Ancient rocks hold evidence for life before oxygen

Somewhere between Earth's creation and where we are today, scientists have demonstrated that some early life forms existed just fine without any oxygen. The 2.52 billion-year-old sulfur-oxidizing bacteria are exceptionally large, spherical-shaped, smooth-walled microscopic structures much larger than most modern bacteria, but similar to some modern single-celled organisms that live in deepwater sulfur-rich ocean settings today, where even now there are almost no traces of oxygen.

While researchers proclaim the first half of our 4.5 billion-year-old planet's life as an important time for the development and evolution of early bacteria, evidence for these life forms remains sparse including how they survived at a time when oxygen levels in the atmosphere were less than one-thousandth of one percent of what they are today.

Recent geology research from the University of Cincinnati presents new evidence for bacteria found fossilized in two separate locations in the Northern Cape Province of South Africa.

"These are the oldest reported fossil sulfur bacteria to date," says Andrew Czaja, UC assistant professor of geology. "And this discovery is helping us reveal a diversity of life and ecosystems that existed just prior to the Great Oxidation Event, a time of major atmospheric evolution."

The 2.52 billion-year-old sulfur-oxidizing bacteria are described by Czaja as exceptionally large, spherical-shaped, smooth-walled microscopic structures much larger than most modern bacteria, but similar to some modern single-celled organisms that live in deepwater sulfur-rich ocean settings today, where even now there are almost no traces of oxygen.

In his research published in the December issue of the journalGeology of the Geological Society of America, Czaja and his colleagues Nicolas Beukes from the University of Johannesburg and Jeffrey Osterhout, a recently graduated master's student from UC's department of geology, reveal samples of bacteria that were abundant in deep water areas of the ocean in a geologic time known as the Neoarchean Eon (2.8 to 2.5 billion years ago).

"These fossils represent the oldest known organisms that lived in a very dark, deep-water environment," says Czaja. "These bacteria existed two billion years before plants and trees, which evolved about 450 million years ago. We discovered these microfossils preserved in a layer of hard silica-rich rock called chert located within the Kaapvaal craton of South Africa."

With an atmosphere of much less than one percent oxygen, scientists have presumed that there were things living in deep water in the mud that didn't need sunlight or oxygen, but Czaja says experts didn't have any direct evidence for them until now.

Czaja argues that finding rocks this old is rare, so researchers' understanding of the Neoarchean Eon are based on samples from only a handful of geographic areas, such as this region of South Africa and another in Western Australia.

According to Czaja, scientists through the years have theorized that South Africa and Western Australia were once part of an ancient supercontinent called Vaalbara, before a shifting and upending of tectonic plates split them during a major change in the Earth's surface.

Based on radiometric dating and geochemical isotope analysis, Czaja characterizes his fossils as having formed in this early Vaalbara supercontinent in an ancient deep seabed containing sulfate from continental rock. According to this dating, Czaja's fossil bacteria were also thriving just before the era when other shallow-water bacteria began creating more and more oxygen as a byproduct of photosynthesis.

"We refer to this period as the Great Oxidation Event that took place 2.4 to 2.2 billion years ago," says Czaja.

Early recycling

Czaja's fossils show the Neoarchean bacteria in plentiful numbers while living deep in the sediment. He contends that these early bacteria were busy ingesting volcanic hydrogen sulfide -- the molecule known to give off a rotten egg smell -- then emitting sulfate, a gas that has no smell. He says this is the same process that goes on today as modern bacteria recycle decaying organic matter into minerals and gases.

"The waste product from one [bacteria] was food for the other," adds Czaja.

"While I can't claim that these early bacteria are the same ones we have today, we surmise that they may have been doing the same thing as some of our current bacteria," says Czaja. "These early bacteria likely consumed the molecules dissolved from sulfur-rich minerals that came from land rocks that had eroded and washed out to sea, or from the volcanic remains on the ocean's floor.

There is an ongoing debate about when sulfur-oxidizing bacteria arose and how that fits into the earth's evolution of life, Czaja adds. "But these fossils tell us that sulfur-oxidizing bacteria were there 2.52 billion years ago, and they were doing something remarkable."

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Ants communicate by mouth-to-mouth fluid exchange

Liquids shared mouth-to-mouth by social insects contain proteins and small molecules that can influence the development and organization of their colonies, according to new research.

The study from the University of Lausanne, Switzerland, suggests Florida carpenter ants can collectively influence their communities by shifting the cocktail of proteins, hormones and other small molecules that they pass mouth-to-mouth to one another and their young through a process called trophallaxis.

"Food is passed to every adult and developing ant by trophallaxis. This creates a network of interactions linking every member of the colony," says senior author Laurent Keller, Professor in the Department of Ecology and Evolution.

"A lot of researchers consider trophallaxis only as a means of food-sharing," adds Professor Richard Benton of the Center for Integrative Genomics, also a senior author of the study. "But trophallaxis occurs in other contexts, such as when an ant is reunited with a nest-mate after isolation. We therefore wanted to see if the fluid exchanged by trophallaxis contains molecules that allow ants to pass other chemical messages to each other, and not just food."

To answer this question, the team, led by first author and postdoctoral researcher Dr Adria LeBoeuf, analysed fluid from pairs of ants engaged in trophallaxis. Surprisingly, they identified a large number of proteins that appear to be involved in regulating the growth of ants, along with high levels of juvenile hormone, an important regulator of insect development, reproduction, and behaviour.

To see what effect this hormone has on the growth of larvae fed by trophallaxis, the scientists added it to the food of larvae-rearing ants and discovered that the hormone made it twice as likely that the larvae would survive to reach adulthood.

