It now appears that women can pass Zika virus to men through sex.
U.S. health officials have reported the first known case of female-to-male sexual transmission of Zika virus. The woman, who was not pregnant, had traveled to a Zika-afflicted region, the U.S. Centers of Disease Control and Prevention reports July 15. On the day of her return to New York City, she had vaginal intercourse with a male partner, who wasn’t wearing a condom.
Three days later, after developing a rash, fever and other symptoms, doctors detected Zika virus RNA in her blood and urine. A week after sex, the woman’s partner, who had not recently traveled outside the United States and had not noticed any mosquito bites, developed similar symptoms. Tests revealed that he also had Zika RNA in his urine.
Scientists knew that men could transmit Zika to women through sex, and had hints that reverse was true as well. Earlier this month, researchers detected Zika RNA in the genital tract of an infected woman.
When the brain runs low on oxygen, red blood cells sense the deficit and hurl themselves through capillaries to deliver their cargo. That reaction, described online August 4 in Neuron, suggests that red blood cells can both detect and remedy low oxygen.
When researchers stimulated the feet of mice, nerve cells fired off signals in the corresponding part of the brain, depleting that area’s oxygen. Red blood cells in capillaries picked up their speed in response. And in artificial capillaries, the lower the oxygen, the faster the red blood cells moved, Jiandi Wan of the Rochester Institute of Technology in New York and colleagues found. That swiftness was caused by the cells becoming more flexible, a bendiness that let them squeeze through narrow capillaries faster. When researchers stiffened red blood cells with a chemical, the effect of low oxygen on speed disappeared.
The results reinforce the complex and important role of blood in the brain. The findings might ultimately be relevant for disorders in which the link between neural activity and blood flow is damaged, including Alzheimer’s disease, says study coauthor Maiken Nedergaard of the University of Rochester Medical Center.
The annual Perseid meteor shower, which peaks on the morning of August 12, might be more dazzling than usual this year. Researchers predict that up to 200 meteors per hour could race across the sky — roughly double the typical rate — as Earth plows through debris left behind by comet 109P/Swift-Tuttle.
Earth usually grazes the edge of the debris stream, home to pieces that flake off the comet during its 133-year journey around the sun. But this year Jupiter’s gravity might have nudged the debris so that Earth passes closer to the center of the swarm.
While the shower peaks tonight, Perseid meteors will be visible for at least two more nights. No special equipment is needed to watch the shower. Just find a dark sky, away from lights, get comfortable and look up. The best time to watch the storm will be between midnight and dawn.
In a macabre twist, the hominid evolutionary tree’s most famous fossil star, Lucy, tumbled to her death from high up in a tree, a controversial new study suggests.
Some of the damage to Lucy’s 3.2-million-year-old partial skeleton most likely occurred when she fell from a height of 13 meters or more, say paleoanthropologist John Kappelman of the University of Texas at Austin and his colleagues. Lucy, an ancient ambassador of a prehuman species called Australopithecus afarensis, must have accidentally plunged from a tree while climbing or sleeping, the scientists propose online August 29 in Nature. Bone breaks from head to ankle fit a scenario in which Lucy dropped the equivalent of least four to five stories, landing feet first before thrusting her arms out in an attempt to break her fall, Kappelman says. Tellingly, the ancient female’s right shoulder blade slammed into the top of her upper arm bone, Kappelman says. The shoulder end of Lucy’s arm bone displays sharp breaks, as well as bone fragments and slivers forcibly driven into the shaft. Such damage frequently appears in present-day people who fall from great heights or are in serious car accidents, Kappelman says. Massive internal bleeding typically follows a body slam as hard as Lucy’s, he adds.
“Lucy probably bled out pretty fast after falling,” Kappelman says. Nonsense, responds paleoanthropologist Tim White of the University of California, Berkeley. He calls the new paper “a classic example of paleoanthropological storytelling being used as clickbait for a commercial journal eager for media coverage.”
