When people think of radioactivity, many imagine it converting cute, fluffy animals into scary, green, glowing mutants. But, that's just a myth. Radioactivity is invisible. The reason we associate radiation with "glowing green" is because many types of instrument dials (such as a clock face) were painted with radioluminescent paint, a mixture that contained a radioactive isotope (often radium) and other chemicals that would emit green light in response to the radiation. Similarly, while it is true that some nuclear power plants produce a hauntingly blue glow, this is not because the radioactive fuel itself is glowing, but because of a strange phenomenon known as Cherenkov radiation, in which particles moving faster than the speed of light emit photons, generally in the UV to blue light range.
However, this is not the whole story. The great radiation/color narrative has taken yet another twist. A team of scientists led by Zbyszek Boratyński has reported in the journal Scientific Reports that Chernobyl radiation has changed the hair color of local rodents.
To determine this, the team captured bank voles in the vicinity of the Chernobyl nuclear plant and measured the nearby soil radiation. Digital photographs were taken of the fur on the animals' backs, and the amount of red color was assessed. The authors found that voles exposed to greater levels of radiation had less red pigmentation. (See graph.)
Why this should be the case is not perfectly clear, but the authors propose an intriguing explanation. The production of red pigment (pheomelanin) requires the consumption of antioxidants. Protection of the body from free radicals, which are generated by radiation, also requires the consumption of antioxidants. So, the authors hypothesize that the rodents synthesize less red pigment in order to save antioxidants for a far more crucial purpose.
There is still much work to be done.
First, the correlation coefficient (r = -0.15) is rather weak. This implies that only about 2% of the observed variation in fur color is explainable by the radiation. (The authors did, however, use an alternate method on a sub-sample which showed a greater correlation.) Repeating the experiment with a larger sample may be necessary.
Second, the ecological significance is unknown. It is possible that voles with differently colored fur are more/less susceptible to predation, or it could be that slight changes in fur coloration have no effect whatsoever. The authors plan to investigate this further.
Finally, the proposed molecular mechanism needs to be verified.
Still, regardless of the outcome of their subsequent investigations, the authors appear to have gained an interesting insight on how animal life has learned to adapt to the less-than-ideal conditions at the Chernobyl disaster site.
Source: Zbyszek Boratyński et al. "Increased radiation from Chernobyl decreases the expression of red colouration in natural populations of bank voles (Myodes glareolus)." Scientific Reports 4: 7141. Published: 21-November-2014. doi:10.1038/srep07141
Belief in vampires was a global phenomenon. Cultures all over the world once believed that certain humans wander the Earth after their death, engaging in acts of decidedly anti-social behavior. Though most sophisticated scholars know that wooden stakes and sunlight work best, each culture had invented various methods of dispatching those vampires permanently into the afterlife.
For instance, in the 1600s and 1700s in Drawsko Pomorskie, a town in northwestern Poland, a suspected vampire was buried with a sickle across his body and/or a stone in his mouth. If the undead was to attempt a nightly prowl, the sickle would disembowel or decapitate him; if that didn't work, the stone would prevent him from biting anybody. Problem solved. (See photos below.)
But just who were these suspected vampires? What could one possibly do in life to become such a social outcast that your neighbors just assumed you might return from the grave to do them harm? The prevailing hypothesis is that these unlucky souls were immigrants. As is the case today, Europeans tended to view outsiders unfavorably. Foreigners are strange, and if anyone is going to turn into a vampire, surely it would be one of those oddballs who smelled weird and talked funny.
With this hypothesis in mind, American and Canadian researchers examined skeletons exhumed from a cemetery outside Drawsko Pomorskie in an excavation that began in 2008. Of the 285 inhabitants, six of them were suspected vampires. (Two of them are pictured above. The first photo depicts a skeleton with a sickle around its neck, while the second photo depicts a skull with a stone placed in its mouth.) Interestingly, the potential vampires were not segregated, but buried alongside everybody else.
