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The now-extinct Neoepiblema acreensis (artist’s impression) is one of the largest rodents ever to have lived in South America, but its brain was minuscule for its size. Credit: J. D. Ferreira et al./Biol. (CC BY 4.0)
12 February 2020
A South American rodent had the heft of a Saint Bernard dog — and a brain the weight of a golf ball.
Behold Neoepiblema acreensis, an 80-kilogram rodent related to chinchillas that lived 10 million years ago in what is now Brazil. José Ferreira and Leonardo Kerber at the Federal University of Santa Maria in Brazil and their colleagues were curious about the brains of these beasts, so they used computerized tomography to peer inside two fossil skulls.To compare brain sizes between creatures of varying weights, scientists can calculate a species’ ‘encephalization quotient’, a measurement of the difference between the expected brain size and actual brain size for an animal of a certain weight. Any value under 1 means an animal’s brain is smaller than expected.The team estimates that the brain of N. acreensis weighed just 47 grams. The encephalization quotient of one individual studied was 0.20; that of the other individual was 0.33. In other words, N. acreensis’ brain was unusually puny in comparison to its body. By contrast, modern South American rodents have an average encephalization quotient above 1.05.The researchers suggest that because N. acreensis had few predators to outwit, a large brain simply wasn’t worth the maintenance costs.
A gold atom’s nucleus (pictured, artist’s impression) has been observed executing an unusual type of spinning motion. Credit: ARSCIMED/SPL
Atomic and molecular physics
13 February 2020
Scientists catch their first glimpse of an intricate type of nuclear movement.
For the first time, physicists have clearly observed a rare and complex motion of atomic nuclei called longitudinal wobbling.An atomic nucleus is composed of protons and neutrons, collectively called nucleons. In an excited state, some nuclei with an odd number of nucleons exhibit a complex wobble — like that of a spinning top — because of their imbalanced geometry. Previous observations detected wobbling around only either the longest or shortest axis of nuclei having fewer than 170 nucleons.Nirupama Sensharma at the University of Notre Dame in Indiana and her colleagues bombarded a ytterbium target with fluorine ions to produce the form, or isotope, of gold called gold-187. Analysis of gamma rays that the nuclei produced as they decayed indicated that the nuclei were wobbling. This makes 187Au the heaviest known wobbling isotope.The team detected the 187Au nucleus wobbling about an axis that was neither its longest nor its shortest, but was of an intermediate length — the first clear observation of such behaviour.
A 3D reconstruction of a human kidney shows interior blood vessels (light green) and structures (purple) that filter waste products. Credit: S. Zhao et al./Cell
13 February 2020
Machine learning helps to expose the molecules and structures within a human kidney, eye and thyroid.
To study the body’s inner workings, scientists generally chop up organs and construct 3D images from several thin slices of tissue — a time-consuming and error-prone process. Now, researchers have developed a way to peer inside intact human organs in microscopic detail. Ali Ertürk at the Munich Helmholtz Centre in Germany and his colleagues soaked organs in chemicals that preserve the structure of tissues while stripping them of fats and pigments that normally block the passage of light. The process makes tissues permeable to dyes and molecules that label specific structures, such as neurons and blood vessels.To take 3D images of the clear organs, the researchers used a microscopy technique that helped them to image thin slices of tissue without having to cut into it. Then, the team developed machine-learning algorithms to rapidly analyse millions of individual cells in the images.Using this approach, the researchers took detailed snapshots of an intact human eye, thyroid and kidney. The method could help to reveal human organ functions in health and disease, the researchers say.
A beam-shaped DNA motor (grey) rolls swiftly along a straight path (black) with the help of DNA ‘legs’ (green) . Credit: A. Bazrafshan et al./Angew. Chem.
Nanoscience and technology
13 February 2020
‘Origami’ nanomotors attain a blistering pace of 100 nanometres per minute.
