How bacteria make their fortresses : Research Highlights

Bacteria enriched skin wound

A skin wound is fringed by hairs (pink-white), and surrounded by immune cells (green) and beneficial bacteria too small to be imaged. Credit: NIAID

Bacteria on your skin could speed healing

The immune system and microbes join forces to overcome injury in mice.

Microbes on the surface of the skin help the immune system to respond to injury and heal wounds.

Immunity research has historically focused on the response to pathogens and inflammation, and so relatively little is known about how our own microbiota interact with and regulate the immune system. Yasmine Belkaid at the National Institute of Health in Bethesda, Maryland, and her colleagues set out to understand how the immune system senses and responds to microbes living on the body. Studying mice, they found that after injury, the immune system recruits different molecules to detect skin microbes than it uses to sense pathogens, and that its response to certain microbes encourages tissue repair.

Future research will explore whether the findings apply to humans, and whether a deeper understanding of certain microbes’ role in immunity could lead to novel approaches to tissue repair, a fundamental challenge in medicine.

Saiga antelope

A male saiga antelope on the steppes of Russia. Credit: Getty

Mass die-off of rare antelope linked to heat

High temperatures and humidity made a harmless bacteria lethal.

Climatic conditions transformed a usually harmless bacterial infection into a dangerous outbreak that killed more than 60% of the world’s saiga antelope.

More than 200,000 saiga antelope (Saiga tatarica tatarica) in Kazakhstan died of a virulent infection over a 3-week period in May 2015. Richard Kock at the Royal Veterinary College in London and his colleagues conducted post-mortem examinations of 33 animals and identified a bacterium (Pasteurella multocida), which caused extensive internal bleeding, as the culprit.

The bacterium does not typically harm healthy saiga, which suggested that an environmental factor might have made the microbe more dangerous. The team analysed weather data from 1979 to the mid-2010s, a period that included three mass die-offs of saiga — in 1981, 1988 and 2015. They found that the outbreaks were linked to relatively high daily temperatures and humidity levels.

Careful management is needed to protect the remaining populations of this critically endangered species, especially in the face of climate change, the authors say.

An X-ray shows the shrunken gastrointestinal tract resulting from a gastric bypass, which can help obese people to lose weight.

An X-ray shows the shrunken gastrointestinal tract resulting from a gastric bypass, an operation that can help obese people to lose weight. Credit: Zephyr/SPL

Surgery that slims also cuts risk of death

Health benefits persist years after procedure.

Weight-loss operations could cut death rates in people who are obese, according to a large study performed in Israel.

Bariatric surgery, which aims to reduce patients’ weight, is known to produce health benefits in the short term, but relatively little is known about its long-term effects. To address this question, Orna Reges at the Clalit Research Institute in Tel Aviv and her colleagues studied the health records of 8,385 people who had undergone gastric bypass or other types of surgery to treat obesity between 2005 and 2014. The researchers examined the patients’ medical outcomes up until the end of 2015 and compared the records against those of more than 25,000 obese individuals of similar age, sex and health who did not receive surgery.

Over a median follow-up period of 4.5 years, mortality rates were significantly lower among people who had had surgery: 1.3% died, compared with 2.3% of non-surgical patients.

Non-endoscopic balloon device

A capsule only 1.6 centimetres long conceals a mini-balloon that can be inflated in the stomach after the capsule is swallowed. Credit: Carla Schaffer/Moinova et al./AAAS

A tiny balloon to survey cancer risk

Inflatable device samples cells for signs of a pre-cancerous condition.

An easily swallowed mini-balloon might offer a way of screening people who are at risk of esophageal adenocarcinoma, a deadly type of cancer.

Sanford Markowitz at Case Western Reserve University in Cleveland, Ohio, and his colleagues developed an aspirin-sized capsule containing an uninflated balloon. After being swallowed, the balloon can be inflated in the stomach, and then pulled through the esophagus and deflated before recovery through the mouth.

The team used the balloon to collect esophageal cells in the hope of identifying a biological marker for a condition called Barrett’s esophagus, which often precedes esophageal adenocarcinoma. A genetic analysis of cells from more than 400 people, including samples retrieved using the balloon technique, revealed a pattern of DNA modifications that accurately detected 90% of Barrett’s-esophagus cases.