"This indicates that juvenile hormone and other molecules transferred mouth-to-mouth over this social network could be used by the ants to collectively decide how their colony develops," says LeBoeuf. "So, when the ants feed their larvae, they aren't just feeding them food, they are casting quantitative ballots for their colony, administering different amounts of growth-promoting components to influence the next generation.

"The effects of juvenile hormone that we see are consistent with previous studies in other ants and in bees where larvae treated with an analogue of this hormone tend to develop into larger workers and even queens."

Along with growth proteins and juvenile hormone, the team also identified small molecules and chemical signals in the carpenter ants' trophallactic liquid that help them recognize their nest-mates. They demonstrated for the first time the presence of chemical cues in the fluid that are known to be important in providing ants with a colony-specific odour that allows them to distinguish family from non-family members.

"Overall, we show that liquid transmitted among ants contains much more than food and digestive enzymes," adds LeBoeuf. "Our findings suggest that trophallaxis underlies a private communication channel that ants use to direct the development of their young, similar to milk in mammals."

"More generally, this opens the possibility that the oral exchange of fluids, such as saliva, in other animals might also serve previously unsuspected roles."

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Depression in young people affects the stomach, anxiety the skin

Mental disorders and physical diseases frequently go hand in hand. For the first time, psychologists have identified temporal patterns in young people: arthritis and diseases of the digestive system are more common after depression, while anxiety disorders tend to be followed by skin diseases.

Physical diseases and mental disorders affect a person's quality of life and present a huge challenge for the healthcare system. If physical and mental disorders systematically co-occur from an early age, there is a risk that the sick child or adolescent will suffer from untoward developments.

Data from 6,500 teenagers

In a project financed by the Swiss National Science Foundation, a research group led by PD Dr. Marion Tegethoff in collaboration with Professor Gunther Meinlschmidt from the University of Basel's Faculty of Psychology has now examined the temporal pattern and relationship between physical diseases and mental disorders in children and young people. In the journal PLOS ONE, they analyzed data from a representative sample of 6,483 teenagers from the US aged between 13 and 18.

The researchers noted that some physical diseases tend to occur more frequently in children and adolescents if they have previously suffered from certain mental disorders. Likewise, certain mental disorders tend to occur more frequently after the onset of particular physical diseases. Affective disorders such as depression were frequently followed by arthritis and diseases of the digestive system, while the same relationship existed between anxiety disorders and skin diseases. Anxiety disorders were more common if the person had already suffered from heart disease. A close association was also established for the first time between epileptic disorders and subsequent eating disorders.

Epilepsy and eating disorders

The results offer important insights into the causal relationship between mental disorders and physical diseases. The newly identified temporal associations draw attention to processes that could be relevant both to the origins of physical diseases and mental disorders and to their treatment. In an earlier study, the same authors had already provided evidence for the relationship between mental disorders and physical diseases in young people.

"For the first time, we have established that epilepsy is followed by an increased risk of eating disorders -- a phenomenon, that had previously been described only in single case reports. This suggests that approaches to epilepsy treatment could also have potential in the context of eating disorders," explains Marion Tegethoff, the study's lead author. From a health policy perspective, the findings underscore that the treatment of mental disorders and physical diseases should be closely interlinked from an early age on.

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Playing video games may have positive effects on young children

Video games are a favorite activity of children, yet its affect on their health is often perceived to be negative. A new study assessed the association between the amount of time spent playing video games and children's mental health and cognitive and social skills, and found that playing video games may have positive effects on young children.

After adjusting for child age, gender, and number of children, the researchers found that high video game usage was associated with a 1.75 times the odds of high intellectual functioning and 1.88 times the odds of high overall school competence. There were no significant associations with any child self-reported or mother- or teacher-reported mental health problems. The researchers also found that more video game playing was associated with less relationship problems with their peers. Based on parent reporting, one in five children played video games more than 5 hours per week.

Results were based on data from the School Children Mental Health Europe project for children ages 6-11. Parents and teachers assessed their child's mental health in a questionnaire and the children themselves responded to questions through an interactive tool. Teachers evaluated academic success. Factors associated with time spent playing video games included being a boy, being older, and belonging to a medium size family. Having a less educated or single mother decreased time spent playing video games.

"Video game playing is often a collaborative leisure time activity for school-aged children. These results indicate that children who frequently play video games may be socially cohesive with peers and integrated into the school community. We caution against over interpretation, however, as setting limits on screen usage remains and important component of parental responsibility as an overall strategy for student success," said Katherine M. Keyes, PhD, assistant professor of Epidemiology at the Mailman School of Public Health.

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Your dog remembers what you did

People have a remarkable ability to remember and recall events from the past, even when those events didn't hold any particular importance at the time they occurred. Now, researchers have evidence that dogs have that kind of "episodic memory" too.

The study found that dogs can recall a person's complex actions even when they don't expect to have their memory tested.

"The results of our study can be considered as a further step to break down artificially erected barriers between non-human animals and humans," says Claudia Fugazza of MTA-ELTE Comparative Ethology Research Group in Budapest, Hungary. "Dogs are among the few species that people consider 'clever,' and yet we are still surprised whenever a study reveals that dogs and their owners may share some mental abilities despite our distant evolutionary relationship."

Evidence that non-human animals use episodic-like memory has been hard to come by because you can't just ask a dog what it remembers. In the new study, the researchers took advantage of a trick called "Do as I Do." Dogs trained to "Do as I Do" can watch a person perform an action and then do the action themselves. For example, if their owner jumps in the air and then gives the "Do it!" command, the dog would jump in the air too.

The fact that dogs can be trained in this way alone wasn't enough to prove episodic memory. That's because it needed to be shown that dogs remember what they just saw a person do even when they weren't expecting to be asked or rewarded. To get around this problem, the researchers first trained 17 dogs to imitate human actions with the "Do as I Do" training method. Next, they did another round of training in which dogs were trained to lie down after watching the human action, no matter what it was.

