Knowledge Update

New York, Sep 19 (IANS) Larger-bodied marine animals are more likely to become extinct than smaller creatures, and humans are to be largely blamed for this, say researchers.

It is a pattern that is unprecedented in the history of life on Earth, and one that is likely driven by human fishing, said the study published in the journal Science.

"We've found that extinction threat in the modern oceans is very strongly associated with larger body size," said Jonathan Payne, a paleobiologist at Stanford University's School of Earth, Energy & Environmental Sciences.

"This is most likely due to people targeting larger species for consumption first," Payne noted.

For the study, the researchers put modern extinction in context by comparing them with Earth's five previous mass extinctions.

"We used the fossil record to show, in a concrete, convincing way, that what is happening in the modern oceans is really different from what has happened in the past," study co-author Noel Heim, a postdoctoral researcher in Payne's lab, said. 

Specifically, the authors found that the modern era is unique in the extent to which creatures with larger body sizes are being preferentially targeted for extinction. 

"What our analysis shows is that for every factor of 10 increase in body mass, the odds of being threatened by extinction go up by a factor of 13 or so," Payne said. 

"The bigger you are, the more likely you are to be facing extinction," Payne noted.

The selective extinction of large-bodied animals could have serious consequences for the health of marine ecosystems, the scientists say, because they tend to be at the tops of food webs and their movements through the water column and the seafloor help cycle nutrients through the oceans, the scientists said.

​New York, Sep 20 (IANS) Some mosquitoes are more likely to feed on cattle than on humans if they carry a specific chromosomal rearrangement in their genes, thus reducing their odds of transmitting the malaria parasite, a new study has found.

The parasite causing the disease is carried by Anopheles mosquitoes species that transmit it to humans by biting them. One of these species is Anopheles arabiensis, which is the primary vector of malaria in East African countries.

Rates of malaria transmission depends on whether mosquitoes bite humans. When mosquitoes bite cattle, malaria does not spread because these animals are dead-end hosts.

The transmission also depends whether mosquitoes rest after their meals in areas where they are likely to encounter pesticides, the study said.

Using a population genomics approach, the study established an association between human feeding and a specific chromosomal rearrangement in the major east African malaria vector.

"Whether there is a genetic basis to feeding preferences in mosquitoes has long been debated. This work paves the way for identifying specific genes that affect this critically important trait," said Bradley Main, researcher at the University of California - Davis, in the US.

In the study, the team sequenced the genomes of 23 human-fed and 25 cattle-fed mosquitoes collected indoors and outdoors from the Kilobero Valley in Tanzania.

An analysis of these genomes allowed them to identify a chromosomal rearrangement -- known as the 3Ra inversion -- associated with cattle feeding.

It however did not appear to have an impact on the mosquitoes' resting behaviours.

Using genetics to better understand and track mosquito behaviour can improve local control strategies.

This knowledge may also open novel avenues for stopping malaria's spread, such as genetically modifying mosquitoes to prefer cattle over people, the researchers noted, in the paper published in the journal PLOS Genetics.

New York, Sep 20 (IANS) Our visual experiences are not be linked to our understanding of numbers, a study, led by an Indian-origin researcher, of people born blind has revealed.

The study showed that the visual cortex -- the part of the brain that receives and processes sensory nerve impulses from the eyes -- in blind people is highly involved in numerical reasoning, suggesting that the brain is vastly more adaptable than previously believed. 

"The number network in brain develops totally independently of visual experience. Blind people have never seen anything in their lives, but they have the same number network as people who can see," said lead author Shipra Kanjlia, a graduate student at Johns Hopkins University in Maryland, US. 

Further, the visual cortex -- also known as the visual area -- involved in doing maths is similar in both blind as well as sighted people, the study said. 

This visual cortex is extremely plastic and, when it isn't processing sight, can respond to everything from spoken language to math problems.

"The brain as a whole could be extremely adaptable, almost like a computer that -- depending on data coming in -- could reconfigure to handle almost limitless types of tasks," explained another researcher Marina Bedny, assistant professor at Johns Hopkins University.

It could someday be possible to re-route functions from a damaged area to a new spot in the brain, she said. "If we can make the visual cortex do math, then we can make any part of the brain do anything," Bedny stated.

For the study, the team involved congenitally blind people and sighted people wearing blindfolds to solve math equations and answer language questions while having a brain scan. 

With the math problems, participants heard pairs of increasingly complicated recorded equations and responded if the value for "x" was the same or different. 

The participants also heard pairs of sentences and responded if the meaning of the sentences was the same or different.

With both blind and sighted participants, the key brain network involved in numerical reasoning, the intraparietal sulcus, responded robustly as participants considered the math problems.

Meanwhile, in blind participants only, regions of the visual cortex also responded as they did math. And the visual cortex did not merely respond, the more complicated the math, the greater the activity was in the vision centre.

In addition, the study demonstrated that this re-purposed vision centre in blind people was not just responding to new functions haphazardly. But, the region has become specialised and segmented by function, like any other part of the brain. 