Barrett’s esophagus is currently diagnosed by passing an endoscope through the mouth into the stomach. The balloon method in combination with DNA analysis could provide an efficient and minimally invasive technique for screening large numbers of people, the authors say.

The colony of endangered African penguins on South Africa’s Robben Island shrank by almost three-quarters between 2008 and 2015.

The colony of endangered African penguins on South Africa’s Robben Island shrank from about 4,200 to some 1,200 breeding pairs between 2008 and 2015. Credit: Richard B. Sherley

Baby penguins benefit from fishing bans

South African survey provides rare evidence on fishery impacts.

Even modest restrictions on fishing can improve survival rates for penguin chicks in South Africa.

Richard Sherley at the University of Exeter, UK, and his colleagues monitored chicks in populations of African penguins (Spheniscus demersus) on South Africa’s Robben Island and neighbouring Dassen Island. For all but one year between 2008 and 2015, fishing was banned within 20 kilometres of one or other of the islands.

The team found that chick survival improved by 11% in years when fishing was prohibited. Computer simulations showed that the fishery closures reduced the risk that these colonies would decline to fewer than 500 breeding pairs by 2025. Below that number, the long-term odds of colony survival drop to less than 50:50.

But the team found that closures had no consistent effect on the African penguin colonies on two other South African islands. All the same, the results provide some of the first evidence that human harvests of small, schooling fish can affect entire populations of marine predators, the authors say.

Image enhancement showed that what was thought to be a hawk carrying an egg is in fact a vulture with a symbol called an ankh.

Image enhancement revealed that this faded painting depicts not a hawk carrying an egg, as previously thought, but a vulture holding a symbol known as an ankh — a rare combination in the art of ancient Egypt. Credit: L. Evans & A. -L. Mourad/J. Archaeol. Sci. Reports

Egyptian tombs depict seldom-seen creatures

Imaging technique reveals painted details lost to time.

Brightly coloured paintings of pigs and other creatures rarely seen in Egyptian art have been found on the walls of ancient tombs by scientists using image-enhancement software.

Detailed depictions of ordinary life adorn 12 tombs at the Beni Hassan cemetery, which sits alongside the Nile River south of Cairo and dates to the period known as the Middle Kingdom, from 2050 to 1650 bc. Hoping to reveal obscured details, Linda Evans and Anna-Latifa Mourad at Macquarie University in Sydney, Australia, examined the artworks with software that highlights trace pigments.

The software revealed details such as a pig and two bats, which are seldom shown in images from the time of the pharaohs. The technique also revealed a previously unidentified bird to be a vulture clutching a religious symbol in its talons.

The technique could be used to uncover a wealth of hidden detail in the extensive wall paintings of ancient Egypt, the researchers say.

A man is treated for malaria in Thailand.

A man is treated for malaria in Thailand. Credit: Pornchai Kittiwongsakul/AFP/Getty

Lethal malaria parasite’s weaknesses revealed

Genomic insights could inform discovery of more durable drugs.

A sweeping genomic analysis of the most deadly malaria parasite has revealed targets for more resilient drugs against the pathogen.

The parasite Plasmodium falciparum has evolved resistance to every licensed drug. To aid the search for compounds that present higher barriers to resistance, a team led by Elizabeth Winzeler at the University of California, San Diego, exposed 262 strains of P. falciparum to a range of antimalarial agents. By analysing the genomes of strains that evolved resistance to the chemicals, the researchers identified the mutations that were most- and least-often linked to the parasite’s ability to survive an onslaught of antimalarial drugs.

The team reasoned that genes with infrequent mutations would make good drug targets, because they seem less likely to adapt to new antiparasitic agents. Some of those genes code for enzymes, which can be targeted by drugs that are easier to administer than other types of therapy.

Water droplets

Supercooled water was made by spraying microscopic water droplets into a vacuum.

The coldest liquid water ever measured

Droplets in a vacuum are supercooled to –42.6 degrees Celsius.

Physicists have observed a record low temperature for liquid water.

