Knowledge Update

​London, Oct 11 (IANS) Mice court one another with ultrasonic love songs that are inaudible to the human ear, and researchers, including one of Indian origin, have found that when mice 'sing', they use a mechanism similar to that seen in the engines of supersonic jets.

"Mice seem to be doing something very complicated and clever to make ultrasound," said study co-author Anurag Agarwal from University of Cambridge. 

Mice, rats and many other rodents produce ultrasonic songs that they use for attracting mates and for territorial defence. These 'singing' mice are often used to study communication disorders in humans, such as stuttering. 

However, until now it was not understood how mice can make these ultrasonic sounds, which may aid in the development of more effective animal models for studying human speech disorders.

"Mice make ultrasound in a way never found before in any animal," lead author of the study Elena Mahrt from the Washington State University noted.

The new research published in the journal Current Biology showed that mice point a small air jet coming from the windpipe against the inner wall of the larynx, causing a resonance and producing an ultrasonic whistle.

Using ultra-high-speed video of 100,000 frames per second the researchers showed that the vocal folds remain completely still while ultrasound was coming from the mouse's larynx.

"This mechanism is known only to produce sound in supersonic flow applications, such as vertical takeoff and landing with jet engines, or high-speed subsonic flows, such as jets for rapid cooling of electrical components and turbines," Agarwal explained.

​Washington, Oct 11 (IANS) Astronauts travelling to Mars might be at risk of long-term brain damage and even dementia due to galactic cosmic ray exposure, said a new study.

To explore a phenomenon called "space brain," researchers from the University of California, Irvine (UCI) exposed rodents to highly energetic charged particles -- fully ionized oxygen and titanium -- at the NASA Space Radiation Laboratory at New York's Brookhaven National Laboratory, Xinhua news agency reported on Monday.

These particles are much like those found in the galactic cosmic rays that will bombard astronauts during extended spaceflights, according to the study published in the journal Scientific Reports, which is part of NASA's Human Research Program.

Six months after exposure, the researchers still found significant levels of brain inflammation and damage to neurons, said Charles Limoli, professor of radiation oncology in UCI's School of Medicine.

Imaging revealed that the brain's neural network was impaired through the reduction of dendrites and spines on these neurons, disrupting the transmission of signals among brain cells.

These deficiencies were parallel to poor performance on behavioural tasks designed to test learning and memory.

In addition, the Limoli team discovered that the radiation affected "fear extinction," an active process in which the brain suppresses prior unpleasant and stressful associations, as when someone who nearly drowned learns to enjoy water again.

"This is not positive news for astronauts deployed on a two-to- three-year round trip to Mars," Limoli said.

"The space environment poses unique hazards to astronauts. Exposure to these particles can lead to a range of potential central nervous system complications that can occur during and persist long after actual space travel -- such as various performance decrements, memory deficits, anxiety, depression and impaired decision-making. Many of these adverse consequences to cognition may continue and progress throughout life."

As a partial solution, Mars-bound spacecraft could be designed to include areas of increased shielding, such as those used for rest and sleep, Limoli noted.

However, these highly energetic charged particles will traverse the ship nonetheless, he added, "and there is really no escaping them."

Limoli's group is also working on preventive treatments involving compounds that scavenge free radicals and protect neurotransmission. 

​Dubai, Oct 9 (IANS/WAM) Dubai Aerospace Enterprise (DAE) has received the Middle East and Africa "Lessor of the Year" award at the Aviation 100 Awards ceremony in recognition of its position as a strong, ambitious and world-class aircraft-leasing company.

New York, Oct 10 (IANS) An adolescent's ability to learn and form memories is closely linked to the reward-seeking behaviour of the brain, researchers have found.

"Studies of the adolescent brain often focus on the negative effects of teenagers' reward-seeking behaviour," said Daphna Shohamy, Associate Professor of psychology at New York's Columbia University. 

However, the study found that this tendency may be tied to better learning as well as a critical feature of adolescence and the maturing brain.

"We identified patterns of brain activity in adolescents that support learning -- serving to guide them successfully into adulthood," Shohamy added.

For the study, the team involved 41 teenagers and 31 adults and scanned the brains of each participant with functional magnetic resonance imaging (fMRI) while they were performing the learning tasks. 