Cracks and breaks throughout Lucy’s skeleton occurred after her death, White asserts. Bone cracking was caused by fossilization and by pressure on fossils embedded in eroding sandstone. Fossilization-related breakage much like Lucy’s — including extensive shoulder-joint damage — appears on the bones of a variety of nonclimbing animals, including gazelles, hippos and rhinos, White says. When people accidentally fall from heights between two and 21 meters, he adds, physicians have documented frequent fractures of the spine, head, elbows, wrists, ankles and feet — but not the shoulders.
Scientists have been unable to decipher how Lucy died since her 1974 discovery in Ethiopia by anthropologist Donald Johanson of Arizona State University in Tempe and his graduate student at that time, Tom Gray. A Johanson-led team, which included White, attributed Lucy’s bone damage primarily to fossilization in a 1982 report.
Intrigued by extensive crushing and breakage at Lucy’s right shoulder joint, Kappelman consulted orthopedic surgeon and study coauthor Stephen Pearce of the Austin Bone and Joint Clinic. When shown a 3-D printed model of Lucy’s skeleton enlarged to the size of a modern human adult (Lucy stood only about 107 centimeters tall, or 3 feet, 6 inches), Pearce said the arm damage looked like that caused by an individual extending an arm to break a steep fall.
Kappelman and colleagues then scoured high-resolution CT scans of Lucy’s bones obtained in 2008, when the ancient skeleton was brought to the University of Texas during a U.S. museum tour.
Along with the upper right arm bone and shoulder blade, damage consistent with hitting the ground after a long fall appeared in bones from an ankle, legs, pelvis, lower back, ribs, jaw and braincase, the researchers say. Fossilization and geological forces caused additional cracking and breaks on Lucy’s remains, as described in the 1982 report, they add. Although initially skeptical that cause of death could be discerned in a fossil individual as old as Lucy, paleoanthropologist William Jungers of the Stony Brook University Medical Center in New York says the evidence indeed points to a fatal fall. No other explanation can account for Lucy’s pattern of bone damage, he says.
If Lucy toppled out of a tree while climbing or snoozing in a nest, her kind must have split time between life on the ground and in trees, Kappelman says. Some researchers have long argued that A. afarensis was built mainly for walking (SN: 12/1/12, p. 16).
Even today, Jungers says, deaths from accidental falls out of trees occur among some African hunter-gatherers, especially when raiding bee’s nests for honey (SN: 8/20/16, p. 10), and in wild chimps, animals more adept at tree climbing than Lucy was.
Lucy’s species could climb trees, White says, but “we do not know how often, or whether for shelter or food.”
As chief scientist for a voyage of the research vessel Endeavor, oceanographer Melissa Omand oversaw everything from the deployment of robotic submarines to crew-member bunk assignments. The November 2015 expedition 150 kilometers off Rhode Island’s coast was collecting data for Omand’s ongoing investigations of the fate of carbon dioxide soaked up by the ocean.
But Omand, an assistant professor at the University of Rhode Island’s campus in Narragansett, wasn’t on the ship. Instead of riding the waves with her crew, she was working, sometimes 16-hour days, inside a dark room at the university’s Inner Space Center — staring at computer monitors in a sort of NASA mission control for oceanographers. When she submitted the trip proposal a year earlier, she hadn’t foreseen that she’d be eight months pregnant with her first child when the ship set sail. Still, missing the trip was unthinkable, she says. The Inner Space Center, she realized, offered a way to direct the mission from shore via satellite. After proposing the solution to her higher-ups, and a lot of meetings that followed, she got permission to be the first chief scientist to remotely lead an Endeavor cruise.
