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Scientists find missing link to understand how plants make vitamin C

Vitamin C is possibly the most important small molecule whose biosynthetic pathway remained a mystery. That is until now.

A group of Dartmouth and UCLA researchers, who normally work on genes involved in aging and cancer in animals, discovered the last piece of the puzzle, they report in a study published online April 26 in the Journal of Biological Chemistry.

Dr. Steven Clarke of the UCLA Molecular Biology Institute and the Department of Chemistry and Biochemistry explains, "We were working on an interesting gene in worms." One insight led to another until, "We uncovered the last unknown enzyme in the synthesis of vitamin C in plants," said Dr. Charles Brenner of Dartmouth Medical School's Norris Cotton Cancer Center and Department of Genetics.

An essential vitamin for people, vitamin C is well known as an antioxidant and enzyme cofactor. Humans lost the ability to make vitamin C and need to take it up from dietary sources, particularly from plants.

Only in 1998 was a biosynthetic pathway proposed to explain how plants make vitamin C. Research since then has confirmed much of the pathway, although the gene responsible for the seventh step of the proposed 10-step pathway from glucose to vitamin C remained unknown.

Key

Ocean's 'twilight zone' may be a key to understanding climate change

Carbon dixoide consumed before it sinks in deep ocean may re-enter atmosphere as greenhouse gas

A major study sheds new light on the role of carbon dioxide once it's transported to the oceans' depths. The research indicates that instead of sinking, carbon dioxide is often consumed by animals and bacteria and recycled in the "twilight zone," a dimly lit area 100 to 1,000 meters below the surface. Because the carbon often never reaches the deep ocean, where it can be stored and prevented from re-entering the atmosphere as a green-house gas, the oceans may have little impact on changes in the atmosphere or climate.

The research is the result of two international expeditions to the Pacific Ocean, and is published in the April 27, 2007, issue of Science.

"These results are particularly important to our efforts today to improve the predictive capacity of numerical models that relate ocean carbon to global climate change on different time scales," said Don Rice, director of NSF's chemical oceanography program.

It also adds a new wrinkle to proposals to mitigate climate change by fertilizing the oceans with iron--to promote blooms of photosynthetic marine plants and transfer more carbon dioxide from the air to the deep ocean.

"The twilight zone is a critical link between the surface and the deep ocean," said Ken Buesseler, a biogeochemist at Woods Hole Oceanographic Institution and lead author of the new study, which is co-authored by 17 other scientists. "We're interested in what happens in the twilight zone, what sinks into it and what actually sinks out of it. Unless the carbon goes all the way down into the deep ocean and is stored there, the oceans will have little impact on climate change."

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New Layer of Ancient Greek Writings Detected in Medieval Book

At first glance, the manuscript appears to be a medieval Christian prayer book.

But on the same pages as the prayers, experts using a high-tech imaging system have discovered commentary likely written in the third century A.D. on a work written around 350 B.C. by the Greek philosopher Aristotle.

The discovery is the third ancient text to emerge from the layers of writing on the much reused pages. In 2002 researchers had uncovered writings by the mathematician Archimedes and the fourth-century B.C. politician Hyperides.

Last year one of the pages was found to contain a famous work by Archimedes about buoyancy that had previously been known only from an incomplete Latin translation.

Project director William Noel, curator of manuscripts at the Walters Art Museum in Baltimore, Maryland, called the latest discovery a "sensational find."

The findings were presented today at a general meeting of the American Philosophical Society in Philadelphia, Pennsylvania.

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New 'super-Earth' found in space

The new planet is not much bigger than the Earth

Astronomers have found the most Earth-like planet outside our Solar System to date, a world which could have water running on its surface.

The planet orbits the faint star Gliese 581, which is 20.5 light-years away in the constellation Libra.

Scientists made the discovery using the Eso 3.6m Telescope in Chile.

They say the benign temperatures on the planet mean any water there could exist in liquid form, and this raises the chances it could also harbour life.

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Cosmic "Baby Picture" Marks Hubble's 17th Birthday

The wonders of astronomy meet the drama of modern art in this latest image from the Hubble Space Telescope.

The color-enhanced image, taken of the distant Carina Nebula, depicts the birth pangs of a dozen stars, as explosions send waves of superheated gases billowing through the southern constellation Carina.