At that time, northwestern Poland was a region that had a large number of immigrants. Therefore, the authors predicted that the six suspected vampires, due to their "outsider" status, were likely to be immigrants. To test this hypothesis, they examined strontium isotope ratios (Sr-87/Sr-86) in the skeleton's teeth. Because strontium is a Group II metal with two valence electrons, it chemically behaves like calcium, allowing it to take the place of calcium in bones and teeth. Sr-86 is a stable isotope, but Sr-87 slowly forms from the beta-decay of rubidium-87. (The half-life of rubidium-87 is 49 billion years.) Variations in the strontium isotope ratio generally result from differences in geographic location.
The region around Drawsko Pomorskie has a strontium istope ratio of about 0.710 to 0.711. If the skeletons of the potential vampires were indeed foreigners, the researchers would have found a different ratio in their teeth.
But they did not. This strongly implies that the skeletons were of locals, not foreigners. So, why did they receive postmortem anti-vampire therapy? The authors conclude:
Individuals ostracized during life for their strange physical features, those born out of wedlock or who remained unbaptized, and anyone whose death was unusual in some way – untimely, violent, the result of suicide, or even as the first to die in an infectious disease outbreak – all were considered vulnerable to reanimation after death.
One possibility the authors entertain is that the suspected vampires were the first victims of a cholera epidemic, but there is little evidence beyond historical speculation to support this.
Unfortunately, it appears for those souls destined to become vampires, death did not bring peace, but rather a continuation of their earthly tribulations.
Source: Gregoricka LA, Betsinger TK, Scott AB, Polcyn M. "Apotropaic Practices and the Undead: A Biogeochemical Assessment of Deviant Burials in Post-Medieval Poland." PLoS ONE 9(11): e113564. (2004) doi:10.1371/journal.pone.0113564
Indian scientists have coupled silver molecules with carbonate ions to hugely enhance the metal's antibacterial activities. If adopted, the unexpected breakthrough could save 1,300 tons of silver, worth roughly $766 million dollars, each year.
Silver is already widely used in medicine as well as the fields of food sanitation and water purification to the tune of around 6,000 tons per year, or about a quarter of annual production. A silver concentration of just 50 parts per billion in drinking water kills more than 99% of bacteria. For this reason, silver is used to disinfect drinking water in many developing countries and even onboard the International Space Station.
In an effort to improve the antimicrobial power of silver, the researchers added various anions to water containing 50 parts per billion of silver. Carbonate, composed of one carbon atom and three oxygen atoms, showed the most potential. Upon further experimentation, they found that a mixture of just 25 parts per billion of silver with the addition of a 20 parts per million of carbonate was enough to reduce E. coli levels in water 100,000 times over. 50 parts per billion of silver alone reduced E. coli amounts 100 times over.
Further testing elucidated why the pairing of silver and carbonate is so successful. Like a boxer strategically softening up his opponent, carbonate destabilizes bacteria's peripheral membrane proteins, allowing silver to sneak in and deliver its knockout blow with far less resistance.
Each year, diarrhea kills 760,000 children under the age of five. According to the World Health Organization, safe drinking water is one of the best ways to prevent the infection. The researchers are hopeful their discovery will make it easier to spread proper water sanitation throughout the developing world.
"This work leads to a new paradigm in the field of affordable water purification by reducing the cost of antimicrobial treatment, particularly in the developing world, without disinfection by-products."
Environmentalists also have reason to cheer the finding. Silver nanoparticles currently leach into oceans and rivers via waste treatment, and this may be damaging marine ecosystems by killing off the good bacteria that support them. Thus, lower silver concentrations in drinking water may be good news for marine bacteria.
(Image: Alchemist-hp, Swathy et. al.)
Source: Swathy, J.R. et al . Antimicrobial silver: An unprecedented anion effect. Sci. Rep. 4 , 7161; DOI:10.1038/srep07161 (2014)
Recently, there has been much talk of various "epidemics" in America. The three most commonly mentioned are suicide, gun violence, and drug overdose. A close examination of the data, however, reveals two surprises: First, one of them is not actually an epidemic. Second, one of them is a much bigger epidemic than most people realize. (See chart.)
The "suicide epidemic" (red line) has received the most attention as of late. This is for good reason. At a rate of 12.54 deaths per 100,000 Americans, the suicide rate is at a 25-year high. The CDC, which provides publicly accessible data (via WISQARS) from 1999 to 2012, shows that the suicide rate over that period has increased by nearly 19.7%.
