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To chase prey, tiger beetles do a superfast dance

10 hours 4 min ago

If a tiger beetle drew a line as it chased its next meal, the resulting pattern would be a tangled mess. But there’s method to the mess, researchers say.

Tiger beetles, known for their speed and agility, do an optimal reorientation dance as they chase prey at blinding speeds, says Jane Wang, professor of mechanical engineering and physics at Cornell University, who tries to find simple physical explanations for complex, hardwired animal behaviors.

This visual representation shows a tracked tiger beetle’s trajectories as it chases prey. By observing a beetle’s chase, scientists have derived a physical law that it follows to optimize its predation strategies. (Credit: Jane Wang/Cornell)

For a new study published online in the Journal of the Royal Society Interface, Wang and colleagues used high-speed cameras and statistical analysis to reveal a proportional control law in which the angular position of prey, relative to the beetle’s body axis, drives the beetle’s angular velocity with a delay of 28 milliseconds. That’s about a half-stride in beetle terms.

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These observations led Wang to propose a physical interpretation of the behavior: that to turn toward its prey, the beetle, on average, exerts a sideways force proportional to the prey’s angular position, measured a half-stride earlier.

“The idea is to find laws that animals use to intercept their prey,” Wang says. “We do it, too (interception)—when trying to catch a baseball, or when chasing someone. But since insects have a smaller number of neurons, their behaviors are more likely hardwired, which makes it possible for us to find and understand the rules they follow.”

Why the tiger beetle? It’s a nice model system, Wang says, which she learned after attending a talk several years ago by entomology professor Cole Gilbert, who studies neural mechanisms of behavior in arthropods and is a coauthor of the new paper.

Tiger beetle time scale

For the experiments, a “dummy prey”—a black bead—was dangled in front of the beetle, which, mistaking the bead for a meal, would give chase. Its chasing patterns were recorded with a high-speed camera.

From an evolutionary point of view, the sensing and moving are intimately connected. Some of the hundreds of thousands of neurons that function for sight are directly connected to the machinery for locomotion, which is directly related to the animal’s instinct to survive—that is, eat. Thus, studying how animals move can provide insight into how they sense their environment, and vice versa, Wang says.

Andreas Haselsteiner, a visiting student in Wang’s lab, is the first author of the study and designed the experiments.

Source: Cornell University

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Toddlers assess fairness and race of playmates

11 hours 9 min ago

New research shows that toddlers can take into account both race and how a person treats someone else when deciding who would make a better playmate.

Jessica Sommerville, associate professor of psychology at the University of Washington, who studies how children develop social behaviors like kindness and generosity, noticed something odd a few years ago. The 15-month-old infants in her experiments seemed to be playing favorites among the researchers on her team, being more inclined to share toys or play with some researchers than others.

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“It’s not like one experimenter was nicer or friendlier to the babies—we control for factors like that,” Sommerville says. She took a closer look at the data and realized that the babies were more likely to help researchers who shared the same ethnicity, a phenomenon known as in-group bias, or favoring people who share their own characteristics.

“At the time, about half of the research assistants in my lab were Asian-American and the other half were Caucasian, and most of the babies in our experiments are Caucasian,” Sommerville says. “We know that by preschool, children show in-group bias concerning race, but results in infants have been mixed.”

Fair and square

She and her research team designed a new experiment to test how race and fairness—a social tendency that infants appear to notice—influence babies’ selection of a playmate.

The findings, published in the online journal Frontiers in Psychology, show that 15-month-old babies value a person’s fairness—whether or not an experimenter equally distributes toys—unless babies see that the experimenter unevenly distributed toys in a way that benefits a person of the same race as the infant.

“It’s surprising to see these pro-social traits of valuing fairness so early on, but at the same time, we’re also seeing that babies have self-motivated concerns too,” Sommerville says.

Forty white 15-month-old babies sat on their parents’ laps while watching two white experimenters divide toys between recipients. One experimenter divided the toys equally, and the other experimenter divided the toys unequally, as shown in the video below.

Later, when the babies had a chance to choose who to play with, 70 percent of the time infants preferred the experimenter who distributed the toys fairly. This suggests that when individuals are the same race as the infant, babies favor fair over unfair individuals as playmates.

Opportunistic toddlers?

Next, Sommerville and her team asked a more complex question. What would happen when individuals who were of the same race as the infant actually stood to benefit from inequity?

In a second experiment, 80 white 15-month-old infants saw a fair and an unfair experimenter distribute toys to a white and to an Asian recipient. Half the babies saw the unfair experimenter give more to the Asian recipient; and the other half of babies saw the experimenter give more to the white recipient.

When it came time to decide a playmate, infants seemed more tolerant of unfairness when the white recipient benefited from it. They picked the fair experimenter less often when the unfair experimenter gave more toys to the white recipient versus the Asian recipient.

“If all babies care about is fairness, then they would always pick the fair distributor, but we’re also seeing that they’re interested in consequences for their own group members,” Sommerville says.

The findings imply that infants can take into account both race and social history (how a person treats someone else) when deciding which person would make a better playmate.

“Babies are sensitive to how people of the same ethnicity as the infant, versus a different ethnicity, are treated—they weren’t just interested in who was being fair or unfair,” says Monica Burns, coauthor of the study and a former University of Washington psychology undergraduate. She’s now a psychology graduate student at Harvard University.

“It’s interesting how infants integrate information before choosing who to interact with, they’re not just choosing based on a single dimension,” she says.

Racial awareness

Sommerville is quick to point out that her findings do not mean that babies are racist. “Racism connotes hostility,” she says, “and that’s not what we studied.”

What the study does show is that babies use basic distinctions, including race, to start to “cleave the world apart by groups of what they are and aren’t a part of,” Sommerville says.

A Psychology of Character grant from Wake Forest University supported the research.

Source: University of Washington

 

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Do animals with germ plasm evolve faster?

12 hours 7 min ago

New research suggests that genes evolve more rapidly in vertebrate species that have germ plasm as a part of their reproductive process.

The study, published in Science, tests a novel theory that early developmental events dramatically alter the vertebrate body plan and the way evolution proceeds.

With germ plasm and without

Early in animal development a subset of cells in an embryo becomes committed to produce Primordial Germ Cells (PGCs). PGCs develop into sperm or eggs. The remaining cells develop as the soma, a term that describes all of the tissues that make up an individual’s body.

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The germ line is an immortal cell lineage, passed on from generation to generation, and charged solely with producing a new embryo at fertilization.

The soma, on the other hand, dies off in every generation. In the most classic biological sense its job is to interpret the effects of natural selection in order to determine genetic fitness, leading to so called “survival of the fittest.”

There are two known ways to make a PGC. There is preformation—material in the egg called germ plasm is inherited directly by a few cells in the embryo, and germ plasm instructs these cells to become PGCs.

Alternatively, PGCs can develop without germ plasm. In this case PGCs can be induced to form by signals secreted from other cells, which are part of the soma. This is called epigenesis.

Faster evolution?

“Biologists are accustomed to thinking about how adult somatic traits impact natural selection and the evolution of new species. What is much less clear is the role of embryological mechanisms in evolution, and how they might contribute to species diversity,” says Andrew Johnson of the University of Nottingham.

He is of the view that the relationship between the germ line (hereditary germ cells that create sperm and eggs) and the soma (cells which form the body of an organism) also impacts on species diversity.

He argues that once a species evolves a substance called germ plasm, germ cells are independent of other cells, so constraints on somatic development are liberated and this enhances a species’ ability to evolve.

As a result, he says, vertebrates such as frogs, fruit flies, and birds, which look unlike their ancestors, came about, and remarkably they evolved much faster than their ancestors did.

Testing the hypothesis

“To investigate the effect germ plasm has on sequence changes we had to look at as many sequences as possible—nearly 12 million sequences were analyzed and processed from 165 different species including mammals, reptiles, amphibians, and fish,” says study coauthor Matt Loose.

With graduate student Teri Evans, Loose wrote computer programs to process these sequences and test the hypothesis. They compared DNA sequences from species that contain germ plasm with related species that use epigenesis instead.

So, for example, they compared DNA from salamanders (epigenesis) with frogs (germ plasm), both of which are amphibians. Unexpectedly, they found that species with germ plasm have a faster rate of sequence change than those without. Thus, frogs evolve faster than salamanders.