In a one-of-a-kind race, DNA motors have achieved some of the fastest speeds and longest distances ever travelled by nanometre-scale machines.The track: a standard glass slide covered with RNA. For the motors, Yonggang Ke, Khalid Salaita and their colleagues at Emory University in Atlanta, Georgia, folded a very long strand of DNA back on itself 16 times to create a 3D beam. The researchers attached 36 ‘legs’ — short RNA strands that could bind the RNA on the track — to each of the beam’s 4 long faces.After the DNA devices were placed on the track, the legs on the bottom face found their footholds within minutes. To start the race, the researchers added an enzyme that breaks apart double-stranded RNA molecules. When the enzyme detached the legs from the track, each beam tipped forward onto its next face, thus rolling in a straight line from its starting point.In a 99-vehicle race, some of the DNA motors sped down the track at more than 100 nanometres per minute, compared with only 10 nanometres per minute for previously developed DNA machines.
As a nation becomes more wealthy, the amount of food wasted by its people grows. Credit: Alamy
12 February 2020
New research explains why food waste is low in the Philippines but high in Belgium.
The world wastes twice as much food as previously estimated — and rich countries are disproportionately responsibleMarkets allow harvested vegetables to rot; families throw out leftovers. These and other forms of loss and waste claim one-third of the world’s food supply, according to an estimate by the United Nations Food and Agricultural Organization (FAO).Monika van den Bos Verma of Wageningen University and Research in The Hague, the Netherlands, and her colleagues wanted to explore how consumer affluence affects food waste. The researchers drew on 2003 data collected by the World Health Organization, the FAO and others to estimate calories purchased, calories consumed and calories wasted by people around the globe.Belgium had the most food waste, and the Philippines had the least. (The study covered two-thirds of the world’s population, and did not include large food-wasting countries such as the United States.) As household spending rose above roughly US$6.70 per day per person, the amount of food waste also rose quickly, but then slowed.Globally, people waste 527 calories per person per day — more than twice as much food as scientists had thought.
Paddles replace pedestrians in Manila. Typhoons, known for dumping torrents of rain, can help to kick-start the dry season in the Philippines and nearby nations. Credit: Ted Aljibe/AFP/Getty
11 February 2020
Strong typhoons in the western Pacific Ocean funnel water vapour east — with effects on Asia’s populous island nations.
Despite their lashing winds and rains, strong typhoons in the western Pacific Ocean also help to cause the dry season in Southeast Asia.Typhoons regularly unleash punishing rains on the Maritime Continent, the expanse of islands and sea that lies between the Indian and Pacific oceans and that includes the Philippines and Indonesia. Using more than 35 years of historical weather data, Enrico Scoccimarro at the Euro-Mediterranean Centre on Climate Change in Bologna, Italy, and his colleagues compared monthly measures of the strength of typhoons in the tropical western Pacific with precipitation over the Maritime Continent and the nearby ocean.Compared with weak typhoons, stronger storms brought heavier precipitation over the ocean, but were associated with drier months in the Maritime Continent. This relationship held even after the team controlled for large-scale climate phenomena, such as El Niño.The researchers’ computer simulations suggest that typhoons and dryness are linked because the storms carry atmospheric water vapour eastward, away from the landmasses. Improving typhoon forecasts, the authors say, could help to better predict the onset of Southeast Asia’s dry season.
The CRISPR–Cas9 enzyme complex (blue and grey) edits DNA (purple). Participants in one of the earliest clinical trials of a CRISPR-based therapy experienced no serious side effects. Credit: Ella Maru Studio/Science Photo Library
CRISPR-Cas9 genome editing
10 February 2020
Immune cells whose genomes have been altered with CRISPR are well-tolerated by three people with cancer.
