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Faster-evolving plants tend to have smaller seeds.
Javier Igea at the University of Cambridge, UK, and his colleagues analysed the masses of individual seeds from more than 30,000 flowering plants. They found that the faster a plant species diversified — by splitting into different strains or species — the smaller its seeds tended to be. The size of the seed also tended to change more quickly over time in fast-evolving plants. The finding confirms that seed size can influence the way in which a plant evolves. For instance, smaller seeds can be dispersed farther, allowing small, isolated populations to grow.
Smaller seeds are also associated with shorter-lived plants, in which more rapid turnover provides more opportunity for mutations to occur.
Armoured ‘footballs‘ can be coaxed into cylinder and dumbbell shapes.
Wrapping droplets of water in a common type of plastic creates liquid marbles, which can function as microscopic ball bearings, miniature vessels for chemical reactions, and various types of sensor.
Scientists have been engineering spherical liquid marbles for more than a decade by encasing droplets in ‘armour’ made of spherical particles. But Syuji Fujii of the Osaka Institute of Technology in Japan and his colleagues sought to cover the marbles with hexagonal plates, which could lead to a wide variety of useful shapes.
The researchers started with powdered poly(ethylene terephthalate) — the plastic used for soft-drink bottles — in the form of tiny, six-sided plates. When the scientists placed water droplets on a layer of the plastic, the plates surrounded them, creating marbles that look like lumpy miniature footballs.
Marbles coated with the main ingredient used in superglue retained their shapes instead of collapsing when the water inside them evaporated. The researchers also found that they could force the droplets into cylinders, dumbbells and even letters by applying external pressure with something as simple as a spatula.
In a solitary species of bee, males gain chances to mate with females when they help guard the little ones.
Teamwork makes parenting easier, even for some insects. Male and female Ceratina nigrolabiata bees pair up temporarily during the breeding season to care for offspring and defend nests.
In bees and other insects, any care that offspring receive generally comes from the mother. But when Michael Mikát at Charles University in Prague and his colleagues examined 460 C. nigrolabiata nests, nearly 90% held a male–female pair of bees. While female bees were foraging, males remained inside the nest to protect it from enemies such as ants. Males protected nests even when the offspring belonged to another male.
The researchers also found that C. nigrolabiata females usually mate with several males. But a male gains mating opportunities with a female by forming a temporary partnership with her. Indeed, the team observed that males gain more offspring the longer they guard a nest — an average of 0.638 offspring for every 7 days of guard duty.
Microscope equipped with mirrors and a laser reveals the back of the retina in real time.
A new type of laser-based microscope can quickly provide a real-time view of living cells in the human retina.
For more than three decades, researchers have probed the human eye with laser-scanning microscopes. These devices use swivelling ‘scanning’ mirrors to direct a laser across a sample and create an image. This method can resolve some individual retinal cells, but imaging of the retina’s central cone cells — which are responsible for the perception of fine detail — usually requires either subsequent processing or complex and specialized equipment.
Joseph Izatt and his colleagues at Duke University in Durham, North Carolina, devised a series of mirrors and lenses that first expands the image formed from the laser light, then redirects the image across the scanning mirrors before it reaches a camera. These steps result in more accurate placement of the laser light onto the camera sensor, resulting in a sharper image.
The technique improves resolution over conventional methods and is much faster. When the setup was used on a living person’s eye, the microscope captured a real-time video of the retina, including clear footage of individual cone cells.
Beer-brewing yeasts might have arisen from a Silk Road rendezvous between strains related to wine-making yeasts.
The yeast needed to brew pale lagers and dark stouts alike has a long and complex pedigree that traces back to yeasts used for European and Asian wines.
Ales, such as the classic English bitters, are fermented by brewer’s yeast (Saccharomyces cerevisiae), while lagers are fermented by Saccharomycespastorianus, a cross between brewer’s yeast and Saccharomyces eubayanus. To pinpoint the origins of beer yeast, Justin Fay at the University of Rochester in New York and his colleagues sequenced the genomes of 47 yeast strains.