After the dogs had learned to lie down reliably, the researchers surprised them by saying "Do It" and the dogs did. In other words, the dogs recalled what they'd seen the person do even though they had no particular reason to think they'd need to remember. They showed episodic-like memory.

Dogs were tested in that way after one minute and after one hour. The results show they were able to recall the demonstrated actions after both short and long time intervals. However, their memory faded somewhat over time.

The researchers say that the same approach can most likely be used and adapted in a wide range of animal species, to better understand how animals' minds process their own actions and that of others around them.

"From a broad evolutionary perspective, this implies that episodic-like memory is not unique and did not evolve only in primates but is a more widespread skill in the animal kingdom," Fugazza says. "We suggest that dogs may provide a good model to study the complexity of episodic-like memory in a natural setting, especially because this species has the evolutionary and developmental advantage to live in human social groups."

For all those dog owners out there: your dogs are paying attention and they'll remember.

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Oceans act as a 'heat sink'

Study sheds new light into global warming ‘hiatus’The so-called global warming "hiatus" phenomenon -- the possible temporary slowdown of the global mean surface temperature (GMST) trend said to have occurred from 1998 to 2013 -- did not in fact occur. New research points to the prominent role global ocean played in absorbing extra heat from the atmosphere by acting as a "heat sink" as an explanation for the observed decrease in a key indicator of climate change.

In a paper published in Earth's Future, a journal of the American Geophysical Union, lead author Xiao-Hai Yan of the University of Delaware, along with leading scientists from the National Oceanic and Atmospheric Administration (NOAA), National Center for Atmospheric Research (NCAR), National Aeronautics and Space Administration (NASA), Scripps Institution of Oceanography, and University of Washington, discuss new understandings of the global warming "hiatus" phenomenon.

In particular, the researchers point to the prominent role played by the global ocean in absorbing the extra heat from the atmosphere by acting as a "heat sink" as an explanation for the observed decrease in GMST, which is considered a key indicator of climate change.

"The hiatus period gives scientists an opportunity to understand uncertainties in how climate systems are measured, as well as to fill in the gap in what scientists know," explained Yan, Mary A.S. Lighthipe Chaired Professor in the College of Earth, Ocean, and Environment and director of UD's Center for Remote Sensing.

"Individually, each of us carries some research into this topic and many of my co-authors are leading scientists who have studied this topic from various and often diverse angles."

"The hiatus in the rise of global surface temperature is over, but understanding the processes involved helps us with future predictions," continued co-author Kevin Trenberth of National Center for Atmospheric Research (NCAR).

Where is the missing heat?

While Yan said it is difficult to reach complete consensus on such a complex topic, after a thorough review of the literature and much discussion and debate, there are a number of key points on which these leading scientists concur:

• From 1998 to 2013, the rate of global mean surface warming, which some call the "global warming hiatus," slowed.

• Natural variability plays a large role in the rate of global mean surface warming on decadal time scales.

• Improved understanding of how the ocean distributes and redistributes heat will help the scientific community better monitor Earth's energy budget.

Earth's energy budget is a complex calculation of how much solar energy enters our climate system from the sun and what happens to it: how much is stored by land, in the ocean or in the atmosphere.

"To better monitor Earth's energy budget, and its consequences, the ocean is most important to consider because the amount of heat it can store is extremely large when compared to the land or atmospheric capacity," said Yan.

According to the paper, arguably, the most appropriate single variable in Earth's system that can be used to monitor global warming is ocean heat content integrated from the surface to different layers and to the bottom of the ocean.

Charting future research

In the near term, the scientists hope this paper will lay the foundation for future research in the global change field. To begin, they suggest the climate community replace the term "global warming hiatus" with "global surface warming slowdown" to eliminate confusion.

"This terminology more accurately describes the pause in the increase of the ocean's global mean surface temperature in the late 20th century," Yan said.

The scientists also called for continued support of current and future technologies for ocean monitoring as a means to reduce observation errors in sea surface temperature and ocean heat content.

This includes maintaining Argo, the main system for monitoring ocean heat content, and the development of Deep Argo to monitor the lower half of the ocean; the use of ship-based subsurface ocean temperature monitoring programs; advancements in the use of robotic technologies such as autonomous underwater vehicles to monitor marginal seas and shelf and coastal regions; and further development of real- or near-real-time deep ocean remote sensing methods.

Yan's research group reported in a 2015 paper that some coastal oceans' (e.g. U.S. East Coast, China Coast) response to the recent global surface warming slowdown are three times larger than what is found in the open ocean.

"Although these regions represent only a fraction of the ocean volume, the changing rate of ocean heat content is faster here and real time data and more research are needed to quantify and understand what is happening," Yan said.

Variability and heat sequestration over specific regions (i.e. Pacific, Atlantic, Indian, Southern Oceans, etc.) was also discussed and requires further investigation. However, there is broad agreement among the scientists and in the literature that the slowdown of GMST increase from 1998-2013 was the "result of increase uptake of heat energy by the global ocean during those years."

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Archaeological excavation unearths evidence of turkey domestication 1,500 years ago

Eggshells and bones from baby turkeys among earliest evidence for turkey domestication

The turkeys we'll be sitting down to eat on Thursday have a history that goes way back. Archaeologists have unearthed a clutch of domesticated turkey eggs used as a ritual offering 1,500 years ago in Oaxaca, Mexico -- some of the earliest evidence of turkey domestication.

