Science Simplified!

Comment

Comment by Dr. Krishna Kumari Challa on April 25, 2014 at 8:14am

Breakthrough harnesses light for controlled chemical reaction
When chemist Tehshik Yoon looks out his office window, he sees a source of energy to drive chemical reactions. Plants "learned" to synthesize chemicals with sunlight eons ago; Yoon came to the field a bit more recently. But this week, in the journal Science, he and three collaborators detail a way to use sunlight and two catalysts to create molecules that are difficult to make with conventional techniques.

In chemistry, heat and ultraviolet (UV) light are commonly used to drive reactions. Although light can power reactions that heat cannot, UV has disadvantages, says Yoon, a chemistry professor at University of Wisconsin-Madison. The UV often used in industry carries so much energy that "it's dangerous to use, unselective, and prone to making unwanted by-products."

Many chemicals exist in two forms that are mirror images of each other, and Yoon is interested in reactions that make only one of those images.

"It's like your hands," Yoon says. "They are similar, but not identical; a left-hand glove does not fit the right hand. It's the same way with molecules in biology; many fail unless they have the correct 'handedness,' or 'chirality.'"

The pharmaceutical industry, in particular, is concerned about controlling chirality in drugs, but making those shapes is a hit-or-miss proposition with UV light, Yoon says.

He says the new technique answers a question posed by a French chemist in 1874, who suggested using light to make products with controlled chirality. "Chemists could never do that efficiently, and so the prejudice was that it was too difficult to do."
- University of Wisconsin-Madison

Comment by Dr. Krishna Kumari Challa on April 25, 2014 at 8:06am

Royal Statistical Society looking for volunteer scientists
Date: 22 Apr 2014

The Royal Statistical Society (RSS) is looking for volunteer scientists to take part in their programme of delivering science and statistics training to journalists.

Volunteers attend a ‘train the trainer’ workshop before signing up to deliver sessions at news outlets and journalism schools throughout the UK. Having successfully run the course for three years, the RSS is looking to widen their pool of volunteers.

Anyone interested in taking part should contact Vinet Campbell, National Coordinator for Science Journalism Training at V.Campbell@rss.org.uk. More information can also be found at their website.
http://www.statslife.org.uk/resources/for-journalists

Comment by Dr. Krishna Kumari Challa on April 25, 2014 at 7:58am

Neuroscientists Discover Brain Circuits Involved in Emotion

Neuroscientists have discovered a brain pathway that underlies the emotional behaviours critical for survival.
New research by the University of Bristol, published in the Journal of Physiology today [23 April], has identified a chain of neural connections which links central survival circuits to the spinal cord, causing the body to freeze when experiencing fear.

Understanding how these central neural pathways work is a fundamental step towards developing effective treatments for emotional disorders such as anxiety, panic attacks and phobias.

An important brain region responsible for how humans and animals respond to danger is known as the PAG (periaqueductal grey), and it can trigger responses such as freezing, a high heart rate, increase in blood pressure and the desire for flight or fight.

This latest research has discovered a brain pathway leading from the PAG to a highly localised part of the cerebellum, called the pyramis. The research went on to show that the pyramis is involved in generating freezing behaviour when central survival networks are activated during innate and learnt threatening situations.

The pyramis may therefore serve as an important point of convergence for different survival networks in order to react to an emotionally challenging situation.
-Journal of Physiology

Comment by Dr. Krishna Kumari Challa on April 25, 2014 at 7:53am

Inspired by the fist-like club of a mantis shrimp, a team of researchers led by University of California, Riverside, in collaboration with University of Southern California and Purdue University, have developed a design structure for composite materials that is more impact resistant and tougher than the standard used in airplanes.

Comment by Dr. Krishna Kumari Challa on April 25, 2014 at 7:49am

Virus-Inspired Coating Protects DNA Nanostructures In The Body
Nanomedicine: A lipid coating could protect DNA drug carriers in the bloodstream
Nanomedicines made from self-assembling DNA structures could last longer inside the bloodstream with a lipid bilayer coating similar to the ones worn by some viruses (ACS Nano 2014, DOI: 10.1021/nn5011914). This protection strategy could make it possible to test new kinds of DNA nanotherapies in animals and bring them to the clinic, the developers say.

DNA is a versatile building block for making nanoparticles with precise shapes that can perform complex tasks. For example, in 2012, researchers used DNA to fashion a drug-carrying box with two locks made from DNA; the box opens to release the drug only if both locks are bound to certain proteins on a target cell (Science, DOI: 10.1126/science.1214081). But researchers struggle to test this and other DNA nanotechnology in animals. Any free-floating DNA in the bloodstream is rapidly destroyed by enzymes. Researchers haven’t yet figured out how to package these DNA machines so that they can survive long enough in the body to do their work.