The raucous stellar nursery makes a particularly fitting subject - scientists released the image today in honor of Hubble's anniversary, marking 17 years since the orbiting telescope was borne into space on the shuttle Discovery.

This painterly picture brings the total number of images that Hubble has taken since 1990 to nearly 500,000.

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Scientists Predict Next Solar Cycle Peak

The peak of the next sunspot cycle will come in late 2011 or early 2012 - potentially affecting airline flights, communications satellites and electrical transmissions. But forecasters can't agree on how intense it will be.

A 12-member panel charged with forecasting the solar cycle said Wednesday it is evenly split over whether the peak will be 90 sunspots or 140 sunspots.

The government's Space Environment Center in Boulder, Colo., tracks space weather and forecasts its changes, which can affect millions of dollars worth of activities such as oil drilling, car navigation systems and astronauts.

Half of the specialists predicted a moderately strong cycle of 140 sunspots expected to peak in October of 2011, while the rest called for a moderately weak cycle of 90 sunspots peaking in August of 2012.

"We're hoping to achieve a consensus sometime in the next six to 12 months," said Douglas Biesecker, a space environment center scientist who is chairman of the forecast panel.

An average solar cycle ranges from 75 to 155 sunspots.

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A Massive Explosion on the Sun

The footage, gathered by Hinode's Solar Optical Telescope (SOT) on Dec. 13, 2006, shows sunspot 930 unleashing a powerful X-class solar flare. It's one of the most detailed movies of a flare solar physicists have ever seen. The SOT has a resolution of 0.2 arcseconds or 0.00006 degrees. Putting those numbers into perspective, the telescope can see features on the sun as small as 90 miles wide from its orbit 93 million miles away.

But resolution is only part of the story. What makes Hinode truly special as a solar telescope "is its unique ability to see the sun's magnetic field," says John Davis, NASA's project scientist for Hinode at the Marshall Space Flight Center. It's an ability Hinode used to reveal the magnetic underpinnings of the Dec. 13th flare.

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Towering Mystery Fossil Was a 'Shroom With a View

At a time when the tallest trees stood just a few feet high, giant "mushrooms" towered over the landscape.

That's the finding being reported by new a paper appearing in the May issue of the journal Geology.

he study adds to the quest to solve a long-standing scientific puzzle: the true nature of a fossil that was the world's largest organism from about 420 million to 370 million years ago.

Called Prototaxites, the mystery life-form was first reported in 1859 based on samples found in Canada.

The ancient organism boasted trunks up to 24 feet (8 meters) high and as wide as three feet (one meter).

Prototaxites was widespread - its fossils are found all over the globe.

Lead study author Kevin Boyce, of the University of Chicago, said the unidentified monstrosity was a staple in textbooks while he was still in school.

"It's fun because it's kind of a classic specimen that people have worried about for a long time," Boyce said. "It's been an outstanding question for 150 years."

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Fibonacci spirals in nature could be stress-related

The Fibonacci sequence -- in which each successive number is the sum of its two preceding numbers -- regularly crops up in nature. It describes the number of petals around daisies, how the density of branches increases up a tree trunk, and how a pine cone's scales are arranged. Now, having performed "stress engineering" to create Fibonacci-sequence spirals on microstructures grown in the lab, physicists in China think they may have found the reason why the sequence is so ubiquitous -- with a little help from a seemingly unrelated physics problem posed over 100 years ago

Stress engineering can be used to create microstructures without using any high-precision patterning equipment. In the technique, a curved "core" material is coated with a different "shell" material at a high temperature. The composite is then cooled while carefully restricting the geometry, and because of difference in the thermal expansion of each material selective parts of the shell buckle under stress, causing patterns to form.

Light Sabers

Ireland: Text messages harm written language?

The rising popularity of text messaging on cell phones poses a threat to writing standards among Irish schoolchildren, an education commission says.

The frequency of errors in grammar and punctuation has become a serious concern, the State Examination Commission said in a report after reviewing last year's exam performance by 15-year-olds.

"The emergence of the mobile phone and the rise of text messaging as a popular means of communication would appear to have impacted on standards of writing as evidenced in the responses of candidates," the report said, according to Wednesday's Irish Times.