"Our research tells us that turkeys had been domesticated by 400-500 AD," explains Field Museum archaeologist Gary Feinman, one of the paper's authors. "People have made guesses about turkey domestication based on the presence or absence of bones at archaeological sites, but now we are bringing in classes of information that were not available before. We're providing strong evidence to confirm prior hypotheses." The results were published in an article in the Journal of Archaeological Science: Reports.

Feinman, along with lead author Heather Lapham from the University of North Carolina at Chapel Hill, and co-author Linda Nicholas also of The Field Museum, discovered the eggs during an excavation in Oaxaca that was home to the Zapotec people going back thousands of years. "It was very exciting because it's very rare to find a whole cluster of intact eggs. This was very unexpected," says Feinman.

"Heather Lapham is an archaeologist who studies animal bones, and she knew immediately that we had found five intact or unhatched eggs that were left as an offering alongside seven newly hatched baby turkeys, of which only their tiny bones survived," says Feinman. Scanning electron microscope analysis of the eggshells confirmed that they were indeed laid by turkeys.

"The fact that we see a full clutch of unhatched turkey eggs, along with other juvenile and adult turkey bones nearby, tells us that these birds were domesticated," says Feinman. "It helps to confirm historical information about the use of turkeys in the area."

The eggs, according to Feinman, were an offering of ritual significance to the Zapotec people. The Zapotec people still live in Oaxaca today, and domesticated turkeys remain important to them. "Turkeys are raised to eat, given as gifts, and used in rituals," says Feinman. "The turkeys are used in the preparation of food for birthdays, baptisms, weddings, and religious festivals."

The new information about when turkeys were domesticated helps amplify the bigger picture of animal domestication in Mesoamerica. "There were very few domesticated animals in Oaxaca and Mesoamerica in general compared with Eurasia," explains Feinman. "Eurasia had lots of different meat sources, but in Oaxaca 1,500 years ago, the only assuredly domestic meat sources were turkeys and dogs. And while people in Oaxaca today rely largely on meat from animals brought over by the Spanish (like chicken, beef, and pork), turkeys have much greater antiquity in the region and still have great ritual as well as economic significance today."

The turkeys that are so important to the Zapotec today are similar birds to the ones that play a role in the American tradition of Thanksgiving. "These are not unlike the kinds of turkeys that would have been around at the first Thanksgiving, and similar to the birds that we eat today," says Feinman.

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People with Ebola may not always show symptoms

25 percent of individuals in a Sierra Leone village were infected with the Ebola virus but had no symptoms, a research team has determined, suggesting broader transmission of the virus than originally thought.

A year after the Ebola epidemic in West Africa, researchers from the Stanford University School of Medicine and other institutions identified 14 individuals previously unknown to have had the disease in a Sierra Leone village that was an Ebola hot spot.

These individuals had antibodies to the virus, suggesting they had been infected at one time. Yet 12 of these individuals said they had had no symptoms during the time of active transmission in the village.

The research confirms previous suspicions that the Ebola virus does not uniformly cause severe disease, and that people may be infected without showing signs of illness, said Gene Richardson, MD, a former fellow in the Division of Infectious Diseases and Geographic Medicine at Stanford who is now a PhD candidate in anthropology at the university. The findings also suggest that the epidemic was more widespread than previously believed. Based on the results of the study, the researchers calculated the prevalence of minimally symptomatic infection to be 25 percent.

"The study corroborates previous evidence that Ebola is like most other viruses in that it causes a spectrum of manifestations, including minimally symptomatic infection," Richardson said. "It provides important evidence on that front. It also means a significant portion of transmission events may have gone undetected during the outbreak. This shows there was a lot more human-to-human transmission than we thought."

The study will be published online Nov. 15 in PLOS Neglected Tropical Diseases. The study also will be presented Nov. 14 at the American Society of Tropical Medicine and Hygiene's annual meeting in Atlanta. Richardson is lead author of the study, and Paul Farmer, MD, PhD, a Harvard professor and director of Partners In Health, is the senior author.

Testing individuals

The research was done in the rural village of Sukudu in Sierra Leone, a country where Richardson and his colleagues cared for hundreds of patients in Ebola treatment units managed by Partners In Health.

The village, with about 900 residents, had been one of three major hot spots in the Kono District, in the eastern part of the country, during the heat of the Ebola crisis between November 2014 and February 2015. There were 34 reported cases of Ebola in the village, including 28 deaths.

More than 28,000 cases of Ebola infection were reported in Africa during the epidemic, the largest and longest in history. More than 11,000 people are estimated to have died because of the disease.

In the aftermath, Richardson and his colleagues decided to go back to the village to try to determine whether the Ebola infection could be minimally symptomatic, as previous studies have suggested. He worked with a local physician and two community health workers in gathering data for the study, a process that was approved by the local village chief.

They used a test known as the ELISA assay, a technique that can detect the presence of an antibody. They first made sure the test was accurate by comparing results from 30 Ebola survivors in Sukudu with those of 132 people in other villages where the virus had not been reported.

Richardson said the test proved to be a reasonable measure of viral antibodies. The researchers then recruited 187 men, women and children from Sukudu who had likely been exposed to Ebola, either because they were living in the same household or had shared a public toilet with a person confirmed to have had the disease.

Of these, 14 were found to be carrying antibodies to Ebola, suggesting they had been infected at some point, though they had not been included in the original count. Twelve of them said they had had no symptoms of the disease, which typically causes fever, unexplained bleeding, headache, muscle pain, rash, vomiting, diarrhea, breathing problems and difficulty swallowing. Two recalled having had a fever at the time of the outbreak, the scientists reported.

Public health efforts not entirely effective

In combining the initial reports of 34 infections with the 14 newly identified cases, the researchers calculated the prevalence of minimally symptomatic infection in the village to have been 25 percent.

