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Tuesday, April 2, 2013

Crucial step in human DNA replication observed for the first time

Tuesday, April 2, 2013

For the first time, an elusive step in the process of human DNA replication has been demystified by scientists at Penn State University. According to senior author Stephen J. Benkovic, an Evan Pugh Professor of Chemistry and Holder of the Eberly Family Chair in Chemistry at Penn State, the scientists "discovered how a key step in human DNA replication is performed." The results of the research will be published in the journal eLife on 2 April 2013.

Part of the DNA replication process -- in humans and in other life forms -- involves loading of molecular structures called sliding clamps onto DNA. This crucial step in DNA replication had remained somewhat mysterious and had not been well studied in human DNA replication. Mark Hedglin, a post-doctoral researcher in Penn State's Department of Chemistry and a member of Benkovic's team, explained that the sliding clamp is a ring-shaped protein that acts to encircle the DNA strand, latching around it like a watch band. The sliding clamp then serves to anchor special enzymes called polymerases to the DNA, ensuring efficient copying of the genetic material. "Without a sliding clamp, polymerases can copy very few bases -- the molecular 'letters' that make up the code of DNA -- at a time. But the clamp helps the polymerase to stay in place, allowing it to copy thousands of bases before being removed from the strand of DNA," Hedglin said.

Hedglin explained that, due to the closed circular structure of sliding clamps, another necessary step in DNA replication is the presence of a "clamp loader," which acts to latch and unlatch the sliding clamps at key stages during the process. "The big unknown has always been how the sliding clamp and the clamp loader interact and the timing of latching and unlatching of the clamp from the DNA," said Hedglin. "We know that polymerases and clamp loaders can't bind the sliding clamp at the same time, so the hypothesis was that clamp loaders latched sliding clamps onto DNA, then left for some time during DNA replication, returning only to unlatch the clamps after the polymerase left so they could be recycled for further use."

To test this hypothesis, the team of researchers used a method called F?rster resonance energy transfer (FRET), a technique of attaching fluorescent "tags" to human proteins and sections of DNA in order to monitor the interactions between them. "With these tags in place, we then observed the formation of holoenzymes -- the active form of the polymerase involved in DNA replication, which consists of the polymerase itself along with any accessory factors that optimize its activity," Hedglin said. "We found that whenever a sliding clamp is loaded onto a DNA template in the absence of polymerase, the clamp loader quickly removed the clamp so that free clamps did not build up on the DNA. However, whenever a polymerase was present, it captured the sliding clamp and the clamp loader then dissociated from the DNA strand."

The team members also found that, during the moments when both the clamp loader and the clamp were bound to the DNA, they were not intimately engaged with each other. Rather, the clamp loader released the closed clamp onto the DNA, allowing an opportunity for the polymerase to capture the clamp, completing the assembly of the holoenzyme. Subsequently, the clamp loader dissociated from DNA. "Our research demonstrates that the DNA polymerase holoenzyme in humans consists of only a clamp and a DNA polymerase. The clamp loader is not part of it. It disengages from the DNA after the polymerase binds the clamp," Hedglin added.

Benkovic noted that this mechanism provides a means for the cell to recycle scarce clamps when they are not in use for productive replication.

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Penn State: http://live.psu.edu

Thanks to Penn State for this article.

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Source: http://www.labspaces.net/127551/Crucial_step_in_human_DNA_replication_observed_for_the_first_time

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US restraint in Syria could aid Iran nuclear talks (The Arizona Republic)

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Why brands tie visibility to sponsorship

By Princewill Ekwujuru

For a brand to reach a predestined target audience and to carve a niche for itself it has to cling to a marketing tool to achieve it?s goal.? Brands support various activities to help develop a particular sector.

Today, brands have become major actors in modern society. They penetrate all spheres of life;? Education, economics, social, cultural,sporting and even religion.

As a result of this pervasiveness brands have come under growing criticism and as major symbols of the? economic and postmodern societies, they are analysed through a number of perspectives: macroeconomics, microeconomics, sociology, psychology, anthropology etc.