Similar comparisons with fish and reptile species identify the same pattern, suggesting it is a generalized feature of animal evolution. These results support the theory that germ plasm provides a selective advantage because it enables more rapid evolution. In addition, they support the view that the relationship between development of the germ line and soma shapes species diversity in the animal kingdom.

“What Matt and I have been working on would not normally have been predicted,” says Johnson. “This paper shows that animals can evolve more rapidly with germ plasm. Typically evolution is thought to be a gradual process, but this work suggests that the evolution of germ plasm can lead to explosive radiations of species.

“Importantly, because of the accelerated rate of evolution, genetic similarities between species can differ from that expected from their phylogenetic relationships. This has broad implications across biological disciplines.”

Axolotls and evolutionary dead ends

Johnson adds, “One of the things that was initially intriguing was that early on we realized that embryos from animals with germ plasm were different than embryos that use epigenesis. In fact, the adult body forms of these animals were not like those of ‘typical vertebrates.’

“This is why we developed the axolotl as an experimental model. Axolotls are ‘typical vertebrates,’ and they don’t contain germ plasm. We found that the mechanisms that control axolotl development are conserved in mammalian embryos. However, they are not found in ‘conventional’ models for vertebrate development, all of which have germ plasm.

“So when germ plasm evolves it leads to evolutionary dead ends. In other words, whereas salamander-like amphibians evolved into reptiles, then mammals, frogs could only evolve into other frogs. A lot of different frogs, but still just frogs.

“For this reason we think axolotl embryos have a very promising future as a model for human development.”

Source: University of Nottingham

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‘SQUID’ method unscrambles ancient rock record

14 hours 21 min ago

A lot can happen to a rock over the course of two and a half billion years. It can get buried and heated; fluids remove some of its minerals and precipitate others; its chemistry changes.

So if you want to use that rock to learn about the conditions on the early Earth, you have to do some geologic sleuthing. You have to figure out which parts of the rock are original and which came later. Now a team of researchers has developed and applied a unique technique that removes much of the guesswork.

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“We want to know what Earth looked like when these ancient rocks were deposited. That’s a giant challenge because a number of processes have scrambled and erased the original history,” says Woodward Fischer, assistant professor of geobiology at California Institute of Technology (Caltech). “This is a first big effort to try to wrestle with that.”

The findings appear in the Proceedings of the National Academy of Sciences.

Using the new method, Fischer and his colleagues examined ancient rocks dating to an age before the rise of oxygen. Today, water feeds the biosphere, providing the electrons needed to support life. But before the evolution of photosynthesis and the accumulation of oxygen in the atmosphere, elements such as iron and sulfur were the source of electrons.

Researchers interested in the early Earth want to determine how and when life figured out how to use these elements. The Caltech team has identified clear evidence that 2.5 billion years ago, sulfate-reducing microbes were already at work.

Fool’s gold

The researchers studied drill core samples collected in South Africa from sedimentary rocks that are slightly older than 2.5 billion years old. They focused on small features within the rocks, called nodules, made of the mineral pyrite.

Also known as fool’s gold, pyrite can be made in a number of ways, including as a product of respiratory metabolism: sulfate-reducing microbes reduce sulfate, which is present in seawater, yielding hydrogen sulfide, and when that hydrogen sulfide mingles with iron, pyrite is produced.

Today, sulfate-reducing microbes are often found in anoxic environments such as marine sediments where the oxygen has been consumed by aerobes but where there is still plenty of organic matter.

It is logical, then, to suspect that these microbes would have been important players on the early Earth, when oxygen was scarce. Comparative genomics studies of sulfate reducers that are living today also suggest that these microbes should have been present 2.5 billion years ago. But this has been difficult to confirm in the rock record.

From current studies, scientists know that sulfate reducers metabolize the various stable isotopes of sulfur in a predictable way: producing light sulfur isotopes first before moving on to produce heavier ones as they run out of substrate. This provides a chemical thumbprint that researchers can look for as they examine pyrite nodules.

The nodules crystalize early within the sediments, with the material at their core forming before the material at their edges. Therefore, to check whether sulfur-reducing organisms were active when a particular pyrite-containing rock formed, a geobiologist should be able to measure the ratios of a nodule’s sulfur isotopes at different points—both near the core and closer to the edges—to see how those ratios changed as the nodule grew.

Wrinkles of time

But the nodules are only about a millimeter in diameter, so researchers have not been able to collect the fine-grained measurements they need in order to identify the isotopic thumbprint. Instead, they often grind up an entire rock sample, measure its isotopic composition, and then compare it to another rock.

Muddying the interpretation even more, these ancient rocks have all been deeply complicated by the wrinkles of time. All of the events and circumstances that have affected them since their deposition have left their chemical marks, by carving away old materials and precipitating new ones.

A geologist can use some of the textures—the marks left in the fabric of the rock—to unravel some of a rock’s history, but only if those textures clearly crosscut or overlap one another. Some of the visual cues can also be misleading. So it can be difficult just to identify which parts of a rock are original and can therefore provide insight about the early Earth.

Fischer’s new technique changes all that. It allows researchers to untangle a rock’s history and to then zoom in and measure the isotopic ratios at a number of points within a single pyrite nodule.

He begins as any geologist would—by looking at a sample with light and electron microscopy to identify the different textures within the rock. Doing that, he might identify a number of pyrite nodules that “look good”—that appear to date to the rock’s original deposition.

Moon rocks

He then uses a technique called scanning SQUID (superconducting quantum interference device) microscopy, which uses a quantum detector to produce a magnetic map of the sample at a very small scale. Pyrite itself is not magnetic, but when it is later altered, it forms a mineral called pyrrhotite, which is magnetic.

Using scanning SQUID microscopy, Fischer has been able to rule out a number of nodules that had appeared to be original but that were in fact magnetic, meaning that they included pyrrhotite. In his South African samples, those deceptive features dated to a volcanic event 500 million years after the rocks were deposited, which sent chemistry-altering fluids through all the layers of sediment and rock that were present at the time.

“If you weren’t using this technique, you’d miss the later alteration,” Fischer says. “Those textures looked good. They would have passed naive tests.”

The final step in the process is to measure the isotopic composition of the nodules using an analytical method called secondary ion mass spectrometry (SIMS). This specialized technique is used to measure the chemistry of thin films and solids with very fine spatial resolution. Materials scientists use it to analyze silicon wafers, for example, and planetary scientists have used it to study bits of rock from the moon. Fischer’s group is one of the few in the world that uses it to study ancient rocks.

History of rocks

In SIMS, a sample under very strong vacuum is bombarded with a beam of cesium ions, which displaces ions from the surface of the sample. A mass spectrometer can measure those so-called secondary ions, providing a count of the sample’s sulfur isotopes. Since the beam can be focused very precisely, the method allows researchers to sample many points within a single nodule, measuring a 13 x 5 grid within a millimeter, for example. The product is essentially a map of the sample’s isotopic composition.

“It’s one thing to say, ‘Wow, rocks are really complicated. There’s just going to be information lost.’ It’s another thing to be able to go back in and say, ‘I know how to piece together the history of this rock and learn something about the early Earth that I didn’t know previously.’”

Using the new technique, Fischer and his colleagues were able to identify which parts of their drill core samples were truly ancient and to then measure the sulfur isotopic composition of those nodules as they grew. And indeed they found the isotopic signature expected as a result of the activity of sulfur-reducing microbes.

“This work supports the hypothesis that microbial sulfate reduction was an important metabolism in organic-rich environments on the early Earth,” Fischer says. “What’s more, we now know how we can ask better questions about ancient rocks. That, for me, is incredibly exciting.”

Additional Caltech coauthors are John Eiler, Joseph Kirschvink, Jena Johnson, and Yunbin Guan. David Fike of Washington University in St. Louis and Timothy Raub of the University of St. Andrews are also coauthors. The Agouron Institute and a NASA Exobiology Award supported the work.

Source: Caltech

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Do ads miss the mark for binational families?

14 hours 36 min ago

Cultural competence may be a larger factor than gender norms for binational couples as they make decisions about what to buy, new research suggests.

Samantha Cross, assistant professor of marketing at Iowa State University, and colleague Mary Gilly, a marketing professor at the University of California, Irvine, interviewed binational families for the study, which appears in the Journal of Marketing.

