Growing planets carve rings and spiral arms out of the gas and dust surrounding their young stars, researchers report in three papers to be published in Astronomy & Astrophysics. And dark streaks radiating away from the star in one of the planet nurseries appear to be shadows cast onto the disk by the clumps of planet-building material close to the star. This isn’t the first time that astronomers have spied rings around young stars, but the new images provide a peek at what goes into building diverse planetary systems.
The three stars — HD 97048, HD 135344B and RX J1615.3-3255 — are all youthful locals in our galaxy. They sit between 460 and 600 light-years away; the oldest is roughly a mere 8 million years old. All the stars have been studied before. But now three teams of researchers have used a new instrument at the Very Large Telescope in Chile to see extra-sharp details in the planet construction zone around each star.
The new instrument, named SPHERE, was designed to record images, spectra and polarimetry (the orientations of light waves) of young exoplanet families. Flexible mirrors within the instrument adapt to atmospheric turbulence above the telescope, and a tiny disk blocks light from the star, allowing faint details around the star to come into view.
Seabird poop helps the Arctic keep its cool, new research suggests.
The droppings release ammonia into the atmosphere, where it reacts with other chemicals in the air to form small airborne particles. Those particles form the heart of cloud droplets that reflect sunlight back into space, researchers propose November 15 in Nature Communications.
Even though the poop’s presence provides only modest cooling, understanding the effect could help scientists better predict how the region will fare under future climate change, says study coauthor Greg Wentworth. “The humor is not lost on me,” says Wentworth, an atmospheric chemist at Alberta Environment and Parks in Canada. “It’s a crucial connection, albeit somewhat comical.” Arctic air temperatures are rising about twice as fast as temperatures in lower latitudes (SN: 12/26/15, p. 8), a shift that could threaten ecosystems and alter global weather patterns. Scientists still don’t fully understand Arctic climate, though.
Earlier this year, Wentworth and colleagues reported finding surprisingly abundant ammonia in Arctic air. They linked the chemical to the guano of the tens of millions of seabirds that flock to the frigid north each summer. Bacteria in the Arctic dine on the feces and release about 40,000 metric tons of ammonia annually. (The smell, Wentworth says, is awful.)
Once in the atmosphere, that ammonia reacts with sulfuric acid and water to form small particles that increase the number of cloud droplets, the researchers now propose. A cloud made up of a lot of smaller droplets will have more surface area and reflect more sunlight than a cloud made up of fewer but larger droplets.
This effect causes on average about 0.5 watts of summertime cooling per square meter in the Arctic, with more than a watt of cooling per square meter in some areas, the researchers estimate using a simulation of the Arctic’s atmospheric chemistry. For comparison, the natural greenhouse effect causes about 150 watts of warming per square meter worldwide. On top of that, carbon dioxide from human activities currently contributes about 1.6 watts per square meter of warming on average.
“Birds are in the equation now” when it comes to cloud formation, says Ken Carslaw, an atmospheric scientist at the University of Leeds in England. Understanding how climate change and human activities in the Arctic impact seabirds could be important to forecasting future temperature changes in the region, he says.
Bacteria may be a meat-eating plant’s best friends thanks to their power to reduce the surface tension of water.
The carnivorous pitcher plant Darlingtonia californica releases water into the tall vases of its leaves, creating deathtraps where insect prey drown. Water in a pitcher leaf starts clear. But after about a week, thanks to bacteria, it turns “murky brown to a dark red and smells horrible,” says David Armitage of the University of Notre Dame in Indiana. Now, he’s found that those bacteria can help plants keep insects trapped. Microbial residents reduce the surface tension of water enough for ants and other small insects to slip immediately into the pool instead of perching lightly on the surface, he reports November 23 in Biology Letters.
Armitage seeded tubes of clean water with fluid from the trap pools of pitcher plants and added dead crickets to feed the microbes. After sitting for a month, the mess had about the same surface tension properties as natural pitcher plant pools. Then, he created a series of increasingly dilute samples of pool soup and dropped harvester ants into each one. He found that the ants sank immediately in all but the bacteria-free water sample.