The fMRI analysis revealed an uptick in hippocampal (brain's memory centre) activity for teenagers -- but not adults -- during reinforcement learning -- a reward signal that helps the brain learn how to repeat the successful choice again. 

Moreover, that activity seemed to be tightly coordinated with activity in the striatum -- a critical component of the brain's reward system. 

The researchers also slipped in random and irrelevant pictures of objects into the learning tasks, such as a globe or a pencil. 

When asked later on, both adults and teens remembered seeing some of the objects. However, only in the teenagers the memory of the objects was associated with reinforcement learning.

"The findings showed that teenagers do not necessarily have better memory, in general, but rather the way in which they remember is different," Shohamy said. 

The results of this research were published in the journal Neuron.

​New York, Oct 10 (IANS) Researchers have identified an enzyme that has caused rifampicin -- a popular antibiotic used to treat bacteria that causes tuberculosis, leprosy, and Legionnaire's disease -- to become less effective and develop more resistance.

The actions of the enzyme Rifampicin monooxygenase -- a flavoenzyme which is a family of enzymes that catalyze chemical reactions essential for microbial survival -- have been found responsible for the antibiotic's resistance.

"Antibiotic resistance is one of the major problems in modern medicine," said Heba Adbelwahab, graduate student at Virginia Polytechnic Institute in the US. 

Rifampicin, also known as Rifampin, has been used to treat bacterial infections for more than 40 years. It works by preventing the bacteria from making RNA, a step necessary for growth.

The findings represent the first detailed biochemical characterisation of a flavoenzyme involved in antibiotic resistance, the researchers said.

"Our studies have shown how this enzyme deactivates rifampicin. We now have a blueprint to inhibit this enzyme and prevent antibiotic resistance," Adbelwahab added.

Tuberculosis, leprosy, and Legionnaire's disease are infections caused by different species of bacteria. While treatable, the diseases pose a threat to children, the elderly, people in developing countries without access to adequate health care, and people with compromised immune systems.

For the study, the team used a special technique called X-ray crystallography to describe the structure of this enzyme. 

They also reported the biochemical studies that allow them to determine the mechanisms by which the enzyme deactivates this important antibiotic.

The results were published in the Journal of Biological Chemistry and PLOS One.

​Washington, Oct 8 (IANS) US President Barack Obama has issued an executive order to lift economic sanctions on Myanmar.

The move came on Friday after Obama's announcement that the US was ready to lift sanctions on the Asian country during Myanmar State Counsellor Aung San Suu Kyi's visit to

Washington, Oct 7 (IANS) International Monetary Fund (IMF) and World Bank leaders have called for measures to promote inclusive growth and resist anti-trade sentiments.

"Globalisation has worked over the years, that it has delivered great benefits to many people. We do not think that it is time to push against it," Xinhua news agency quoted IMF

London, Oct 9 (IANS) The absence of a particular molecule from cells can make tumours recur even after immunotherapy, a group of researchers from Germany has found.

Immunotherapy is a new and highly promising form of treatment for cancer.

A team of researchers from the Max Delbruck Center for Molecular Medicine in the Helmholtz Association (MDC) and the Berlin Institute of Health (BIH) and Charite -- Universitatsmedizin Berlin will help doctors in selecting suitable target points for immunotherapy.

One form of immunotherapy for cancer is T-cell receptor gene therapy that involves removing T-cells (a type of immune cell) from the blood and altering them in the test tube to enable them to target cancer cells.

"The tumours are not recognised by the T-cells. We want to find out how to reduce the frequency with which the cancer recurs after treatment," biologist Ana Textor said.

To achieve this, the researchers trained two different types of T-cell. One of the T-cell types permanently destroyed the tumours in a mouse model. After treatment with the other T-cell type, initial tumour regression was followed by recurrence.

The researchers found that when the tumour recurred, a particular molecule on the cell surface -- called the epitope -- was no longer present on the cell surface in sufficient quantity.

This was because the epitopes in these cancer cells were no longer correctly trimmed enzymatically -- in this case by the enzyme ERAAP.

By contrast, the epitopes on the cells of the successfully treated tumour did not require processing by ERAAP and were therefore also not dependent on stimulation by interferon gamma.

According to Textor, epitopes that do not need processing by the enzyme ERAAP are therefore, likely to be a better choice for immunotherapy.

The findings were published in the Journal of Experimental Medicine.