While some parts of the cortex are doing math, other parts are doing language, etc. 

Even in a resting state, brain scans show these new brain regions connect to traditional parts of the brain responsible for math and language in sighted people, the researchers concluded.

The findings were published online in the journal Proceedings of the National Academy of Sciences.

London, Sep 20 (IANS) Researchers, including one of Indian-origin, have found that people with epilepsy are at significantly higher risk of experiencing discrimination due to health problems than the general population.

This risk is greater for them than those with other chronic health problems such as diabetes, asthma and migraines.

People with epilepsy also had a greater likelihood of experiencing domestic violence and sexual abuse than the general population, according to the study published in the journal Epilepsia.

The analysis also found that such psychosocial adversities could help explain why individuals with epilepsy are at an increased risk of developing depression and anxiety disorders.

"We still don't know enough about why people with epilepsy develop depression and anxiety disorders much more often than the general population. Our findings suggest that adverse life events such as discrimination may be important," said senior author Dheeraj Rai from University of Bristol in Britain.

For the study, the researchers used data from the the Adult Psychiatric Morbidity Survey 2007 that included comprehensive interviews with 7,403 individuals living in private residences in England. 

Doctor-diagnosed epilepsy and other chronic conditions were established by self-report.

Discrimination, domestic violence, physical and sexual abuse, and other stressful life events were assessed using computerised self-completion and a face-to-face interview, respectively.

The researchers found that people with epilepsy were sevenfold more likely to have reported experiencing discrimination due to health problems than the general population without epilepsy. 

"This paper demonstrates that despite all of the advances made over the last 100 years, the experience of discrimination continues to be a significant problem for people with epilepsy," first author of the study Victoria Nimmo-Smith from University of Bristol said.

​New York, Sep 19 (IANS) Apple continues hiring augmented and virtual reality experts, an area which the company's CEO Tim Cook has been refering to all year, a media report said.

London, Sep 16 (IANS) Envy is the most common basic personality trait shaping human behaviour -- and is found among almost one-third of the human population, an interesting study has found.

The study on human behaviour found that 90 per cent of the human population can be divided into four main basic personality traits -- optimistic, pessimistic, trusting and envious. 

In the study, the researchers from Universidad de Zaragoza in Spain analysed the responses of 541 volunteers to hundreds of social dilemmas.

Participants were put into pairs and given options that either led to collaboration or conflict with others. 

Based on the results, the researchers developed a computer programme to classify people according to their behaviour.

The largest proportion of people (30 per cent) turned out to be "envious". They did not mind what they achieved as long as they were better than everyone else.

While the optimists (20 per cent) believed that they and their partner will make the best choice for both of them, the pessimists (20 per cent) selected options which they saw as the lesser of two evils.

The trusting group (20 per cent) were born collaborators who always cooperated and did not mind if they win or lose.

There is a fifth, undefined group, representing 10 per cent, which the algorithm is unable to classify in relation to a clear type of behaviour, the researchers said. 

The researchers argue that this allows them to infer the existence of a wide range of subgroups made up of individuals who do not respond in a determined way to any of the outlined models. 

"The results go against theories which states that humans act purely rationally for example, and, therefore, they should be taken into consideration in redesigning social and economic policies, as well as those involved in cooperation," said Yamir Moreno from the Universidad de Zaragoza. 

"These types of studies are important because they improve existing theories on human behaviour by giving them an experimental base," Moreno concluded in the study published in the journal Science Advances. 

New York, Sep 17 (IANS) A team of researchers has discovered a new mechanism for a bacterial toxin to inhibit inflammation in a commonly inherited autoinflammatory disease.

Familial Mediterranean fever (FMF), also known as Armenian disease, is a hereditary inflammatory disorder caused by mutations in MEFV -- a gene that leads to continuous activation of a protein called pyrin -- causing problems in regulating inflammation in the body. 

The study showed that a toxin in Yersinia pestis, which is the bacterial agent of plague, targets and inhibits the protein pyrin. 

"This finding is very significant because it may explain the natural selection process behind a chronic condition that affects a high prevalence of people originating around the Mediterranean Sea," said lead author James Bliska, Professor at the Stony Brook University in New York, US. 

Thousands of individuals from many ethnic origins of the Mediterranean, such as Armenians, Italians, Greeks and Arabs have FMF, the study said.

In addition, the bacterial toxin hijacks human kinases to phosphorylate and inhibits pyrin, a process that could be translated into therapeutics for FMF, Bliska added.

The hereditary inflammatory disease of FMF usually strikes individuals at some point in childhood and continues throughout adulthood. 

They occur in bouts called attacks that last one to three days. Arthritic attacks may last for weeks or months.

Fever, abdominal pain, chest pain, achy, swollen joints, constipation followed by diarrhea, a red rash on legs, especially below the knees, muscle aches, a swollen, tender scrotum, include the signs and symptoms of FMF.