Bacterial populations in a pitcher leaf are akin to those in a mammal gut or bovine rumen, Armitage’s preliminary analysis finds. The microbes can help digest the prey as well as catch it, he says.
A bird in laser goggles has helped scientists discover a new phenomenon in the physics of flight.
Swirling vortices appear in the flow of air that follows a bird’s wingbeat. But for slowly flying birds, these vortices were unexpectedly short-lived, researchers from Stanford University report December 6 in Bioinspiration and Biomimetics. The results could help scientists better understand how animals fly, and could be important for designing flying robots (SN: 2/7/15, p. 18). To study the complex air currents produced by birds’ flapping wings, the researchers trained a Pacific parrotlet, a small species of parrot, to fly through laser light — with the appropriate eye protection, of course. Study coauthor Eric Gutierrez, who recently graduated from Stanford, built tiny, 3-D‒printed laser goggles for the bird, named Obi.
Gutierrez and colleagues tracked the air currents left in Obi’s wake by spraying a fine liquid mist in the air, and illuminating it with a laser spread out into a two-dimensional sheet. High-speed cameras recorded the action at 1,000 frames per second.
The vortex produced by the bird “explosively breaks up,” says mechanical engineer David Lentink, a coauthor of the study. “The flow becomes very complex, much more turbulent.” Comparing three standard methods for calculating the lift produced by flapping wings showed that predictions didn’t match reality, thanks to the unexpected vortex breakup.
SAN FRANCISCO — Cell biologists are learning more about how the Zika virus disrupts brain cells to cause the birth defect microcephaly, in which a baby’s brain and head are smaller than usual. Meantime, several strategies to combat the virus show preliminary promise, researchers reported at the American Society for Cell Biology’s annual meeting. Among the findings:
Brain cell die-off Zika causes fetal brain cells neighboring an infected cell to commit suicide, David Doobin of Columbia University Medical Center reported December 6. In work with mice and rats, Doobin and colleagues found suggestions that the cells’ death might be the body’s attempt to limit spread of the virus.
The researchers applied techniques they had previously used to investigate a genetic cause of microcephaly to narrow when in pregnancy the virus is most likely to cause the brain to shrink. Timing of the virus’s effect varied by strain. For one from Puerto Rico, brain cell die-off happened in mice only in the first two trimesters. But a strain from Honduras could kill developing brain cells later into pregnancy. Microcephaly can lead to seizures, mental impairment, delays in speech and movement and other problems.
Enzyme stopper Disrupting a Zika enzyme could help stop the virus. The enzyme, NS3, causes problems when it gloms on to centrioles, a pair of structures inside cells needed to divvy up chromosomes when cells divide, Andrew Kodani, a cell biologist at Boston Children’s Hospital reported December 6.
Zika, dengue and other related viruses, known as flaviviruses, all use a version of NS3 to chop joined proteins apart so they can do their jobs. (Before chopping, Zika’s 10 proteins are made as one long protein.) But once NS3 finishes slicing virus proteins, the enzyme moves to the centrioles, where it can mess with their assembly, Kodani and colleagues found. Something similar happens in some genetic forms of microcephaly.
A chemical called an anthracene can help fend off dengue, so Kodani and colleagues tested anthracene on Zika as well. Small amounts of the chemical can prevent NS3 from tinkering with the centrioles, the researchers found. So far the work has only been done in lab dishes. Protein face-off Another virulent virus could disable Zika. Work with cells grown in lab dishes suggests a bit of protein, or peptide, from the hepatitis C virus, could muck up Zika’s proteins.
The peptide interferes with HSP70, a protein that helps assemble complexes of other proteins, including ones involved in protein production. That peptide and other compounds were already known to inhibit hepatitis C replication, UCLA virologist Ronik Khachatoorian and colleagues had previously discovered. The hepatitis C virus peptide stops Zika virus proteins from being made and hampers assembly of the virus, Khachatoorian reported December 5.
Cells grown in the lab devour nano-sized wires of silicon through an engulfing process known as phagocytosis, scientists report December 16 in Science Advances.
