~ This Week In Science ~

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Researchers at the University of Cambridge in the United Kingdom have reportedly identified quadruple-helix human DNA for the first time ever. Though four-stranded DNA molecules were synthesized in the lab more than 50 years ago, never before have such “G-quadruplexes,” so named because they were thought to occur in guanine-rich regions of the genome, been observed in human cells. The Cambridge scientists provide strong evidence that such four-helix DNA does exist in humans, and suggested that it may play a central role in human disease.

“It’s early days, but if we can map exactly where these G-quadruplex structures pop up in the genome, we may learn how better to control genes or other cellular processes that go awry in diseases like cancer,” study leader Shankar Balasubramanian told Nature. “That’s the long-term vision anyway.’’

Balasubramanian and his team made an antibody that bound tightly to G-quadruplex structures, but not to traditional double-helix DNA, and found that it bound to many different sites on human chromosomes in cultured tumor cells. They published their findings earlier this week (January 20) inNature Chemistry.

Birds and humans use stars to navigate (at least, our pre-GoogleMaps ancestors did), but can insects map their routes?For dung beetles, a new study says the answer is yes. The African insects appear to find their way via the Milky Way. It’s the first evidence that any insect can orientate themselves with the sky, and the first evidence that any animal uses the Milky Way as a map of sorts.Even on clear, moonless nights, many dung beetles still manage to orientate along straight paths,” said Marie Dacke of Lund University in Sweden. “This led us to suspect that the beetles exploit the starry sky for orientation — a feat that had, to our knowledge, never before been demonstrated in an insect.”Dung beetles are so named because they search out piles of dung to roll into balls (yes, that’s dinner). They roll the balls in a straight line so that they won’t risk having their meal stolen by other beetles.To test their navigation, researchers watched the beetles in a planetarium under a starry sky, a sky showing only the Milky Way, and an overcast sky. The beetles had no problem maintaining their straight lines under the first two skies, but couldn’t do it when the Milky Way was indistinguishable.Most stars are probably too dim for the insects’ eyes, the researchers said in the study published online in Current Biology.

 

One question may remain unanswered: Is it more fascinating that these creatures navigate by the Milky Way, or eat dung for dinner?

Although light manipulation techniques have existed since the 1970s, this is the first time a light beam has been used to draw objects towards the light source, albeit at a microscopic level. Researchers from the University of St Andrews and the Institute of Scientific Instruments (ISI) in the Czech Republic have found a way to generate a special optical field that efficiently reverses radiation pressure of light. The new technique could lead to more efficient medical testing, such as in the examination of blood samples. In the US science fiction show, a tractor beam was a method of using a beam of light which could pull space-ships and other large objects towards the source of the light. The team, led by Dr Tomas Cizmar, Research Fellow in the School of Medicine at the University of St Andrews, with Dr Oto Brzobohaty and Professor Pavel Zemanek, both of ISI, discovered a technique which will allow them to provide 'negative' force acting upon minuscule particles. Normally when matter and light interact the solid object is pushed by the light and carried away in the stream of photons. Such radiation force was first identified by Johanes Kepler when observing that tails of comets point away from the sun.