“She doesn’t let many obstacles get in her way,” says Colleen Durkin, an oceanographer at Moss Landing Marine Laboratories in California, who participated in the cruise. “That’s one of the fun things about working with her. She’s willing to try new things.” Her commitment to her science and her drive to find creative solutions are helping Omand tackle a big problem in oceanography. For a decade, she has been studying the mechanisms — such as currents and the dining and dying of microorganisms — that move carbon and nutrients through the ocean. In a breakout paper, published last year in Science, she reported the discovery that eddies can pull carbon from phytoplankton deep into the ocean, a previously undescribed phenomenon. Studying the fate of that carbon isn’t just interesting, she says, it’s vital to predicting the fate of our climate. “The ocean has a huge capacity to absorb excess carbon dioxide in our atmosphere,” Omand says. But as the planet warms, atmosphere and ocean might interact differently. Scientists need all the information they can get to figure out how to adapt to those changing conditions and mitigate the effects of climate change.
Omand, 36, first got her feet wet on the rivers and lakes surrounding her hometown of Toronto. In her teens, she worked as a canoe guide, exploring the region’s waterways. “That was absolutely the root of my interest in earth science and environmental issues,” she says. “I’m essentially doing the same thing now, just on a much bigger boat.”
After starting off as a premed student at the University of Guelph in Canada, she was ultimately drawn to the university’s physics program. “I found it very satisfying that all these problems boiled down to a few underlying rules and equations,” she says. During her undergraduate studies, her focus was millions and millions of kilometers away from Earth’s oceans. She coded software used to help calibrate X-ray instruments on NASA’s Mars Exploration Rovers, which identified the makeup of Martian rocks. While considering areas of physics for her graduate studies, Omand received an email that altered her heading. Chris Garrett, a professor (now emeritus) at Canada’s University of Victoria, introduced her to physical oceanography. “He showed me demonstrations of what happens to dye in a rotating water tank,” she recalls. “I was hooked by that.” The churning of water appealed to Omand for the same reason the field of physics did: Whether in tanks or oceans, the water’s movements can be expressed by a set of specific equations, called the Navier-Stokes equations.
Omand has applied these equations in much of her work. During a Ph.D. at the Scripps Institution of Oceanography in La Jolla, Calif., she and colleagues studied the origins of a red tide off California’s coast. The team found that the red tide, fertilized by a layer of nutrients, had been festering under the ocean surface for a week before being drawn upward. Omand and her colleagues used a Jet Ski modified with a GPS system and scientific instruments to collect data. Later, as a postdoctoral researcher at Woods Hole Oceanographic Institution in Massachusetts, she and mentor Amala Mahadevan investigated mechanisms to explain how nitrogen, an important nutrient for phytoplankton, moves around below the sunlit layer of the sea.
During her time at Woods Hole, Omand also started tracking the journey of CO2 taken in by springtime algae blooms in the North Atlantic. When the phytoplankton in these colossal blooms, which can stretch hundreds of kilometers across, die or are digested by other marine life, particles containing organic carbon are released into the water. The heavier of these particles sink, quarantining the carbon from the atmosphere. About 30 percent of all CO2 emitted by human activities has ended up in the oceans, thanks in part to these sinking particles.
Scientists had believed that smaller particles would remain near the surface. But with robotic submarines called gliders that cruised up and down the water column sensing light scattered by the particles, Omand and colleagues found a surprisingly large amount of small carbon particles. These particles were around 100 to 350 meters deep, in the ocean’s “twilight zone,” where phytoplankton rarely live. Omand combined measurements such as temperature and salinity from several gliders to explain how the particles got pulled so far down. By analyzing those measurements alongside computer simulations and satellite data — an innovative mix of sources that provided finer details and the bigger picture — she showed that the carbon-rich particles were carried down by spiraling ocean currents called eddies. Water escaping these bowl-shaped depressions can become sandwiched between deeper ocean layers, remaining trapped along with any particles even once an eddy subsides.
The accompanying carbon drain cools the Earth, says Eric D’Asaro, an oceanographer at the University of Washington in Seattle who collaborated with Omand on the research. Though the finding doesn’t change the total amount of carbon known to be taken in, the study identifies a new mechanism that could account for as much as half of all carbon known to be pulled into the deep North Atlantic during spring. The mechanism could also play a role elsewhere in the world’s oceans, D’Asaro, Omand and colleagues reported in April 2015 in Science.