Silicon-infused cells could merge electronics with biology, says John Zimmerman, a biophysicist now at Harvard University. “It’s still very early days,” he adds, but “the idea is to get traditional electronic devices working inside of cells.” Such hybrid devices could one day help control cellular behavior, or even replace electronics used for deep brain stimulation, he says. Scientists have been trying to load electronic parts inside cells for years. One way is to zap holes in cells with electricity, which lets big stuff, like silicon nanowires linked to bulky materials, slip in. Zimmerman, then at the University of Chicago, and colleagues were looking for a simpler technique, something that would let tiny nanowires in easily and could potentially allow them to travel through a person’s bloodstream — like a drug. Zimmerman’s team had previously shown that cells could take in silicon nanowires, but no one knew how it worked. So he added the nanowires to different kinds of cells — including human umbilical vein cells, rat nerve cells and mouse immune cells — in laboratory dishes. Under a microscope, Zimmerman says, “you can see the cell grab the wire, wrap a membrane around it, and pull it inside — kind of like a lasso.” Then, the wire travels on molecular tracks through the cell’s interior to settle around the nucleus. Molecular tests suggested that nanowires entered via phagocytosis, a process by which some cells take in bacteria and cellular junk. During phagocytosis, a cell’s membrane encapsulates the junk, forming a pouch that carries the cargo to a recycling center inside the cell.
Not all cell types swallowed the wires, though. Knowing which types do, and how the wires get inside is important, Zimmerman says, because it could help in predicting where they would end up in the body. But there’s still a long way to go from nanowire-loaded cells to working electronic devices, says Mark Reed, a physicist at Yale University. “This is the big question,” he says — because the nanowires aren’t actually hooked up to anything yet.
Tricking some bug into drowning takes finesse, especially for a hungry meat eater with no brain, eyes or moving parts. Yet California pitcher plants are very good at it.
Growing where deposits of the mineral serpentine would kill most other plants, Darlingtonia californica survives in low-nutrient soil by being “very meat dependent,” says David Armitage of the University of Notre Dame in Indiana. Leaves he has tested get up to 95 percent of their nitrogen from wasps, beetles, ants or other insects that become trapped inside the snake-curved hollow leaves. The leaves don’t collect rainwater because a green dome covers the top. Instead, they suck moisture up through the roots and (somehow) release it into the hollow trap. “People have been doing weird experiments where they feed [a plant] meat and milk and other things to try to trigger it to release water,” Armitage says. Experiments tempting the green carnivore with cheese, beef broth, egg whites and so on suggest there’s some sort of chemical cue.
However the water enters the leaf pool, it starts out clear. As insects drown, the liquid darkens to a murky brown or red and “smells just horrible,” he says. The soupiness comes from bacteria, which help doom prey by lowering the surface tension of the drowning pool, Armitage reports in the November Biology Letters. Ants or other small insects sink below the surface immediately instead of floating at the top. But first, pitchers lure victims to the pool by repurposing an old plant ploy: free nectar. It’s “highly nitrogen-rich and full of sugars, so it’s delicious — I’ve tasted it,” Armitage says. Pitcher plants sprout blooms, but the trap nectar doesn’t come from the drooping flowers. A roll of tissue near the pitcher mouth oozes the treat.
That nectar-heavy roll curves onto what’s called the fishtail appendage. Mature plants (2 years or older) grow this forked tissue like a moustache at the pitcher mouth. Biologists for more than a century have presumed that this big, red-veined, lickable prong worked as an insect lure. Armitage, however, tested the idea and says it may be wrong. Clipping fishtails off individual leaves, or even off all the leaves in a small patch, did nothing to shrink the catch compared with fully mustachioed leaves, he reported in the American Journal of Botany in April 2016. The only thing fishtails lure, for the time being at least, are puzzled botanists.
Earth was momentarily ripe for the evolution of animals hundreds of millions of years before they first appeared, researchers propose.