Similarly, school shootings and other mass killings result in highly partisan debates about the "gun violence epidemic." However, the CDC data does not show that this even is an epidemic. Instead, the homicide-by-firearm rate (purple line) has been declining from a high of 4.27 per 100,000 in 2006 to 3.76 per 100,000 in 2012, a roughly 12% drop. The average American is more than three times as likely to commit suicide than to be shot and killed.
The most shocking data are the deaths due to unintentional drug poisonings (green line). From 1999 to 2012, deaths by drug overdose increased from 4.00 per 100,000 to 10.54 per 100,000, a whopping 164% increase. While the suicide rate has slowly climbed over the past decade, the death rate from unintentional drug overdoses has skyrocketed. Indeed, the term "epidemic" was invented for trend lines like this. (Note: More detailed information on what exactly constitutes unintentional drug poisoning can be found in the ICD-10 under codes X40-X49.)
It should be noted that accidental drug overdoses include far more people than just celebrities and gangbangers who snort cocaine and guzzle alcohol. Indeed, a substantial proportion of overdoses are with prescription drugs, such as opioids (e.g., OxyContin, Vicodin) and benzodiazepines (e.g., Xanax, Valium, Ativan). Additionally, as reported this week in an article appropriately titled "The Great American Relapse," The Economist notes that heroin is making a comeback. Deaths from heroin overdoses have doubled from 2010 to 2012 as opioid painkiller addicts forego expensive prescription meds for cheaper heroin from the street.
As it turns out, our society's habit of reaching for the medicine cabinet for every (heart)ache and pain is quite literally killing us.
The explosive growth in the number of deaths due to unintentional drug overdoses is nothing short of a national emergency. Yet, the phenomenon gets very little attention in the popular press. Unfortunately for our highly medicated society, this is one problem that we cannot solve by popping more pills.
Source: Centers for Disease Control and Prevention, National Center for Injury Prevention and Control. Accessed: 23-Nov-2014.
For decades, mankind's physical abilities have steadily increased. With every broken world record, humans have demonstrated the potential to throw farther, run faster, and jump higher. More recently, scientists, athletes, and spectators alike have wondered if or when we'll reach a ceiling. A new study published in PLoS ONE shows that, as far as distance running is concerned, we may be getting close.
Researchers from the University of Washington and the Mayo Clinic teamed up to analyze the 40 fastest male performances in the 5,000 meters, the 10,000 meters, and the marathon for each year from 1980 to 2003. They also tallied and plotted the number of athletes who turned in elite performances each year, deemed to be under 13:20 for the 5000 meters, 27:45 for the 10000 meters, and 2:10 for the marathon (shown below).
The researchers found that, for the past decade, performance in the 5,000 and 10,000-meter races has leveled off. In fact, there have been no new world records for either since 2004 and 2005 respectively, the longest gap between world records since the 1940s.
Men still seem to be making progress in the marathon, however. In fact, the world record (still pending official ratification) was set at the Berlin Marathon in September. Kenya's Dennis Kimetto ran the 26.2 miles in 2:02:57.
"All indices of [marathon] speed show a nearly linear increase in speed with an increased number of elite performances over the three plus decades we sampled," lead researcher Timothy Kruse reported.
Kruse and his colleagues announced three possible interpretations of the data. First, improved drug testing may be preventing athletes from using compounds like erythropoietin to boost the number of red blood cells in the blood stream and thus improve their aerobic capacity, a process colloquially known as "blood-doping." Second, more lucrative financial incentives for marathons may have drawn elite runners away from the 5,000 and 10,000-meter events. And third, men may be nearing a "physiological upper limit."
As men near the 2-hour mark for the marathon, which would require a blistering average speed of 13.1 miles per hour, many openly wonder whether or not that milestone will be eclipsed. If current trends continue, it's certainly possible.
Source: Kruse TN, Carter RE, Rosedahl JK, Joyner MJ (2014) Speed Trends in Male Distance Running. PLoS ONE 9(11): e112978. doi:10.1371/journal.pone.0112978
As Americans collectively remain overweight and obese, many scientists have sought to understand precisely why this is so. Most broadly, the answer is tied to socioenvironmental evolution, which encompasses a host of factors. For example, we're eating differently than we used to, we're eating more than we used to, and we're moving a lot less than we used to.