In this context however brands have become credible only through the persistence and repetition of their value proposition. No wonder brands like MTN, Coca Cola, Etisalat, Airtel queue behind sponsorship, scholarship awards as Corporate Social Responsibility, CSR, to support cultural activities, festivals, music concerts and? football competitions to mention a few to drive their brand visibility because of the inherent benefits behind such.

That is the reason students of University of Lagos, UNILAG, will not forget in a hurry the immense contribution of? Life is Good, LG, to raising the standard of Education in Nigeria, particularly in their school with the award of scholarship to 400 and 500 students of the faculty of? Engineering who performed meritoriously in their academics.

By this gesture,? LG Electronics consumer electronics and mobile communications has kept it?s promise by awarding scholarships to new set of students.

This sponsorship conducted annually is part of the company?s? CSR activities which primary aim is empowering young people as well as developing the educational sector, ensuring that youths who are the future leaders are adequately empowered and given financial support in order to enable them achieve their dreams and aspirations.

At the award ceremony, the Managing Director, LG Electronics West Africa Operations, Mr. Deog Jun Kim said, ?This scholarship is being awarded to 10 students of 400 and 500 levels from the Faculty of Engineering who emerged as best students after a careful selection by both the university authority and LG Electronics based on their Grade Points of 4.0 to 5.0, which made them stand out from their colleagues.?

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Source: http://www.vanguardngr.com/2013/03/why-brands-tie-visibility-to-sponsorship/

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Monday, April 1, 2013

NASA announces competition to improve Robonaut's sight

NASA's got some of the sharpest minds in the world (actual, you know, rocket scientists), sure, but they'll be the first to tell you that sometimes you've got to look outside for the best solution to a complicated problem. In recent years, that's meant the organization has partnered with the likes of SpaceX to help transfer materials to the International Space Station. The desire to look outside has also taken the form of competitions, which, in the past, have sought to improve the efficiency of solar arrays and help better understand the massive amounts of data collected from various missions over a 30-year period.

This latest competition, a partnership with TopCoder, deals with the unspeakably appealing category of space robots, aiming to improve the vision of NASA's head of menial space station tasks, Robonaut. At present, the 'bot's got the sort of sight problems that would have no doubt barred its fleshier counterparts from making their way through the training program.

Filed under: Robots, Science

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Source: TopCoder

Source: http://feeds.engadget.com/~r/weblogsinc/engadget/~3/6zyF6XAgrr8/

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Worries over teen sex may be overblown, report says

Despite periodic media scares, young teens are remarkably unlikely to be sexually active, new research finds. And even older teens are delaying sex more frequently than in the past.

The study, published online today (April 1) in the journal Pediatrics, found that a mere 2.4 percent of 12-year-olds had ever had sex. At 16, a third of teens reported sexual activity, a number that climbed to 71 percent by age 18 and 19.

Low rates of sexual activity among young adolescents have been the norm for decades, study researchers said. Recently, however, older teens seem more inclined to take it slow, too.

"Policymakers and the media often sensationalize teen sexual behavior, suggesting that adolescents as young as 10 or 11 are increasingly sexually active," study researcher Lawrence Finer of the nonprofit Guttmacher Institute said in a statement. "But the data just don't support that concern. Rather, we are seeing teens waiting longer to have sex, using contraceptives more frequently when they start having sex, and being less likely to become pregnant than their peers of past decades." [Teen Pregnancy Rates by State]

The findings match earlier studies that put the current teen pregnancy rate at a 40-year low. A report released in 2012 found that teen pregnancies peaked in 1990 and declined 42 percent over the next 18 years. As of 2008, the most recent year data were available, 68 per every 1,000 teens experienced a pregnancy.

Finer and his co-author Jesse Philbin, also of Guttmacher, used nationally representative data from the National Survey of Family Growth to track teens' sexual histories over time. The data come from the years 2006 to 2010.

