Knowledge Update

​New York, Feb 21 (IANS) Love to eat fish and other seafood? Be careful, as eating mercury-rich fish such as shark and swordfish may increase the risk of developing amyotrophic lateral sclerosis (ALS) -- that takes away the ability of nerve cells to interact with the body's muscles -- a study has warned.

Mercury -- a heavy metal known to be toxic at high levels, causing brain, heart, kidney, lung and immune system damage -- is found high in swordfish and shark, while salmon and sardines typically have lower levels. 

However, the study does not suggest a higher risk of ALS -- also referred to as Lou Gehrig's disease -- from general consumption of seafood.

"For most people, eating fish is part of a healthy diet. But questions remain about the possible impact of mercury in fish," said Elijah Stommel from Dartmouth College in New Hampshire, US.

For the study, the team surveyed 518 people, 294 of whom had ALS and 224 of whom did not and the frequency that the participants reported eating fish with high mercury levels. 

Researchers also measured the levels of mercury found in toenail samples of participants with ALS.

The results, presented at the American Academy of Neurology's 69th Annual Meeting in Boston, revealed that 61 per cent people had a 25 per cent estimated annual mercury intake. These were at double the risk for ALS compared to those with lower levels.

The findings does not negate the fact that eating fish provides many health benefits.

But, people should choose species that are known to have a lower mercury content and avoid consuming fish caught in waters where there is mercury contamination, the researchers suggested.

New York, Feb 20 (IANS) People living in big cities with a large density of population are more likely to prefer long-term romantic relationships, have fewer children and invest more in education, suggesting that they value quality over quantity, researchers say.

The findings showed that urban citizens are more likely to adopt a 'slow life strategy', contrary to the popular notion that crowded places are chaotic and socially problematic.

"People who live in dense places seem to plan for the future more, prefer long-term romantic relationships, get married later in life, have fewer children and invest a lot in each child. They generally adopt an approach to life that values quality over quantity," said lead author Oliver Sng, a postdoctoral fellow at the University of Michigan. 

In environments where population density is low and there is thus relatively little competition for available resources, there are few costs but lots of advantages to adopting a 'fast' strategy.

On the other hand, when the environment gets crowded, individuals have to compete vigorously with others for the available resources and territory, the researchers said.

"So a slow strategy -- in which one focuses more on the future and invests in quality over quantity -- tends to enhance the reproductive success of individuals in high density environments," added Steven Neuberg Professor at Arizona State University. 

For the study, published in the Journal of Personality and Social Psychology, the team used data from nations around the world and the 50 US states. 

In a series of experiments -- for example, in which people read about increasing crowdedness or heard sounds of a crowded environment -- they found that perceptions of crowdedness cause people to delay gratification and prefer slower, more long-term, mating and parenting behaviours.

​New York, Feb 20 (IANS) Unlike other forms of caregiving, mothers singing to their babies is a universal behaviour, and new research shows that the act could be mutually beneficial for both the mother and the child.

While the songs provide the babies much-needed sensory stimulation that can focus their attention, the act of singing can help mothers bond with their babies and also fight postpartum depression, the study said.

Mothers experience a much-needed distraction from the negative emotions and thoughts associated with depression, while also feeling empowered as a parent.

The study, published in the Journal of Music Therapy, also explored the acoustic parameters in the singing voices of mothers with post-partum depression.

"The extraction and analysis of vocal data revealed that mothers with post-partum depression may lack sensitivity and emotional expression in their singing," said study author Shannon de l'Etoile, Professor of Music Therapy at University of Miami Frost School of Music in the US.

"Although the infants were still engaged during the interaction, the tempo did not change and was somewhat robotic," de l'Etoile said.

But the the lack of sensitivity and emotional expression seemed to matter less to the infants as long as they were listening to their mothers.

"Mothers around the world sing to their infants in remarkably similar ways, and infants prefer these specialized songs," de l'Etoile said. 

"The tempo and key certainly don't need to be perfect or professional for mothers and infants to interact through song. In fact, infants may be drawn to the personalised tempo and pitch of their mother, which encourage them to direct their gaze toward and ultimately communicate through this gaze," she added.

New York, Feb 20 (IANS) Sensational content have more staying power than substantive posts on the microblogging platform Twitter, says a study.