Now that we've gotten ourselves stuck in such a heavy state, scientists are concerned that it will be difficult to dislodge ourselves. Specifically, if studies in mice are any indication, obesity risk may be transferable to offspring via epigenetics. In other words, parental obesity may effect how children's genes are expressed, making kids more likely to store excess calories as fat and more likely to develop diabetes. Considering that the rate of childhood obesity has more than doubled in the past thirty years, this is certainly possibly. However, more research needs to be performed, to first convincingly confirm these effects in humans, and then to potentially create treatments to counter them.
Today, in the journal Mayo Clinic Proceedings, post-doctoral researcher Dr. Edward Archer of the University of Alabama provided a theoretical framework to help guide these efforts. He dubbed his idea the Maternal Resources Hypothesis. Formed via an analysis of the current scientific literature, it states that because mothers are, on average, eating more and exercising less than in years past, they are storing more energy as fat and passing on more nutrients to fetuses in utero, resulting in larger babies with more fat at birth. Larger babies, coupled with a more sedentary lifestyle during childhood, means that these children will be predisposed to obesity. Since the number of fat cells is largely set during childhood, obesity early on can elevate a person's risk for obesity for the rest of their life. If, indeed, these children remain obese into adulthood and have children, the cycle continues.
Archer's hypothesis is intriguing. Now that it's out there, future studies will either confirm or refute it.
If it does prove correct, Archer believes that it highlights a key tool to alleviating the current obesity pandemic. He urges women planning on motherhood to be physically active throughout their entire lives in order to prepare their metabolisms for pregnancy and thus have metabolically healthy children.
"Active moms are the cure," Archer said.
The onus for obesity isn't only on moms, however. Last year, a study showed that children born to obese fathers had discernible differences in gene expression compared to children born to normal weight fathers.
Would-be moms and dads should strongly consider living a lifestyle that involves eating less and moving more. Not just for themselves, but for their kids.
Source: Archer, Edward. "The Childhood Obesity Epidemic as a Result of Nongenetic Evolution: The Maternal Resources Hypothesis." Mayo Clin Proc. n Dec 2014; http://dx.doi.org/10.1016/j.mayocp.2014.08.006
Biologists have categorized life into three large domains: Bacteria, Archaea (weird, bacteria-like microbes), and Eukarya (unicellular and multicellular organisms such as fungi, plants, and animals that possess nucleated cells). Under this classification system, viruses are left out in the cold. They certainly are not "alive" in the classical sense because they are not capable of metabolizing or replicating on their own. But it does not feel quite right to classify them as "inanimate," either, because they are built of biological molecules and contain genetic information. Thus, for the most part, viruses languish in the no man's land between the living and the dead.
The debate about how to classify viruses received a jolt with the discovery of extremely large viruses (such as Pandoravirus) that are so gigantic they can be seen with a light microscope and contain more genetic information than some bacteria. It has been proposed, due to some intriguing similarities in DNA sequences -- specifically, in the gene that encodes for an enzyme called RNA polymerase -- that such large viruses actually constitute a "fourth domain" of life. If that is the case, then perhaps all viruses should be awarded this new status.
"Sacrebleu!" say French scientists in a recent issue of Trends in Microbiology. Considering viruses to be a fourth domain would unnecessarily complicate evolutionary biology. For instance, the authors indicate that using RNA polymerase to redraw the tree of life presents a gigantic challenge. Large viruses do not all cluster into a single new domain. Instead, classifying life based on RNA polymerase would likely demand the creation of several new domains. (See figure.)
Such a phylogenetic tree is unwieldy, or as evolutionary biologists call it, "non-parsimonious." A foundation of building evolutionary trees is that they ought to be as simple as possible. This is referred to by scientists as the principle of parsimony but is more colloquially known as Occam's Razor. Essentially, a model that requires fewer assumptions (in this case, evolutionary changes) is superior to a model that requires more.
