Knowledge Update

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.

​London, June 18 (IANS) A deficiency in the amount of vitamin D in the body may lead to high risk of chronic kidney diseases, especially in children, says a new study.

Vitamin D deficiency has been found common in children with chronic kidney disease (CKD) -- the longstanding disease of the kidneys leading to renal failure. 

Researchers have identified certain modifiable and non-modifiable factors associated with vitamin D deficiency in children with CKD. 

According to the study, nearly two-thirds of children suffering from vitamin D deficiency were also suffering from certain abnormalities like glomerulopathy -- a set of diseases affecting the nephrons.

Vitamin D levels were found lower in winter months than at other times of the year.

"Vitamin D levels are influenced more strongly by seasonal factors, the type of disease and nutritional supplementation than by common variants in vitamin D regulating genes," said Anke Doyon, at the University of Heidelberg in Germany.

Deficiency in Vitamin D may also increase the risk of osteoporosis, cancer, cardiovascular disease and autoimmune disorders, the researchers said.

Children with kidney disease who took vitamin D supplements had vitamin D levels that were two-times higher than those who did not take supplements.

"Supplementation practices should be reconsidered and intervention studies are needed to define guidelines how to monitor and treat vitamin D deficiency in children with chronic kidney disease," Doyon suggested.

The team analysed 500 children affected with kidney diseases in 12 European countries.

The findings published in the Clinical Journal of the American Society of Nephrology (CJASN), could help physicians protect the health of these young patients, the researchers concluded.​

Paris, June 17 (IANS) France's economic growth is expected to accelerate to 1.6 per cent this year, The National Institute of Statistics and Economic Studies (Insee) has said.

Insee in a report said it expects the country's jobless claims to fall too due to improving investment and household expenditure, Xinhua news agency reported.

​Moscow, June 16 (IANS) Russia's economic recession is expected to end this year, Economic Development Minister Alexei Ulyukayev said on Thursday.

"The low point of recession has passed, and there is a rapid economic recovery," Ulyukayev said at the St. Petersburg International Economic Forum that started earlier in the

​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. ​

New York, June 17 (IANS) Exercise, even a small amount, can help alleviate symptoms of attention-deficit/hyperactivity disorder (ADHD) in adults, say researchers.

ADHD symptoms can lead to depression, low energy and motivation, poor performance at work or school and also increased traffic accidents.

A single bout of exercise has psychological benefits for adults with these elevated ADHD symptoms, which lead to anxiety, the findings showed.

"Exercise is already known as a stress reducer and mood booster, so it really has the potential to help those suffering with ADHD symptoms," said the study's senior author Patrick O'Connor, professor at University of Georgia in the US. 

"And while prescription drugs can be used to treat these symptoms, there's an increased risk of abuse or dependence and negative side effects. Those risks don't exist with exercise," O'Connor said.

The study tested 32 young men with elevated ADHD symptoms who cycled at a moderate intensity for 20 minutes on one day, and on another day sat and rested for 20 minutes as a control condition. 

The participants were asked to perform a task requiring focus both before and after the different conditions, and researchers noted leg movement, mood, attention and self-reported motivation to perform the task.

As a result, researchers found that it was only after the exercise when the participants felt motivated to do the task. They also felt less confused and fatigued and instead felt more energetic. 

The study was published in the journal Medicine and Science in Sports and Exercise.

Interestingly, leg movements and performance on the task did not change after the exercise - rather, the exercise helped the young men feel better about doing the task.​

​New York, June 17 (IANS) Women who go to college intending to become engineers stay in the profession less often than men, as a result of gender disparities faced by them during their assignments, finds a new study.

Overall, about 20 per cent of under-graduate engineering degrees are awarded to women, but only 13 per cent of the engineering workforce is female, the study said.

The findings showed that women often feel marginalised, especially during internships, other summer work opportunities, or team-based educational activities.

"Gender makes a big difference. Informal interactions with peers and everyday sexism in teams and internships are particularly salient building blocks of [gender] segregation," said Susan Silbey, Professor at Massachusetts Institute of Technology.

Women are more likely than men to enter the field of engineering with the explicit notion that it will be a "socially responsible" profession that will "make a difference in people's lives."

But, gender dynamics seem to generate more opportunities for men to work on the most challenging problems, while women tend to be assigned routine tasks or simple managerial duties.

"For many women, their first encounter with collaboration is to be treated in gender stereotypical ways," the researchers rued.

“As a result of their experiences at these moments, women who have developed high expectations for their profession -- expecting to make a positive social impact as engineers -- can become disillusioned with their career prospects," Silbey added.

For the study, the team asked more than 40 undergraduate engineering students to keep twice-monthly diaries that generated more than 3,000 individual diary entries that the scholars systematically examined.

The diary entries frequently mentioned the everyday gender disparities these women faced.

Thus, such gender disparities leads women to question whether other professions could be a better vehicle for affecting positive change in the society -- their key motivator -- and thus prompt them to leave engineering, said the paper published in the journal Work and Occupations.​