Research Highlights

Our pick of the latest scientific literature

  • Volume 551
  • Issue 7679
Glowing plasma jets shoot away from a black hole in this artist’s rendering.

Glowing plasma jets shoot away from a black hole in this artist’s rendering. ESO/WFI (visible); MPIfR/ESO/APEX/A. Weiss et al. (microwave); NASA/CXC/CfA/R. Kraft et al. (X-ray)

Astronomy and astrophysics

A black hole’s jets light up in less than a second

Plasma jets start to shine just after less-fortunate material swirls towards its doom.

Plasma jets shot from a black hole take about 0.1 seconds to start glowing.

Material spiralling towards a black hole emits X-rays. But some matter manages to escape ingestion and form plasma jets, which stream into space and then start to glow with visible light. A team led by Poshak Gandhi at the University of Southampton, UK, observed this process by training the William Herschel Telescope in La Palma, Spain, and NASA’s NuSTAR orbital telescope on a black hole in the Cygnus constellation.

As the densest chunks of matter approached the black hole, they gave off especially bright X-rays, but there was no immediate spike in visible light. Instead, corresponding flares of visible light lagged an average of 0.1 seconds behind the X-rays. That lag represents the time that it takes for a jet to start glowing.

These measurements will help to refine theories about why the jets shine, the scientists say.

The ancestors of many modern primates, like this pygmy marmoset, were among the first mammals to abandon a nocturnal schedule.

The ancestors of many of today’s primates, such as this pygmy marmoset, were among the first mammals to abandon a nocturnal schedule. Mark Bowler/NPL

Evolution

Early mammals were creatures of the night

First mammals shunned daylight to avoid dinosaurs.

Mammals were nocturnal until the dinosaurs’ decline made the daytime safer.

Most modern mammals — even those that are awake only during the day — show adaptions for the dark, such as an eye shape that maximizes low-light vision. These observations gave rise to the ‘nocturnal bottleneck’ hypothesis that the earliest mammals were active at night to avoid their hungry and dangerous rivals, the dinosaurs.

To test that idea, Roi Maor at Tel Aviv University in Israel, Kate Jones at University College London and their colleagues mapped the habits of more than 2,400 mammalian species onto a family tree and extrapolated the behaviour of ancestral mammals. They found evidence that mammals began to favour daylight hours only after dinosaurs died out some 66 million years ago. The ancestors of today’s monkeys and apes were among the earliest mammals to come into the light, abandoning their nocturnal habits as early as 50 million years ago.

Mammals’ new comfort with daytime life might help to explain their global success, the authors say.

Designated best sailors, fishing spiders take advantage of breezes to scud along the surface of ponds.

Designated best sailors, fishing spiders take advantage of breezes to scud along the surface of ponds. Olaf Craasmann/S. Mammola et al./PeerJ

Zoology

Champion spiders’ achievements are lauded

A new list celebrates biggest, smallest, oldest and 96 other arachnid records.

From largest to fastest to first in orbit, 99 record-holding achievements by spiders have been singled out for recognition, in the hope of raising interest in the oft-maligned creatures.

Stefano Mammola and Marco Isaia at the University of Turin in Italy and their colleagues compiled the list, including 44 Guinness World Records held by spiders, to raise interest in arachnid biology. The paper celebrates the anatomy, behaviour and palaeontology of spiders, from the most massive — the Goliath bird-eater (Theraphosa blondi), weighing up to 170 grams — to the farthest-travelled, two female Araneus diadematus spiders that lived on NASA’s Skylab space station in 1973.

Other record-holders include Darwin’s bark spider (Caerostris darwini), which produces the strongest silk — more than ten times tougher than Kevlar — and fishing spiders (Pisauridae) that can travel atop bodies of water, earning the title of best sailors.

Stem cells

Some stem cells are so efficient that just a few will do

Versatile stem cell completely replenishes the blood cells and immune system of macaques.

A potent type of stem cell can give rise to the entire immune system — and all blood cells.

Previous studies have suggested that several cell types, acting in waves, replenish blood and immune cells that are obliterated by chemotherapy or other causes. In a study in pig-tailed macaques (Macaca nemestrina), Hans-Peter Kiem at the Fred Hutchinson Cancer Research Center in Seattle, Washington, and his colleagues inserted genetic tags into thousands of types of stem cell and tracked them over time. The team found that low levels of a single type of stem cell were capable of generating all blood cells and the entire immune system, and maintaining them for up to 7.5 years. The scientists discovered that humans have a corresponding type of stem cell that expresses many of the same key genes.

The discovery could help to refine stem-cell therapies, potentially leading to treatment with fewer cells, fewer cell types and possibly fewer side effects, the researchers say.

Patterns of molecular groups on the DNA of grapevines, such as these in Australia’s Barossa Valley, vary between vineyards.

Grapevines from different vineyards, such as these plants in Australia’s Barossa Valley, bear different patterns of molecules on their DNA. Diana Mayfield/Lonely Planet Images/Getty

Plant sciences

Grapevine DNA changes hold clues to a wine’s source

‘Epigenetic’ changes could help to explain why one wine is fruity and another bold.

Chemical modifications to grape genes may be responsible for some of the subtle differences between one bottle and the next.