There are treatments but no cures, and complications such as arthritis and vasculitis can occur after many prolonged inflammatory episodes. 

The findings, published in Cell Host & Microbe, can be used to better understand the genetic origins of FMF and explore new therapies for the disease.

​London, Sep 17 (IANS) Colour patterns, known as countershading, in Psittacosaurus -- a long-lost species of dinosaur -- protected them from predators, finds a new study.

Psittacosaurus was light on its underside and darker on top and most likely lived in an environment with diffuse light, such as in a forest.

Psittacosaurus had horns on either side of its head and long bristles on its tail and lived in the early Cretaceous period in China and has been found in the same rock strata where many feathered dinosaurs have been found.

"The fossil, which is on public display at the Senckenberg Museum of Natural History in Germany, preserves clear countershading, which has been shown to function by counter-illuminating shadows on a body, thus making an animal appear optically flat to the eye of the beholder," said Jakob Vinther of the Schools of Earth Sciences and Biological Sciences in the study published in the journal Current Biology 

"By reconstructing a life-size 3D model, we were able to not only see how the patterns of shading changed over the body, but also that it matched the sort of camouflage which would work best in a forested environment," said Innes Cuthill, Professor at the University of Bristol in Britain.

Vinther realised that structures previously thought to be artifacts or dead bacteria in fossilised feathers were actually "melanosomes" -- small structures that carry melanin pigments found in the feathers and skin of many animals.

In order to investigate what environment the Psittacosaurus had evolved to live in, the researchers took another cast of the model and painted it all grey.

They then placed it in the Cretaceous plant section of Bristol Botanic Garden and photographed it under an open sky and underneath trees to see how the shadow was cast under those conditions.

By comparing the shadow to the pattern in the fossil they could then predict what environment the Psittacosaurus lived in.

"We predicted that the Psittacosaurus must have lived in a forest. This demonstrates that fossil colour patterns can provide not only a better picture of what extinct animals looked like, but they can also give new clues about extinct ecologies and habitats," Vinther added.

The researchers found how well these colour patterns actually worked to camouflage the dinosaur.

The researchers say that they would now like to explore other types of camouflage in fossils and to use this evidence in understanding how predators could perceive the environment and to understand their role in shaping evolution and biodiversity.

New York, Sep 18 (IANS) Greater emphasis on immune system-based prevention should be central to new efforts to prevent cancer, researchers say.

"The body's immune system is capable of intercepting pre-malignancies and preventing cancer. It does so countless times every day in all of us. That natural ability is what we want to leverage," said Elizabeth M. Jaffee from the Johns Hopkins University in the US.

"Building upon our innate defenses against cancer is the foundation of new immunotherapies, which have shown great promise in a very short time," Jaffee added.

New research tools and other developments now make it possible to decipher in detail how different cancers begin, how benign or precancerous tissues turn malignant and deadly, the researchers said.

However, "if we are ever to eradicate this scourge, we must work to prevent it from occurring altogether," noted Scott M. Lippman, Director of Moores Cancer Center at the University of California - San Diego.

Prevention research has made strides, but progress has been anecdotal and isolated.

"If the goal is eradication of cancer, we need a radically new focus, investment and approach to premalignant diseases and cancer prevention, one that is supported and sustained by broad, deep efforts like the Cancer Moonshot and Human Vaccines Project," Lippman added.

Continued and new development of cancer vaccines like the human papilloma virus (HPV) vaccine which provides almost 100 per cent protection against strains linked to several types of cancer, will be critical he said, in the paper published in the journal PNAS

London, Sep 18 (IANS) Removing one carotid body from some patients with high blood pressure can provide immediate and sustained fall in blood pressure, finds a new study.

Carotid bodies, a small cluster of chemoreceptors and supporting cells located near the fork (bifurcation) of the carotid artery that feed the brain with blood, appear to be a cause of high blood pressure.

"The falls in blood pressure are impressive -- more than pharmacological medication -- and demonstrate the potential for targeting the carotid body to treat hypertension," said Angus Nightingale, researcher at the University of Bristol, England.

The carotid bodies detect the levels of oxygen in blood and when this falls they raise the alarm of a potential emergency by signalling to the brain to increase breathing and blood pressure.

"Treating the carotid body is a novel approach and a potential game changer as we believe we are reducing one of the main causes for hypertension in many patients. High blood pressure treatment typically tackles the symptoms targeting the end organs such as the heart, kidneys and blood vessels, and not the causes," said Julian Paton, researcher at the University of Bristol, England.

The clinical trial demonstrated that the carotid bodies in patients who responded to resection had raised carotid body activity. These patients breathed more at rest and produced exaggerated breathing responses when the oxygen level in their blood was lowered.

"Although this surgical approach to controlling high blood pressure was successful, we don't think this will be the solution in the long term. We now need to find a drug that dampens down an overactive carotid body and resets the blood pressure thermostat to a normal level," Nightingale added.

The research study was published recently in the Journal of American College of Cardiology: Basic to Translational Science.