Preliminary results from one of the earliest clinical trials of CRISPR—Cas9 provide evidence that the technique is safe and feasible to use for treating human diseases.‘Designer’ immune cells with enhanced abilities to seek and attack tumours have shown promise in treating some cancers. But researchers would like to improve methods to bolster immune cells’ cancer-fighting powers. One option is the use of CRISPR–Cas9, a method for making targeted changes to the genome.Edward Stadtmauer and Carl June at the University of Pennsylvania in Philadelphia and their colleagues collected immune cells called T cells from three people with cancer. Using a conventional genetic-engineering method, the team gave the T cells the ability to recognize a protein produced by some cancer cells. The researchers also used CRISPR–Cas9 to block the T cells’ production of three proteins that might inhibit the cells’ ability to target tumours.After being reintroduced into the trial participants’ bodies, the T cells thrived for at least 9 months without causing any significant side effects. However, cancer in all three participants has since continued to progress.
Even teenagers who tend to wake up early benefit from starting school late in the day, according to a study of Argentine adolescents. Credit: Getty
10 February 2020
When lessons start at 7:45 a.m., morning-loving students do better than those who naturally wake up later.
Whether they’re early birds or not, teenagers could get healthy amounts of sleep and improve their academic performance by attending school in the evening, according to a study of Argentinian adolescents.Around the world, secondary school tends to start very early in the morning. But the biological clock ticking away inside many adolescent brains doesn’t align with school schedules, resulting in sleep loss and other problems.María Juliana Leone at the National Council of Scientific and Technical Research in Buenos Aires and her colleagues collected sleep data from teenagers at a local secondary school at which students were randomly assigned to start classes at 7:45 a.m., 12:40 p.m. or 5:20 p.m. The researchers placed students on a continuum from early-rising ‘larks’ to later-rising ‘owls’, according to their preferred waking time.Analysis of students who started school in the morning showed that, compared with larks, owls had overall lower grades that worsened as they advanced through school. Almost no students on the morning schedule got adequate sleep, leading researchers to suggest that a progressive delay of school start times throughout adolescence could benefit all.
Workers handle oranges in Axtla de Terrazas, Mexico. Mexican oranges sold in the United States can have a higher carbon footprint than oranges from more distant groves. Credit: Mauricio Palos/Bloomberg/Getty
07 February 2020
Fruit hauled by container ship can prove more environmentally friendly than that carried shorter distances by road.
An analysis of oranges transported to market in four US cities shows that fruit imported from farms thousands of kilometres away can have a smaller carbon footprint than fruit that travels much shorter distances.Eric Bell and Arpad Horvath at the University of California, Berkeley, looked at the ‘cradle-to-market’ greenhouse-gas emissions of oranges that travelled from agricultural regions, including those in California, Florida, Mexico and Chile, to four destinations: New York City; Los Angeles, California; Chicago, Illinois; and Atlanta, Georgia. The authors found that how an orange travels to market can be a bigger factor in the size of its carbon footprint than the distance it covers.That’s because oranges freighted from afar are often transported by container ships and trains, which can carry much larger quantities than trucks and use much less fuel per kilo of oranges. For example, oranges that travel from Mexico to New York by truck have a travel-related carbon footprint six times larger than that of oranges that travel from Chile to New York by container ship, even though the distance from Chile is more than twice that from Mexico.
An ion trap uses electric fields to hold a charged particle in place. Scientists used a similar device to immobilize a ytterbium ion before chilling it. Credit: Andrew Brookes, National Physics Laboratory/SPL
Atomic and molecular physics
07 February 2020
A crowd of atoms helps to cool an ion to less than one ten-thousandth of a kelvin.
Researchers have cooled an ion in an ultra-cold gas until it moved so slowly that it exhibited quantum behaviour. For decades, physicists have blasted materials with lasers to cool them to temperatures of just a fraction of a kelvin. Scientists have applied this technique to individual ions, which carry a charge, and to low-density gases consisting of uncharged atoms; both targets respond to chilling in ways predicted by the laws of quantum physics, which govern the Universe at very small scales.To study how ultracold atoms and ions interact under quantum conditions, Rene Gerritsma at the University of Amsterdam and his colleagues used electric fields to trap a single ytterbium ion. They then placed the ion inside a cloud of several thousand lithium atoms that a laser had pre-cooled to just a few millionths of a kelvin. This cooled the ion to less than one ten-thousandth of a kelvin — slowing its thermal motion to a crawl.Observations of the ion colliding with surrounding atoms revealed quantum effects, a first for an ion inside a cloud of neutral atoms.