The two felt it was important to look specifically at families in which one spouse was born and raised in the US and the other in a different country, to truly see the impact of cultural differences on household decisions.

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Past research on the household decision-making process has primarily focused on the influence of gender. Today, families make more joint household decisions than 20 or 30 years ago, as more women are working outside the home and gender roles have evolved.

However, Cross finds those gender roles did not always apply to binational families and that is something businesses need to recognize.

“We make assumptions about a man and woman coming into a business or a service environment and those assumptions of gender roles are perhaps based on assumptions about cultural expectations,” Cross says. “If you have a binational household all of those roles may be reversed and you’re making assumptions that may be detrimental to getting their business.”

Cultural competence is an advantage

The study finds that in binational families, spouses who understand the day-to-day cultural norms have an advantage both outside and inside the home. When the wife had that advantage, traditional gender roles were often reversed or blurred.

For example, wives living in their native country handled more of the investment decisions for the family, whereas the husbands were primarily responsible for the finances if their wife was from another country.

Similarly, meal planning and grocery shopping was predominately handled by the immigrant wife, but spouses shared the responsibility when the husband was from another country. In participant households with a US husband and an immigrant wife, the majority of role allocation tends to be gender-based.

“If you’re a female immigrant spouse, you play a different role in the home than a male immigrant spouse. But even so, the male immigrant spouse is going to defer to the female native spouse,” Cross says. “I thought that was fascinating because the males were coming from some very hierarchical societies where they can be very gender driven in terms of their roles.”

How do people work together?

Cross and Gilly looked at 15 consumer decision categories ranging from vehicle and grocery purchases to children’s toys and computers. The majority of these decisions were made collectively. But those made by one spouse over the other, because of cultural competence, offer insights that are also beneficial in the workplace.

“If we can understand how two people from different cultures negotiate and how they make it work, it can tell us a lot about how other types of cross-cultural teams and organizations or even different companies work together,” Cross says.

The study also finds that immigrants do gain their own level of cultural competence over time, but never at the same comfort level as their spouse. Still, this increased cultural competence gives immigrants an advantage in the marketplace.

Binational families also compromise on certain decisions based on the sacrifice made by the spouse from a different country. For example, the immigrant spouse may make vacation decisions to visit family in their home country.

Cross and Gilly interviewed 18 families—16 couples, two individual spouses—living in the US for the study. Immigrant participants were from Mexico, Philippines, Taiwan, Chile, Australia, Iran, Belarus, Vietnam, and South Africa.

Source: Iowa State University

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How video surveillance could improve hygiene

15 hours 59 min ago

In an effort to boost health outcomes, researchers use video surveillance to better understand hand-washing hygiene practices of children in developing world settings.

One of the best defenses against infectious disease is one of the most simple—hand-washing.

Still, despite years of global public awareness campaigns, hand-washing rates remain low. Caregivers of young children in low-income, developing world settings are found to wash their hands only 17 percent of the time after using the toilet.

Overall, when students were alone at a hand-cleaning station, hand-cleaning rates averaged 48 percent, compared to 71 percent when at least one other student was present. (Credit: Amy Pickering)

A new study finds that video surveillance can provide insights into hand-washing behavior. When another person is present, for example, hand-washing rates increase 23 percent. These findings could, in turn, inform the design, monitoring, and evaluation of hygiene campaigns.

“Hopefully, video surveillance will be added to the toolbox for accurately measuring hand hygiene behavior, thus improving monitoring and evaluation of interventions around the world,” says Amy Pickering, the study’s lead author and a research associate at the Stanford Woods Institute for the Environment.

“Hand-washing is notoriously difficult to study. Video surveillance looks to be a promising strategy for obtaining reliable information, even in resource-constrained settings,” adds coauthor Jenna Davis, a senior fellow at Woods.

School children

The study, published in the journal PLOS ONE, was carried out using video cameras installed in the washing areas outside latrines of four public schools in the sprawling Kibera slum of Nairobi, Kenya. Parents and administrators gave permission for the study, and teachers were informed in advance.

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Pickering acknowledged that the students’ awareness of the cameras—teachers alerted them—likely affected their behavior. Still, Pickering points to the study’s findings as valuable data showing advantages of video surveillance over in-person observation.

Those advantages include lower cost, less time commitment, and faster, more reliable data processing. Having two research assistants watch video and record data is possible with in-person observation, but would add significant cost and logistical complications, while likely influencing hand washers’ behavior to an even greater extent.

Both methods of observation found the hand-cleaning rate after toileting was higher among girls—a 4 percent difference, according to video surveillance, and a 3 percent difference, according to in-person observation.

Sanitizer vs. soap

Both video observation and in-person observation demonstrated longer hand cleaning times for hand washing with soap as compared to rubbing with sanitizer.

Students at schools equipped with soap and water, instead of sanitizer, were 1.3 times more likely to wash their hands during simultaneous video surveillance and in-person observation when compared with periods of in-person observation alone.

Overall, when students were alone at a hand-cleaning station, hand-cleaning rates averaged 48 percent, compared to 71 percent when at least one other student was present.

Hand-cleaning rates showed an overall trend of increasing as the number of other people present at hand-cleaning stations increased, with the exception of a slight decrease in hand cleaning when more than 10 people were observed.

Based on the findings, the authors suggest the following strategies for better hygiene:

  • Placement of hand cleaning materials in public locations
  • Scheduling specific times for bathroom breaks between classes
  • Designating specific students to be hand hygiene “champions”
  • Formation of student clubs to demonstrate and promote hand hygiene to classmates

Source: Stanford University

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Drought and fire push Amazon forests to tipping point

16 hours 15 min ago

Deforestation and fragmentation of forests in the Amazon help create tinderbox conditions for wildfires in remnant forests and contribute to rapid and widespread loss of trees during drought years, researchers say.

The findings show that forests in the Amazon could reach a tipping point when severe droughts coupled with forest fires lead to large-scale loss of trees, making recovery more difficult.

The experimental burns set by the researchers move slowly and at low intensities in the forest interior, but they can still have damaging effects on trees that are not adapted to fire. (Credit: Penn State)

“We documented one of the highest tree mortality rates witnessed in Amazon forests,” says Jennifer Balch, assistant professor of geography at Penn State.

“Over the course of our experiment, 60 percent of the trees died with combined drought and repeated fire. Our results suggest that a perfect firestorm, caused by drought conditions and previous fire disturbance, crossed a threshold in forest resistance.”

Climate change is expected to warm the air in the Amazon region by several degrees and substantially reduce regional precipitation, making understanding the interactions between droughts and fires even more important, Balch says.

“However, even before any prediction of Amazon climate warming occurs, our study demonstrates that drought and fire are already driving forest dieback.”

More intense fires

The eight-year study is the largest and longest-running fire experiment in tropical forests. The team of researchers burned 50-hectare forest plots in the southeastern Amazon, a region prone to the effects of climate change.

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The plots were burned every year, every three years, or not at all. The timeframe for the study included 2007, a year of severe drought. By comparing the tree deaths for the plots each year, the researchers could assess the effect of drought on fire intensity and tree deaths.

“Drought causes more intense and widespread fires,” says lead author Paulo Brando of the Instituto de Pesquisa Ambiental da Amazônia, Carnegie Institution for Science, and Woods Hole Research Center.

“Four times more adult trees were killed by fire during a drought year, which means that there was also more carbon dioxide released to the atmosphere, more tree species loss, and a greater likelihood of grasses invading the forest.”

‘Big trees begin to die’

Fragmented forests are more susceptible to the negative impacts of drought and fire and drought leads to an increase in fuel such as leaves and branches. The findings are key, in part, because most climate change models have not included the impacts of fires on Amazonian forests.

“Basically, none of the models used to evaluate future Amazon forest health include fire, so most of these predictions grossly underestimate the amount of tree death and overestimate overall forest health,” says Michael Coe of Woods Hole Research Center.

Fire as a forest management tool can contribute to an increase in severe fires because the resulting thinner canopy leads to drier forest conditions. This lack of humidity does not dampen fires but does encourage airflow between fields and forests. Fragmented forests also have more edge space, which is susceptible to both fire and invasive grasses—another potential fuel.