In other words, posts about provocative topics are retweeted more by users, thereby making Twitter appear more like a tabloid than a substantive discussion forum for a casual user, the study suggests.

The findings are based on analysis of tweets sent before, during and after the Republican primary debates leading up to the 2016 US presidential election.

"Whereas during the debate tweets focused on a mix of substantive topics, the tweets that had the longest staying power after the debates were those that focused on the more sensationalist news events, often through pictures and videos," said the study by researchers from University of Pennsylvania and Columbia University in the US.

"As such, a user coming to Twitter after the debate was over would have encountered a different topical and emotional landscape than one who had been following the site in real-time, one more closely resembling a tabloid than a substantive discussion forum," the study said.

The study found that entertaining or sensational posts wash out more substantive tweets overtime, The Daily Pennsylvanian reported on Monday. 

Twitter has a greater impact on political discourse than other social media platforms because Twitter users often see content from people they do not know, one of the study authors Ron Berman from The Wharton School, University of Pennsylvania, was quoted as saying.

Twitter users can search using a hashtag or trending topic to see public tweets from a diverse population of users.

​Beijing, Feb 20 (IANS) Majority of Chinese families that have a second child are happier, according to a survey.

The survey, jointly conducted by Radio Guangdong News Channel and a number of fertility websites, interviewed nearly 10,000 two-child families, with 63 per cent reporting feeling happier after the birth of the second child, Xinhua news agency reported on Monday.

The major reason for the rise in happiness was seeing two children grow up together.

After decades of the one-child policy, many parents are believed to be concerned as to whether their first child could accept a younger sibling.

However, the survey found that 44 per cent of children were fine with a younger sibling, and only 1.5 per cent could not accept a sibling at all.

"Though having a second child is often described as tiring, it is not a burden but a happiness to see two children beginning to get along well and keeping each other company," said Zhu Yuzi, who worked for the survey team and is a mother of two.

Starting in the late 1970s, China's one-child policy ended on January 1, 2016, when the government allowed all married couples to have two children.

In 2016, there were 18.67 million newborns in China, 11 per cent more than in 2015, and about 45 per cent of them were not the first child, according to the National Health and Family Planning Commission.

According to the survey, though 47 per cent of parents have husbands that help more with the child-raising after a second child, 57 per cent of wives said they had to quit their jobs to take care of the children.

New York, Feb 19 (IANS) Researchers have developed an electrode that is more durable and could allow for improved restoration of mobility after spinal cord accidents, as well as improved powered prosthetic limbs.

This "glassy carbon" electrode that is patterned inside chips lasts longer in the body and transmits clearer and more robust signals than available electrodes.

When people suffer spinal cord injuries and lose mobility in their limbs, it is a neural signal processing problem. The brain can still send clear electrical impulses and the limbs can still receive them but the signal gets lost in the damaged spinal cord.

According to the study, published in the journal Nature Scientific Reports, this new chip can record neural electrical signals and transmit them to receivers in the limb, bypassing the damage and restoring movement.

"Glassy carbon is much more promising for reading signals directly from neurotransmitters. You get about twice as much signal-to-noise. It's a much clearer signal and easier to interpret," said Sam Kassegne, one of the study's lead investigators. 

The current material for electrodes in these devices is thin-film platinum which can fracture and fall apart over time.

Researchers in Kassegne's lab are using these new and improved brain-computer interfaces to record neural signals both along the brain's cortical surface and from inside the brain at the same time.

​New York, Feb 19 (IANS) In a first, researchers have found that neurotransmitter dopamine -- a chemical that acts in various brain systems to spark the motivation necessary to work for a reward -- was involved in human bonding.

In the research, published in the journal Proceedings of the National Academy of Sciences, a researcher studied 19 mother-infant pairs and found that the results had important implications for therapies addressing disorders of the dopamine system.

"The infant brain is very different from the mature adult brain -- it is not fully formed," said Lisa Feldman Barrett of Northeastern University psychology.

"Our study shows that a biological process in one person's brain, the mother's, is linked to behaviour that gives the child the social input that will help wire his or her brain normally. That means parents' ability to keep their infants cared for leads to optimal brain development, which over the years results in better adult health and greater productivity," Barrett added.

