Saturday, September 29, 2007

Birds Can "See" Earth's Magnetic Field


To find north, humans look to a compass. But birds may just need to open their eyes, a new study says.

Scientists already suspected birds' eyes contain molecules that are thought to sense Earth's magnetic field. In a new study, German researchers found that these molecules are linked to an area of the brain known to process visual information.

In that sense, "birds may see the magnetic field," said study lead author Dominik Heyers, a biologist at the University of Oldenburg.

Magnetic Orientation

Human-made compasses work by using Earth as an enormous magnet and orienting a tiny magnet attached to a needle to the planet's north and south poles.

Scientists have thought for years that migratory birds may use an internal compass to navigate between their nesting areas and wintering grounds, which can be separated by thousands of miles.

The new research helps explain how this natural compass may work.

Heyers and his colleagues injected migratory garden warblers with a special dye that can be traced as it travels along nerve fibers.

The team put one type of tracer dye into the eyes and another in a region of the brain called Cluster N, which is most active when birds orient themselves.

When the birds got their bearings, both tracers traveled to and met in the thalamus, a region in the middle of the brain responsible for vision.

"That shows there is direct linkage between the eye and Cluster N," Heyers said.

The finding strongly supports the hypothesis that migratory birds use their visual system to navigate using the magnetic field.

"The magnetic field or magnetic direction may be perceived as a dark or light spot which lies upon the normal visual field of the bird," Heyers said, "and which, of course, changes when the bird turns its head."

The study was published in a recent issue of the Public Library of Science journal PLoS ONE.

More Navigational Tools

Scientists not involved with the study said it is impressive and well done, but cautioned that there are more pieces to the puzzle of how birds navigate on their long migrations.

"An animal that has to migrate over great distances needs to have both a compass and a map," said Cordula Mora, a biologist who recently completed her postdoctoral research at the University of North Carolina, Chapel Hill.

Mora's work suggests that birds may use magnetic crystals in their beaks to sense the intensity of the magnetic field and thus glean information on their physical location.

"If you have a compass, you know where north, south, east, [and] west [are], but you don't know where you are, so you don't know where you should be going," she said.

Study author Heyers said "both [map and compass] systems may act in concert."

Robert Beason is a wildlife research biologist with the U.S. Department of Agriculture in Sandusky, Ohio, and an expert on bird navigation.

He noted that stars may also either fully or in part provide the birds with their visual bearing—not the magnetic field.

The next step is to figure out where all this information comes together in the bird brain, he noted.

"That's probably going to tell us where the navigation center for birds is," he said.

Thursday, September 27, 2007

"Ugly" Albino Ratfish Captured


This ghostly animal is a completely different kettle of fish.

The albino white-spotted ratfish caught this summer during a marine survey in Washington's Puget Sound is the first albino fish ever spotted by local scientists.

Ratfish, bottom-dwelling relatives of skates and stingrays, are usually brown with white spots that act as camouflage.

The fish probably owe their name to their exceptionally long tails and rodentlike teeth that crush up clams and other prey lurking in the mud.

"They're pretty ugly," John Reum, the University of Washington doctoral student who caught the fish, told the Associated Press news agency.

The foot-long (30-centimeter-long) pearly white female seen here had pale green eyes and was estimated to be about two or three years old—just an adolescent.

"This animal would stand out like a beacon," fisheries professor Ted Pietsch told the AP. "I don't know why it wasn't eaten long before."

But the rare creature's luck ran out—it died shortly after capture.

It now sparkles as the only albino specimen in the university's collection of 7.2 million fish.

New Artificial Reefs "Grow" From Mideast Peace Deal


In a rare example of Middle East cooperation, Israelis and Jordanians have joined together to create a string of artificial coral reefs in the Red Sea.

The international effort is meant to attract divers and snorkelers to artificial reefs to allow the area's damaged natural reefs to heal.

A high diversity of corals thrive in the Gulf of Aqaba, which lies at the northern end of the Red Sea and is bordered by both Israel and Jordan as well as Egypt and Saudia Arabia farther south.

These reefs draw tourists from around the world to the neighboring resort cities of Elat, Israel, and Al 'Aqabah, Jordan.

The tourism dollars are a boon to the region's economy, but an onslaught of snorkelers and divers has taken a damaging toll. Many of the reefs are literally dying, experts say.

Reefs on Jordan's coast, though still at risk, have so far suffered less from human pressures than those on the more heavily visited Israeli and Egyptian coast.