Under strict conditions, water can exist in a liquid state well below its freezing point. But reliably measuring the temperature of ‘supercooled’ water is challenging. To do so, Robert Grisenti at the GSI Helmholtz Centre for Heavy Ion Research in Darmstadt, Germany, and his colleagues sprayed micrometre-sized droplets of water into a vacuum. Molecules of water evaporated from the surface of the droplets, making them smaller and colder.

The droplets cool in proportion to how much they shrink, which enabled the researchers to determine the water’s temperature by measuring droplet size with a laser. The team calculated the water’s temperature to be –42.6 degrees Celsius.

Because supercooled water occurs naturally in Earth’s upper atmosphere, gaining a better understanding of its properties, as well as how and when it transforms into ice, could help researchers to develop more reliable climate models, say the authors.


A researcher adjusts equipment at the X-ray laser facility in Menlo Park, California. Credit: Andy Freeberg/SLAC National Accelerator Laboratory/CC BY-NC-SA 2.0

Powerful pulses of X-rays see through molecules in an instant

Electrons are corralled to create an X-ray laser that snaps shots in just ten quadrillionths of a second.

An accelerator has generated brief X-ray bursts three times more powerful than any other such pulse, in an advance that promises to deliver sharper images of biological molecules and chemical structures.

Only a few sites in the world produce X-ray free-electron-laser pulses, which are created by coaxing bunches of electrons into swerving back and forth. This motion forces them to emit bright bursts of X-rays. Marc Guetg and his colleagues at the SLAC National Accelerator Laboratory in Menlo Park, California, devised techniques to pack electrons closely together just before they emit the X-rays, overcoming the electrons’ tendency to repel each other.

The resulting laser pulses last for only ten quadrillionths of a second and are the brightest ever produced. Such powerful flashes can image objects such as individual viruses with very high spatial resolution. The briefness of the pulse means that scientists can capture the atomic structure of a target before the pulse damages it, the authors say.

Crohn's colon sample

A section of large intestine shows inflammation that is a hallmark of Crohn’s disease. Credit: Michael Bonert/<a href=””>CC BY-SA 3.0</a>

One gene links two different diseases

A stretch of DNA is implicated in both Crohn’s and Parkinson’s diseases.

A gene associated with Parkinson’s disease might also have a role in a debilitating intestinal disorder.

Crohn’s disease is an inflammatory bowel condition that is particularly common in Ashkenazi Jewish populations. Inga Peter of the Icahn School of Medicine at Mount Sinai in New York City and her colleagues analysed gene sequences in more than 2,000 people with Crohn’s disease and 3,600 individuals without the condition, all of whom were of Ashkenazi Jewish descent.

The team found a link between Crohn’s disease and a particular DNA sequence in a gene called LRRK2. The variant DNA causes the LRRK2 protein to become more active than the typical protein — as does a Parkinson’s disease-associated variant in the same part of the protein.

The researchers say that the findings could help to explain the mechanism underlying the two seemingly unrelated diseases.

Primitive moths

This fossilized scale bedecked either a moth or a butterfly that lived some 200 million years ago. Credit: Bas van de Schootbrugge

Moths fluttered before flowers bloomed

Earliest butterflies and moths might have sipped sugary drops from trees.

Butterflies and moths evolved at least 70 million years earlier than previously thought — well before the emergence of flowering plants.

Bas van de Schootbrugge at Utrecht University in the Netherlands and his colleagues combed through sediments from Germany to collect microfossils of the tiny scales that cover the body, wings and legs of moths and butterflies, a group known collectively as Lepidoptera. The team dated the sediments containing the scales to around 200 million years ago. The scales’ features lead the authors to conclude that the fossils belong to the earliest known moths and butterflies.

The find demonstrates that Lepidoptera were already fluttering some 75 million years before flowering plants appeared. The proboscis, the characteristic lepidopteran tube-like mouthpiece, may have been used by the earliest species to drink sugary, nectar-like droplets found on conifer cones and other early botanical structures, the authors say.

