Knowledge Update

​New York, June 18 (IANS) Scientists have identified a single gene pathway that can disrupt Zika and similar viruses from spreading in the body and also act as a potential drug target for such deadly diseases.

The findings showed that disabling SPCS1 -- in both human and insect cells -- reduces viral infection and does not negatively affect the cells themselves.

"We wanted to find out if we could identify genes present in the host cells that are absolutely required by the virus for infection," said Michael Diamond, Professor at Washington University.

While the absence of SPCS1 gene shut down the spread of flaviviruses, eliminating the gene had no detrimental effect on other types of viruses, including alphaviruses, bunyaviruses and rhabdoviruses, the researchers said.

"In these viruses, without SPCS1 gene the chain reaction doesn't happen and the virus can't spread. So this gene can act as a potential drug target because it disrupts the virus but not the host," Diamond added.

Viruses hijack host cells to replicate and spread, making them dependent upon the genetic material of the organisms they infect. 

If a cell lacks a gene that the virus requires for infection, the virus will have to stop in its tracks and will enable the cells to survive. Thus the missing gene becomes vital to spread of the virus.

"Flaviviruses appear to be uniquely dependent particularly on SPCS1 gene to release the viral particle," Diamond noted. 

For the study, published in the journal Nature, the team first conducted experiments on West Nile virus and then found that the same results held true for other Flaviviridae family members, including Zika, dengue, yellow fever, Japanese encephalitis and hepatitis C viruses.

Using gene-editing technology called CRISPR that is capable of selectively shutting down individual genes, the researchers identified only nine key genes that the virus relies on for infection or to spread. ​

​New York, June 19 (IANS) Consuming high-quality plant-based diet such as whole grains, fruits, vegetables, nuts, seeds and legumes, can substantially lower the risk of developing Type 2 diabetes, says a new study led by an Indian-origin scientist.

The findings showed that eating a healthy version of such diet was linked with a 34 per cent lower diabetes risk, while a less healthy version -- including foods such as refined grains, potatoes, and sugar-sweetened beverages -- was linked with a 16 per cent increased risk.

Such diets are high in fibre, antioxidants, unsaturated fatty acids, and micronutrients such as magnesium and are low in saturated fat.

"The study highlights that even moderate dietary changes in the direction of a healthful plant-based diet can play a significant role in the prevention of type 2 diabetes," said Ambika Satija, professor at the Harvard T.H. Chan School of Public Health in Boston.

Adherence to a plant-based diet was found low in animal foods, with a 20 per cent reduced risk of Type 2 diabetes.

Healthy plant foods may also be contributing to a healthy gut microbiome, the authors said.

"A shift to dietary pattern marking higher plant-based foods and lower in animal-based foods, especially red and processed meats, can confer substantial health benefits in reducing risk of type 2 diabetes," added Frank Hu, Professor at Harvard Chan School.

The study, published in an online journal named PLOS Medicine, was the first to make distinctions between healthy plant-based diets and less healthy ones that include things like sweetened foods and beverages, and some animal foods, which may be detrimental for health.

The researchers conducted a 20 years survey of more than 200,000 male and female health professionals, and questioned them on their diet, lifestyle, medical history, and new disease diagnoses.

The diets of the participants were evaluated using a plant-based diet index, in which they assigned plant-derived foods in higher scores than animal-derived foods.

"These findings provide further evidence to support current dietary recommendations for chronic disease prevention," Satija suggested.​

New York, June 19 (IANS) Researchers have found that a perfect storm of a rapidly warming climate and human activities killed giant Ice Age species including elephant-sized sloth and powerful sabre-toothed cats that once roamed the plains of Patagonia.

Human activity that gradually lead to the warming of climate caused the extinction of the megafauna around 12,300 years ago, said the researchers.

"The study shows that human colonisation didn't immediately result in extinctions, but only as long as it stayed cold," said lead researcher Alan Cooper, professor at the University of Adelaide in Australia.

Species such as the South American horse, giant jaguar and sabre-toothed cat, and the enormous one-tonne short-faced bear (the largest land-based mammalian carnivore) were found widely across the South American country of Patagonia, but seemed to disappear shortly after humans arrived.

The pattern of rapid human colonisation through the Americas, coinciding with contrasting temperature trends in each continent, allowed the researchers to disentangle the relative impact of human arrival and climate change.

"More than 1,000 years of human occupation passed before a rapid warming event occurred, and then the megafauna were extinct within a hundred years," Cooper added in the paper published in the journal Science Advances.

The only large species to survive were the ancestors of present day llama and alpaca, the researchers said.