Richardson said it is unknown if an asymptomatic individual is capable of transmitting the virus. Because these individuals did not have an active case of the disease, "They were not passing it along in the usual way, through vomiting or diarrhea," he said. "It's unclear if they can pass it along it sexually."

The virus has been shown to hide out for months in semen, even after symptoms have subsided, with some published cases of survivors transmitting the virus through sexual contact.

Richardson said the study indicates that public health efforts to prevent infection and contain the virus during the epidemic were not entirely effective.

"It reminds us that we need to do a much, much better job in future epidemics," Richardson said.

He and his colleagues are now working in other villages in Sierra Leone where public health surveillance was poor during the epidemic, testing and interviewing individuals to get a better handle on the true number of people affected during the crisis.

"We expect to find a lot more undocumented survivors, so we can begin to answer the question of what was the true burden of disease," he said.

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Scientists uncover genetic evidence that 'we are what we eat'

Researchers have demonstrated that the diets of organisms can affect the DNA sequences of their genes.

In a study on two groups of parasites, the team detected differences in DNA sequences that could be attributed to the composition of their food.

The results are published in the journal Genome Biology.

Study co-author Dr Steven Kelly, from Oxford's Department of Plant Sciences, said: 'Organisms construct their DNA using building blocks they get from food. Our hypothesis was that the composition of this food could alter an organism's DNA. For example, could a vegetarian panda have predictable genetic differences from a meat-eating polar bear?

'To test this hypothesis, we picked simple groups of parasites to use as a model system. These parasites share a common ancestor but have evolved to infect different hosts and eat very different foods.

'We found that different levels of nitrogen in a parasite's diet contributed to changes in its DNA. Specifically, parasites with low-nitrogen, high-sugar diets had DNA sequences that used less nitrogen than parasites with nitrogen-rich, high-protein diets.'

The study involved groups of eukaryotic parasites (Kinetoplastida) and bacterial parasites (Mollicutes) that infect different plant or animal hosts.

The results, based on novel mathematical models developed by the researchers, reveal a previously hidden relationship between cellular metabolism and evolution. They provide new insights into how DNA sequences can be influenced by adaptation to different diets.

Furthermore, the team found it is possible to predict the diets of related organisms by analysing the DNA sequence of their genes.

Study co-author Emily Seward, a doctoral candidate in Oxford's Department of Plant Sciences, said: 'It has been unclear why very closely related organisms can look so different in their genetic makeup. By bringing together two fundamental aspects of biology -- metabolism and genetics -- we have advanced our understanding of this area.

'It's a difficult question to answer, because there are so many factors that can influence the DNA sequence of an organism. But our study explains a very high percentage of these differences and provides evidence that we really are what we eat.

'We are now looking at more complex organisms to see if we will find the same thing.'

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Peculiarities of huge equatorial jet stream in Saturn's atmosphere revealed

The atmosphere of the planet Saturn, a gas giant ten times bigger than the Earth consisting mostly of hydrogen, has a wider, more intense jet stream than all the planets in the Solar System. Winds gusting at speeds of up to 1,650 km/h blow from West to East in the equatorial atmosphere, thirteen times the strength of the most destructive hurricane force winds that form on the Earth's equator. This huge jet stream also extends about 70,000 km from north to south, more than five times the size of our planet.

This huge jet stream also extends about 70,000 km from north to south, more than five times the size of our planet. There is as yet no theory capable of explaining the nature of this stream nor the sources of energy feeding it. Back in 2003 the same team warned in an article published in Nature of the drastic reduction in winds on the cloud level with respect to what had been observed when the Voyager space probes visited the planet.

"In June last year, using a simple 28-cm telescope belonging to the Aula EspaZio Gela (Space Lecture Room), we discovered the presence of a white spot on Saturn''s equator that was moving at speeds of 1,600 km/h, a speed that had not been observed on Saturn since 1980," said Agustín Sánchez-Lavega, lead author of the work and also director of the Aula EspaZio Gela and Planetary Sciences Group of the UPV/EHU-University of the Basque Country. Observations obtained a month later by members of the Planetary Sciences Group using the PlanetCam camera developed by this team and fitted to the 2.2-m telescope at the Calar Alto Observatory in Almería (Spain) enabled the speed of this atmospheric structure to be confirmed. Images obtained by observers in other countries using small telescopes were also used in the study.

The researchers were able to study the phenomenon in detail after obtaining observation time of the Hubble Space Telescope granted by its director in order to capture images of Saturn at a time when the Cassini probe in orbit around it had poor vision of the planet. "It is very difficult to obtain observation time in Hubble because it is highly competitive, but its high quality images have been decisive in the research," explained Sánchez-Lavega.

1,650 km/h winds

By studying the movement of the clouds that formed the white spot (an enormous storm of about 7,000 km) and of those present in its surrounding areas, the researchers were able to obtain new, valuable information about the structure of the planet's huge equatorial jet stream. Furthermore, the researchers established the heights reached by the different atmospheric structures and determined that the winds increase dramatically the lower they go. They reach speeds of 1,100 km/h in the upper atmosphere but achieve up to 1,650 km/h at a depth of about 150 km. Furthermore, while the deep wind is stable, in the upper atmosphere the speed and width of the equatorial stream are highly changeable, perhaps due to the seasonal insolation cycle on Saturn, and their intensity is increased by the changing shadowing of the rings above the equator.

There is another significant meteorological phenomenon above the planet's equator and which could affect the winds: the Semi-annual Oscillation (SAO), which occurs about 50 km above the cloud deck and which causes the temperatures to oscillate and the winds to change direction and strength from East to West. And if the complexity of Saturn's equatorial meteorology were not enough, it is at these latitudes where the so-called Great White Spot developed three times, in 1876, 1933 and 1990; this is a gigantic storm that manages to go all the way round the planet and which has only been seen on six occasions during the last one hundred and fifty years. The study by the Planetary Sciences Group reports that this gigantic storm is another of the agents of change in the equatorial jet stream.