This is not the only problem with a viral fourth domain. The biggest difference between cells and viruses is their method of replication. All three domains of life replicate by cell division, which implies that this trait was derived from the Last Universal Common Ancestor (LUCA). (In other words, LUCA is the theoretical ancestor of Bacteria, Arcahea, and Eukarya.)
Viruses, which do not replicate by cell division, probably evolved independently multiple times, "here, there, and everywhere," as the authors conclude. Some probably evolved before LUCA, and others well after LUCA. Many have likely exchanged genetic material via horizontal gene transfer. Lumping them all into a fourth domain, therefore, makes little sense.
Though the debate over the classification of viruses may at first seem to be purely academic, it touches upon underlying questions that are of much greater significance: What exactly is life, and how did it evolve? The answer to those questions may be partially found within the enigmatic world of the viruses.
Source: Patrick Forterre, Mart Krupovic, and David Prangishvili. "Cellular domains and viral lineages." Trends in Microbiology, 22 (10): 554-558. October 2014.
Around 252 million years ago, a Great Dying occurred. In a geologic blink of an eye, 96% of all marine species and 70% of all terrestrial species went extinct. Volcanoes, rapid climate change, or an asteroid impact may have been to blame; it could have even been all of the above. Regardless of what caused the Great Dying, the effect was akin to hitting a giant "reset" button on Earth. The planet became a blank slate, and new species emerged to write their stories.
It was in this setting that paleontologists believe that Garjainia madiba, a newly discovered species of reptile, thrived. G. madiba belonged to the Erythrosuchidae family, a group of apex predators that gained a widespread foothold on the new Earth. Closely related to modern day Crocodilians, the erythrosuchids are known for their distinct, large, and deep head, making them kind of "cute." The largest among them was Erythrosuchus, which sported a massive head on a squat frame. Erythrosuchus was 16 feet long and 7 feet tall.
G. madiba was big, but it wasn't that big. Estimates put its length at around 6 feet. The smaller size likely suited it just fine, however. In the wake of the Great Dying, much of the bigger land animals had died off, so G. madiba may have been one of the largest at the time. Geologically, it's been pinned down as the oldest known erythrosuchid in the southern hemisphere. Larger species like Erythrosuchus likely evolved later on.
The current G. madiba fossil was found in South Africa, but another was found in Europe. To the group of paleontologists who described the discovery yesterday in PLoS ONE, that demonstrates "that erythrosuchids became established as the largest terrestrial predators across a broad swath of Pangaea within five million years of the end-Permian mass extinction event."
(Images: Mark Witton, Dmitry Bogdanov)
Source: Gower DJ, Hancox PJ, Botha-Brink J, Sennikov AG, Butler RJ (2014) A New Species of Garjainia Ochev, 1958 (Diapsida: Archosauriformes: Erythrosuchidae) from the Early Triassic of South Africa. PLoS ONE 9(11): e111154. doi:10.1371/journal.pone.0111154
Mind control -- specifically, the ability to manipulate machines or the environment through the power of our thoughts -- has long been the fascination of sci-fi enthusiasts. Now, a team of European researchers has made a giant leap toward turning this sci-fi fantasy into reality: They have demonstrated human mind control of gene expression in a mouse. And, they used some of the best tools of neuroscience, physics and synthetic biology to accomplish it.
Volunteers were trained how to generate different mental states, such as concentration or meditation, which produce fluctuations in neuronal voltage that are more commonly known as brain waves. Subjects wore an EEG (electroencephalography) headset that detected the brain waves and interpreted the mental state. The data was then sent, via Bluetooth (the same technology that connects a smartphone to a wireless headset or to a car stereo), to a small computer. Based on the mental state, the computer sent either an ON or OFF signal to an electromagnetic field generator. (See diagram below.)
When the subject was meditating, the field generator was sent an ON signal, and it created an alternating magnetic field. This allowed the authors to utilize wireless energy transfer which, as its name implies, powers a device without the use of wires. The alternating magnetic field created by the transmitter coil induced an electric current in a receiver coil, which ultimately powers the device. (This phenomenon, known as induction, is also used to power electric toothbrushes and alerts stoplights to the presence of a car.) In this case, the device is a special implant placed on the back of a mouse under its skin. When the implant was powered, it turned on a near-infrared light.