Green Bank Telescope

Data collected at Green Bank Observatory in West Virginia point to a massive black hole as a potential source of bright radio flares. Credit: Jim Lo Scalzo/EPA/REX/Shutterstock

Astronomy and astrophysics

Puzzling flashes from space have an exotic source

A black hole–neutron star duo might produce the brilliant signals.

A neutron star embedded in a powerful magnetic field might be the source of fleeting radio signals that have long mystified astronomers.

Short, powerful pulses of radio-frequency light emanating from far outside the Galaxy are known as fast radio bursts (FRBs). But the origin of these blazingly bright flashes has been a mystery.

To establish where FRBs come from, Jason Hessels at the University of Amsterdam and his colleagues analysed a succession of bursts from a source called FRB 121102. The team relied on data from the Arecibo Observatory in Puerto Rico and the Green Bank Observatory in West Virginia. The bursts lasted as little as 30 microseconds each, a duration that points to a neutron star — the collapsed core of a massive star — as their origin.

Other properties of the burst show that the source is embedded in a strong magnetic field. Given FRB 121102’s extreme magnetic environment, the authors suggest that the bursts come from a neutron star that is either near a massive black hole or inside a highly magnetized supernova remnant.

Female impala in Mozambique’s Gorongosa National Park, where civil war took a heavy toll on wildlife in the 1980s and 1990s.

Female impala in Mozambique’s Gorongosa National Park, where civil war took a heavy toll on wildlife in the 1980s and 1990s. Credit: Robert Pringle

Human conflicts can devastate wildlife

Warfare drives population trends of many African mammals.

Frequent armed warfare in many of Africa’s nature reserves has contributed to the decline of some of the continent’s iconic beasts, including giraffes and hippopotamuses.

Although armed conflict often devastates local fauna, it can be protective — if, for example, people avoid habitats where battles rage. To understand the overall effect of warfare on wildlife, Joshua Daskin and Robert Pringle at Princeton University in New Jersey analysed data collected between 1946 and 2010 on more than 250 populations of large herbivorous mammals in Africa. More than 70% of the protected areas where the animals lived were affected by armed conflict during the study period.

The researchers found that conflict is the most important driver of population trends: as the number of conflicts rose, population growth rates fell. Some populations exhibited slower growth, whereas others shrank. But few populations vanished entirely, suggesting that war-torn herds can recover. The authors say that sustaining conservation programmes in war zones and aiding animals immediately after a ceasefire could save many vulnerable wildlife populations.

Emperor penguins

Emperor penguins, which can reach heights of 1.2 metres, glide through the cold sea off Antarctica. Credit: Paul Nicklen/Getty

Emperor penguins break their fast with night-time snacks

Expectant fathers don’t starve themselves as long as thought.

Emperor penguins are renowned for spending months without eating while they breed and incubate eggs — activities that they must complete on solid ground. Now, scientists have caught some of the birds sneaking off for late-night snacks.

Gerald Kooyman at the Scripps Institution of Oceanography in La Jolla, California, and his colleagues attached satellite tags to four emperor penguins (Aptenodytes forsteri) from the Cape Washington colony, which is one of the southernmost populations, in Antarctica. The researchers found that despite the birds’ reputation, the penguins left the ice during long Antarctic winter nights to forage for food in the sea.

This colony of penguins lives closer than many others to the ocean’s edge, which might allow the penguins to shorten their fasting periods and improve their condition — and so their chances of successfully incubating an egg to hatching. Any birds that move south as the climate warms might benefit from a shorter winter fast.

Inequality mapping

This map of travel time to cities shows places where trips take only minutes (bright yellow) versus where they take weeks (purple). Credit: The Malaria Atlas Project, University of Oxford

For many, it’s a long way to the city

Access to urban centres is vastly unequal.

Nearly half of the residents of low-income countries live more than one hour’s travel from a city, where vital resources such as education and health care are concentrated.

Access to schools, jobs and hospitals is essential for human well-being. Although 80% of the global population lives within an hour of a city, accessibility varies widely between high- and low-income countries. Daniel Weiss at the University of Oxford, UK, and his colleagues mapped overland travel time to thousands of cities worldwide. They found that nine out of ten people in wealthy countries, mainly in Europe and North America, can reach a city within an hour, compared to just 50% of people in low-income countries, such as those in sub-Saharan Africa.