"All these phenomena occur on a different scale to a certain extent on our own planet. So by studying them in this way in other worlds in totally different conditions we can make progress in understanding and modelling them," he concluded.


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Brazilian free-tailed bat is the fastest flyer in the animal kingdom

Bats are not just skilful aviators, they can also reach record-breaking speeds

Up to now, the speed record for horizontal flight was held by birds from the swift family: the common swift, for example, can reach speeds of over 100 kilometers per hour. Investigators have now discovered a new front-runner among the acrobats of the air. However, the animal involved here is not a bird but a bat: the Brazilian free-tailed bat shoots through the night skies at over 160 kilometers per hour.

Together with colleagues from the USA, researchers at the Max Planck Institute for Ornithology in Radolfzell have now discovered a new front-runner among the acrobats of the air. However, the animal involved here is not a bird but a bat: the Brazilian free-tailed bat shoots through the night skies at over 160 kilometers per hour. Their aerodynamic body shape and longer than average wings compared to other bat species enable them to reach such vast speeds.
Birds are still a model for aviation engineers today and remain unequaled when it comes to flight characteristics. While birds can take off at comparatively low speeds, even the most modern aircraft must reach a speed of around 300 kilometers per hour to be able to lift off. The main contributing factors here are the animals' aerodynamic, projectile-like body shape and their low weight due to special bones. Moreover, the narrow wings found in faster-flying species also enable greater lift relative to the aerodynamic force invested.

Swifts, like the common swift (Apus apus), which can reach speeds of 110 kilometers per hour, are considered the fastest birds in the world at horizontal flight. Peregrine falcons can even reach speeds of up to 300 kilometers per hour when diving. In contrast, due to their wing structure, bats generate greater resistance, and are generally considered slower flyers.

Animals with long and narrow wings usually fly faster than those with shorter and wider ones. For this reason, the scientists selected the Brazilian free-flying bat (Tadarida brasiliensis) for their study. Even the experts themselves were surprised by their results: "Initially, we could hardly believe our data, but they were correct: at times, the female bats, which weigh between 11 and 12 grams, flew at speeds of over 160 kilometers per hour -- a new record for horizontal flight," says Kamran Safi from the Max Planck Institute for Ornithology.

The data on the bats' flying speeds were collected using a radio transmitter weighing just half a gram and attached to the their backs using an adhesive and fell off after two to five days. Its regular beeping signal was localized using a mobile receiver installed on a small aircraft. "It was not easy for the pilot to follow the fast-flying animals so that we could localize them accurately and measure their flight path continuously," explains Dina Dechmann. The scientists also evaluated the data recorded by the closest weather station and noted the wind conditions at the time of the studied flights. "External factors like landscape and tailwinds cannot explain these results, as they had no impact on the maximum speeds," says Dechmann.

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Evolution purged many Neanderthal genes from human genome

Larger populations allowed humans to shed weakly deleterious gene variants that were widespread in Neanderthals, new research indicates.

Neanderthal genetic material is found in only small amounts in the genomes of modern humans because, after interbreeding, natural selection removed large numbers of weakly deleterious Neanderthal gene variants, according to a study by Ivan Juric and colleagues at the University of California, Davis, published November 8th, 2016 in PLOS Genetics.

Humans and Neanderthals interbred tens of thousands of years ago, but today, Neanderthal DNA makes up only 1-4% of the genomes of modern non-African people. To understand how modern humans lost their Neanderthal genetic material and how humans and Neanderthals remained distinct, Juric and colleagues developed a novel method for estimating the average strength of natural selection against Neanderthal genetic material. They found that natural selection removed many Neanderthal alleles from the genome that might have had mildly negative effects. The scientists estimate that these gene variations were able to persist in Neanderthals because Neanderthals had a much smaller population size than humans. Once transferred into the human genome, however, these alleles became subject to natural selection, which was more effective in the larger human populations and has removed these gene variants over time.

The study is one of the first attempts to quantify the strength of natural selection against Neanderthal genes. It enhances the understanding of how Neanderthals contributed to human genomes (along with Harris and Nielsen, Genetics 2016). It also confirms previous reports that East Asian people had somewhat higher initial levels of Neanderthal ancestry than Europeans. These findings shed new light on the role of population size on losing or maintaining Neanderthal ancestry in humans, and add to our understanding of our close relatives -- the Neanderthals.

Of the study, Ivan Juric says: "For a while now we have known that humans and Neanderthals hybridized. Many Europeans and Asians-along with other non-African populations-are the descendants of those hybrids. Previous work has also shown that, following hybridization, many Neanderthal gene variants were lost from the modern human population due to selection. We wanted to better understand the causes of this loss. Our results are compatible with a scenario where the Neanderthal genome accumulated many weakly deleterious variants, because selection was not effective in the small Neanderthal populations. Those variants entered the human population after hybridization. Once in the larger human population, those deleterious variants were slowly purged by natural selection.

The key finding of our study therefore is that the current levels of Neanderthal ancestry in modern humans are in part due to long-term differences in human and Neanderthal population sizes. The human population size has historically been much larger, and this is important since selection is more efficient at removing deleterious variants in large populations. Therefore, a weakly deleterious variants that could persist in Neanderthals could not persist in humans. We think that this simple explanation can account for the pattern of Neanderthal ancestry that we see today along the genome of modern humans.