The team found that beer-brewing strains derive their ancestry from close relatives of yeasts used in Europe to ferment wine grapes and from relatives of Asian strains that produce rice wine such as sake. But the researchers also found the genomic fingerprints of mysterious strains that are either unknown or extinct.
The geographic origin of grape-wine yeast is debated, but if it was domesticated in Europe, it might have interbred with Asian yeast along the Silk Road to give rise to beer yeast, the authors say.
Programme’s success shows that the country could end mortality from the disease.
A measles vaccination campaign in India saved the lives of tens of thousands of children between 2010 and 2013.
In 2010, the Indian government launched a campaign to introduce a two-dose measles vaccine in districts where rates of single-dose vaccination were low. To study the campaign’s impact, Prabhat Jha at the University of Toronto in Canada and his colleagues analysed data from a large-scale study of mortality in India.
Over the three years that followed the campaign’s launch, measles-related deaths among young children fell by 27% in districts where the campaign had been rolled out, with greater declines in mortality for girls than boys. In non-campaign districts, measles mortality dropped by only 11%. The team’s analysis suggests that the campaign saved the lives of 41,000–56,000 children during that period — equivalent to 39–57% of the expected number of measles deaths nationwide.
The authors suggest that the elimination of measles in India could be feasible, although difficult, requiring continued efforts to increase vaccination rates and monitor mortality.
Drug candidate imitates a naturally occurring immune protein that binds to influenza virus.
A molecule that mimics an antiviral antibody protects mice from ordinarily lethal doses of influenza.
The flu virus causes hundreds of thousands of deaths every year — and many more when a major new variant emerges. The viral proteins that vaccines and drugs are designed to target mutate continually, making therapies difficult to develop.
Maria van Dongen at Janssen Pharmaceutical Companies of Johnson & Johnson in Leiden, the Netherlands, Ian Wilson at the Scripps Research Institute in La Jolla, California, and their colleagues engineered a small molecule that mimics the action of a natural antibody that is active against a broad spectrum of flu strains. Like the antibody, the molecule, JNJ4796, binds to an infrequently mutated region of a flu surface protein. When mice were given the molecule, it protected 100% of the animals against an otherwise lethal dose of the H1N1 flu strain.
Small molecules are easier to make than antibodies and can be administered as a pill, whereas antibodies are injected.
Lop off the heads of these ribbon worms, then watch.
Many species of marine ribbon worm have gained the power to regrow their heads — an unprecedented example of related animals independently mastering the trick of regeneration.
Eduardo Zattara at the Smithsonian Institution’s National Museum of Natural History in Washington DC and his colleagues cut off the heads of individuals from 22 species of ribbon worm and observed that 5 species sprouted new heads. The researchers also found published accounts of 3 other species with this ability.
The team’s analysis of the ribbon-worm family tree suggests that head replacement arose at least four times in separate worm lineages. The lineage of the species Lineus sanguineus evolved the ability to replace a missing head only 10 million to 15 million years ago, which is much more recently than other animals are known to have acquired the art of regeneration.
This means that L. sanguineus could provide a valuable model for understanding how regeneration evolves, the authors say.
A snowy blanket helps shield one of the world’s largest ice sheets from the Sun.
The boundary between Greenland’s snow-covered and snowless areas plays a significant part in how the island’s ice sheet melts.
Greenland’s melting ice accounts for more than one-quarter of global sea-level rise. To understand the factors that influence melting, Jonathan Ryan at Brown University in Providence, Rhode Island, Laurence Smith at the University of California, Los Angeles, and their colleagues looked at Greenland’s ‘snowline’. At elevations below the snowline, the ice is bare, and often darker than the snow that blankets the ice above the snowline. The line shifts up and down Greenland’s slopes throughout the seasons.
The researchers used satellite imagery to map the snowline from 2001 to 2017. The line’s average elevation at the end of summer ranged from a low of 1,330 metres in 2009 to a high of 1,650 metres in 2012. Fluctuations in the snowline were the single most important factor in how much of the Sun’s energy the ice sheet absorbed from year to year.
Computer modellers need to account for this effect to improve their predictions of how much and how quickly Greenland’s ice will melt in the future.