Improving access to cities and the economic, educational and health benefits they offer is vital for advancing fair and sustainable development, the authors say.

Rewritable paper

When the paper is dipped in a solvent, the colour image on it will vanish, allowing for reuse. Credit: Y. Ma et al./Nature Commun./CC BY 4.0

Printer paper comes clean — over and over again

Specialized metallic inks make picture-perfect images on rewritable paper.

Rewritable paper can be printed with text or images — and then erased and reused more than six months later.

Wei Huang at the Nanjing University of Posts and Telecommunications in China and his colleagues coated paper with layers of polymers and highly reactive chemical groups, or ligands. The team also created a range of inks by dissolving salts of iron, copper or other metals in water. Each metallic salt, when daubed on the paper, reacted with the ligand to create a different colour.

The group produced luminescent prints by changing the ligand. And ligands that included zinc ions allowed plain water to be used as environmentally friendly ink.

To wipe the paper clean, the researchers treated the paper with either solvents or heat, which break the connection between the ligand and the metal ions.

Famine memorial

A sculpture in Dublin commemorates the millions of people whose lives were affected by the Great Famine that struck Ireland in the 1840s. Credit: Jean Brooks/Alamy

When the going gets tough, women are tougher than men

Women live longer than men through famine, epidemics and other trials.

When men and women are subjected to harsh conditions, it’s the women who live longer.

James Vaupel at the University of Southern Denmark in Odense and his colleagues studied seven populations that endured famine, epidemics or enslavement. The researchers found that during crises, girls and women lived longer than their male counterparts. For example, in Ireland during the Great Famine, which lasted from 1845 to 1849, life expectancy dropped from around 38 years for both sexes to about 19 years for men and 22 years for women.

The team traced much of the effect to infancy: newborn girls were more resilient than newborn boys. The minimal behavioural differences between male and female infants suggest that the difference in survival at that age is biological, the authors say.

Female green sea turtles return to the water after laying eggs near the Great Barrier Reef.

Female green sea turtles return to the water after laying eggs near the Great Barrier Reef. Credit: D. Parer & E. Parer-Cook/Minden/Getty

Turtle sex skewed by rising temperatures

Warming sands near the Great Barrier Reef have had a drastic effect on the number of males.

Almost every youngster in one of the world’s biggest populations of green turtles is female, a bias that probably results from rising temperatures on the animals’ natal beaches.

Sea-turtle eggs that are incubated at warmer temperatures are more likely to produce female hatchlings. Michael Jensen at the National Oceanic and Atmospheric Administration in La Jolla, California, and his colleagues studied two groups of green turtles living on the Great Barrier Reef. One hatches on cooler, southern beaches, and another — one of the world’s largest — hatches on warmer northern shores. The researchers found a moderate bias towards females among the first group. More drastically, in turtles that hatched further north, 87% of adults and up to 99.8% of immature animals were female.

Combined with temperature records, the results suggest that warmer temperatures in the northern Great Barrier Reef have led to mostly female offspring since the early 1990s.

Galaxies from the very early Universe

Two massive galaxies dance towards each other in this artist’s rendering. Credit: NRAO/AUI/NSF/D. Berry

Astronomy and astrophysics

A record-setting galaxy churns out stars

Hulking star system dates to the infant days of the Universe.

The biggest and brightest galaxy yet discovered in the far reaches of the Universe is sprouting stars at great speed.

Massive galaxies in their formative years are rarely spotted in the early Universe, because it takes extremely sensitive surveys of vast areas of the sky to find them. Daniel Marrone at the University of Arizona in Tucson and his colleagues studied infrared images taken by the Atacama Large Millimeter/submillimeter Array of a bright object dated to 780 million years after the Big Bang.

Previous observations suggested that the object was one gargantuan galaxy, but Marrone’s team found that it is a pair of galaxies in the process of merging. One of the galaxies is the biggest yet observed in this era of the Universe, producing enough new stars each year to equal 2,900 Suns in mass.

The object could be one of the largest and most distant galaxies in the early Universe, offering crucial insights into the formation of such objects, the authors say.



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