A model projects that the rhesus macaque, which lives across Asia, harbours a large array of microbes that could infect people. Credit: Magnus Lundgren/Wild Wonders of China/NPL
06 February 2020
Scientists identify two primate species as hosts of a high number of pathogens that can jump to Homo sapiens.
The mammals that are most likely to pass diseases to humans are those that easily share their bacteria and viruses across species boundaries.Disease-causing microbes that have jumped from animals to humans include Ebola virus and the coronavirus behind the 2020 epidemic in China. Maya Wardeh at the University of Liverpool, UK, and her colleagues collected information on 1,560 mammalian species, including their geographical ranges, their interactions with humans and their pathogens. Using machine-learning software, the researchers organized the animals into a network that revealed how the species share 3,986 pathogens with one another.Mammals that share pathogens with many other species are more likely to serve as reservoirs for human diseases, the researchers found. Among the species predicted to harbour the highest number of potential human pathogens are chimpanzees (Pan troglodytes), rhesus macaques (Macaca mulatta) and red foxes (Vulpes vulpes).The researchers say that the findings could help to identify how bacteria, viruses and other infectious agents jump to humans.
Well hello, cutie pie! The sing-song tones of parentese promote babies’ language development. Credit: Getty
04 February 2020
Formal instruction in ‘parentese’ might seem unnecessary, but researchers find that coaching caregivers leads to chattier children.
Baby talk can sound silly, but the simple, high-pitched speech that adults use when speaking to infants and toddlers could help children to learn new words.Scientists know that hearing parentese — slow, melodic speech featuring exaggerated vowels — can boost infants’ language skills. These abilities are important predictors of a child’s success in school.To study how coaching parents in parentese affected their children’s language learning, Naja Ferjan Ramírez, Sarah Roseberry Lytle and Patricia Kuhl at the University of Washington in Seattle asked the families of 71 US infants to record themselves interacting with their babies at 6, 10, 14 and 18 months of age. The researchers assigned 48 families to coaching sessions that included tips for language-learning activities.Over a year, coached parents increased their use of parentese by 21%, whereas parents who weren’t coached increased it by 12%. At 18 months, children of coached parents produced an average of about 2,200 vocalizations in 12 hours, nearly 40% more than infants whose families didn’t receive coaching.
A farmer and cart in Cuba, where small-scale and conservation-minded agricultural practices might account for the cleanliness of the nation’s rivers. Credit: Karen Brodie/Getty
04 February 2020
The island’s waterways have lower levels of fertilizer-linked pollution than the Mississippi River in the United States.
Despite centuries of colonization and agriculture, Cuba’s rivers are in good health.Sugarcane and cattle farming on the island date back to the late fifteenth century. To measure water quality in Cuba’s rivers today, Paul Bierman at the University of Vermont in Burlington, Rita Hernández at the Cienfuegos Center for Environmental Studies in Cuba and their colleagues sampled water in 25 river basins in central Cuba. This is the first time in more than 60 years that scientists from Cuba and the United States have joined forces to study the island’s hydrology.More than 80% of the samples had levels of Escherichia coli bacteria that exceeded international standards for recreational use. The bacteria are indicators of faecal contamination, and probably came from the cattle that graze on many riverbanks.Despite the island’s history of large-scale agriculture, the rivers studied had much lower levels of dissolved nitrogen — an indicator of fertilizer use — than did the Mississippi River Basin in the United States. The researchers speculate that this is due to Cuba’s transition to smaller-scale, more sustainable farming practices since the 1990s.
Mount St. Helens erupts in 2004. Painstakingly restored analogue tapes document the volcano’s 1980 eruption, which killed 57 people. Credit: John Pallister/USGS/Getty
04 February 2020
Scientific sleuthing uncovers data from the run-up to a massive blast at Mount St. Helens.