By-product of rubber tyres is transformed into valuable organic semiconductors.
When the rubber meets the road, it invariably leaves behind traces of the chemicals used to harden it during tyre manufacture. These chemicals, notably 2-(methylthio)-bezothiazole (MTBT), wash into waterways, where they can pose a health hazard if left untreated. The reactions used to break down MTBT just leave behind more waste — benign but useless.
Researchers in China report that they have found a way to not only neutralize MTBT, but also turn it into something valuable: an organic semiconductor. These are cheaper and more flexible than metallic semiconductors, and can be incorporated into items such as mobile-phone displays. Hui Huang at the University of the Chinese Academy of Sciences in Beijing and his colleagues applied a method that relies on a metal catalyst, acid and heat.
The team experimented with different recipes and temperatures to turn the MTBT into several different semiconductor compounds. One could be used to build a field-effect transistor, a key component of electronic devices. From another, the researchers created semiconductor nanoparticles, which can act as fluorescent dyes that allow scientists to image living cells in action.
Shifts in pressure system could increase flood damage as Earth’s climate warms.
The occurrence of devastating European floods correlates with large-scale fluctuations in atmospheric pressure known as the North Atlantic Oscillation (NAO). As scientists improve their predictions for the NAO, society will be better able to prepare for future flooding.
Stefano Zanardo and his colleagues at Risk Management Solutions in London, UK, analysed historical records of severe European floods going back to 1870, and compared them with the prevailing pattern of atmospheric pressure at the time of the floods. When the NAO is in its ‘positive’ state, a strong low-pressure system over Iceland funnels winds and storms across Northern Europe. Conversely, when the NAO is in its negative state, a weak low-pressure system over Iceland makes Southern Europe wetter than usual.
Floods in Northern Europe have tended to occur — and cause most damage — when the NAO was positive during winter, and when sufficient rain had already fallen for the ground to become saturated.
Atmospheric-pressure patterns over Europe may shift with future climate change, and officials should take this into account when assessing a region’s flood risk, the scientists say.
One species’ silk can make almost a full revolution when exposed to sufficient humidity.
A strand of spider silk roughly 10 centimetres long can twist itself through nearly 100 rotations when exposed to moisture, an attribute that might be useful for making artificial muscles.
During the past decade or so, scientists have discovered that spider silk — known for its extraordinary strength — can twist and contract in humid conditions. To explore this property further, Dabiao Liu at Huazhong University of Science and Technology in Wuhan, China, Markus Buehler at the Massachusetts Institute of Technology in Cambridge and their colleagues dangled a pendulum from a strand of silk and placed the apparatus in a chamber in which humidity could be controlled.
When the relative humidity reached about 70%, the silk (and pendulum) began to twist. The team tested silk from three species of spider and found that a one-millimetre-long section of silk from Nephila pilipes could twist by almost 360 degrees — a greater range of rotation than can be achieved with devices made of carbon nanotubes and powered by electricity. The twisting could be halted, and then resumed, by lowering and raising the humidity across the 70% threshold.
This capability could one day be used to create soft robots or smart fabrics woven from twisting threads, the authors write.
Long hot spells have affected every ocean on Earth, and are likely to grow in severity.
As marine heatwaves become longer and more frequent, they threaten to take a huge toll on global biodiversity and the services that the world’s oceans provide to humans.
During a marine heatwave, temperatures at the ocean’s surface are substantially warmer than usual for days at a time. Globally, the number of days marked by such heatwaves rose by more than 50% during the past century, and in the past decade there were several events of record-breaking intensity.
To examine the impact of these events, Dan Smale at the Marine Biological Association of the United Kingdom in Plymouth and his colleagues combined data on biodiversity, species’ heat tolerance and human pressures such as overfishing and pollution. The scientists found that heatwaves have caused harm in all ocean basins, affecting a wide range of organisms and biological processes. Loss of seagrasses and kelp forests is disrupting nutrient cycling, robbing species of their habitats and reducing carbon burial. Local extinctions are degrading commercial fisheries.
Future climate change will make marine heatwaves still more severe, the researchers warn.
