findings were published on Aug. 15 in the journal Science.
“The discovery of this novel form of inter-organism communication shows that this is happening a lot more than any one has previously realized,” said Westwood, who is an affiliated researcher with the Fralin Life Science Institute. “Now that we have found that they are sharing all this information, the next question is, ‘What exactly are they telling each other?’.”
Westwood examined the relationship between a parasitic plant, dodder, and two host plants, Arabidopsis and tomatoes. In order to suck the moisture and nutrients out the host plants, dodder uses an appendage called a haustorium to penetrate the plant. Westwood previously broke new ground when he found that during this parasitic interaction, there is a transport of RNA between the two species. RNA translates information passed down from DNA, which is an organism’s blueprint.
His new work expands this scope of this exchange and examines the mRNA, or messenger RNA, which sends messages within cells telling them which actions to take, such as which proteins to code. It was thought that mRNA was very fragile and short-lived, so transferring it between species was unimaginable.
But Westwood found that during this parasitic relationship, thousands upon thousands of mRNA molecules were being exchanged between both plants, creating this open dialogue between the species that allows them to freely communicate. Through this exchange, the parasitic plants may be dictating what the host plant should do, such as lowering its defenses so that the parasitic plant can more easily attack it. Westwood’s next project is aimed at finding out exactly what the mRNA are saying.
“Parasitic plants such as witchweed and broomrape are serious problems for legumes and other crops that help feed some of the poorest regions in Africa and elsewhere,” said Julie Scholes, a professor at the University of Sheffield, U.K., who is familiar with Westwood’s work but was not part of this project. “In addition to shedding new light on host-parasite communication, Westwood’s findings have exciting implications for the design of novel control strategies based on disrupting the mRNA information that the parasite uses to reprogram the host."
There's now overwhelming evidence that a child's future health is influenced by more than just their parents' genetic material, and that children born of unhealthy parents will already be pre-programmed for greater risk of poor health, according to researchers. "The reality is, the child doesn't quite start from scratch -- they already carry over a legacy of factors from their parents' experiences that can shape development in the fetus and after birth. Depending on the situation, we can give our children a burden before they've even started life," experts say.
At fertilization, the gametes endow the embryo with a genomic blueprint, the integrity of which is affected by the age and environmental exposures of both parents. Recent studies reveal that parental history and experiences also exert effects through epigenomic information not contained in the DNA sequence, including variations in sperm and oocyte cytosine methylation and chromatin patterning, noncoding RNAs, and mitochondria. Transgenerational epigenetic effects interact with conditions at conception to program the developmental trajectory of the embryo and fetus, ultimately affecting the lifetime health of the child. These insights compel us to revise generally held notions to accommodate the prospect that biological parenting commences well before birth, even prior to conception.
When Apple announced the iPhone 4S on October 4, 2011, the headlines were not about its speedy A5 chip or improved camera. Instead they focused on an unusual new feature: an intelligent assistant, dubbed Siri. At first Siri, endowed with a female voice, seemed almost human in the way she understood what you said to her and responded, an advance in artificial intelligence that seemed to place us on a fast track to the Singularity. She was brilliant at fulfilling certain requests, like “Can you set the alarm for 6:30?” or “Call Diane’s mobile phone.” And she had a personality: If you asked her if there was a God, she would demur with deft wisdom. “My policy is the separation of spirit and silicon,” she’d say.
Over the next few months, however, Siri’s limitations became apparent. Ask her to book a plane trip and she would point to travel websites—but she wouldn’t give flight options, let alone secure you a seat. Ask her to buy a copy of Lee Child’s new book and she would draw a blank, despite the fact that Apple sells it. Though Apple has since extended Siri’s powers—to make an OpenTable restaurant reservation, for example—she still can’t do something as simple as booking a table on the next available night in your schedule. She knows how to check your calendar and she knows how to use OpenTable. But putting those things together is, at the moment, beyond her.
Now a small team of engineers at a stealth startup called Viv Labs claims to be on the verge of realizing an advanced form of AI that removes those limitations. Whereas Siri can only perform tasks that Apple engineers explicitly implement, this new program, they say, will be able to teach itself, giving it almost limitless capabilities. In time, they assert, their creation will be able to use your personal preferences and a near-infinite web of connections to answer almost any query and perform almost any function.