"There is increasing construction, industrial development, and tourism around the gulf. Elat and [Al ']Aqabah are fast-growing cities and pressure on the reefs is growing," said Fuad Al Horani of the Marine Science Station (MSS) in Al 'Aqabah.

MSS and a team from the Elat campus of Ben-Gurion University (BGU) are spearheading the reef construction.

A 1994 peace deal between Israel and Jordan mandated that the two countries work together on combating marine pollution, natural resources issues, and coastal reef protection in the gulf.

Researchers are also gathering critical data on these complex ecosystems, including coral survival rates and patterns as well as the effects of human behavior on reefs.

Reviving the Reef

Using cranes and large parachutes, the team has already sunk huge concrete structures, each weighing 4.2 tons, into water 19 to 22 feet (6 to 7 meters) deep. Before installation, corals were nursed in special tubes designed to fit in holes drilled into the artificial reef.

In September researchers aided by university students and Israeli schoolchildren glued the tubes across the surfaces of the irregularly shaped modular building blocks.

About 250 of the coral-filled tubes have already been planted on the reef, and more are in the works.

Inner areas of the new human-made reef are barred to prevent the entry of divers and encourage new coral growth and colonization by fish and other marine life.

"Usually when something bad happens to a protected marine area, you can only say, Okay, we lost a part of it," said Nadav Shashar, BGU's marine biologist and project supervisor.

"But here we are actually able to reclaim an area. This used to be a coral reef and it died. But now we can go back and build a new one."

Just two months after initial construction, more than 20 species of fish—along with invertebrates including corals, fan worms, and tunicates—have settled naturally on the reef.

Shashar anticipates the artificial structure will need between five and ten years to evolve into a viable reef ecosystem.

But fish populations will likely fully colonize the project within a year.

When completed, the project will include three reefs in Jordanian waters and two in Israel. But it is not intended to replace natural ecosystems.

Instead, the new reefs provide alternate dive areas and help in the reclamation of specific reefs.

Artificial vs. Natural

There are biological differences between natural and artificial reefs.

Natural reefs contain tiny ecosystems that are dependent on light and nutrients as well as sea current strengths and speeds, Al Horani of Jordan's MSS said.

Artificial reefs do not necessarily provide the physical infrastructures for these micro-ecosystems.

"We are trying to create different types of micro-ecosystems within the structures we are developing," Al Horani said. For instance, some surfaces are exposed to full sunlight, and others are more shaded.

Shashar of Israel's BGU intentionally designed the new reef in a way that does not mimic a natural reef, but rather provides an alternate habitat for rare species.

Similar Pressures

Natural reefs in the U.S.—including the Florida Keys and Hawaii—and the Bahamas are also facing dangerous pressures similar to those of the Gulf of Aqaba reefs.

Bob Leeworthy of the National Oceanic and Atmospheric Administration was not involved in the Gulf of Aqaba project.

He has worked on a Florida Keys artificial reef study that involved the intentional sinking of a decommissioned U.S. naval vessel.

Such projects can help save natural reefs by taking stress off them, he said.

"It was a win-win situation in the sense that total use—including scuba diving, snorkeling, glass-bottom boat rides, and fishing—increased while the use of the surrounding natural reefs declined," Leeworthy said.

Advertising the artificial reef site led to a direct increase in business traffic at local scuba outfitters, he added. Anecdotal information suggests that visitor interest in the artificial site remains steady today.

Both MSS's Al Horani and BGU's Shashar said relations between the Israeli and Jordanian team members are positive.

"We have common goals," Al Horani said.

"Without this kind of collaboration we can't really control the environmental factors that might negatively influence the Gulf of Aqaba."

Wednesday, September 26, 2007

Lethal Bacteria Turn Deadlier After Space Travel


Bacteria can change into more infectious and deadly organisms after a stint in space, a new experiment suggests.

A science experiment on board space shuttle Atlantis in 2006 included Salmonella typhimurium bacteria, which is often fatal in humans.

When the bacteria—which had been safely isolated from the space crew—returned to Earth, scientists injected them into mice.

They found the space-faring bacteria caused death quicker and more often than Earth-restricted organisms.

The findings are concerning for future astronauts who will embark on longer space missions farther away from Earth-based medical help, experts say.

Genetic Transformations

Cheryl Nickerson is an associate professor of microbiology at Arizona State University's Biodesign Institute and lead author of the study.

Nickerson wanted to see if space's low-gravity environment would affect Salmonella. Usually a culprit in food poisoning, the bacteria can cause vomiting, fever, diarrhea, and abdominal cramps. Most types of Salmonella, which can grow on most foods, are fatal in the elderly or young if left untreated.