“These forests are tough and can take a lot, but if drought reaches a certain level, big trees begin to die,” says study coleader Daniel Nepstad of the Earth Innovation Institute. “We now know that severe drought also makes fires more intense, creating a second tree mortality threshold.”

Humans fuel Amazon fires

“Efforts to end deforestation in the Amazon must be accompanied by programs and policies that reduce the accidental spread of land management fires into neighboring forests and effectively control forest fires when started,” the authors write in the Proceedings of the National Academy of Sciences.

The results are important because large portions of the Amazon forest already experience droughts and are susceptible to fire—they are broken into smaller blocks by agriculture and they are close to humans, who are the predominant source of fire in the Amazon. NASA satellite data provided regional context for results from the experimental burns.

“In 2007, fires in Southeast Amazonia burned 10 times more forest than in an average climate year—an area equivalent to a million soccer fields,” says Douglas Morton of NASA.

“These smaller forest fragments have more edges than large blocks of forest, which exposes them to the hotter, drier conditions in the surrounding landscape and makes them more vulnerable to escaped fires,” says coauthor Marcia Macedo of the Woods Hole Research Center.

By 2011, around 8 percent of Southeast Amazonia’s forests were less than 328 feet from an agricultural or pasture clearing. This lattice-like network of degraded forest edges is now extremely susceptible to future fire.

The National Science Foundation, Packard Foundation, NASA, and Max Planck Institute for Biogeochemistry supported the research.

Source: Penn State

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Fish in acidic water less able to smell predators

16 hours 25 min ago

Fish living on coral reefs where carbon dioxide seeps from the ocean floor are less able to detect predator odor than fish from normal coral reefs, according to a new study.

The study confirms laboratory experiments showing that increased carbon dioxide concentrations in the ocean can seriously affect the behavior of reef fishes.

The new study is the first to analyze the sensory impairment of fish from CO2 seeps, where pH is similar to what climate models forecast for surface waters by the turn of the century.

Juvenile fishes from a carbon dioxide seep, such as these damselfishes, were less able to detect predator odor than fishes from a control coral reef, according to the new study. (Credit: Georgia Tech)

“These results verify our laboratory findings,” says Danielle Dixson, an assistant professor in the School of Biology at Georgia Institute of Technology (Georgia Tech).

“There’s no difference between the fish treated with CO2 in the lab in tests for chemical senses versus the fish we caught and tested from the CO2 reef.”

Do ocean changes harm fish?

The pH of normal ocean surface water is around 8.14. The new study examines fish from so-called bubble reefs at a natural CO2 seep in Papua New Guinea, where the pH is 7.8 on average. With today’s greenhouse gas emissions, climate models forecast pH 7.8 for ocean surface waters by 2100, according to the Intergovernmental Panel on Climate Change (IPCC).
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“We were able to test long-term realistic effects in this environment,” Dixson says. “One problem with ocean acidification research is that it’s all laboratory based, or you’re testing something that’s going to happen in a 100 years with fish that are from the present day, which is not actually accurate.”

Previous research had led to speculation that ocean acidification might not harm fish if they could buffer their tissues in acidified water by changing their bicarbonate levels.

The study is the first to show that fishes’ sensory systems are impaired under ocean acidification conditions in the laboratory. “They can smell but they can’t distinguish between chemical cues,” Dixson says.

Carbon dioxide released into the atmosphere is absorbed into ocean waters, where it dissolves and lowers the pH of the water. Acidic waters affect fish behavior by disrupting a specific receptor in the nervous system, called GABAA, which is present in most marine organisms with a nervous system. When GABAA stops working, neurons stop firing properly.

Coral reef habitat studies have found that CO2-induced behavioral changes, similar to those observed in the new study, increase mortality from predation by more than fivefold in newly settled fish.

Smell of a predator

Fish can smell a fish that eats another fish and will avoid water containing the scent. In Dixson’s laboratory experiments, control fish given the choice between swimming in normal water or water spiked with the smell of a predator will choose the normal water. But fish raised in water acidified with carbon dioxide will choose to spend time in the predator-scented water.

Juvenile fish living at the carbon dioxide seep and brought onto a boat for behavior testing had nearly the identical predator sensing impairment as juvenile fish reared at similar CO2 levels in the lab, the new study finds.

The fish from the bubble reef were also bolder. In one experiment, the team measured how far the fish roamed from a shelter and then created a disturbance to send the fish back to the shelter. Fish from the CO2 seep emerged from the shelter at least six times sooner than the control fish after the disturbance.

Despite the dramatic effects of high CO2 on fish behaviors, relatively few differences in species richness, species composition, and relative abundances of fish were found between the CO2 seep and the control reef.

“The fish are metabolically the same between the control reef and the CO2 reef,” Dixson says. “At this point, we have only seen effects on their behavior.”

The researchers did find that the number of large predatory fishes was lower at the CO2 seep compared to the control reef, which could offset the increased risk of mortality due to the fishes’ abnormal behavior, the researchers say.

Prep for the future

In future work, the research team will test if fish could adapt or acclimate to acidic waters. They will first determine if the fish born at the bubble reef are the ones living there as adults, or if baby fish from the control reef are swimming to the bubble reef.

“Whether or not this sensory effect is happening generationally is something that we don’t know,” Dixson says.

The results do show that what Dixson and colleagues found in the lab matches with what is seen in the field.

“It’s a step in the right direction in terms of answering ocean acidification problems.” Dixson says. “The alternative is just to wait 100 years. At least now we might prepare for what might be happening.”

The research appears online in Nature Climate Change. Philip Munday from James Cook University in Australia is the study’s lead author. The Australian Institute for Marine Science, a Grant for Research and Exploration by the National Geographic Society, and the ARC Centre of Excellence for Coral Reef Studies supported the work.

Source: Georgia Tech

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For maximum happiness, pick concrete goals

16 hours 32 min ago

Pursuing concrete goals, like making a friend smile, rather than general ones, like making a friend happy, is a path to happiness, say researchers.

When you pursue concretely framed goals, your expectations of success are more likely to be met in reality. On the other hand, broad and abstract goals may bring about the dark side of happiness—unrealistic expectations.

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These are the conclusions of a study in the Journal of Experimental Social Psychology by Jennifer Aaker, a social psychologist and professor of marketing at the Stanford Graduate School of Business.

The pursuit of happiness is one of the most essential quests in life, and happiness is often considered a hallmark of psychological health. But it is more mysterious and complex than most people might imagine—and not always readily achievable, the researchers point out.

Acts of benevolence

“Although the desire for personal happiness may be clear, the path to achieving it is indefinite. One reason for this hazy route to happiness is that although people often think they know what leads to happiness, their predictions about what will make them happy are often inaccurate,” Aaker says.

One underappreciated way to increase one’s own happiness is to focus on elevating the happiness of others. The researchers conducted six experiments involving 543 people from laboratory studies and national survey pools. The level of abstraction of one’s “prosocial” goal—voluntary behavior intended to benefit someone else—was the critical factor of interest.

‘Concrete’ happiness

The results show that acts designed to improve the well-being of others will lead to greater happiness for givers when these acts are associated with concretely framed, prosocial goals as opposed to abstractly framed prosocial goals—despite people’s intuitions to the contrary.

For example, an experiment involving bone marrow transplants focused on the whether giving those who need bone marrow transplants “greater hope”—the abstract goal—or giving those who need bone marrow transplants a “better chance of finding a donor”—the concrete goal—made a giver more happy.

The answer: Helping someone find a donor resulted in more happiness for the giver. This, the researchers wrote, was driven by givers’ perceptions that their actual acts better met their expectations of accomplishing their goal of helping another person.

Expectations vs. reality

Aaker and coauthors show that these “happiness effects” are due to smaller gaps between one’s expectations of achieving the goal and the actual result when one’s goal is framed more concretely. Simply, the more abstract goals are often more unrealistic.

Is prosociality always a good goal to chase? According to this study, it depends. Sometimes people pursue prosociality in a way that is less than optimal.

“Discrepancies between aspirations and reality can be critical factors that, in extreme cases, may even lead the act of helping to eventually becoming a source of unhappiness,” explains lead author Melissa Rudd, Aakers’ former student who is currently an assistant professor of marketing at the University of Houston.

For example, when people pursue abstract prosocial goals and expect their relentless giving to result in tremendous and rapid change for the better—and it fails to materialize—they can suffer from “helper burnout,” which can negatively impact happiness.