Polished ‘skull cup’ and human bones bearing tooth marks point to cannibalism in Europe in around 5000 BC.
Marks on a skullcap and other well-scraped human bones suggest that cannibalism was prevalent among prehistoric people in the south of the Iberian Peninsula.
Archaeologists discovered the 6,000-year-old remains inside a Spanish cave. On closer inspection, Jonathan Santana at Durham University, UK, and his colleagues found marks on some of the bones that indicated someone had chewed them and sucked their nutrient-rich marrow. In addition, a skullcap had been skinned, polished and boiled, apparently to give it a smooth appearance. This carefully prepared cranium, known as a skull cup, might have been used in cannibalistic rituals.
The finds strongly indicate that early Iberian farming communities included human flesh in their diets. But why they ate their kin and carved their skulls is unclear.
Cannibalism might have been a habit among extremely violent groups that kept enemies’ heads as trophies, the researchers suspect. But the finds could also be remnants of funerary ceremonies in which people consumed flesh of deceased family members and preserved relics of their loved ones.
Correction: An earlier version of this article misstated the age of evidence for cannibalism in Europe. That evidence dates to around 5000 BC, not 3000 BC. The article also misstated the date of the bones suggestive of cannibalism. They are more than 6,000 years old, not more than 5,000 years old.
Wind and wave action drive the build-up of microplastics at remote ocean sites.
Small pieces of floating plastic pose an increasing threat to marine species, but human-made microplastic particles are not distributed evenly throughout the seas.
Victor Onink at Utrecht University in the Netherlands and his colleagues used a model of ocean currents to investigate which physical processes control the accumulation of plastic particles in ‘garbage patches’ of the ocean. They found that wind-driven circulation of the upper ocean is responsible for the high concentration of plastic debris in certain regions of the subtropical North Pacific and North Atlantic oceans.
By contrast, the team found that wave movement, another component of large-scale ocean circulation, seems to increase the amount of microplastic reaching the remote Arctic Ocean. Because some particle-transport models still don’t account for wave-induced drift, plastic pollution in the Arctic might be worse than commonly estimated, the scientists say.
Catching up on sleep over the weekend doesn’t undo the negative metabolic effects of sleep deprivation.
Getting extra sleep at weekends probably isn’t enough to reduce health risks related to insufficient sleep during exhausting working weeks, according to a short-term study of young adults.
Lack of sleep has been linked to a range of disorders, including diabetes and heart disease. Kenneth Wright at the University of Colorado Boulder and his colleagues studied what happens when people try to compensate for insufficient sleep during the week by sleeping late at weekends.
The team found that a group of 14 young adults who slept for only 5 hours each night for 9 consecutive nights snacked more after dinner, gained more weight and exhibited reduced insulin sensitivity compared with a control group of adults who slept up to 9 hours each night. In a third group, an additional 14 participants slept only 5 hours per night during the working week, but were then allowed to sleep as much as they wanted over the weekend. Even so, during the subsequent week, the negative metabolic effects of sleeplessness persisted.
Technique ties up an innocuous protein before it gathers into dangerous clumps.
A disease-causing protein has been tricked into taking a molecular ‘bait’ that keeps the protein from clumping into poisonous little balls.
An otherwise useful protein found in most of the body’s tissues, TDP-43 sometimes malfunctions and forms neurotoxic clumps inside the brain. Such clumps are typically found in the brain tissue of people who have a degenerative brain condition, such as amyotrophic lateral sclerosis or Alzheimer’s disease.
Christopher Donnelly at the University of Pittsburgh in Pennsylvania and his colleagues designed a light-sensitive TDP-43 protein and introduced it into cultured human cells. When exposed to flashing light, the protein molecules gathered into clusters that were toxic to neuron-like cells.
TDP-43 usually binds to short strands of genetic material, so the researchers used short RNA molecules to snare the faulty proteins. These snared proteins were unable to damage cells.
The authors say that their approach could also help scientists to ‘bait’ proteins involved in other degenerative brain diseases, potentially leading to a new class of therapies.
Channel design allows fluid droplets to self-propel in a controlled manner.
