Archive for October 4th, 2011

October 4, 2011

New technique gives precise picture of how regulatory RNA controls gene activity

LincRNAs (long intergenic non-coding RNAs) seem to be the flavor du jour for researchers studying the many functions of various types of RNA, in addition to the traditional role of carrying genetic information from DNA to the cellular structures where proteins are made. Very recent research showed that lincRNAs regulate gene expression in embryonic stem cells. Another lab has now come up with a technique for determining exactly where on a cell’s chromosones a given lincRNA binds in order to regulate gene expression.

New Stanford technique gives precise picture of how regulatory RNA controls gene activity – Stanford University

A new technique developed by researchers at the Stanford University School of Medicine allows researchers to identify the exact DNA sequences and locations bound by regulatory RNAs. This information is necessary to understand how the recently identified RNA molecules control the expression of neighboring and distant genes.

The study offers a startling glimpse into the intricate world of gene expression and how RNA, once thought to be only a lowly cellular messenger, actively unlocks our DNA-based genome. “We used to have to just infer where these RNAs were acting based on their biological effects,” said Howard Chang, MD, PhD, professor of dermatology. “But now we can identify precisely where on the chromatin they are binding. We’ve found that these sites are focal, numerous and sequence-specific.”

This research greatly improves lab techniques for studying lincRNA, but doesn’t itself identify new functions.

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October 4, 2011

Fermi Bubbles Are Burps from a Star-Eating Black Hole

The following story may be recalled from almost a year ago, if only because of the eye-catching illustration:

NASA’s Fermi Telescope Finds Giant Structure in our Galaxy

NASA’s Fermi Gamma-ray Space Telescope has unveiled a previously unseen structure centered in the Milky Way. The feature spans 50,000 light-years and may be the remnant of an eruption from a supersized black hole at the center of our galaxy.

“What we see are two gamma-ray-emitting bubbles that extend 25,000 light-years north and south of the galactic center,” said Doug Finkbeiner, an astronomer at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., who first recognized the feature. “We don’t fully understand their nature or origin.”

Since gamma rays are the most energetic form of electromagnetic radiation (far more potent than X-rays), the existence of large, though diffuse, clouds of them above and below the plane of our galaxy wasn’t something to be taken lightly.

Now there is a proposed explanation: indigestion from star consumption by the Milky Way’s central black hole:

Fermi Bubbles Are Burps from a Star-Eating Black Hole – Technology Review

Last year, astronomers analysing data from NASA’s orbiting Fermi Gamma Ray Telescope made an extraordinary announcement. They said that Fermi had spotted two giant bubbles emanating from the centre of the galaxy, stretching some 20,000 light years above and below the galactic plane.

These bubbles are clearly some kind of shockwave in which high energy electrons interact with photons, giving up their energy in the form of gamma rays.

But what could have caused such a shockwave, which is many times bigger than astronomers would expect to see from a supernova?

Today, Kwong Sang Chen at The University of Hong Kong and a few pals say think they know. They say the bubbles are the remnants of stars that have been eaten by the supermassive black hole at the centre of the galaxy.

The researchers believe than their model also helps explain a completely different issue: the energy distribution of very high-energy cosmic rays.

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