But, encouraging givers to “reframe their prosocial goals in more concrete terms” would allow expectations to be better calibrated, increasing personal happiness, the researchers argue.

Givers are likely to experience greater happiness if they frame their prosocial goals in concrete rather than abstract terms.

Business nuances

The results have implications for the world of business. For instance, marketing or products that claim to help consumers achieve abstractly framed goals—like making someone else happy—might not be the best business decision. Instead, it might be wiser to reframe these promised goals in more specific, concrete terms.

Consider, for example, Tom’s Shoes. The company promises that if a customer buys a pair of shoes, they will deliver another pair to a child in need.

“Concrete initiatives such as this may be a more realistic way to accurately set consumers’ expectations from the outset and leave them happier in the end,” Aaker says.

Boosting happiness

Ultimately, people seek to be happy, and one clear path toward happiness is through prosocial behaviors.

“A prosocial act can not only boost the happiness of the recipient, but it can boost the happiness of the giver as well,” Aaker explains.

“However,” cautions Rudd, “not all prosocial goals are created equal.”

The researchers hope that future work will yield a deeper understanding of how to harvest happiness—such as by helping others—and how to avoid any unhappiness traps along the way. Sometimes, people pursue happiness ineffectively—as in giving to well-intentioned but broadly defined causes—which may leave them dissatisfied.

As Aaker notes, people often do not realize why they are left feeling unfulfilled— leading them to repeat their mistakes in the future.

But, on the bright side, greater happiness is just within reach when the goal of giving is realistically focused and viewed through a concrete lens.

Michael Norton, an associate professor of business at Harvard University, coauthored the study.

Source: Stanford University

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Deadly parasite nibbles human cells to death

17 hours 52 min ago

A parasitic amoeba that causes a potentially deadly infection kills human cells by nibbling them to death—much like a piranha attacks its prey.

Until now, researchers had assumed that the amoeba, Entamoeba histolytica, killed and then engulfed and consumed human cells. But new research upends that idea, suggesting instead that it takes small bites of the cell until the cell dies—and then loses all interest in eating the corpse.

Entamoeba histolytica parasites (blue) ingesting bites of intestinal cells in an explanted mouse intestine (green), captured using live two-photon microscopy. (Credit: Katherine Ralston and David Zemo)

“This is the first demonstration that nibbling can serve as a way to kill other cells,” says Katherine S. Ralston, a researcher at the University of Virginia.

“The findings suggest that amoebae might invade and destroy host intestinal tissue by nibbling alive the cells that line the gut. Intriguingly, there are hints that organisms can also nibble. Perhaps this process is more common than we realize, and it is taken to the extreme in the case of the amoebae, which use nibbling to kill.”

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It’s important to understand Entamoeba histolytica, because it causes a potentially fatal diarrhea common in the developing world. Approximately a third of all infants are infected within their first year of life in the Bangladeshi slum where the researchers work.

The amoebae colonize the colon and begin their nasty work, which can produce diarrhea, inflammation of the colon, bowel diseases—or no symptoms at all.

Unstable cell membranes

Rather than poisoning human cells, as has been previously thought, the amoebae appear to nip at the cellular membrane, as a goldfish might nip at another goldfish. Eventually, the amoeba consumes enough of the membrane—the cell’s casing—that the membrane becomes unstable and the cell dies. The amoeba then detaches itself from its dinner and moves on to another, still-living meal.

“It has been 111 years exactly since this parasite was named ‘histolytica’ for its ability to lyse tissues, says William A. Petri Jr., chief of the University of Virginia’s infectious diseases and international health division.

“Finally, the way it kills has been discovered. This provides an avenue to explore how best to prevent and treat this parasite that infects up to one of every three children by their first birthday in Bangladesh.”

The researchers hope the new findings will help lead to new treatments for amoebiasis, the disease the amoebae cause.

The findings are published as a letter in Nature. Other researchers at University of Virginia and at Jawaharlal Nehru University in New Delhi, India, are coauthors.

Source: University of Virginia

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Ice cores show Clean Air Act eased acid rain

Mon, 04/14/2014 - 11:59

An analysis of core samples from the Greenland ice sheet finds clear evidence of the success of the US Clean Air Act and also shows a link between air acidity and how nitrogen is preserved in layers of snow.

Forty-five years ago, acid rain was killing fish and dissolving stone monuments on the East Coast. Air pollution rose beginning with the Industrial Revolution and started to improve when the US Clean Air Act of 1970 required coal power plants and other polluters to scrub sulfur out of their smokestacks.

Ice core drilling at Summit, Greenland. (Credit: Joel Savarino, LGGE)

For a new study published in the Proceedings of the National Academy of Sciences, researchers began their study of ice cores interested in smog, not acid rain—but discovered a link between the two forms of pollution in the geologic record.
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Nitrogen is emitted as a short-lived compound, NOx, which causes ground-level ozone, the main ingredient in smog, and relates to compounds that are the “detergent” of the atmosphere. Sources of NOx include smokestacks and vehicle tailpipes, as well as wildfires, soil microbes, or reactions triggered by lightning strikes.

Teasing out the sources of NOx through history might tell us about the atmosphere of the past, how methane, ozone, and other chemicals change in the atmosphere, and also provide a measure of global human emissions.

“How much the nitrate concentrations in ice core records can tell about NOx and the chemistry in the past atmosphere is a longstanding question in the ice-core community,” says lead author Lei Geng, a postdoctoral researcher in atmospheric sciences at University of Washington.

Sulfur and nitrogen emissions

Unlike other gases, short-lived NOx can’t be measured directly from air bubbles trapped in ice cores. Within a day or two most of the NOx changes into nitrate, a water-soluble molecule essential to life that gets deposited in soil and snow.

Earlier research by co-author Eric Steig, professor of Earth and space sciences, suggested that comparing amounts of the two stable forms of nitrogen—nitrogen-15 and nitrogen-14—in nitrate could pinpoint the emission sources of NOx. Ice cores from Greenland and North American lake sediments showed the nitrogen-15 ratio gradually decreasing since 1850, suggesting a corresponding rise in human emissions.

Not so fast, the new research says. The detailed measurements of nitrate, NOx and sulfur show the nitrogen isotope ratio leveling off in 1970, and suggests that ratio is sensitive to the same chemicals that cause acid rain.

“This shows that the relationship between emissions and the isotopes is less direct than we thought, and the final signal recorded in the Greenland ice cores is actually not just the nitrogen emission, but the combined effect of sulfur and nitrogen emissions,” Steig says.

‘Dramatic impact’

The ice cores used in the study were collected in 2007 at Summit Station, Greenland. Total amounts of nitrate for each year were measured and calculated at South Dakota State University, where Geng did his doctoral work. The different forms, or isotopes, were measured in University of Washington’s IsoLab.

The work shows that the long-term decrease in the nitrogen-15 isotope since 1850, and its leveling off in 1970, are linked to changes in air chemistry. Airborne nitrate can exist as a gas or a particle, and nitrate with lighter isotopes tends to exist as a gas. But the total fraction of nitrate present as gas or particle varies with the acidity of the atmosphere, and the acidic air causes more of the light isotopes to exist as a gas.

“The isotope records really closely follow the atmospheric acidity trends,” says coauthor Becky Alexander, associate professor of atmospheric sciences. “You can really see the effect of the Clean Air Act in 1970, which had the most dramatic impact on emission of acid from coal-fired power plants.”

What’s more, airborne nitrate dissolves in water and falls at the poles as snow. While that snow sits on the ground, sunlight bouncing off the surface triggers chemical reactions that send some of it back into a gas form. Acid air can also influence the reactivity of nitrate in snow and thus the preservation of nitrate in ice cores.

Other ice core records might also be affected by acidity in air, Alexander says. No effect would be expected for stable gases like carbon dioxide and oxygen, or for the water molecules used to calculate temperature variations through time. But acidity in air could influence deposition and preservation of other volatile compounds such as chlorine, mercury, or organic materials in ice cores.

Eventually, better understanding of the air chemistry during formation of the layers could allow researchers to correct for the effect, extracting better information of the past from these compounds in the geologic record.

The National Science Foundation funded the research. Scientists from University of Grenoble in France contributed to the study.