To solve this problem, William M. Shih, a synthetic biologist at Harvard University, looked to nature for inspiration. Viruses, which are essentially groups of genes that use living cells to replicate, have already developed strategies to endure in the bloodstream. One is to coat themselves with a protective lipid bilayer.

Shih decided to mimic this strategy. He first designed a simple octahedron-shaped wireframe of DNA using software his group had previously developed. Given the dimensions of a structure, this software generates a recipe list of DNA strands that will self-assemble into the desired shape. A DNA synthesis company makes the strands, and the researchers mix them in the lab.

Each strut in the DNA octahedron is made up of six 28-nm-long double helices held together by shorter strands. The Harvard group created attachment points on the interior and exterior surfaces of the octahedron using single-stranded pieces of DNA. On the interior, these handles bind to complementary DNA strands that carry fluorescent dyes so that the scientists could track the particles in animals. The exterior handles bind to complementary strands carrying lipids.

This created a 50-nm-diameter DNA octahedron with “greasy plugs” on it, Shih says. “Then we take this hairball and mix it with a solution of giant liposomes in surfactant.” The lipids from the liposomes stick to the plugs, eventually creating a continuous coating on the DNA frame. The completed structure is about 70 to 80 nm in diameter.

http://cen.acs.org/articles/92/web/2014/04/Virus-Inspired-Coating-P...

Comment by Dr. Krishna Kumari Challa on April 25, 2014 at 7:27am

Animal Kingdom Communication
UM researcher discovers the most effective animal signal strategies.
There are all sorts of signaling strategies in nature. Peacocks puff out their feathers and spread their colorful tails; satin bowbirds build specialized stick structures, called bowers, and decorate them with blue and shiny objects; and European bitterling males show off bright nuptial coloration during spawning season. Each species has evolved a unique method to communicate with others.
“Signaling can have profound fitness implications for individuals that are either signaling or receiving the signal,” says Gavin M. Leighton, author of a new study on the effectiveness of signaling systems.

“For instance, individuals may signal to attract mates, or they may signal to rivals in order to defend a territory. Additionally, many biological models of cooperative behavior require individuals to signal how cooperative they were in past interactions.”
Effective communication is not just about the signaler, according to the study, the receiver also needs to assess the signaler efficiently. For instance, one of the most effective strategies from the perspective of female birds is assessing groups of males called leks, where females can assess multiple males in a short period of time.
“When receivers had to assess individual signalers one at a time, the accuracy of their ranking of signalers decreased compared to when all the signalers could be observed simultaneously.”
The study also shows that individuals that used non-food items, like a twig, in their signaling display had the least effective strategy. Surprisingly, individuals that invest in ecological structures, such as building a nest, improved the ability of the females to rank signalers, but the effect was fairly weak.
“The most unexpected finding was that investing in some sort of temporally stable structure only weakly improved the ability for receivers to assess signalers,” Leighton, said. “I originally suspected that investing in a structure would allow individuals to quickly convey their signaling effort over time in a single, observable feature. While I did find that structures helped, the effect was not as strong as other the other variables.”
In order to investigate specific characteristics of systems and provide the ranking of signalers by receivers, Leighton designed a computer model that represents salient features of many signaling systems, across a variety of scenarios. The model is called an agent-based model. It allows the researcher to program individual entities with specified behaviors. Then, the software provides the ranking information to the researcher. Included in the analyses were different species of birds, fishes and insects.

“The study systematically models a series of behavioral and ecological conditions. To the best of my knowledge no one has performed a general analysis of these different types of signaling systems.”
The study assumes that in every scenario individuals had perfect memory. In other words, when a receiver saw a signaling individual, they were able to unambiguously assign this effort to a specific individual. In nature, individuals probably make errors in assigning signaling effort or forget the effort of individuals over time.
“By itself, this seems like an unwarranted assumption, however, it is not easy to compare across signaling systems where memory also varies with the species in question,” Leighton says.
In the future, the researcher would like to include variation in the memory of individual receivers in these models. “There may be effects of imperfect memory that influence signaling effectiveness and I think this would be a good next step.”
http://www.miami.edu/index.php/news/releases/animal_kingdom_communi...

Comment by Dr. Krishna Kumari Challa on April 25, 2014 at 6:16am

Risk factors for food allergy.

The dual-allergen exposure hypothesis is the theory that exposure to food allergens through the skin can lead to allergy, while consumption of these foods at an early age may actually result in tolerance. Depending on the balance of these exposures, either tolerance or allergy will “win.” Children with eczema, for example, have a disrupted skin barrier that could allow exposure to food proteins in the environment – such as peanut oil in creams or peanut residue on tables. Under the hypothesis, if these children avoid peanuts but are still exposed to them in the environment, they might be more likely to develop peanut allergy.

http://blogs.scientificamerican.com/food-matters/2014/04/23/prevent...