Chemical clues in ancient rocks suggest that 2.32 billion to 2.1 billion years ago, shallow coastal waters held enough oxygen to support oxygen-hungry life-forms including some animals, researchers report the week of January 16 in the Proceedings of the National Academy of Sciences. But the first animal fossils, sponges, don’t appear until around 650 million years ago, following a period of scant oxygen known as the boring billion (SN: 11/14/15, p. 18). “As far as environmental conditions were concerned, things were favorable for this evolutionary step to happen,” says study coauthor Andrey Bekker, a sedimentary geologist at the University of California, Riverside. Something else must have stalled the rise of animals, he says.
Microbes began flooding Earth with oxygen around 2.3 billion years ago during the Great Oxidation Event. This breath of oxygen enabled the eventual emergence of complex, oxygen-dependent life-forms called eukaryotes, an evolutionary line that would later include animals and plants. Scientists have proposed that the Great Oxidation Event wasn’t a smooth rise, but contained an “overshoot” during which oxygen concentrations momentarily peaked before dropping to a lower, stable level during the boring billion. Whether that overshoot was enough to support animals was unclear, though.
Bekker and colleagues tackled this question using a relatively new way to measure ancient oxygen. Rock weathering can wash the element selenium into the oceans. In oxygen-free waters, all of the selenium settles onto the seafloor. But in water with at least some oxygen, only a fraction of the selenium is deposited. And the selenium that is laid down is disproportionately that of a lighter isotope of the element, leaving atoms of a heavier isotope to be deposited elsewhere. If ancient coasts contained relatively abundant oxygen, the researchers expected to find more light selenium close to shore and more heavy selenium in deeper, oxygen-deprived waters. Analyzing shales formed under deep waters around the world, the researchers found just such an isotope segregation. These shales had an abundance of the heavier selenium, leading researchers to infer that the lighter version of the element was concentrated closer to shore.
Oxygen concentrations in coastal waters were at least nearly one percent of present-day levels and “were flirting with the limits of what complex life can survive,” proposes study coauthor Michael Kipp, a geochemist at the University of Washington in Seattle. While the environment was probably suitable for eukaryotes, life hadn’t evolved enough by this point to take advantage of the situation, Kipp proposes. The appearance of eukaryotes in the fossil record would take hundreds of millions of years of more evolution (SN Online: 5/18/16), he says, and the first animals even longer. Tracking selenium is such a new technique, though, that “interpretations could change as we better understand how it works,” says Philip Pogge von Strandmann, a geochemist at University College London. Currently the method is “tricky,” he says, especially for precisely estimating oxygen concentrations.
Legos have provided the inspiration for small, fluid-ferrying devices that can be built up brick-by-brick.
Tools for manipulating tiny amounts of liquid, known as microfluidic devices, can be used to perform blood tests, detect contaminants in water or simulate biological features like human blood vessels. The devices are easily portable, about the size of a quarter and require only small samples of liquid.
But fabricating such devices is not easy. Each new application requires a different configuration of twisty little passages, demanding a brand new design that must be molded or 3-D printed.
Scientists from the University of California, Irvine created Lego-style blocks out of a polymer called PDMS. Their bricks contained minuscule channels, half a millimeter wide, that allowed liquid to flow from brick to brick with no leaks. New devices could be created quickly by rearranging standard blocks into various configurations, the scientists report January 24 in the Journal of Micromechanics and Microengineering.
Gender bias works in subtle ways, even in the scientific process. The latest illustration of that: Scientists recommend women less often than men as reviewers for scientific papers, a new analysis shows. That seemingly minor oversight is yet another missed opportunity for women that might end up having an impact on hiring, promotions and more.
Peer review is one of the bricks in the foundation supporting science. A researcher’s results don’t get published in a journal until they successfully pass through a gauntlet of scientific peers, who scrutinize the paper for faulty findings, gaps in logic or less-than-meticulous methods. The scientist submitting the paper gets to suggest names for those potential reviewers. Scientific journal editors may contact some of the recommended scientists, and then reach out to a few more.
But peer review isn’t just about the paper (and scientist) being examined. Being the one doing the reviewing “has a number of really positive benefits,” says Brooks Hanson, an earth scientist and director of publications at the American Geophysical Union in Washington, D.C. “You read papers differently as a reviewer than you do as a reader or author. You look at issues differently. It’s a learning experience in how to write papers and how to present research.”