“Siri is chapter one of a much longer, bigger story,” says Dag Kittlaus, one of Viv’s cofounders. He should know. Before working on Viv, he helped create Siri. So did his fellow cofounders, Adam Cheyer and Chris Brigham.
For the past two years, the team has been working on Viv Labs’ product—also named Viv, after the Latin root meaning live. Their project has been draped in secrecy, but the few outsiders who have gotten a look speak about it in rapturous terms. “The vision is very significant,” says Oren Etzioni, a renowned AI expert who heads the Allen Institute for Artificial Intelligence. “If this team is successful, we are looking at the future of intelligent agents and a multibillion-dollar industry.”
Research suggests that reducing or neutralizing one variety of the APOE gene would not harm the brain, while making Alzheimer’s less likely.
The 40-year-old man showed up in Dr. Mary Malloy’s clinic with sadly disfiguring symptoms. His hands, elbows, ears and feet were blemished with protruding pustules and tuber-like welts, some so painful it was hard for him to walk. He suffered from a rare genetic condition called dysbetalipoproteinemia, which caused his cholesterol levels to soar so high that pools of fatty tissue seemed to bubble up under his skin.
But there was something else about this patient. He was missing a gene that, when present in one form, greatly increases the risk of developing Alzheimer’s disease. Dr. Malloy, who co-directs the Adult Lipid Clinic at the University of California, San Francisco, and her colleagues saw an opportunity to answer an important neurological riddle: Does the absence of the gene — named apolipoprotein E, or APOE, after the protein it encodes — hurt the brain?
If a person with this rare condition were found to be functioning normally, that would suggest support for a new direction in Alzheimer’s treatment. It would mean that efforts — already being explored by dementia experts — to prevent Alzheimer’s by reducing, eliminating or neutralizing the effects of the most dangerous version of APOE might succeed without causing other problems in the brain.
The researchers, who reported their findings on Monday in the journal JAMA Neurology, discovered exactly that. They ran a battery of tests, including cognitive assessments, brain imaging and cerebrospinal fluid analyses. The man’s levels of beta-amyloid and tau proteins, which are markers of Alzheimer’s, gave no indication of neurological disease. His brain size was unaffected, and the white matter was healthy. His thinking and memory skills were generally normal.
“This particular case tells us you can actually live without any APOE in the brain,” said Dr. Joachim Herz, a neuroscientist and molecular geneticist at University of Texas Southwestern Medical Center, who was not involved in the research. “So if they were to develop anti-APOE therapies for Alzheimer’s, we would not have to worry about serious neurological side effects.”
In the movie “Terminator 2,” the shape-shifting T-1000 robot morphs into a liquid state to squeeze through tight spaces or to repair itself when harmed.
Now a phase-changing material built from wax and foam, and capable of switching between hard and soft states, could allow even low-cost robots to perform the same feat.
The material — developed by Anette Hosoi, a professor of mechanical engineering and applied mathematics at MIT, and her former graduate student Nadia Cheng, alongside researchers at the Max Planck Institute for Dynamics and Self-Organization and Stony Brook University — could be used to build deformable surgical robots. The robots could move through the body to reach a particular point without damaging any of the organs or vessels along the way.
Robots built from the material, which is described in a new paper in the journal Macromolecular Materials and Engineering, could also be used in search-and-rescue operations to squeeze through rubble looking for survivors, Hosoi says.
he worst outbreak of Ebola, which has killed 961 people and triggered an international public health emergency, may have started with a 2-year-old patient in a village in Guinea.
About eight months ago, the toddler, whom researchers believe may have been Patient Zero, suffered fever, black stool and vomiting. Just four days after showing the painful symptoms, the child died on December 6, 2013, according to a report published in The New England Journal of Medicine.
Scientists don't know exactly how the toddler contracted the virus. Ebola is spread from animals to humans through infected fluids or tissue, according to the World Health Organization.
"In Africa, infection has been documented through the handling of infected chimpanzees, gorillas, fruit bats, monkeys, forest antelope and porcupines," WHO says, though researchers think fruit bats are what they call the virus's "natural host."
After the child's death, the mother suffered bleeding symptoms and died on December 13, according to the report. Then, the toddler's 3-year-old sister died on December 29, with symptoms including fever, vomiting and black diarrhea. The illness subsequently affected the toddler's grandmother, who died on January 1, in the family's village of Meliandou in Guéckédou.