They found that in any give age group, the likelihood of a teen being sexually active is lower than any time in the past 25 years. What's more, more than 80 percent of 16-year-olds having sex for the first time used contraceptives, the researchers found. A year later, 95 percent of those teens had taken up contraceptive use. Those rates were similar to the numbers seen in teens initiating sex after age 16.

Younger teens had a more troubling pattern, with adolescents who began having sex before age 14 using contraceptives less frequently and taking longer to adopt them into their sexual repertoire.

Another alarming discovery was that of the few young adolescents who reported having sex, many or most did not do so voluntarily. The researchers found that 0.6 percent of 10-year-olds reported having sex; 62 percent of females who said they'd had sex by that age reported that it was coerced.

Similarly, 1.1 percent of 11-year-olds reported having sex, and 50 percent of the females in that group said their first time was coerced.

Follow Stephanie Pappas on Twitter?and Google+. Follow us @livescience, Facebook?& Google+. Original article on LiveScience.com.

Source: http://news.yahoo.com/teen-sex-fears-overblown-175530287.html

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Teachers' gestures boost math learning

Monday, April 1, 2013

Students perform better when their instructors use hand gestures ? a simple teaching tool that could yield benefits in higher-level math such as algebra.

A study published in Child Development, the top-ranked educational psychology journal, provides some of the strongest evidence yet that gesturing may have a unique effect on learning. Teachers in the United States tend to use gestures less than teachers in other countries.

"Gesturing can be a very beneficial tool that is completely free and easily employed in classrooms," said Kimberly Fenn, study co-author and assistant professor of psychology at Michigan State University. "And I think it can have long-lasting effects."

Fenn and Ryan Duffy of MSU and Susan Cook of the University of Iowa conducted an experiment with 184 second-, third- and fourth-graders in Michigan elementary classrooms.

Half of the students were shown videos of an instructor teaching math problems using only speech. The others were shown videos of the instructor teaching the same problems using both speech and gestures.

The problem involved mathematical equivalence (i.e., 4+5+7=__+7), which is known to be critical to later algebraic learning. In the speech-only videos, the instructor simply explains the problem. In the other videos, the instructor uses two hand gestures while speaking, using different hands to refer to the two sides of the equation.

Students who learned from the gesture videos performed better on a test given immediately afterward than those who learned from the speech-only video.

Another test was given 24 hours later, and the gesture students actually showed improvement in their performance while the speech-only students did not.

While previous research has shown the benefits of gestures in a one-on-one tutoring-style environment, the new study is the first to test the role of gestures in equivalence learning in a regular classroom.

The study also is the first to show that gestures can help students transfer learning to new contexts ? such as transferring the knowledge learned in an addition-based equation to a multiplication-based equation.

Fenn noted that U.S. students lag behind those in many other Western countries in math and have a particularly hard time mastering equivalence problems in early grades.

"So if we can help them grasp this foundational knowledge earlier," she said, "it will help them as they learn algebra and higher levels of mathematics."

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Michigan State University: http://www.newsroom.msu.edu

Thanks to Michigan State University for this article.

This press release has been viewed 31 time(s).

Source: http://www.labspaces.net/127534/Teachers__gestures_boost_math_learning

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AT&T to begin HTC One pre-sales this week, starting with 32GB for $250

True to form, carriers won't stop being so coy about the HTC One. We still haven't received any official information regarding the flagship's pricing or specific availability, but thanks to one of our eagle-eyed tipsters, we at least have a solid idea of AT&T's particular plans for the device. The operator is set to begin pre-orders of the One this week, with the 32GB flavor being offered in both silver and black hues for $249.99. The exclusive 64GB model likely won't be ready in time for early adopters, but it'll go for $299.99 once it does show up on store shelves. Our tipster tells us pre-sales will begin in the retail channel on April 5th, while pending marketing materials indicate the One can be pre-ordered online the day before. If this is the case, we expect it won't be long before AT&T delivers the official news, and hopefully T-Mobile and Sprint will do the same; we'll keep you posted as soon as it happens.

[Thanks, anonymous]

Filed under: Cellphones, Wireless, Mobile, HTC, AT&T