"The ancient genetic data show that only the late arrival in Patagonia of a population of guanacos from the north saved the species, all other populations became extinct," explained Jessica Metcalf from the University of Colorado-Boulder, in the US.

"In 1936 Fell's cave, a small rock shelter in Patagonia, was the first site in the world to show that humans had hunted Ice Age megafauna. So it seems appropriate that we're now using the bones from the area to reveal the key role of climate warming, and humans, in the megafaunal extinctions," noted Fabiana Martin from University of Magallanes in Chile.

The team studied ancient DNA extracted from radiocarbon-dated bones and teeth found in caves across Patagonia, and Tierra del Fuego, to trace the genetic history of the populations.​

New York, June 19 (IANS) Diminishing a person's belief in free will can lead them feeling less like their true selves and drive them to depression, finds a new study.

The findings showed that feeling alienated from one's true self can increase anxiety, depression and decision dissatisfaction.

"Whether you agree that we have free will or that we are overpowered by social influence or other forms of determinism, the belief in free will has truly important consequences," said lead author Elizabeth Seto, Student at Texas A and M University in the US.

On the other hand, knowing one's true self positively influences self-esteem and one's sense of meaning in life.

In addition, lack of free will may prompt people to behave without a sense of morality, particularly when one has a goal to improve the quality of life for individuals and the society at large.

"When we experience or have low belief in free will and feel 'out of touch' with who we are, we may behave without a sense of morality," Seto added in the study which was published in Social Psychological and Personality Science.

Previous studies have shown that minimising belief in free will can increase cheating, aggression, and conformity and decrease feelings of gratitude.

"Our findings suggest that part of being who you are is experiencing a sense of agency and feeling like you are in control over the actions and outcomes in your life," Seto explained.

"If people are able to experience these feelings, they can become closer to their true or core self," Seto said.

To influence the feeling of free will, the team randomly separated nearly 300 participants into groups and then asked questions to evaluate their sense of self.

Those in the low free will group showed significantly greater feelings of self-alienation and lower self-awareness than those in the high free will group.

In a follow-up study, a similarly sized group of participants experienced the same free will manipulation and were then presented a choice: keeping money for themselves or donating to a charity.

After making their decision, researchers asked them how authentic they felt about their decision.

The participants in low free will belief group reported less authenticity during the decision making task than their high freewill counterparts.​

New York, June 18 (IANS) Still waiting to hear from aliens and getting excited about the UFO sightings? Well, according to astronomers, extra-terrestrials are not likely to call the Earth for the next 1,500 years.

The team from Cornell University made this assumption by deconstructing the Fermi paradox and paring it with the mediocrity principle into a fresh equation.

The Fermi paradox says billions of Earth-like planets exist in our galaxy yet no aliens have contacted or visited us. 

Thus the paradox: the cosmos teems with possibility. 

The mediocrity principle is the idea that because we are not in any special location in the universe, we should not be anything special in the universe, physics.org reported.

“We haven't heard from aliens yet, as space is a big place. But that doesn't mean no one is out there," said Cornell student Evan Solomonides who presented the study at the American Astronomical Society's meeting in San Diego, California, recently.

Hunting for extra-terrestrials means sending out signals like television broadcasts, for example. 

As Earth's electronic ambassador, TV and radio signals are sent into space as a by-product of broadcast. 

Earth's broadcast signals have reached every star within about 80 light years from the Sun - about 8,531 stars and 3,555 Earthlike planets as our Milky Way galaxy alone contains 200 billion stars.

"Even our mundane, typical spiral galaxy - not exceptionally large compared to other galaxies - is vast beyond imagination," Solomonides added. 

"Those numbers are what make the Fermi Paradox so counterintuitive. We have reached so many stars and planets, surely we should have reached somebody by now, and in turn been reached … this demonstrates why we appear to be alone,” he added.

Combining the equations for the Fermi paradox and the mediocrity principle, the authors suggests Earth might hear from an alien civilisation when approximately half of the Milky Way Galaxy has been signalled in about 1,500 years.

Yervant Terzian, Cornell's Tisch Distinguished University Professor of Astronomy, is the co-author of the paper.​

Bangalore, June 18 (IANS) The cells that have led to the rise of the most complex life forms on earth, including multicellular organisms such as animals or plants, probably evolved as a result of growing initimacy belween their single-celled relatives , say researchers including one from Bangalore's National Centre for Biological Sciences.

The first living beings on earth were single-cell organisms. Those cells were quite simple, but during the course of evolution they gave way to a more complex cellular lineage - the eukaryotes, or cells with a nucleus.