The area in southern Guinea is close to the Sierra Leone and Liberia borders. The illness spread outside their village after several people attended the grandmother's funeral. Funerals tend to bring people in close contact with the body. Ebola spreads from person to person through contact with organs and bodily fluids such as blood, saliva, urine and other secretions of infected people. It has no known cure.
Researchers at the Salk Institute say they have discovered a key control mechanism on regulatory T cells (Tregs) that determine if they send a halt signal to killer T cells during a pathogenic attack on the immune system. The new research (“Function of a Foxp3 cis-Element in Protecting Regulatory T Cell Identity”), published in Cell, could help develop treatments for autoimmune disorders as well as some types of cancer, according to the scientists.
When faced with pathogens, the immune system summons a swarm of cells made up of Tregs and killer T cells. Basically, Tregs tell killer T cells to halt “their attack” when invaders are cleared. Without this signal killer T cells continue their activities and turn on the body, causing inflammation and autoimmune disorders such as allergies, asthma, rheumatoid arthritis, multiple sclerosis, and type 1 diabetes.
“We discovered a mechanism responsible for stabilizing the cells that maintain immune system balance,” said senior author Ye Zheng, Salk Ph.D., assistant professor and holder of the Hearst Foundation Developmental Chair. “The immune system plays a huge role in chronic inflammation and if we can better understand the immune system, we can start to understand and treat many diseases.”
Tregs are like the surveillance system of the immune response, noted Dr. Zheng, adding that this surveillance system is “key to healthy immune reactions, but it can be kicked into overdrive or turned entirely off.” For about a decade, researchers knew that the key to Tregs' peacekeeping ability was the Foxp3 gene, but they weren't sure how exactly it worked. Scientists also knew that under certain conditions, Tregs can go rogue: They transform into killer T cells and join in the immune system battle. This change means that they lose the ability to send a “halt” signal and add to inflammation.
In the new paper, Dr. Zheng's lab reports that a particular genetic sequence in Foxp3 is solely responsible for the stability of a Treg. If they removed the sequence, dubbed CNS2, Tregs became unstable and often morphed into killer T cells—the type of cell they are supposed to be controlling—resulting in autoimmune disease in animal models.
“Conserved noncoding sequence 2 (CNS2), a CpG-rich Foxp3 intronic cis-element specifically demethylated in mature Tregs, helps maintain immune homeostasis and limit autoimmune disease development by protecting Treg identity in response to signals that shape mature Treg functions and drive their initial differentiation,” wrote the researchers. “In activated Tregs, CNS2 helps protect Foxp3 expression from destabilizing cytokine conditions by sensing TCR/NFAT activation, which facilitates the interaction between CNS2 and Foxp3 promoter. Thus, epigenetically marked cis-elements can protect cell identity by sensing key environmental cues central to both cell identity formation and functional plasticity without interfering with initial cell differentiation.”
From their origins in the 1940s as sequestered, room-sized machines designed for military and scientific use, computers have made a rapid march into the mainstream, radically transforming industry, commerce, entertainment and governance while shrinking to become ubiquitous handheld portals to the world.
This progress has been driven by the industry's ability to continually innovate techniques for packing increasing amounts of computational circuitry into smaller and denser microchips. But with miniature computer processors now containing millions of closely-packed transistor components of near atomic size, chip designers are facing both engineering and fundamental limits that have become barriers to the continued improvement of computer performance. Have we reached the limits to computation?
In a review article in this week's issue of the journal Nature, Igor Markov of the University of Michigan reviews limiting factors in the development of computing systems to help determine what is achievable, identifying "loose" limits and viable opportunities for advancements through the use of emerging technologies. His research for this project was funded in part by the National Science Foundation (NSF).
"Just as the second law of thermodynamics was inspired by the discovery of heat engines during the industrial revolution, we are poised to identify fundamental laws that could enunciate the limits of computation in the present information age," says Sankar Basu, a program director in NSF's Computer and Information Science and Engineering Directorate. "Markov's paper revolves around this important intellectual question of our time and briefly touches upon most threads of scientific work leading up to it."
The article summarizes and examines limitations in the areas of manufacturing and engineering, design and validation, power and heat, time and space, and information and computational complexity.
Via Jocelyn Stoller