The light, in turn, activated a pathway genetically engineered into cells that were also placed inside the implant in a cultivation chamber. (See diagram below.)
The photons activated a protein (DGCL) taken from the photosynthetic bacterium Rhodobacter. When exposed to near-infrared light, the protein creates a metabolite called c-di-GMP, which is sensed by a protein receptor called STING. Ultimately, STING results in the activation of yet another genetically engineered gene that encodes an enzyme called SEAP. This enzyme was secreted into the blood of the mouse, and its presence could be detected with a simple chemiluminescence assay.
In summary: Brain waves --> Bluetooth (microwave photons) --> Electric current --> Magnetic field --> Another electric current (in the implant) --> Near-infrared photons --> Activation of cellular genetic pathway --> Enzyme produced and secreted into the blood.
Immediate applications for this technology are probably still years (decades) away. But, the idea of altering gene expression by the power of thought alone is both intriguing and frightening.
Source: Marc Folcher et al. "Mind-controlled transgene expression by a wireless-powered optogenetic designer cell implant." Nature Communications 5:5392. Published online: 11-Nov-2014. DOI: 10.1038/ncomms6392
In 1998, researchers using the Hubble Space Telescope made an astounding discovery. Gazing at the Virgo Cluster of galaxies a dizzying 53.8 million light years distant, they spotted 600 red giant stars adrift in intergalactic space. Ripped from their home galaxies during tumultuous collisions with others, the stars were no longer governed predominantly by the gravity of one galaxy, but by the faint, distant pulls of many. Artists imagined the skies of planets in orbit around these lonely stars: blank and dark, flecked only with the "fuzzy apparitions" of nearby galaxies.
At the time, the study's lead astronomer Harry Ferguson estimated that there might be as many as 10 million more of these "rogue" stars in the Virgo Cluster, stars less luminous than red giants and thus too indistinct to see with any certainty. A new report published in the journal Science shows that Ferguson may have vastly underestimated their number.
According to the study, as many as half of the universe's stars may dwell outside of galaxies, representing a stellar population previously unknown to science!
Caltech astrophysicist Michael Zemcov led the international team of researchers that contributed to the fascinating finding, which materialized out of an effort to explain fluctuations in the Extragalactic Infrared Background light (EBL), basically all of the accumulated radiation in the universe resulting from star formation. Analyzing data collected from the CIBER mission, an orbiting instrument with tools specifically designed to observe the EBL, the researchers determined that light from stars stripped from their galaxies best explained the fluctuations, ruling out effects from primordial galaxies and black holes in the process.
"If confirmed, these observations reveal an unexpected stellar population, with as many as half the stars in the local universe being outside galaxies," NASA astronomer Harvey Moseley commented. "It is remarkable that such a major component of the universe could have been hiding in plain sight as an infrared background between the stars and galaxies."
The presence of all these intergalactic stars would also help explain another peculiar mystery, Zemcov notes. Currently, the light produced from known populations of galaxies and quasars is not nearly enough to explain observations of hydrogen, which serves as an accurate proxy for the amount of light in the universe. In other words, there are far more photons of light than there should be. The quandary has been termed the "photon underproduction crisis."
The Carnegie Institute of Washington’s Juna Kollmeier described the baffling puzzle thusly: "It's as if you're in a big, brightly-lit room, but you look around and see only a few 40-watt lightbulbs."
The stars residing outside of galaxies could very well be those missing lightbulbs, or at least some of them anyway.
Stars go rogue when they are ejected from their home galaxies as a result of galaxy collisions. In the cosmic sense, interactions between the one hundred billion galaxies in the known universe are actually quite common, and have likely occurred many, many times over the 13.8 billion year lifespan of the universe. Our own Milky Way Galaxy is set to collide with the Andromeda Galaxy in roughly four billion years. Seeing as how our sun will still be around by that time, it potentially could join the newly found and immense population of intergalactic stars, and the Earth may find itself along for the ride.
Source: Zemcov et. al. "On the origin of near-infrared extragalactic background light anisotropy." Science 7 NOVEMBER 2014 • VOL 346 ISSUE 6210
(Image: H. Ferguson (STScI), N. Tanvir (IoA), T. von Hippel (U. Wisc.), NASA)