Source: University of Washington

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Teens with epilepsy at greater risk of poisoning

Mon, 04/14/2014 - 11:30

Children and young adults with epilepsy are more likely to suffer poisonings, broken bones, and burns compared to those without the neurological disorder, research shows.

The new study also shows that young people with epilepsy are more than twice as likely to be poisoned by medication. This jumps to four times the risk in patients aged between 19 and 24 years old.

The patients, all aged between 12 months and 24 years old at the time of their diagnosis, are also almost one and a half times more likely to suffer a burn-related injury and almost 25 percent more at risk of breaking an arm or leg.

The study authors say the findings highlight the need for further research into whether young people with the condition are at greater risk from an accidental or intentional overdose of their epilepsy drugs or other medication. Doctors and other healthcare professionals should warn epilepsy patients of the increased risk associated with their illness.

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“More research is needed to understand why people with epilepsy have a greater number of medicine-related poisonings and whether the poisonings are intentional or accidental,” says Vibhore Prasad, of the division of primary care at the University of Nottingham.

“This is the first study in the UK population to estimate the risk of fractures, burns, and poisonings. The risk of a poisoning in the next five years for 1,000 people with epilepsy is about 20 extra poisonings compared to people who do not have epilepsy.”

More injuries

Epilepsy is a chronic condition caused by a sudden burst of electrical activity in the brain, causing a temporary interruption in the way the brain normally works and resulting in a seizure. In the UK alone there are more than 600,000 people with epilepsy.

Previous studies into the condition have suggested that these seizures—and the side effects caused by some anti-epilepsy drugs—put patients at a greater risk of accidental injuries.

However, most research may have overestimated this risk because they focused primarily on people with more severe epilepsy, such as institutionalized adults or those being treated in epilepsy clinics.

The new study, published in the journal Pediatrics, is the first to investigate the potential risk of injury exclusively in children and young people with and without epilepsy.

The research, which was carried out in association with scientists at the London School of Hygiene and Tropical Medicine, used general practitioner records from almost 12,000 patients with epilepsy to study the incidence of injury over an average of two and a half years and compared it with the records of around 47,000 non-epileptic people.

Doctors and other healthcare professionals can use the findings to make children and young adults diagnosed with epilepsy, and their parents, more aware of the risk of injury and to inform existing guidelines on treatment.

In particular, researchers cite the need for more information relating to the safe storage of medicines and the supervision of children while taking their medication to be given by doctors at the time of prescribing and by pharmacists when dispensing prescriptions.

Source: University of Nottingham

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Microchip could detect infection in artificial joints

Mon, 04/14/2014 - 10:55

A tiny microchip could improve postoperative care for patients with knee replacements and other surgical implants by detecting early signs of infection.

Alexander Star, an associate professor of chemistry at the University of Pittsburgh, says the new chip, which is engineered to detect pH levels in the body, will be able to alert doctors to encroaching bacterial infection, which causes acidosis, a drop in pH levels in nearby tissue.

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The chip, festooned with tiny carbon nanotubes (engineered segments of carbon that are efficient electrical conductors) and treated with a proprietary polymer, reads pH levels and transmits the information to a radio frequency identification reader held by a doctor. The wirelessly powered chip can be attached to implants and can stay in the body long term.

One in 100 Americans has an artificial joint, Star says, “and bacterial infections are a common complication of the implant.” Infection can damage the body surrounding the implant, and bacterial films, resistant to antibiotics, can colonize the implant itself.

To catch infection early without having to resort to invasive measures could lead to faster treatment. “This is a very attractive detection mechanism for monitoring the condition of the implant,” Star says. “It may alleviate the need for further surgical intervention.” A paper on the chip appears online in Scientific Reports.

Star and his team have developed similar chip/nanotube sensors that can be affixed to a toothbrush to detect bad breath (the presence of hydrogen sulfide) and another that can identify the beginning of an asthma attack by measuring nitric oxide. Another Star-developed chip measures acetone in breath, an indicator of diabetes.

A National Energy Technology Laboratory grant supported the research.

Source: University of Pittsburgh

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Hormone seems to connect depression, memory loss

Mon, 04/14/2014 - 08:40

Past research has long indicated that depression is a big risk factor for memory loss in aging adults. But it is still unclear exactly how the two issues are related and whether there is potential to slow memory loss by fighting depression.

A preliminary study, published in Psychoneuroendocrinology, delves more deeply into the relationship between depression and memory loss, and how this connection may depend on levels of insulin-like growth factor, or IGF-1.

Prior research has shown that IGF-1, a hormone that helps bolster growth, is important for preserving memory, especially among older adults.

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The collaborative study finds that people with lower cognitive ability were more likely to have had higher depressive symptoms if they also had low levels of IGF-1. Reversely, participants with high levels of IGF-1 had no link between depressive symptoms and memory.

Three factors

Senior author Kathi L. Heffner, assistant professor in the University of Rochester School of Medicine and Dentistry’s department of psychiatry, had originally examined possible associations between IGF-1 and memory in a sample of 94 healthy older adults, but couldn’t find strong or consistent evidence.

Heffner then approached the study’s lead author Feng (Vankee) Lin, assistant professor at the School of Nursing, for input because of her expertise in cognitive aging. Lin is a nurse researcher whose collaborative work focuses on developing multi-model interventions to slow the progression of cognitive decline in at-risk adults, and reduce their risk of developing dementia and Alzheimer’s disease.

“Vankee spearheaded the idea to examine the role of depressive symptoms in these data, which resulted in the interesting link,” Heffner says.

The association discovered between memory loss, depression, and IGF-1 means that IGF-1 could be a very promising factor in protecting memory, Lin says.

“IGF-1 is currently a hot topic in terms of how it can promote neuroplasticity and slow cognitive decline,” Lin says.

“Depression, memory, and the IGF-1 receptor are all located in a brain region which regulates a lot of complicated cognitive ability. As circulating IGF-1 can pass through the blood-brain barrier, it may work to influence the brain in a protective way.”

Future applications

Lin says more data studies are needed of people with depression symptoms and those with Alzheimer’s disease, but this study opens an important door for further research on the significance of IGF-1 levels in both memory loss and depression.

“It really makes a lot of sense to further develop this study,” Lin says. “If this could be a way to simultaneously tackle depression while preventing cognitive decline it could be a simple intervention to implement.”

Heffner says that clinical trials are underway to determine whether IGF-1 could be an effective therapeutic agent to slow or prevent cognitive decline in people at risk.

“Cognitive decline can also increase risk for depressive symptoms, so if IGF-1 protects people from cognitive decline, this may translate to reduced risk for depression as well,” Heffner says.

Researchers from Ohio University and Texas Tech University Health Sciences Center contributed t the study. Funding came from the National Institute on Aging and University of Rochester CTSA award, and from the National Center for Advancing Translational Sciences of the National Institutes of Health.

Source: University of Rochester

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These ‘spaceship’ viruses can kill E. coli in food

Mon, 04/14/2014 - 07:49

Treating food products with select bacteriophages—viruses that target and kill bacteria—could significantly reduce concentrations of E. coli, a new study shows.

In the study, an injection of bacteriophages—also known informally as “phages”—nearly eradicated a toxin-producing strain of E. coli in contaminated spinach and ground beef, in some cases decreasing E. coli concentrations by about 99 percent.

The research suggests that bacteriophage treatment could be an effective tool to help ensure the safety of food products, says Paul Ebner, associate professor of animal sciences at Purdue University.

“Phage treatment is a way of harnessing the natural antibacterial properties of phages to limit E. coli and other important foodborne pathogens,” Ebner says. “Applying this kind of therapy to contaminated foods will make them safer.”

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While most strains of E. coli are harmless, some can cause severe and potentially fatal illnesses. The strain used in Ebner’s study , E. coli O157:H7, caused more than 63,000 illnesses, 2,100 hospitalizations, and 20 deaths in the US in 2011. Ingesting as few as 10 colony-forming units of E. coli O157:H7 can result in serious illness.

Most E. coli infections are caused by eating undercooked meat contaminated with the bacteria, but outbreaks associated with fresh produce such as spinach are on the rise.

Testing the ‘phage cocktail’

Ebner and graduate students Yingying Hong and Yanying Pan infected fresh spinach leaves and ground beef with about 10 million cells of E. coli, a far greater amount than typically found in contaminated food products, Ebner says.