From our study, we cannot conclude that differences in demography explain everything. For instance, genes that were deleterious only in human-Neanderthal hybrids might have existed, and sexual selection or other forms of selection against hybrids could have been very important processes during human-Neanderthal hybridization. Still, I find it fascinating to think that if the Neanderthals had reached larger population sizes in Europe, or if modern human populations had grown slower, some of us today would probably carry a lot more Neanderthal ancestry in our genome."

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New model explains the moon's weird orbit

Simulations suggest a dramatic history for the Earth-moon duo

The moon, Earth's closest neighbor, is among the strangest planetary bodies in the solar system. Its orbit lies unusually far away from Earth, with a surprisingly large orbital tilt. Planetary scientists have struggled to piece together a scenario that accounts for these and other related characteristics of the Earth-moon system. A new research paper, based on numerical models of the moon's explosive formation and the evolution of the Earth-moon system, comes closer to tying up all the loose ends than any other previous explanation.





A new research paper, based on numerical models of the moon's explosive formation and the evolution of the Earth-moon system, comes closer to tying up all the loose ends than any other previous explanation. The work, published in the October 31, 2016 Advance Online edition of the journal Nature, suggests that the impact that formed the moon also caused calamitous changes to Earth's rotation and the tilt of its spin axis.

The research suggests that the impact sent Earth spinning much faster, and at a much steeper tilt, than it does today. In the several billion years since that impact, complex interactions between Earth, the moon and sun have smoothed out many of these changes, resulting in the Earth-moon system that we see today. In this scenario, the remaining anomalies in the moon's orbit are relics of the Earth-moon system's explosive past.

"Evidence suggests a giant impact blasted off a huge amount of material that formed the moon," said Douglas Hamilton, professor of astronomy at the University of Maryland and a co-author of the Nature paper. "This material would have formed a ring of debris first, then the ring would have aggregated to form the moon. But this scenario does not quite work if Earth's spin axis was tilted at the 23.5 degree angle we see today."

Collisional physics calls for this ring of debris -- and thus the moon's orbit immediately after formation -- to lie in Earth's equatorial plane. As tidal interactions between Earth and the moon drove the moon further away from Earth, the moon should have shifted from Earth's equatorial plane to the "ecliptic" plane, which corresponds to Earth's orbit around the sun.

But today, instead of being in line with the ecliptic plane, the moon's orbit is tilted five degrees away from it.

"This large tilt is very unusual. Until now, there hasn't been a good explanation," Hamilton said. " But we can understand it if Earth had a more dramatic early history than we previously suspected."

Hamilton, with lead author Matija Cuk of the SETI institute and their colleagues Simon Lock of Harvard University and Sarah Stewart of the University of California, Davis, tried many different scenarios. But the most successful ones involved a moon-forming impact that sent Earth spinning extremely fast -- as much as twice the rate predicted by other models. The impact also knocked Earth's tilt way off, to somewhere between 60 and 80 degrees.

"We already suspected that Earth must have spun especially fast after the impact" Cuk said. "An early high tilt for Earth enables our planet to lose that excess spin more readily."

The model also suggests that the newly-formed moon started off very close to Earth, but then drifted away -- to nearly 15 times its initial distance. As it did so, the sun began to exert a more powerful influence over the moon's orbit.

According to the researchers, both factors -- a highly tilted, fast spinning Earth and an outwardly-migrating moon -- contributed to establishing the moon's current weird orbit. The newborn moon's orbit most likely tracked Earth's equator, tilted at a steep 60-80 degree angle that matched Earth's tilt.

A key finding of the new research is that, if Earth was indeed tilted by more than 60 degrees after the moon formed, the moon could not transition smoothly from Earth's equatorial plane to the ecliptic plane. Instead, the transition was abrupt and left the moon with a large tilt relative to the ecliptic -- much larger than is observed today.

"As the moon moved outward, Earth's steep tilt made for a more chaotic transition as the sun became a bigger influence," Cuk said. "Subsequently, and over billions of years, the moon's tilt slowly decayed down to the five degrees we see today. So today's five degree tilt is a relic and a signature of a much steeper tilt in the past."

Hamilton acknowledges that the model doesn't answer all the remaining questions about the moon's orbit. But the model's strength, he says, is that it offers a framework for answering new questions in the future.

"There are many potential paths from the moon's formation to the Earth-moon system we see today. We've identified a few of them, but there are sure to be other possibilities," Hamilton said. "What we have now is a model that is more probable and works more cleanly than previous attempts. We think this is a significant improvement that gets us closer to what actually happened."

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Nanobionic spinach plants can detect explosives

After sensing dangerous chemicals, the carbon-nanotube-enhanced plants send an alert. Spinach is no longer just a superfood: By embedding leaves with carbon nanotubes, engineers have transformed spinach plants into sensors that can detect explosives and wirelessly relay that information to a handheld device similar to a smartphone.

Spinach is no longer just a super Nanobionic spinach plants can detect explosivesfood: By embedding leaves with carbon nano tubes, MIT engineers have transformed spinach plants into sensors that can detect explosives and wirelessly relay that information to a handheld device similar to a smartphone. This is one of the first demonstrations of engineering electronic systems into plants, an approach that the researchers call "plant nanobionics."

"The goal of plant nanobionics is to introduce nanoparticles into the plant to give it non-native functions," says Michael Strano, the Carbon P. Dubbs Professor of Chemical Engineering at MIT and the leader of the research team.

In this case, the plants were designed to detect chemical compounds known as nitroaromatics, which are often used in landmines and other explosives. When one of these chemicals is present in the groundwater sampled naturally by the plant, carbon nanotubes embedded in the plant leaves emit a fluorescent signal that can be read with an infrared camera. The camera can be attached to a small computer similar to a smartphone, which then sends an email to the user.

"This is a novel demonstration of how we have overcome the plant/human communication barrier," says Strano, who believes plant power could also be harnessed to warn of pollutants and environmental conditions such as drought.