“Her work sets the table for the next decade in terms of understanding the interaction between the turbulence of the ocean and how carbon is injected down to depth,” says David Siegel, an oceanographer from the University of California, Santa Barbara. “She’s going to be one of the new leaders of this field.”
Now a mother — her daughter was born a few weeks after the cruise — and an assistant professor at the University of Rhode Island, Omand continues her creative problem-solving, often by calling on unexpected technology. On a research trip in June (she was on the ship this time), Omand used an iPhone in a waterproof case to automatically snap pictures every half hour of particles raining down from the ocean’s top layer. Scientists previously measured the rates of sinking particles with traps that provided no information about how the rates changed throughout the day. Omand got the idea to affix her old iPhone to the traps after being offered only $40 for the used phone. “There’s got to be something really amazing I can do with this,” she thought.
Next spring, Omand will harness the same telepresence software she used for the 2015 Endeavor trip to virtually take undergraduate students on board. Omand’s ability to harness technology to solve tricky scientific challenges is a big reason why she can identify new truths about our oceans, says Mahadevan. “Every problem she touches,” Mahadevan says, “something beautiful comes out.”
Mercury has gotten some new wrinkles in its old age. The innermost planet shows signs of relatively recent tectonic activity, a new study suggests.
Tiny cliffs on the surface — just tens of meters high and a few kilometers long — resemble breaks in the planet’s crust, researchers report online September 26 in Nature Geoscience. The diminutive sizes of the cliffs, their sharp edges and lack of large overlapping craters imply that the faults are geologically young — less than 50 million years old. That’s much younger than Mercury’s larger, eroded scarps seen elsewhere, which probably arose more than 3.5 billion years ago. The small scarps indicate that the surface still fractures as Mercury cools and contracts, the researchers suggest, though other explanations are possible. Thomas Watters, a geologist at the Smithsonian Institution in Washington, D.C., and colleagues discovered the young escarpments in images taken by NASA’s MESSENGER spacecraft, which orbited Mercury from 2011 to 2015. During the last 18 months of the mission, the spacecraft inched closer to the surface of Mercury, revealing new details such as these small scarps. The mission ended with an intentional crash landing on April 30, 2015 (SN Online: 4/30/15).
Mercury’s continued contraction isn’t surprising, says Sean Solomon, a planetary scientist at Columbia University. “It’s demanded by physics,” he says. Mercury has gradually cooled over its 4.6-billion-year history. As it cools, it shrinks. Sometimes that shrinkage cracks the surface. All of the other rocky planets shrivel over time as well, but their atmospheres have erased much of the evidence. Only on Mercury and the moon — both airless — is the history of contraction preserved because of limited erosion.
It’s not clear, though, if these new faults are related to that shrinking. “In and of themselves, they don’t tell us very much,” says Paul Byrne, a planetary geologist at North Carolina State University in Raleigh. Without an analysis of how the small, young scarps relate to the large, old scarps, he says, it’s hard to draw conclusions. The new arrivals could just as well be produced by shifting rubble or shock waves from run-ins with asteroids, and if so would not be a sign of continuing tectonic activity.
A closer inspection of Mercury will have to wait until the European spacecraft BepiColombo, scheduled to launch in 2018, arrives in late 2024. While its altitude will be similar to MESSENGER’s, BepiColombo will get a better look at Mercury’s southern hemisphere, which should allow researchers to get a more global view of how all these wrinkles in the surface tie together.
Metallic odyssey Scientists are getting closer to turning hydrogen into a solid metal, Emily Conover reported in “Chasing a devious metal” (SN: 8/20/16, p. 18).