The researchers then treated the food with a “phage cocktail,” a liquid containing three kinds of phages selected for their ability to quickly and efficiently kill E. coli. Using a variety of phages also helps prevent the bacteria from developing resistance.

After 24 hours, the treatment had reduced E. coli concentrations in the spinach, stored at room temperature, by more than 99.9 percent. E. coli dropped by more than 99.8 percent and about 99.8 percent in spinach after 48 and 72 hours, respectively.

In ground beef stored at room temperature, the phages cleaned up about 99 percent of E. coli bacteria within 24 hours. The number of E. coli in refrigerated and undercooked ground beef shrunk by about 68 percent and 73 percent, respectively.

“Bacteria have viruses just like we do,” Ebner says. “We’re taking what already exists in nature and concentrating it to have an impact on these bacteria.”

Like tiny ‘spaceships’

The search-and-destroy methods of phages sound like the stuff of science fiction: Spaceship-like phages dock onto the receptor sites of a host bacterium cell and deploy a syringe-like device that penetrates the cell wall. They inject their own DNA into the host cell, transforming it into a phage-making factory. The cell assembles phages until it contains so many it explodes, releasing the next generation of phages to find new hosts.

“Phages are the most abundant life forms on the planet—if you consider viruses to be alive,” Ebner says. “You can eat thousands of phages just by licking your lips.”

Ingesting phages does not pose a threat to human health because phages are highly host-specific, only targeting certain types of bacteria, says Ebner.

“Phage therapy is a way of using microbes beneficially, similar to using probiotics in yoghurt,” he says.

Interest in using phages as antibacterial treatments has increased with the rise of antibiotic-resistant bacteria. The host specificity of phages can be an advantage over broad-spectrum antibiotics, which can wipe out both pathogenic and beneficial bacteria, Ebner says.

He says phage therapy is not a substitute for antibiotics, but “it can be very effective when used at specific time points and for shorter periods.”

The paper is published in the Journal of Animal Science.

Source: Purdue University

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Silly Putty component helps build ‘carpet’ for stem cells

Mon, 04/14/2014 - 07:46

The sponginess of the environment where human embryonic stem cells are growing affects the type of specialized cells they eventually become, a new study shows.

The researchers coaxed human embryonic stem cells to turn into working spinal cord cells more efficiently by growing the cells on a soft, ultrafine carpet made of a key ingredient in Silly Putty. Their study is appears online in Nature Materials.

Researchers cultured stem cells on ultrafine carpets made of microscopic posts of a key ingredient in Silly Putty. (Credit: Ye Tao, Rose Anderson, Yubing Sun, Jianping Fu)

This research is the first to directly link physical, as opposed to chemical, signals to human embryonic stem cell differentiation. Differentiation is the process of the source cells morphing into the body’s more than 200 cell types that become muscle, bone, nerves, and organs, for example.

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Jianping Fu, assistant professor of mechanical engineering at University of Michigan, says the findings raise the possibility of a more efficient way to guide stem cells to differentiate and potentially provide therapies for diseases such as amyotrophic lateral sclerosis (Lou Gehrig’s disease), Huntington’s, or Alzheimer’s.

In the specially engineered growth system—the ‘carpets’ Fu and his colleagues designed—microscopic posts of the Silly Putty component polydimethylsiloxane serve as the threads. By varying the post height, the researchers can adjust the stiffness of the surface they grow cells on. Shorter posts are more rigid—like an industrial carpet. Taller ones are softer—more plush.

‘Carpet’ for stem cells

The team found that stem cells they grew on the tall, softer micropost carpets turned into nerve cells much faster and more often than those they grew on the stiffer surfaces.

After 23 days, the colonies of spinal cord cells—motor neurons that control how muscles move—that grew on the softer micropost carpets were four times more pure and 10 times larger than those growing on either traditional plates or rigid carpets.

“This is extremely exciting,” Fu says. “To realize promising clinical applications of human embryonic stem cells, we need a better culture system that can reliably produce more target cells that function well. Our approach is a big step in that direction, by using synthetic microengineered surfaces to control mechanical environmental signals.”

New nerve cells?

Fu is collaborating with doctors at the University of Michigan Medical School. Eva Feldman, professor of neurology, studies amyotrophic lateral sclerosis, or ALS. It paralyzes patients as it kills motor neurons in the brain and spinal cord.

Researchers like Feldman believe stem cell therapies—both from embryonic and adult varieties—might help patients grow new nerve cells. She’s using Fu’s technique to try to make fresh neurons from patients’ own cells. At this point, they’re examining how and whether the process could work, and they hope to try it in humans in the future.

“Professor Fu and colleagues have developed an innovative method of generating high-yield and high-purity motor neurons from stem cells,” Feldman says. “For ALS, discoveries like this provide tools for modeling disease in the laboratory and for developing cell-replacement therapies.”

Signaling pathway

The researchers verified that the new motor neurons they obtained on soft micropost carpets showed electrical behaviors comparable to those of neurons in the human body.

They also identified a signaling pathway involved in regulating the mechanically sensitive behaviors. A signaling pathway is a route through which proteins ferry chemical messages from the cell’s borders to deep inside it. The pathway they zeroed in on, called Hippo/YAP, is also involved in controlling organ size and both causing and preventing tumor growth.

Fu says his findings could also provide insights into how embryonic stem cells differentiate in the body.

“Our work suggests that physical signals in the cell environment are important in neural patterning, a process where nerve cells become specialized for their specific functions based on their physical location in the body,” he says.

Source: University of Michigan

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How a tiny coral-eating worm hides in plain sight

Mon, 04/14/2014 - 07:46

A tiny parasitic worm, which is all but invisible due to its excellent camouflage, may be a significant threat to its host, the staghorn coral Acropora.

“The biology of this worm is amazing,” says Jörg Wiedenmann, professor of biological oceanography at the University of Southampton and head of the university’s Coral Reef Laboratory. “By using molecular biological techniques, we found out how the worm accomplishes this excellent camouflage.

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“When eating the coral tissue it also takes up the symbiotic alga of the coral. Instead of digesting them completely, it keeps a certain number of them alive and distributes them in its guts so that it perfectly mimics the appearance of the coral.

“Moreover, it also incorporates the green fluorescent protein pigments that lend the glowing greenish coloration to the coral host to perfect its camouflage.”

As reported in the journal Coral Reefs, the Amakusaplana acroporae flatworm has been scientifically described very recently and has been found in the wild only in one location on the Great Barrier Reef.

In contrast, it is well known to aquarium hobbyists who keep staghorn corals and fear infestations of the parasite, since it can wipe out coral cultures within a short period of time.

A worm without predators

“At the moment, there are no known natural predators of this parasite and only consequent quarantine can efficiently control its spread in land-based coral cultures,” Wiedenmann says.

“The worm is already distributed in coral cultures all over the word including regions bordering coral reefs. We do not know whether the parasite occurs naturally in these reefs and if it is controlled by natural enemies there. If this is not the case, a release of the parasite into an environment which is not adapted to its presence might have unforeseeable consequences for the regional Acropora populations.”

“It is important to continue to raise the awareness among aquarium hobbyists that tank inhabitants should never be returned to the wild, since this might unintentionally contribute to the spread of parasites and diseases.

Moreover, the hosts of these parasites themselves—corals, fishes, and seaweeds—can create dramatic problems for ecosystems to which they are non-native. The spread of the lionfish Pterois through the Caribbean or of Caulerpa algae through the Mediterranean Sea are examples of marine invasions by ornamental species.

“It would be good if every shop were obliged to take the animals that they have sold back if requested—that would certainly reduce the risk of people releasing ornamental creatures in the wild when they feel that they cannot take care of them anymore.”

Source: University of Southampton

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Minority homeowners may face ‘double-edged sword’

Mon, 04/14/2014 - 06:24

A new study finds that while homeownership can spark feelings of pride in people of any race, it tends to be more meaningful for minorities.

On the other hand, because blacks and Latinos are more likely to buy homes in disadvantaged communities and less likely to be able to move out, they ultimately tend to feel dissatisfied with their community—and potentially with their purchase.

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“Homeownership may be considered a double-edged sword,” says Meredith Greif, a sociologist at Johns Hopkins University. “For minorities, the highs of homeownership are higher while the lows are lower.”