Serving as a peer reviewer can also be a networking tool for scientific collaborations, as reviewers seek out authors whose work they admired. And of course, scientists put the journals they review for on their resumes when they apply for faculty positions, research grants and awards.
But Hanson didn’t really think of looking at who got invited to be peer reviewers until Marcia McNutt, a geophysicist and then editor in chief of Science, stopped by his office. McNutt — now president of the National Academy of Sciences in Washington, D.C. — was organizing a conference on gender bias, and asked if Hanson might be able to get any data. The American Geophysical Union is a membership organization for scientists in Earth and space sciences, and it publishes 20 scientific journals. If Hanson could associate the gender and age of the members with the papers they authored and edited, he might be able to see if there was gender bias in who got picked for peer review.
“We were skeptical at first,” he says. Hanson knew AGU had data for who reviewed and submitted papers to the journals, as well as data for AGU members. But he was unsure how well the two datasets would match up. To find out, he turned to Jory Lerback, who was then a data analyst with AGU. Merging the datasets of all the scientific articles submitted to AGU journals from 2012 to 2015 gave Lerback and Hanson a total of 24,368 paper authors and 62,552 peer reviews performed by 14,919 reviewers. For those papers, they had 97,083 author-named reviewer suggestions, and 118,873 editor-named reviewer requests.
While women were authors less often and submitted fewer papers, their papers were accepted 61 percent of the time. Male authors had papers accepted 57 percent of the time. “We were surprised by that,” Hanson says. While one reviewer of Hanson and Lerback’s analysis (a peer-reviewer on a paper about peer review surely must feel the irony) suggested that women might be getting higher acceptance rates due to reverse discrimination, Hanson disagrees. He wonders if “[women] are putting more care into the submission of the papers,” he says. Men might be more inclined to take more risks, possibly submitting papers to a journal that is beyond their work’s reach. Women, he says, might be more cautious. When suggesting reviewers, male authors suggested female reviewers only 15 percent of the time, and male editors suggested women just 17 percent of the time. Female authors suggested women reviewers 21 percent of the time, and female editors suggested them 22 percent of the time. The result? Women made up only 20 percent of reviewers, even though 28 percent of AGU members are women and 27 percent of the published first authors in the study were women.
The Earth and space sciences have historically had far fewer women than men, but the numbers are improving for younger scientists. “We thought maybe people were just asking older people to review papers,” says Lerback. But when Lerback and Hanson broke out the results by age, they saw the gender discrepancy knew no age bracket. “It makes us more confident that this is a real issue and not just an age-related phenomenon,” Lerback says. She and Hanson report their analysis in a comment piece in the January 26 Nature.
“It’s incredibly compelling data and one of those ‘why hasn’t someone done this already’ studies,” says Jessi Smith, a social psychologist at Montana State University in Bozeman. While it’s disheartening to see yet another area of bias against women, she notes, “this is good that people are asking these questions and taking a hard look. We can’t solve it if we don’t know about it.”
The time when authors are asked to suggest reviewers might play a role, Smith notes. When scientific papers are submitted online, the field for “suggested reviewers” is often last. “That question for ‘who do you want’ always surprises me,” admits Smith. It’s a very small thing, but she notes that when people are tired and in a hurry, “that’s when these biases take place.”
Knowing that the bias exists is part of the battle, Hanson says, but it’s also time for things to change. He’s pushing for more diversity in the journals’ editorial pool — for gender, nationality and underrepresented minorities. It’s also helpful to remember that suggesting people for peer review isn’t just about the author’s work. “Even small biases, if they happen repeatedly, can have career-related effects,” he says.
Peer-reviewer selection is something that hasn’t gotten a lot of scientific attention. “I think getting a dialog going for everyone to be aware of opportunity gaps, [asking] ‘what can I do to make sure I’m not contributing to this’… I think that will be important to keep editors and authors aware and accountable,” Lerbeck says. She’s now experiencing the peer-review life first hand: She’s now a graduate student at the University of Utah in Salt Lake City. While there, she’s starting a group to discuss bias — to make sure that the conversations keep going.