The first eukaryote is thought to have arisen when prokaryotes - the kingdoms of archaea and bacteria - joined forces. Prokaryotes are single-celled organisms that have no cell nucleus.

But in an Opinion paper published in the journal Trends in Cell Biology, researchers have now proposed that the molecular machinery essential to eukaryotic life was probably borrowed, little by little over time, from those simpler ancestors.

"We are beginning to think of eukaryotic origins as a slow process of growing intimacy - the result of a long, slow dance between kingdoms, and not a quick tryst, which is the way it is portrayed in textbooks," said Mukund Thattai from National Centre for Biological Sciences.

The proposal is based on new genomic evidence derived from a deep-sea vent on the ocean floor.

The eukaryotic cells of plants, animals, and protists are markedly different from those of their single-celled, prokaryotic relatives, the archaea and bacteria. 

Eukaryotic cells are much larger and have considerably more internal complexity, including many internal membrane-bound compartments.

Although scientists generally agree that eukaryotes can trace their ancestry to a merger between archaea and bacteria, there has been considerable disagreement about what the first eukaryote and its immediate ancestors must have looked like. 

As Thattai and his colleagues Buzz Baum and Gautam Dey of University College London explained in their paper, that uncertainty has stemmed in large part from the lack of known intermediates that bridge the gap in size and complexity between prokaryotic precursors and eukaryotes. 

As a result, they said, the origin of the first eukaryotic cell has remained "one of the most enduring mysteries in modern biology."

That began to change last year with the discovery of DNA sequences for an organism, that no one has ever actually seen, living near a deep-sea vent on the ocean floor. 

The genome of the archaeon known as Lokiarchaeum ('Loki' for short) contains more "eukaryotic signature proteins" (ESPs) than any other prokaryote. 

Importantly, among those eukaryotic signature proteins are proteins critical for eukaryotes' ability to direct traffic amongst all those intercellular compartments.

"The genome can be seen as 'primed' for eukaryogenesis. With the acquisition of a number of key genes and lipids from a bacterial symbiont, it would be possible for Loki-type cells to evolve a primitive membrane trafficking machinery and compartmentalisation," Baum said.

The researchers predict that, when Loki is finally isolated or cultured, "it will look more like an archaeon than a proto-eukaryote and will not have internal compartments or a vesicle-trafficking network." 

But its morphology and/or cell cycle might have complexities more often associated with eukaryotes, they noted.​

​New York, June 19 (IANS) People with Parkinson's disease have a form of impaired decision-making that may be a major contributor to the movement problems that characterise the disease, a team of researchers has found.

Undertaken by researchers from the University of California - Los Angeles, the study suggested that the neurological factors underlying Parkinson's may be more complex than commonly believed. 

The study, publishing in the journal Current Biology also, could pave the way for strategies to detect Parkinson's earlier in its course.

The led team found that as compared to healthy individuals, people with early-stage Parkinson's have difficulty with perceptual decision-making only when the sensory information before them is weak enough that they must draw on prior experiences. 

When the sensory information is strong, individuals with Parkinson's are able to make decisions as well as people who are healthy.

"This tells us that the problem for people with Parkinson's disease is not walking per se, but rather in generating the walking pattern without the assistance of sensory information," said study senior author Michele Basso.

"The patients with Parkinson's disease in our study were impaired only when they had to rely on memory information to guide their actions. We believe this fundamental problem of decision-making in the absence of sufficient sensory information may be what is underlying some of the movement disorder symptoms," Basso added.

The disease has no cure, although medication or surgery can relieve symptoms to a certain extent.

"Parkinson's disease has long been seen as purely a motor problem, limited mostly to a section of the brain called the basal ganglia and a neurotransmitter called dopamine that is not produced at sufficient levels," Basso noted.​

New York, June 18 (IANS) Researchers led by an Indian-origin scientist have developed a software that can turn any smartphone into an eye-tracking device, a discovery that can help in psychological experiments and marketing research.

In addition to making existing applications of eye-tracking technology more accessible, the system could enable new computer interfaces or help detect signs of incipient neurological disease or mental illness.

Since few people have the external devices, there's no big incentive to develop applications for them. 

“Since there are no applications, there's no incentive for people to buy the devices. We thought we should break this circle and try to make an eye tracker that works on a single mobile device, using just your front-facing camera,” explained Aditya Khosla, graduate student in electrical engineering and computer science at Massachusetts Institute of Technology (MIT).

Khosla and his colleagues from MIT and University of Georgia built their eye tracker using machine learning, a technique in which computers learn to perform tasks by looking for patterns in large sets of training examples.

Currently, Khosla says, their training set includes examples of gaze patterns from 1,500 mobile-device users. 