Greif set out to determine whether owning a home means different things to blacks, Latinos, and whites, and whether owning a home can increase a resident’s chance of neighborhood dissatisfaction in disadvantaged communities. The study appears online in Urban Studies.

Studying homeowners in Los Angeles County through information from the 2001 Los Angeles Family and Neighborhood Survey and the 2000 Census, she found that whites had significantly higher rates of homeownership than blacks and Latinos. Whites were also most likely to live in “desirable” neighborhoods with greater property values, better services, and higher prestige.

Greif’s findings suggest, however, that living in these enviable communities may not provoke the same sense of pride and achievement for whites that it does for the blacks and Latinos living there—just as living in disadvantaged communities may not spark the same level of concern.

“Whites have more of an economic buffer,” she says. “There is less at stake for them one way or the other.”

For blacks, owning a home, particularly in a more advantaged community, may evoke feelings of conquering the odds. The feelings are similar among Latinos, many of whom are immigrants looking to assimilate socially and economically.

Black and Latino homeowners, however, are significantly less likely to be able to buy homes in the neighborhoods that would elicit those feelings.

In 2002, the median net worth of white households was 15 times that of black households and 10 times that of Latino households, meaning blacks and Latinos put considerably more of their net worth into buying a home. So when minorities were faced with signs of neighborhood deterioration—graffiti, litter, abandoned buildings—they were much more anxious about the threat to their most vital asset.

Overall, Greif found all homeowners are more attuned to their communities than renters, in both good and bad ways. Homeownership can foster stronger neighborhood satisfaction in advantaged communities but undermine it in less advantaged ones.

“These findings speak to the ongoing dialogue surrounding the benefits of homeownership—and for whom,” Greif says.

Source: Johns Hopkins University

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Copper catalyst makes ethanol without crops

Mon, 04/14/2014 - 05:58

Scientists have found a highly efficient way to make liquid ethanol from carbon monoxide gas. The discovery could provide an eco-friendly alternative to conventional ethanol production that uses corn and other crops.

“We have discovered the first metal catalyst that can produce appreciable amounts of ethanol from carbon monoxide at room temperature and pressure —a notoriously difficult electrochemical reaction,” says Matthew Kanan, an assistant professor of chemistry at Stanford University and coauthor of the study that appears in Nature.

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Most ethanol today is produced at high-temperature fermentation facilities that chemically convert corn, sugarcane, and other plants into liquid fuel. But growing crops for biofuel requires thousands of acres of land and vast quantities of fertilizer and water.

In some parts of the United States, it takes more than 800 gallons of water to grow a bushel of corn, which, in turn, yields about 3 gallons of ethanol.

The new technique developed by Kanan and graduate student Christina Li requires no fermentation and, if scaled up, could help address many of the land- and water-use issues surrounding ethanol production today. “Our study demonstrates the feasibility of making ethanol by electrocatalysis,” Kanan says. “But we have a lot more work to do to make a device that is practical.”

Copper nanocrystals

Two years ago, Kanan and Li created a novel electrode made of a material they called oxide-derived copper. They used the term “oxide-derived” because the metallic electrode was produced from copper oxide.

“Conventional copper electrodes consist of individual nanoparticles that just sit on top of each other,” Kanan says. “Oxide-derived copper, on the other hand, is made of copper nanocrystals that are all linked together in a continuous network with well-defined grain boundaries. The process of transforming copper oxide into metallic copper creates the network of nanocrystals.”

For the new study, Kanan and Li built an electrochemical cell—a device consisting of two electrodes placed in water saturated with carbon monoxide gas. When a voltage is applied across the electrodes of a conventional cell, a current flows and water is converted to oxygen gas at one electrode (the anode) and hydrogen gas at the other electrode (the cathode). The challenge was to find a cathode that would reduce carbon monoxide to ethanol instead of reducing water to hydrogen.

“Most materials are incapable of reducing carbon monoxide and exclusively react with water,” Kanan says. “Copper is the only exception, but conventional copper is very inefficient.”

In the experiment, Kanan and Li used a cathode made of oxide-derived copper. When a small voltage was applied, the results were dramatic.

“The oxide-derived copper produced ethanol and acetate with 57 percent faradaic efficiency,” Kanan says. “That means 57 percent of the electric current went into producing these two compounds from carbon monoxide. We’re excited because this represents a more than 10-fold increase in efficiency over conventional copper catalysts. Our models suggest that the nanocrystalline network in the oxide-derived copper was critical for achieving these results.”

Making the process carbon neutral

The team is looking for ways to create other fuels and improve the overall efficiency of the process. “In this experiment, ethanol was the major product,” Kanan says. “Propanol would actually be a higher energy-density fuel than ethanol, but right now there is no efficient way to produce it.”

In the experiment, Kanan and Li found that a slightly altered oxide-derived copper catalyst produced propanol with 10 percent efficiency. The team is working to improve the yield for propanol by further tuning the catalyst’s structure.

Ultimately, Kanan would like to see a scaled-up version of the catalytic cell powered by electricity from the sun, wind, or other renewable resource.

For the process to be carbon neutral, scientists will have to find a new way to make carbon monoxide from renewable energy instead of fossil fuel, the primary source today.

Kanan envisions taking carbon dioxide (CO2) from the atmosphere to produce carbon monoxide, which, in turn, would be fed to a copper catalyst to make liquid fuel. The CO2 that is released into the atmosphere during fuel combustion would be re-used to make more carbon monoxide and more fuel—a closed-loop, emissions-free process.

“Technology already exists for converting CO2 to carbon monoxide, but the missing piece was the efficient conversion of carbon monoxide to a useful fuel that’s liquid, easy to store and nontoxic,” Kanan says.

“Prior to our study, there was a sense that no catalyst could efficiently reduce carbon monoxide to a liquid. We have a solution to this problem that’s made of copper, which is cheap and abundant. We hope our results inspire other people to work on our system or develop a new catalyst that converts carbon monoxide to fuel.”

Jim Ciston, a senior staff scientist with the National Center for Electron Microscopy at Lawrence Berkeley National Laboratory, is a coauthor of the study.

Stanford University, the National Science Foundation, and the US Department of Energy supported the study.

Source: Stanford University

 

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Luck can save you from public scorn

Fri, 04/11/2014 - 11:14

Researchers tested people’s beliefs about luck. What they found was that Spock was right—humans are “highly illogical” and will let “lucky” offenders off the hook.

Psychology professor Heather Lench and her team at Texas A&M University find that a person who acts immorally or recklessly, but who is “lucky” by escaping dire consequences, is judged less harshly than an “unlucky” person, even when both have committed the same act. The study will appear in the British Journal of Psychology.

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“Moral luck” is a term used in philosophy that describes situations in which a person is subjected to moral judgments by others despite the fact that the assessment is based on factors beyond his or her control, i.e. “luck.”

Lench, who specializes in emotion and cognition—how emotions influence our thinking—explains that test subjects were given a hypothetical situation in which two men stand on a highway overpass and each blindly tosses a brick down onto the traffic below. One brick is red and the other is green. One brick hits the pavement harming no one, but the other smashes through a car roof, killing someone. The two committed the same immoral act, yet one was lucky that no one was killed.

The two men are arrested and test subjects were asked if the two men are equally blameworthy, deserving of the same punishment. In other words, do we need to know the color of the brick to be able to punish them or do they deserve the same punishment regardless of one being luckier than the other?

“We found that when people were faced with this scenario, more of them placed the blame on the man that killed someone,” Lench explains. “Both threw a brick, so logically they should both be held accountable, but the lucky guy gets away with it.”

She adds the test subjects were also asked whether they believed, in general, that people should be punished based on their actions—what they intended to do—or whether or not their actions happened to hurt someone.

“In general, people reported that the luck of the outcome shouldn’t matter and that offenders should be judged based on intent,” she says. “However, when faced with the consequences, emotions come into play and they judge based on the outcome rather than the intent.”

Lench likens the brick scenario to drunk driving. “When two people drive drunk, but one hits and kills a child, he is punished more severely than the man who didn’t hurt anyone, although they committed the same offense of drunk driving—it’s just that one got lucky.

“Generally we have a hard time incorporating our abstract beliefs about the way we think the world should work into how it actually works,” she notes. “In the abstract, we don’t value luck, but in our actual judgments of others, we do.”

Source: Texas A&M

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