“If, as some scientists think, [metallic hydrogen] formed under intense pressure remains solid at room temperature, why don’t we find any on our planet?” asked Michael Brostek. “If formed in a star that subsequently explodes, wouldn’t some make its way to us like other elements we have that were formed within stars? “We do not believe that conditions exist in stars for solid metallic hydrogen to form,” says Harvard University physicist Isaac Silvera. “The temperatures are too high.” Above a certain temperature, solid metallic hydrogen would convert to a more stable phase. If that transition temperature is low enough, it could explain why we don’t see metallic hydrogen on Earth.
The relationship between metallic hydrogen and everyday hydrogen is similar to the relationship between diamond and graphite, a more stable phase. “If diamond is heated to a few thousand degrees Kelvin, it will convert to graphite,” Silvera says. “I do not recommend experimenting with a valuable stone!”
Pass the salt In “Quenching society’s thirst” (SN: 8/20/16, p. 22), Thomas Sumner reported on next-generation desalination technologies that use improved and energy-efficient materials. Desalination efforts could help meet the world’s growing need for freshwater.
Reader Sallie Reynolds wondered what happens to the salt left behind. Most desalination plants end up with briny leftover water that they pump deep underground (away from sources of drinking water) or dilute into a nearby water source, such as the ocean. But some facilities extract salt crystals from the desalination leftovers using evaporation ponds. In solid form, the salt can be stored, transported or dumped at landfills. “This salt could potentially be used for industrial purposes, such as glassmaking, tanning, metal refining and cement manufacturing,” Sumner says. “The downside of evaporation ponds is that you need a lot of available space and a relatively warm, dry climate.”
Sun spotting The sun’s magnetic field rises to the surface no faster than about 500 kilometers per hour — the same speed that gas rises and falls within the sun. Moving gas may help guide the field, Christopher Crockett reported in “Gas steers sun’s magnetic fields” (SN: 8/20/16, p. 5).
Mary Jane Knox wondered whether planets, moons and other celestial bodies in the solar system might contribute to the formation of sunspots and other solar activity: “Could they be reflecting the sun’s rays back on it causing hot spots which might allow the eruption of the magnetic fields?”
Planets don’t have anything to do with dark spots on our sun, Crockett says. Sunspots, which are cooler than the surrounding gas, are caused by strong magnetic fields that prevent hot gas from bubbling up to the surface. “Planets were once considered culprits,” he notes. In 1972, aerospace engineer Karl Wood calculated that periodic planetary alignments seemed to correspond to upticks in sunspot activity. But later work showed no link.
For other stars, planets may play a role in boosting solar activity. Some stars host planets roughly the size of Jupiter on very tight orbits. Magnetic fields from a few of these worlds appear to trigger hot spots on their parent stars.
Correction “Quenching society’s thirst” (SN: 8/20/16, p. 22) states that a floating desalination farm would cover three-tenths of a square kilometer of ocean. In fact, each floating farm would stretch 300 meters long by 100 meters wide, covering only three-hundredths of a square kilometer of ocean. This area could provide about a square kilometer’s worth of stacked cultivable surfaces, depending on the crop.
Maps have long been used to show the animal kingdom’s range, regional mix, populations at risk and more. Now a new set of maps reveals the global distribution of genetic diversity.
“Without genetic diversity, species can’t evolve into new species,” says Andreia Miraldo, a population geneticist at the Natural History Museum of Denmark in Copenhagen. “It also plays a fundamental role in allowing species populations to adapt to changes in their environment.” Miraldo and her colleagues gathered geographical coordinates for more than 92,000 records of mitochondrial DNA from 4,675 species of land mammals and amphibians. The researchers compared changes in cytochrome b, a gene often used to measure genetic diversity within a species, and then mapped the average genetic diversity for all species within roughly 150,000 square-kilometer areas. For both mammals and amphibians, the tropical Andes and the Amazon have high genetic diversity, shown in dark blue. The same is true for mammal species in subtropical regions of South Africa and amphibian species in eastern North America, Miraldo and colleagues report in the Sept. 30 Science. Areas affected by people, such as cities and croplands, show lower genetic diversity. The maps are a snapshot and so can’t quantify humans’ impact on this key marker, Miraldo notes. But she hopes the work provides a baseline to monitor how human activity and changes in climate affect the distribution of genetic diversity around the globe.
