When a banana ripens, it turns yellow -- unless you look at it under a black light, in which case, it appears bright blue, a new study has found.
The banana's blue glow was discovered by scientists at the University of Innsbruck in Austria and Columbia University in New York, the first team to look for this phenomenon in bananas.
The researchers think the coloring is related to the degradation of chlorophyll that occurs as the banana ripens and could aid animals who eat bananas and can see in the ultraviolet range of the spectrum
Chlorophyll is the green pigment present in plants that allows them to obtain energy from light during photosynthesis .
As the banana ripens, the chlorophyll begins to break down -- a process called catabolism -- and the resulting products are concentrated in the banana peel.
Under ultraviolet light , more commonly known as black light, these breakdown products fluoresce, or glow, blue.
"Surprisingly, this blue luminescence has been entirely overlooked," said study team leader Bernhard Kräutler of the University of Innsbruck.
Before the team's discovery, detailed in the Oct. 10 early online edition of the journal Angewandte Chemie (German for "Applied Chemistry"), fluorescing chlorophyll catabolytes, or products of breakdown, had only been found in higher plants and were short-lived.
While the banana's blue glow does diminish as it ripens, its catabolytes are unusually long-lived.
This long duration could be due to one of the breakdown products identified in the banana peel by the team, which has a stabilizing effect and has never been seen before as a chlorophyll breakdown product.
Just why this degradation occurs differently in the banana fruit than other plants, even banana leaves, isn't completely known, but Kräutler has a couple hunches.
"In contrast to humans, many of the animals that eat bananas can see light in the UV range," he said. "The blue luminescence of the banana fruit could give them a distinct signal that the fruit is ripe."
Another possibility is that the chlorophyll breakdown products also serve a biological function for the banana, as the stable products could help keep the fruit viable for longer, Kräutler said.
One of the world's most valuable fossil beds has been rediscovered, having been forgotten during Victorian times.
Fossils recovered near Christian Malford in Wiltshire, England, caused a sensation when they were unearthed in 1840 because they were the first to include the flesh of Jurassic wildlife.
Phil Wilby, of the British Geological Survey, has now rediscovered the site and led the first dig there in more than 150 years. He hopes that freshly recovered fossils can help to explain why tens of thousands of animals died simultaneously in episodes repeated many times over about a million years.
Fossil hunters and academics flocked to the area in the 1840s and 1850s to dig out extraordinarily well-preserved specimens of fish and squid-like creatures. But despite its importance as an extremely rare source of fossilized soft tissues preserved along with hard bones and shells, the location of the site was lost.
Stress Can Make You Itch, Study Indicates
Stress has been found to activate the immune system in the skin of mice, causing them to itch. The same likely holds true for humans, researchers say.
Itching remains somewhat mysterious . It is similar to pain in how it develops and plays out in our bodies. Because the skin is on the front lines against infection, it is a place where white blood cells attack invading bacteria and viruses. The immune cells in skin can overreact, though, causing inflammatory skin diseases such as dermatitis and psoriasis. Stress is also known to increase odds of everything from the common cold to cancer. Researchers figured stress could exacerbate skin disease by increasing the number of immune cells in the skin.
To test the idea, they stressed out some mice. Indeed, more white blood cells were pumped into the skin. By blocking the function of two proteins that attract immune cells to the skin, called LFA-1 and ICAM-1, the scientists prevented the stress-induced increase in white blood cells in the skin. Taken together, these data suggest that stress activates immune cells, which in turn are central in initiating and perpetuating skin diseases, the researchers conclude in the November issue of the American Journal of Pathology.
The work, funded by the German Research Foundation, was led by Petra Arck of Charité of the University of Medicine Berlin and McMaster University in Canada.
Gala Party for Broken-Down 'Doomsday Machine'
The world's largest scientific machine may have malfunctioned soon after its spectacular start and still be out of action. But that didn't stop dignitaries, donors and diplomats from inaugurating the broken atom smasher Tuesday with pomp and pageantry. Taking particular pride was Robert Aymar, director general of CERN, the European Organization for Nuclear Research.