Decades-old analogue tapes have yielded unprecedented details of earthquakes that shook Mount St. Helens in the months leading up to its cataclysmic eruption in 1980.The eruption of the volcano in southwestern Washington State was the deadliest in modern US history. In the months before the eruption, a handful of seismic stations monitored the shaking of the ground around the volcano, but the stations saved data only sporadically.Analogue tapes of seismic recordings languished in storage for years until 2005, when Stephen Malone at the University of Washington in Seattle retrieved the tapes and began the slow process of recovering the data stored on them. Malone hunted for old equipment on which to play the tapes, and baked some of them to stabilize their protective coating. In the end, he recovered a near-continuous record of quakes for the two-month period that shows how magma was moving in the ground beneath the volcano.The new data hold no hints that a big eruption was on the way. But scientists could use them to better understand how the ground rumbles around and beneath an active volcano.
Actor Michael J. Fox, who was only 29 when he was diagnosed with early-onset Parkinson’s disease, has become a public face of the illness. Credit: Jason LaVeris/Getty
03 February 2020
Scientists pinpoint molecular changes that could help to reveal people at risk of developing the disease before age 50.
Parkinson’s disease that develops in young and middle-aged people might be caused by cellular abnormalities present since birth.About 10% of Parkinson’s cases are diagnosed in people who are 21 to 50 years old, among them film star Michael J. Fox, who was diagnosed at age 29. To find molecular markers of this ‘young-onset’ Parkinson’s, Clive Svendsen at the Cedars-Sinai Board of Governors Regenerative Medicine Institute in Los Angeles, California, and his colleagues reprogrammed blood cells from 22 people with young-onset Parkinson’s to make stem cells, which were then grown into brain cells.These cells contained a build-up of α-synuclein proteins, thought to be toxic to neurons, and dysfunctional lysosomes, cellular structures that would normally clear the unwanted proteins. Because the problems could be traced back to the stem cells, the researchers suspect that the study participants were born with defective cellular machinery.The researchers found that the drug PEP005 efficiently reduces the accumulations of α-synuclein in both cultured cells and the brains of live mice.
A shark is weighed in New Bedford, Massachusetts, as part of the North Atlantic Monster Shark Tournament. Recreational shark hunting accounts for a growing proportion of shark catches. Credit: Maddie Meyer/Getty
31 January 2020
Hobbyists’ harvest of sharks and rays has soared, and catch-and-release is no solution.
The volume of fish caught recreationally more than tripled in the 60 years to 2014, and a recent uptick in recreational shark hunting is damaging fragile populations.The United Nations agency that documents fishing statistics almost exclusively monitors commercial fisheries. To quantify the impact of pleasure fishing, Dirk Zeller at the University of Western Australia in Crawley and his colleagues reconstructed the amount of fish caught annually in 125 countries. The researchers analysed reports from events such as fishing jamborees and gathered data on factors such as the number of licensed recreational fishers per state to scale up to a global estimate.The results showed that recreational catches increased from about 280,000 tonnes in the mid-1950s to around 900,000 tonnes in 2014. The hunting of sharks and rays for fun has been rising more steeply than other forms of recreational fishing since 1990, and now accounts for up to 6% of recreational catches worldwide. Although shark hunters often release the fish, a previous study of hammerhead sharks found that the majority of fish that were hooked and released died before reaching reproductive age.
Escherichia coli bacterium. Bioengineering can turn E. coli bacteria into efficient chemical factories. Credit: Steve Gschmeissner/SPL
31 January 2020
Bacteria churn out chemical bounty after researchers tinker with genes for longevity and cell division.