Despite efforts to prevent food allergy (FA) in children, IgE-mediated FAs are increasing in westernized countries. Previous preventive strategies, such as prolonged exclusive breast-feeding and delayed weaning onto solid foods, have recently been called into question. The present review considers possible risk factors and theories for the development of FA. An alternative hypothesis is proposed, suggesting that early cutaneous exposure to food protein through a disrupted skin barrier leads to allergic sensitization and that early oral exposure to food allergen induces tolerance. Novel interventional strategies to prevent the development of FA are also discussed.
http://www.ncbi.nlm.nih.gov/pubmed/22464642

Comment by Dr. Krishna Kumari Challa on April 25, 2014 at 5:29am

Comment by Dr. Krishna Kumari Challa on April 23, 2014 at 9:04am

Agenetic disease has been cured in living, adult animals for the first time using a revolutionary genome-editing technique that can make the smallest changes to the vast database of the DNA molecule with pinpoint accuracy.

Scientists have used the genome-editing technology to cure adult laboratory mice of an inherited liver disease by correcting a single "letter" of the genetic alphabet which had been mutated in a vital gene involved in liver metabolism. A similar mutation in the same gene causes the equivalent inherited liver disease in humans — and the successful repair of the genetic defect in laboratory mice raises hopes that the first clinical trials on patients could begin within a few years, scientists said.

The success is the latest achievement in the field of genome editing. This has been transformed by the discovery of Crispr, a technology that allows scientists to make almost any DNA changes at precisely defined points on the chromosomes of animals or plants.

Crispr — pronounced "crisper" — was initially discovered in 1987 as an immune defence used by bacteria against invading viruses. Its powerful genome-editing potential in higher animals, including humans, was only fully realised in 2012 and 2013 when scientists showed that it can be combined with a DNAsniping enzyme called Cas9 and used to edit the human genome . Since then there has been an explosion of interest in the technology because it is such a simple method of changing the individual letters of the human genome — the 3 billion "base pairs" of the DNA molecule — with an accuracy equivalent to correcting a single misspelt word in a 23-volume encyclopaedia.

In the latest study, scientists at the Massachusetts Institute of Technology (MIT) used Crispr to locate and correct the single mutated DNA base pair in a liver gene known as LAH, which can lead to a fatal build-up of the amino acid tyrosine in humans and has to be treated with drugs and a special diet. The researchers effectively cured mice suffering from the disease by altering the genetic make-up of about a third of their liver cells using the Crispr technique, which was delivered by high-pressure intravenous injections.

"We basically showed you could use the Crispr system in an animal to cure a genetic disease, and the one we picked was a disease in the liver which is very similar to one found in humans," said professor Daniel Anderson of MIT, who led the study.

"The disease is caused by a single point mutation and we showed that the Crispr system can be delivered in an adult animal and result in a cure. We think it's an important proof of principle that this technology can be applied to animals to cure disease," Anderson said. "The fundamental advantage is that you are repairing the defect , you are actually correcting the DNA itself," he said. "What is exciting about this approach is that we can actually correct a defective gene in a living adult animal."

Jennifer Doudna, of the University of California, Berkeley , who was one of the codiscoverers of the Crispr technique , said professor Anderson's study is a "fantastic advance" because it demonstrates that it is possible to cure adult animals living with a genetic disorder.

"Obviously there would be numerous hurdles before such an approach could be used in people, but the simplicity of the approach, and the fact that it worked, really are very exciting," professor Doudna said. "I think there will be a lot of progress made in the coming one to two years in using this approach for therapeutics and other real-world applications," she added.
''Scientists ‘edit’ DNA to correct adult genes and cure diseases ''
http://www.independent.co.uk/news/science/revealed-scientists-edit-...

Comment by Dr. Krishna Kumari Challa on April 23, 2014 at 8:57am

Parts of Antarctica, one of the coldest places on Earth, were as warm as today's California coast about 40 million years ago with temperatures as high as 17 degrees Celsius, a new study has found.

Researchers also found that the polar regions of the southern Pacific Ocean once registered 21st-century Florida heat.

The findings underscore the potential for increased warmth at Earth's poles and the associated risk of melting polar ice and rising sea levels, the researchers said.

Led by scientists at Yale University, the study focused on Antarctica during the Eocene epoch, 40-50 million years ago, a period with high concentrations of atmospheric CO2 and consequently a greenhouse climate.

Today, Antarctica is year-round one of the coldest places on Earth, and the continent's interior is the coldest place, with annual average land temperatures far below zero degrees Fahrenheit.

The new measurements can help improve climate models used for predicting future climate, according to co-author Hagit Affek, associate professor of geology & geophysics at Yale.
-PTI

• ‹ Previous
• 1
• …
• 897
• 898
• 899
• 900
• 901
• …
• 996
• Next ›
• Page