Plastic smells like supper for some seabirds. When the ubiquitous material ends up in the ocean, it gives off a chemical that petrels, prions and shearwaters often use to locate food, researchers report November 9 in Science Advances. That might lead the birds to ingest harmful junk instead of a real meal.
Researchers at the University of California, Davis let small beads of three common plastics linger off the coast of California. After a few weeks, the once-clean plastic accumulated grit, grime and bacteria that gave off an odiferous gas called dimethyl sulfide (SN: 2/20/16, p. 20). Phytoplankton give off the same gas, and certain seabirds use the odor as a cue that dinner is nearby. Birds that rely more heavily on dimethyl sulfide as a beacon for a nearby meal are more likely to ingest plastic than birds that don’t, the team found. Other marine animals that use the cue could also be fooled.
NEW ORLEANS — Chronic sleep problems are associated with atrial fibrillation — a temporary but dangerous disruption of heart rhythm — even among people who don’t suffer from sleep apnea. An analysis of almost 14 million patient records has found that people suffering from insomnia, frequent waking and other sleep issues are more likely than sound sleepers to experience a condition in which the upper chambers of the heart quiver instead of rhythmically beating, allowing blood to briefly stagnate.
“Even if you don’t have sleep apnea, is there something about sleep disruption that puts you at a higher risk of fibrillation,” said Gregory Marcus, a cardiologist at the University of California, San Francisco. “We should put a higher priority on studying sleep itself.” Marcus and Matthew Christensen, from the University of Michigan, presented their results November 14 at the annual meeting of the American Heart Association. People with atrial fibrillation have double the risk of having a heart attack, and up to five times the risk of stroke. Although the heart condition can be a consequence of aging, its prevalence is rising at about 4 percent per year for reasons that aren’t totally explained. In the United States, about 5 million people currently have the condition, and that number is expected to rise to 12 million by 2030.
A large body of studies has found that sleep apnea, which occurs when a person stops breathing during the night, can lead to atrial fibrillation and a host of other health concerns. Identifying a risk of atrial fibrillation among people with no sleep apnea is unexpected, says Richard Becker, director of the University of Cincinnati Heart, Lung & Vascular Institute, who was not part of the study.
Marcus, Christensen and colleagues analyzed data from three different sources, including the California Healthcare Cost and Utilization Project, a database of almost 14 million patients. They also drew on records from more than 4,600 participants of Health eHeart Study who had filled out a sleep survey, and from the Cardiovascular Health Study, which has tracked more than 5,700 people for more than a decade. Those data allowed the researchers to follow patients over time, tracking which came first — the fibrillation or the sleep issues. The researchers included a variety of sleep disorders, such as insomnia, nighttime waking and shortened periods of rapid eye movement, or REM, sleep.
Among the results: People who frequently woke had a 33 percent greater chance of developing atrial fibrillation in one analysis, and a 47 percent higher chance in another. For the eHeart group, insomnia increased the odds by 17 percent. And among more than 14 million California records studied, insomnia increased the odds of future atrial fibrillation by 36 percent. Analysis of a subgroup undergoing sleep studies showed that less REM sleep also was associated with a higher probability of developing atrial fibrillation.
The study can’t explain why a lack of sleep even with normal breathing might hurt the heart, but the authors hypothesize that the mechanism could be tied to the body’s stress response.
Becker believes that cardiologists should emphasize sleep just as they do diet and exercise for lifestyle management. To workaholic, screen-fixated Americans, “this study sends a powerful message about wellness as a continuum throughout the day and night,” he says. “It offers clinicians and the public a 360-degree view of what is important for good health.”