Genetic engineering can transform Escherichia coli bacteria into tiny ‘factories’ that efficiently produce valuable chemicals — and have a small carbon footprint.Microbial factories that turn renewable feedstocks such as simple sugars into ethanol or other useful commodities have been touted for their sustainability. But their productivity depends on many factors, including the lifespan of the bacteria themselves.Liming Liu and his colleagues at Jiangnan University in Wuxi, China, singled out specific genes associated with ageing in E. coli. By deleting these genes or boosting their activity, the team changed the microbes’ lifespan to optimize their yield of two products.The researchers found that reducing the number of times E. coli cells divide during their lifetime allowed the bacteria to produce 50% more of a biodegradable polymer. By contrast, when the scientists instead extended the microbes’ overall lifetime, the bacteria could produce high concentrations of butyrate, a compound used in pharmaceuticals and by the food and beverage industry, among others.
Don’t just lie there: lotus leaves atop long stems curve and ripple without the vertical support of the water’s surface. Credit: Fan Xu
29 January 2020
Scientists explore why some lotus leaves lie smooth and flat, but others are deeply ruffled.
Floating lotus leaves retain their flat, circular shape thanks to the water that supports them.The leaves of a young lotus (Nelumbo nucifera) lie flat on the surface of ponds and lakes, with only small ripples forming at the edge. But long stems often push the leaves of full-grown plants above the water’s surface. Such leaves typically have a wavy, warped appearance.Fan Xu and his colleagues at Fudan University in Shanghai, China, modelled the physics of lotus leaves and found that those sprouting from long stems experience a critical amount of strain that causes the leaves to warp as they grow. But floating leaves experienced vertical support from the water, allowing them to stay mostly flat and to form wrinkles on only the edges.The team confirmed these findings with experiments on sheets of rubber cut to the shapes of different leaves. When lying on water, the rubber leaves experienced only slight buckling on the edges. But when removed from water and suspended in the air, the entire leaf became warped.
People with gastric cancer (tumour, top left) in their families had a lower risk of developing the disease after taking drugs that wipe out ulcer-causing bacteria. Credit: Biophoto Associates/SPL
29 January 2020
Eradication of the microbe that causes gastric ulcers has a potentially life-saving side effect.
Ridding the gut of the ulcer-causing bacterium Helicobacter pylori could prevent stomach cancer in people with a family history of the disease.H. pylori infects more than half of all people, and has been linked to peptic ulcers and gastric cancer, which kills more people worldwide than all but two other cancers. Il Ju Choi at the National Cancer Center in Goyang, South Korea, and his colleagues studied 1,676 people with H. pylori infection who had a close relative with stomach cancer. Half of the participants received a placebo. The other half received a cocktail of antibiotics, which eradicated H. pylori in most but not all of the participants who took the drugsAbout 9 years later, 1.2% of participants who had been treated with the cocktail had developed stomach cancer, compared with 2.7% of those who had received the placebo. Stomach cancer occurred in only 0.8% of those whose H. pylori population had been eradicated, compared with 2.9% of those who remained infected.
This meat-cutting knife was found with Neanderthal fossils in the Altai Mountain foothills in Russia. Credit: IAET
27 January 2020
Stone tools found in a Siberian cave hint at a rugged intercontinental journey.
A rich trove of fossils and stone tools in a Siberian cave suggests Neanderthals made an extraordinary 3,000-kilometre trek from Europe to colonize central Asia about 60,000 years ago.Neanderthals have been found at numerous sites in Europe and western Asia, but the origins of Siberian populations have been elusive. Kseniya Kolobova at the Russian Academy of Sciences in Novosibirsk, Richard Roberts at the University of Wollongong, Australia, and their colleagues unearthed 74 Neanderthal fossils and 90,000 stone tools and other artefacts at Chagyrskaya Cave in Siberia’s Altai Mountains. The researchers argue that the tools closely match the style of Neanderthal tools found in Crimea and northern Caucasus, suggesting the Chagyrskaya Neanderthals originated in eastern Europe.The tool analysis supports a 2019 DNA study suggesting that a Neanderthal from Chagyrskaya Cave was more closely related to Neanderthals from Europe than to Neanderthals at Denisova Cave, located 100 kilometres east of Chagyrskaya. The Neanderthal remains at Denisova Cave are more than 100,000 years old, and probably represent an earlier wave of migration.