When the bacteria returned to Earth, genetic sequencing showed that 167 genes and 73 proteins had been altered.

One protein, called Hfq, helped control more than a third of the altered genes. Hfq regulates RNA—the code of bacterial life—during stressful events. When activated, the protein previously had been shown to strengthen several types of pathogens.

An technique called scanning electron microscopy also showed some Salmonella were starting to form biofilms, a protective slime layer.

On Earth, biofilms can grow on ship hulls and clog pipes, costing industry billions of dollars. Biofilms also worsen some diseases and reduce the effectiveness of many antibiotics.
Nickerson and colleagues, whose study appears online in today's Proceedings of the National Academies of Sciences, have tested bacteria in a variety of harsh environments.

"In the last few decades, huge leaps of knowledge have been made when we test biology in extremes," she said.

"Situations where it is very hot, very acidic, or low oxygen have taught us an enormous amount about how cells respond to those environments, and from that we've made huge advances in biotech and bioengineering."

All About the Fluids

It's not lower gravity that makes bacteria deadlier in space.

The key environmental change is a mechanical force known as fluid shear, or the motion of fluid around a cell.

In human gastrointestinal tracts, this current slows down or even stops, creating an area of low fluid shear. These environments allow bacterial infections to flourish. Space is also a low-shear environment.

"Fluid shear ... is an environmental signal that had been overlooked for quite a while," Nickerson said.

That's because ground-based techniques can't replicate accurate fluid shear environments.

But in space, scientists can control fluid shear far better than in any Earth-based lab.

Deep Impact

By understanding the role of fluid shear on the evolution of disease-causing bacteria, scientists hope to offer better techniques to fight disease on Earth.

David Niesel, chair of microbiology and immunology at the University of Texas at Galveston, was not involved in the study.

"[The study] is a nice piece of work. It shows an increase in virulence in an animal model and a molecular mechanism that could account for that," he said.

"Anything we learn about how bacteria respond to new environments and their virulence mechanisms may help us understand how these organisms cause disease, and that gives us new opportunities to come up with therapeutics to combat disease on Earth."

Understanding how bacteria alter themselves in space will be especially important for future long-term missions, such as colonization of the Moon or a manned mission to Mars.

"What happens in microgravity at the cellular level is not really well understood," said Steve Maclean, a Canadian astronaut and crew member on the 2006 Atlantis shuttle that housed the experiment.

Since bacteria are always present inside humans, it is impossible to prevent any of the organisms from getting into the space shuttle.

"Given that bacteria survive better and our immune system is functioning at a lower level, does this increase your risk of infection?" Maclean said.

"It's something to think about before we go to Mars."

Tuesday, September 25, 2007

Dolphin "Chat Line" to Help Deaf Mom's Calf "Talk"


An underwater "chat line" may help stimulate communication development in an unborn dolphin—in ways the calf's mother, which is deaf, cannot.

Castaway, a pregnant Atlantic bottlenose dolphin, has been living at the Marine Mammal Conservancy (MMC) in Key Largo, Florida, since January, when she was found stranded in Vero Beach.

A battery of tests determined that the mother-to-be is profoundly deaf. Deafness can be fatal for dolphins in the wild. The animals rely on echolocation—the sending and receiving of sound waves—to socialize, find prey, and avoid predators.

"Dolphins live in a world of sound," said MMC president Robert Lingenfelser. "The inability to hear makes them blind, in a sense."

Scientists do not know what caused Castaway's deafness, but they doubt that the dolphin has been deaf since birth.

The bottlenose is about 27 years old. Researchers believe it is highly unlikely that she would have survived so long in the wild, even with help from her pod, if the dolphin had been deaf its entire life.

Concerns for Calf

Castaway's deafness could also hinder her ability to teach her calf vital developmental skills.

The first few months of life are the most critical for newborn dolphins to learn survival skills, Lingenfelser says.

To date, Castaway has only uttered a few sounds in a low-frequency monotone—a stark contrast to an average dolphin's steady stream of high-frequency chirps, squeaks, and clicks.

"Probably our biggest concern is that the calf will not develop the ability to communicate if the mother is not communicating," said Jill Borger-Richardson, director of research and education at Dolphins Plus, a Key Largo dolphin and marine mammal research and education facility.

Dolphins Plus scientists have consequently recorded several "conversations" of their hearing dolphins. Those recordings are now being played in Castaway's pen via underwater speakers to promote the fetal calf's communication development.