Connoisseurs have long attributed a wine’s qualities to its DNA and its ‘terroir’ — the interaction of factors such as genetics, farming practices and environmental variables, like a vineyard’s soils. Carlos Lopez at the University of Adelaide in Australia and his colleagues wondered whether terroir is influenced by a common alteration to DNA — the addition and removal of chemical tags called methyl groups. Such modifications, known as epigenetic changes, do not alter DNA sequence but can affect gene activity. The scientists sampled grapevines (Vitis vinifera L.) of the Shiraz cultivar from 22 vineyards in Australia’s Barossa region. They found that a vineyard’s location affected methylation levels, which in some cases varied more with location than a vine’s DNA.

The results suggest that epigenetic modifications help to explain differences between wines produced in different regions, the scientists say.

Methicillin-resistant Staphylococcus aureus, which causes pneumonia and sepsis, is adept at fending off antibiotics.

Methicillin-resistant Staphylococcus aureus, which causes pneumonia and sepsis, is adept at fending off antibiotics. E. García-Fernández et al./Cell

Microbiology

Statins disarm antibiotic-resistant bacteria

Drugs that lower cholesterol also render a dangerous pathogen vulnerable to antibiotics.

Certain drug-resistant bacteria become susceptible to antibiotics when treated with cholesterol-lowering statin drugs.

Daniel Lopez of the Spanish National Research Council in Madrid and his colleagues studied the ‘superbug’ methicillin-resistant Staphylococcus aureus (MRSA). The bacterium causes difficult-to-treat, sometimes deadly infections as a result of its ability to shrug off a number of antibiotics, including the penicillin derivative methicillin. The cell membrane of MRSA is highly fluid, but it contains specialized sections that are more rigid. These sections may serve as scaffolds for groups of proteins to work together.

The researchers found that the protein PBP2a, which gives MRSA its antibiotic resistance, collects in these membrane ‘microdomains’. Treatment with statins interfered with microdomain lipids and PBP2a activity. Mice infected with MRSA were much more likely to survive on a regimen of statins and antibiotics than on antibiotics alone.

Disruption of membrane microdomains could offer a new strategy for fighting multi-drug-resistant infections with conventional antibiotics, the authors say.

The hulking boulders, dubbed the Bull and the Cow, would not have needed a mega-storm to catapult them to the cliff tops. Charles Ommanney/The Washington Post/Getty

Climate sciences

Lofty stones reveal ancient storm secrets

Boulders’ rise to epic heights suggests that modest sea-level rise could batter shores.

Mega-storms need not be invoked to explain the presence of house-sized boulders high atop a cliff on the island of Eleuthera in the Bahamas.

Previous studies suggested that the boulders were deposited during storms more powerful than any in recorded history. Alessio Rovere at the University of Bremen in Germany, Maureen Raymo at Columbia University in New York City and their colleagues combined field surveys with fluid-dynamic and boulder-transport models to analyse two of the biggest boulders. These weigh hundreds of tonnes, and attained their current positions during the most recent interglacial period (116,000–128,000 years ago), when sea levels were 6–9 metres higher than they are at present. The team found that waves created by a storm similar to 2012’s Hurricane Sandy — a severe but not exceptional storm — could have pushed the boulders inland from the edge of the roughly 15-metre-high cliff, even if sea levels had been only 3.5 metres above current levels.

The results suggest that after only modest sea-level rise, cliffs and other coastal barriers could be more vulnerable to erosion by waves — even if storms do not grow more intense.

Images printed in a lead-based ink become visible when salts are added. C. Zhang et al./Nat. Commun. (CC BY 4.0)

Chemistry

‘Invisible’ ink can be made visible, then invisible, and back again

Ink based on lead ions might keep secrets safer.

A lead-based ink can be used to print invisible messages that become legible when decrypted with a chemical trigger.

Conventional ‘invisible’ inks are not very secure, because they are easily read under ultraviolet (UV) light. A team led by Liang Li at Shanghai Jiao Tong University in China developed an ink made of lead ions linked by organic molecules to form a crystalline material. Ordinarily, the ink scatters almost no light. But when compounds called halide salts are added, they pervade the ink’s crystalline structure, forming nanocrystals that fluoresce under UV light. The salts can be flushed out with solvents such as methanol to render the ink invisible again.

Logos and illustrations printed with this ink could be made visible and invisible 20 times. If concerns about the ink’s toxicity can be overcome, the method could be used in anti-counterfeit measures on documents such as banknotes.

These prehistoric designs in a cave on the Caribbean island of Mona were scooped into the ceiling. Project El Corazon del Caribe

Archaeology

Prehistoric artists crafted animal droppings into complex paints

Deep in Caribbean caves, artists mixed guano and plant gums to paint faces and geometric patterns.

Prehistoric Caribbean peoples used pigments made partly of bird or bat guano to create extensive cave art.

Jago Cooper of the British Museum in London and his colleagues found thousands of artworks in dozens of caves on Mona Island, near Puerto Rico. Scanning electron microscopy, spectroscopy and other analyses show that artists crafted some images by scooping out the soft deposits on the cave walls. Other motifs were painted using pigments composed of both guano from the cave floor and plant-based binders that the artists brought to the caves.

The images — depicting faces, animals and geometric designs — were made as early as the eleventh century AD, according to radiocarbon dating and other methods. Many artworks are found far from cave entrances, meaning ancient people ventured deep into dark zones to work.

The authors say that their analytical techniques can be applied to artworks at a wide variety of archaeological sites.

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