Previously, the largest data sets used to train experimental eye-tracking systems had topped out at about 50 users.

To assemble data sets, "most other groups tend to call people into the lab," Khosla says. 

"It's really hard to scale that up. Calling 50 people in itself is already a fairly tedious process. But we realised we could do this through crowdsourcing,” he added.

In the paper, the researchers report an initial round of experiments, using training data drawn from 800 mobile-device users. 

On that basis, they were able to get the system's margin of error down to 1.5 centimetres, a twofold improvement over previous experimental systems.

The researchers recruited application users through Amazon's Mechanical Turk crowdsourcing site and paid them a small fee for each successfully executed tap. The data set contains, on average, 1,600 images for each user.

The team from MIT's Computer Science and Artificial Intelligence Laboratory and the University of Georgia described their new system in a paper set to presented at the "Computer Vision and Pattern Recognition" conference in Las Vegas on June 28.

​New York, June 16 (IANS) Scientists have discovered an ancient space rock in a Swedish quarry which is a type of meteorite never before found on the Earth and can shed more light on the evolution of life.

The new meteorite, called Ost 65, appears to be from the missing partner in a massive asteroid collision 470 million years ago. 

The collision sent debris falling to the Earth over about a million years and may have influenced a great diversification of life in the Ordovician Period which lasted almost 45 million years, beginning 488.3 million years ago and ending 443.7 million years ago. 

One of the objects involved in this collision is well-known. It was the source of L-chondrites, the most common type of meteorite. But the identity of the object that hit it has been a mystery.

"In our entire civilisation, we have collected over 50,000 meteorites and no one has seen anything like this one before," said study co-author Qing-zhu Yin, professor of geochemistry and planetary sciences at University of California-Davis. 

"Discovering a new type of meteorite is very, very exciting,” he added in a paper reported in the journal Nature Communications.

Ost 65 was discovered in Sweden's Thorsberg quarry, source of more than 100 fossil meteorites. 

Measuring just under four-inches wide, it looks like a gray cow patty plopped into a pristine layer of fossil-rich pink limestone. 

By measuring how long Ost 65 was exposed to cosmic rays, the team established that it travelled in space for about a million years before it fell to the Earth 470 million years ago. 

This timeline matches up with L-chondrite meteorites found in the quarry.

According to the researchers, about 100 times as many meteorites slammed into the Earth during the Ordovician Period compared with today owing to the massive collision in the asteroid belt. 

This rain of meteorites may have opened new environmental niches for organisms, thus boosting both the diversity and complexity of life on Earth.

"I think this shows the interconnectedness of the entire solar system in space and time, that a random collision 470 million years ago in the asteroid belt, could dictate the evolutionary path of species here on Earth," Yin explained.​

​New York, June 16 (IANS) Obese people may find it difficult to stay away from sweet foods than individuals who are lean, because of a dysfunction in their brains, finds a new study.

Extra body fat can exert effects on how our brains perceive rewards when we eat sweets, the study said.

The findings showed that the reward system in obese people brains' operates in a different manner than in those who are lean.

As people move from adolescence to adulthood, they tend to be less fond of sweets as a result of a decrease in dopamine levels -- the main chemical in the brain that makes us feel good. 

The fall in dopamine levels makes the older adults less attracted to sweets.

Both younger age and fewer dopamine receptors were found to be associated with a higher preference for sweets in those of normal weight. 

"We found disparities in preference for sweets between individuals and also found individual variations in dopamine receptors," said Tamara Hershey, Professor at Washington University.

"Some people have high levels and some low. In people with normal weight having fewer dopamine receptors was associated with a higher preference for sweets," Hershey noted.

However, in people with obesity, that is not the case, the researchers said.

Dysfunctioning in the brain's reward system of obese individuals makes them more vulnerable to sweet cravings.

The relationship between their age, sweetness preferences and dopamine receptors also did not follow the pattern seen in people who weighed less.

Insulin resistance or some other metabolic change linked to obesity could contribute to the absence of these associations in the obese group, the researchers explained.

"We believe we may have identified a new abnormality in the relationship between reward response to food and dopamine in the brains of individuals with obesity," lead author M Yanina Pepino, Assistant Professor at Washington University, added.

For the study, published online in the journal Diabetes, the team analysed 20 healthy volunteers who were aged between 20-40 years and compared them with 24 people considered obese, each of whom had a body mass index of 30 or higher. 

The participants received drinks containing varying levels of sugar to determine the degrees of sweetness each individual preferred. 

Positron emission tomography (PET) scans was conducted to identify dopamine receptors linked to rewards in each person's brain. ​