To conduct the study, the researchers used a machine capable of performing two types of brain scans simultaneously--functional magnetic resonance imaging, or fMRI and positron emission tomography, or PET.

fMRI studied the brain in slices, front to back, like a loaf of bread and tracked blood flow to its various parts. 

Barrett's team tied the mothers' level of dopamine to her degree of synchrony with her infant as well as to the strength of the connection within a brain network called the medial amygdala network that, within the social realm, supports social affiliation.

"We found that social affiliation is a potent stimulator of dopamine. This link implies that strong social relationships have the potential to improve your outcome if you have a disease, such as depression, where dopamine is compromised," Barrett noted.

​London, Feb 19 (IANS) It is not the brain that determines whether a person is a lefty or a righty, but the spinal cord, a study has claimed.

Until now, it had been assumed that differences in gene activity of the right and left hemisphere might be responsible for a person's handedness -- people's tendency to naturally favour the use of one hand over the other. 

But the recent study demonstrated that gene activity in the spinal cord is asymmetrical already in the womb and could be linked to the handedness of a person.

"Our findings suggest that molecular mechanisms for epigenetic regulation within the spinal cord constitute the starting point for handedness, implying a fundamental shift in our understanding of the ontogenesis of hemispheric asymmetries in humans," said Sebastian Ocklenburg from Ruhr University Bochum in Germany.

According to ultrasound scans carried out in the 1980s, a preference for moving the left or right hand develops in the womb from the eighth week of pregnancy. From the 13th week of pregnancy, unborn children prefer to suck either their right or their left thumb.

Arm and hand movements are initiated via the motor cortex in the brain. It sends a corresponding signal to the spinal cord, which in turn translates the command into a motion. 

However, the motor cortex is not connected to the spinal cord from the beginning. In fact, even before the earliest indications of hand preference appear, the spinal cord has not yet formed a connection with the brain, stated researchers in the paper appearing in the journal eLife.

In addition, environmental factors were found to be controlling whether spinal cord activity was greater on the left or right side.

For the study, the team analysed the gene expression in the spinal cord during the eighth to 12th week of pregnancy and detected marked right-left differences in the eighth week -- in precisely those spinal cord segments that control the movements of arms and legs. 

​New York, Feb 19 (IANS) Adult stem cells collected directly from human fat are more stable than other cells -- such as fibroblasts from the skin -- and have the potential for use in anti-ageing treatment, says a study.

Stem cells collected directly from human fat -- called adipose-derived stem cells (ASCs) -- can make more proteins than originally thought, showed the findings published in the journal Stem Cells.

"Our study shows these cells are very robust, even when they are collected from older patients," said the study's lead author Ivona Percec from Perelman School of Medicine at the University of Pennsylvania.

"It also shows these cells can be potentially used safely in the future, because they require minimal manipulation and maintenance," Percec said.

The researchers made the discovery after developing a new model to study chronological ageing of these cells.

Stem cells are currently used in a variety of anti-ageing treatments and are commonly collected from a variety of tissues.

But Percec's team specifically found ASCs to be more stable than other cells, a finding that can potentially open the door to new therapies for the prevention and treatment of aging-related diseases.

"Unlike other adult human stem cells, the rate at which these ASCs multiply stays consistent with age," Percec said.

"That means these cells could be far more stable and helpful as we continue to study natural aging," Percec noted.

London, Feb 19 (IANS) Researchers have developed hens that do not produce their own chicks and can be used as surrogates to lay eggs from rare breeds.

Using gene-editing techniques, this could help to boost breeding of endangered birds, as well as improving production of commercial hens, researchers wrote in the study published in the journal Development.

A team led by the University of Edinburgh's Roslin Institute used a genetic tool called TALEN to delete a section of chicken DNA. They targeted part of a gene called DDX4, which is crucial for bird fertility.

"These chickens are a first step in saving and protecting rare poultry breeds from loss in order to preserve future biodiversity of our poultry from both economic and climate stresses," said lead researcher Mike McGrew from the University of Edinburgh's Roslin Institute. 

Researchers noted that donor primordial germ cells from other breeds could be implanted into the gene-edited chickens as they are developing inside an egg. 

The surrogate hens would then grow up to produce eggs containing all of the genetic information from the donor breeds.

The surrogate chickens are the first gene-edited birds to be produced in Europe.