Underwater Chat Line

Once the calf is born, scientists plan to turn off the stereo and give Castaway the opportunity to communicate with her calf on her own.

If Castaway's verbal repertoire does not improve, staff will try opening up a live chat line between the dolphins at MMC and those at Dolphins Plus. Even then, success is not guaranteed.

"At the very least, [these efforts] might help the calf assimilate into its pod when it's moved to a new facility," Borger-Richardson said. "If it's not going to hurt them, we might as well give it a try."

Castaway has a mid-May due date. MMC scientists will monitor the bottlenose and her newborn calf for at least nine months before transporting the pair to another facility.

Given Castaway's deafness and her calf's potential developmental delays, neither dolphin will be released into the wild.

The World Map Master Baby Genius

Monday, September 24, 2007

'Lunar Ark' Proposed in Case of Deadly Impact on Earth


The moon should be developed as a sanctuary for civilization in case of a cataclysmic cosmic impact, according to an international team of experts.

NASA already has blueprints to create a permanent lunar outpost by the 2020s

But that plan should be expanded to include a way to preserve humanity's learning, culture, and technology if Earth is hit by a doomsday asteroid or comet, said Jim Burke of International Space University (ISU) in France.

Burke, once a project manager on some of the earliest American lunar landings, now heads an ISU study on surviving a collision with a near-Earth object.

An impact of the size that wiped out the dinosaurs hasn't happened since long before the rise of humans, he pointed out.

Yet scientists' expanding knowledge of asteroids and craters left throughout the solar system has created a consensus that Earth remains vulnerable to a civilization-crushing collision.

This calls for the creation of a space age Noah's ark, Burke said.

Lunar Ark

Humans are just beginning to send trinkets of technology and culture into space. NASA's recently launched Phoenix Mars Lander, for example, carries a mini-disc inscribed with stories, art, and music about Mars.

The Phoenix lander is a "precursor mission" in a decades-long project to transplant the essentials of humanity onto the moon and eventually Mars.

The International Space University team is now on a more ambitious mission: to start building a "lunar biological and historical archive," initially through robotic landings on the moon.

Laying the foundation for "rebuilding the terrestrial Internet, plus an Earth-moon extension of it, should be a priority," Burke said.

The founders of the group Alliance to Rescue Civilization (ARC) agreed that extending the Internet from the Earth to the moon could help avert a technological dark age following "nuclear war, acts of terrorism, plague, or asteroid collisions."

But the group also advocates creating a moon-based repository of Earth's life, complete with human-staffed facilities to "preserve backups of scientific and cultural achievements and of the species important to our civilization," said ARC's Robert Shapiro, a biochemist at New York University.

"In the event of a global catastrophe, the ARC facilities will be prepared to reintroduce lost technology, art, history, crops, livestock, and, if necessary, even human beings to the Earth," Shapiro said.

ARC hopes to finance the planned moon outpost into a lunar ark of recovery in part through donations from billionaire philanthropists.

"The establishment of an ARC sanctuary would for the first time provide a compelling purpose for the colonization of space."

If the international lunar outpost of the 2020s expands into a colony and then a city, "it is possible that a whole new phase in civilization may develop—the branching of history into one stream on Earth and another on the moon," ISU's Burke added.

This "dual-world expansion" could be within reach by the end of this century, he said.

"Look at the last century, when we went from the Wright brothers to the Apollo missions—along with man's great expansion of his understanding of the cosmos."

Plan B?

Kilian Engel, an instructor at the International Space University who is involved in post-doomsday research, said the lunar archive is actually Plan B.

"Plan A involves creating an international network of astronomers to scan space for asteroids and comets that might threaten Earth, a global task force to formulate a strategy to prevent impacts with the planet, and a new generation of spacecraft to carry out these missions," Engel said.

More awareness of the danger posed by asteroids and comets is now spreading across the United States and the world.

In 2005 Congress directed NASA to figure out how to survey space for threatening near-Earth objects, as well as how to develop spacecraft to deflect or shoot them out of space.

Yet NASA receives less than five million U.S. dollars per year to conduct this "Spaceguard Survey," which is aimed at finding near-Earth objects greater than 0.62 mile (a kilometer) in diameter.

NASA has reviewed options that range from building titanic space tugboats to nudge asteroids off a collision course with Earth to crashing "kinectic impactors" into an oncoming comet.