"When CERN chooses to be audacious, amazing things can happen," Aymar told government ministers, scientists and diplomats gathered for the event.
A 100-voice Welsh choir sang. An orchestra played. German Research Minister Annette Schavan proclaimed the inauguration of the ailing machine a great day for international science. The atom smasher -- called the Large Hadron Collider -- is the result of a project that began two decades ago. Parts of it were built in various countries around the world. Financial contributions came from the 20 member nations of CERN as well as Russia, Canada, India, Japan and the United States.
The purpose is to smash protons from hydrogen atoms together at high energy and record what particles come off the collisions, giving scientists a better idea of the makeup of the smallest components of everything in the universe, including the Earth and the human beings on it. Aymar conceded there was great disappointment the collider had been sidelined by an electrical problem within days of its startup Sept. 10. CERN has blamed the shutdown on the failure on a single, badly soldered electrical connection.
The damage will take much of the planned winter shutdown to repair. But the hope is the machine, which fires beams of protons at near the speed of light inside a 27-kilometer (17-mile) tunnel, can be back in action as planned next spring. Aymar said the machine would return to use after scientists have "made sure the LHC will not suffer such damage again."
"The LHC will profoundly change our view of the universe," he said.
Scientists have taken the setback in stride, stressing that particle colliders always have such problems in the startup phase and pointing to the LHC's unprecedented success in sending beams around in both directions within a few hours on the first day.
"Frankly it was a surprise that it worked the first time without a glitch," Raymond L. Orbach, U.S. undersecretary for science at the U.S. Department of Energy, told The Associated Press.
"I have no doubts they'll get back into operation within three to four months," said Arden L. Bement, director of the U.N. National Science Foundation, who attended the inauguration with Orbach. "The machine is pushing the frontiers of science in almost every system and subsystem. So there's been a lot of stretch and there's risk involved, but without the risk you can't really do the science."
The Large Hadron Collider is the biggest atom smasher ever built. Schavan said it will be at the center of the world's largest community of researchers -- some 9,000 scientists who plan to work on it.
The setback underscored the complexity of the US$10 billion collider, installed under the Swiss-French border on the outskirts of Geneva. Because the equipment operates at temperatures colder than outer space, it took a month to warm the damaged section enough for human beings to be able to look and work inside.
The massive electromagnets that guide the beam appear to have escaped damage, according to CERN spokesman James Gillies. But 29 of the magnets will likely have to be brought to the surface because insulation and other parts around them were damaged. The fault occurred nine days after the launch of the collider.
The organization performs maintenance during the winter, when the cost of electricity rises and makes it too expensive to run the machine. But scientists lost about two months of ironing the kinks out of the equipment so they could move more quickly toward collisions in the spring.
The collider, which CERN calls "the largest and most complex scientific instrument ever built," can make the collisions between atoms occur at energies seven times higher than ever before possible.
That will help scientists probe even deeper into the mysteries of matter, showing them on a tiny scale what happened one-trillionth of a second after the so-called Big Bang, which many scientists theorize was the massive explosion that formed the universe.
The theory holds that the universe was rapidly cooling at that stage and matter was changing rapidly. The collider uses superconductivity -- the ability of some metals to conduct electricity without any resistance in the extreme cold -- to operate the electromagnets at high efficiency to guide the beams of protons until they collide.
The failure was caused by an electrical arc that punctured an enclosure holding the liquid helium used to keep the collider cold, said a CERN statement. Some six tons of helium leaked out as a result.
The remaining 114 tons of liquid helium in the collider was unaffected by the leak, said Gillies.
The failure also sent "soot-like dust" into the firehose-size pipes through which the beams of protons are guided, he said. The pipes, which are supposed to be an extreme vacuum inside so that nothing will obstruct the proton beams, will have to be cleaned.
Physicists have used smaller, room-temperature colliders for decades to study the atom. They once thought protons and neutrons were the smallest components of the atom's nucleus, but the colliders showed that they are made of quarks and gluons and that there are other forces and particles. And they still have other questions about antimatter, dark matter and particle mass they hope they can answer with CERN's new collider.
Plans are now to put proton beams back into the collider by May or June, Gillies said.
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