Strano is the senior author of a paper describing the nanobionic plants in the Oct. 31 issue of Nature Materials. The paper's lead author is Min Hao Wong, an MIT graduate student who has started a company called Plantea to further develop this technology.

Environmental monitoring

Two years ago, in the first demonstration of plant nanobionics, Strano and former MIT postdoc Juan Pablo Giraldo used nanoparticles to enhance plants' photosynthesis ability and to turn them into sensors for nitric oxide, a pollutant produced by combustion.

Plants are ideally suited for monitoring the environment because they already take in a lot of information from their surroundings, Strano says.

"Plants are very good analytical chemists," he says. "They have an extensive root network in the soil, are constantly sampling groundwater, and have a way to self-power the transport of that water up into the leaves."

Strano's lab has previously developed carbon nanotubes that can be used as sensors to detect a wide range of molecules, including hydrogen peroxide, the explosive TNT, and the nerve gas sarin. When the target molecule binds to a polymer wrapped around the nanotube, it alters the tube's fluorescence.

In the new study, the researchers embedded sensors for nitroaromatic compounds into the leaves of spinach plants. Using a technique called vascular infusion, which involves applying a solution of nanoparticles to the underside of the leaf, they placed the sensors into a leaf layer known as the mesophyll, which is where most photosynthesis takes place.

They also embedded carbon nanotubes that emit a constant fluorescent signal that serves as a reference. This allows the researchers to compare the two fluorescent signals, making it easier to determine if the explosive sensor has detected anything. If there are any explosive molecules in the groundwater, it takes about 10 minutes for the plant to draw them up into the leaves, where they encounter the detector.

To read the signal, the researchers shine a laser onto the leaf, prompting the nanotubes in the leaf to emit near-infrared fluorescent light. This can be detected with a small infrared camera connected to a Raspberry Pi, a $35 credit-card-sized computer similar to the computer inside a smartphone. The signal could also be detected with a smartphone by removing the infrared filter that most camera phones have, the researchers say.

"This setup could be replaced by a cell phone and the right kind of camera," Strano says. "It's just the infrared filter that would stop you from using your cell phone."

Using this setup, the researchers can pick up a signal from about 1 meter away from the plant, and they are now working on increasing that distance.

"A wealth of information"

In the 2014 plant nanobionics study, Strano's lab worked with a common laboratory plant known as Arabidopsis thaliana. However, the researchers wanted to use common spinach plants for the latest study, to demonstrate the versatility of this technique. "You can apply these techniques with any living plant," Strano says.

So far, the researchers have also engineered spinach plants that can detect dopamine, which influences plant root growth, and they are now working on additional sensors, including some that track the chemicals plants use to convey information within their own tissues.

"Plants are very environmentally responsive," Strano says. "They know that there is going to be a drought long before we do. They can detect small changes in the properties of soil and water potential. If we tap into those chemical signaling pathways, there is a wealth of information to access."

These sensors could also help botanists learn more about the inner workings of plants, monitor plant health, and maximize the yield of rare compounds synthesized by plants such as the Madagascar periwinkle, which produces drugs used to treat cancer.

"These sensors give real-time information from the plant. It is almost like having the plant talk to us about the environment they are in," Wong says. "In the case of precision agriculture, having such information can directly affect yield and margins."
 

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Vaccinating against dengue may increase Zika outbreaks

Vaccinating against dengue fever could increase outbreaks of Zika, suggests new research. The study identifies a potentially serious public health concern. More than a third of the world's population lives in areas where dengue is endemic and cases of co-infection with Zika have already been reported.

The research identifies a potentially serious public health concern. More than a third of the world's population lives in areas where dengue is endemic and cases of co-infection with Zika have already been reported.

Conducted at York University's Laboratory for Industrial and Applied Mathematics using mathematical modelling, the research was led by Biao Tang, an exchange PhD student from Xi'an Jiaotong University, in collaboration with York Professor Jianhong Wu and Tang's supervisor, Professor Yanni Xiao at Xi'an Jiaotong University. As dengue and Zika are both part of the Flaviviridae family transmitted through a common mosquito host, the researchers wanted to know how vaccinating for one would affect the incidence of the other.

"Vaccinating against one virus could not only affect the control of another virus, it could in fact make it easier for the other to spread," says Wu. "Recent evidence suggests that dengue virus antibodies can enhance the Zika virus infection. For that reason, we developed a new math model to investigate the effect of dengue vaccination on Zika outbreaks."

The paper, "Implication of vaccination against dengue for Zika outbreak," was published in Scientific Reports.

The team's model shows that vaccinations for dengue increase the number of people contracting Zika. It also shows that the more people in a particular population that are vaccinated against dengue, the earlier and larger the Zika outbreak. The research also found that the most effective way to minimize the unintended effect of dengue vaccinations on Zika outbreaks is through an integrated strategy that includes mosquito control.

"We concluded that vaccination against dengue among humans can significantly boost Zika transmission among the population and hence call for further study on integrated control measures on controlling dengue and Zika outbreak," says Xiao.

The researchers note their findings do not discourage the development and promotion of dengue vaccine products, however, more work needs to be done to understand how to optimize dengue vaccination programs and minimize the risk of Zika outbreaks.

According to the World Health Organization, the global incidence of dengue has grown dramatically in recent decades, with about half of the world's population now at risk. In some Asian and Latin American countries, severe dengue is a leading cause of serious illness and death among children. Whereas the outbreaks of Zika have occurred in Africa, the Americas, Asia and the Pacific, and has been linked to microcephaly and Guillain-Barré syndrome. Although vaccines for dengue have been developed and are in use, there is no vaccine for Zika.


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