Liquid droplets placed in channels with flexible walls can whisk themselves through tiny ducts — without any help from external forces.
In ‘microfluidic’ devices, minute volumes of liquid course through microscopic channels, allowing researchers to analyse samples of one-millionth of a litre or even less. But the dominant influence of surface forces can make it tricky to control the movement of fluid in these devices.
Dominic Vella and his colleagues at the University of Oxford, UK, clamped two parallel glass coverslips at one end, leaving the other end open. When a drop of water was placed in this channel, the glass walls bulged outwards, creating a pressure difference that gradually pushed the droplet through the duct (as shown below).
In previously designed microfluidic devices that use a similar form of self-propulsion, a droplet of oily liquid moves through a channel in the opposite direction from a droplet of water-soluble liquid. But in the current design, the bending of the walls ensures that both oily and water-based substances move in the same direction, potentially increasing the technology’s practical uses.
This new mechanism of motion — which the authors dub ‘bendotaxis’ — could be used to create self-cleaning surfaces and pipes that clear themselves.
The planet’s distant hydrogen veil billows much further than scientists suspected.
Earth’s outermost atmosphere is so big that it engulfs the Moon.
A cloud of hydrogen atoms, known as the geocorona, makes up the distant reaches of the planet’s atmosphere. The geocorona’s full extent has long been a mystery, and Apollo astronauts captured a picture of it glowing in the Sun’s ultraviolet rays in 1972 without realizing that they were inside it.
Between 1996 and 1998, the newly operational Solar and Heliospheric Observatory (SOHO) gazed Earthwards and mapped the geocorona three times. The measurements made by SOHO’s sensitive detectors during this period show that the hydrogen cloud peters out about 630,000 kilometres from the planet — well beyond the distance at which the Moon orbits.
Researchers led by Igor Baliukin at the Space Research Institute of the Russian Academy of Sciences in Moscow made the discovery only recently while digging through the SOHO data archives. Astronomers should be aware of the geocorona’s ultraviolet glow and how it might affect observations from future space telescopes, says the team.
Glass that quickly becomes opaque could reduce the need for air conditioning in buildings and vehicles.
A ‘smart’ window can turn quickly from clear to dark thanks to layers of nickel oxide and electrolytes.
Transparent windows that become opaque on command can be used to control the amount of light and heat that enter buildings and vehicles. The technology saves energy, but current smart windows darken slowly and often have a blueish tint when partially opaque.
A team led by Christopher Barile at the University of Nevada in Reno developed a window that has layers of nickel oxide, lithium ions and electrolyte gel coating the inside of the pane. When a current is applied to these layers, the nickel oxide, acting as an electrode, soaks up the lithium ions and turns opaque. The current also prompts the electrolyte ions to form deposits on another window coating that serves as a second electrode. This blocks more light. These two effects have no strong colour bias, eliminating the coloured tint of existing smart windows.
Windows made according to this formula can switch states quickly — blocking 94% of light within 60 seconds — and in tests cycled between opaque and transparent at least 4,000 times without significant degradation.
Beloved fruit has a tangled family tree — but owes much of its fragrance and sweetness to just one ancestor.
The strawberries people enjoy today at picnics and parties have their roots in four wild plants found around the globe.
Cultivated strawberries have complicated genomes that geneticists have struggled to decode. By analysing a large portion of the strawberry’s DNA, Patrick Edger at Michigan State University in East Lansing, Steven Knapp at the University of California, Davis, and their colleagues estimate that 4 species hybridized with one another more than 1 million years ago, yielding the lineage that gave rise to today’s crop.
The heritage of the ‘garden strawberry’ began with a cross between two Japanese species, Fragaria iinumae and Fragaria nipponica. A plant from the resulting family then bred with Fragaria viridis, which is widespread in Europe and Asia. Later, that lineage mingled in North America with a local subspecies of Fragaria vesca called bracheata to yield the strawberries we know and love.
In an analysis of gene expression, the team found that strawberry flavour, colour and aroma are controlled mainly by F. vesca genes. This suggests that, over time, genes from the other three genomes were suppressed as those from the F. vesca genome rose to dominance.