Nuke Option

In March 2007 researchers at NASA's Near-Earth Object Program released a report that said nuclear explosions are ten to a hundred times more effective in diverting killer asteroids than non-nuclear alternatives.

Even so, "30 to 80 percent of potentially hazardous near-Earth objects are in orbits that are beyond the capability of current or planned launch systems," the report said.

And even if NASA eventually develops a nuclear-tipped, anti-asteroid launch vehicle, rocketing hydrogen bombs into space "is prohibited by the Outer Space Treaty of 1967," ISU's Burke said.

That UN-brokered treaty prohibits the deployment of nuclear weapons in Earth orbit, in outer space, or on any other celestial body.

Yet as astronomers across the globe piece together predictions on potential asteroids of mass destruction, UN members could vote to amend the space treaty to prepare a nuclear response to such threats.

Sunday, September 23, 2007

Giant Bugs a Thing of the Past, Study Suggests


For the giant insects that roamed Earth 300 million years ago, there was something special in the air.

A higher concentration of oxygen in the atmosphere let dragonflies sometimes grow to the size of hawks, and some millipede-like bugs reached some six feet (two meters) in length, a new study suggests.

Now that the proportion of oxygen has decreased, however, bugs can't grow much larger than they do now, the authors write.

The reason: The bigger an insect, the bigger the proportion of its body devoted to its tracheal system, which functions like a lung but is far less efficient at large sizes.

"[The tracheal system] explains why they are small," said study co-author Jon Harrison, a professor of environmental physiology at Arizona State University. "It takes up all the room."

The study appears this week in the journal Proceedings of the National Academy of Sciences.

Bigger Bodies, Bigger Lungs

Scientists have long puzzled over why bugs once grew to gigantic proportions but are now among Earth's more diminutive creatures.

"There were hundreds of ideas to explain the small size, but none of them could be proven," said lead study author Alexander Kaiser, of Midwestern University's Department of Basic Sciences.

So Kaiser and colleagues decided to test the idea that it was it was an insect's respiratory system that limited its size by studying beetles and fruit flies.

The team looked at beetles by peering through their exoskeletons with new x-ray beam technology at Argonne National Laboratory in Illinois.

This allowed the scientists to see how much room was dedicated to the respiratory system among four species of darkling beetles ranging from 0.1 to 1.3 inches (3.2 to 33 millimeters) in length.

Insects carry oxygen to cells differently from humans. Instead of a single breathing tube, bugs have several pairs of holes known as spiracles along their bodies.

These holes connect to tubes called tracheae, which transport oxygen to cells and remove carbon dioxide.

The x-ray scans revealed that as beetles become larger, tracheae take up proportionally more room in their bodies because they need to be longer and wider to deliver enough oxygen. This, in turn, inhibits growth by crowding other organs.

The tracheae in the larger beetles took up 20 percent more room than in smaller beetles.

The area where the body and legs meet is particularly limiting, because that opening can only get so big, Harrison noted.

In the smallest beetle, tracheae take up 2 percent of the region, compared with 18 percent in the largest.

Using that information, Harrison estimated that the maximum beetle size under current oxygen levels would be about six inches (15 centimeters).

That coincides roughly with the largest known living beetle, the Titanic longhorn.

"This paper is really interesting in part because there is still a lot we don't know about how insects breathe," said Scott Kirkton, an assistant professor of biology at Union College in Schenectady, New York, who was not associated with the study.

Something in the Air

During the late Carboniferous period (354 to 290 million years ago), however, oxygen levels were much higher than they are now, partly because coal swamps that leaked the gas into the air were very common.

"Back then, there was 31 to 35 percent oxygen in the air," study lead author Kaiser said. "Now we have about 21 percent."

That meant insects needed smaller quantities of air to meet their oxygen demands, allowing the creatures to grow much larger.

"The tracheal diameter can be narrower and still deliver enough oxygen for a much larger insect," Kaiser said.

The team, though, is still trying to definitely show that this phenomenon explains why Carboniferous insects were so large.

Neither fruit flies nor beetles were around, or even had close relatives, during the Carboniferous, so the team hopes to extend its research to more ancient insects such as dragonflies, Kaiser said.

The scientists have already experimented with fruit flies in a lab at Arizona State, raising them in tanks with different levels of oxygen.

Under higher concentrations of oxygen the fruit flies definitely get bigger, Harrison said.

Life-Forms "Resurrected" After Millennia in Ice


Imagine sticking some bacteria in the freezer and taking them out millions of years later to find that they are still alive.

That would be similar to what happened recently, when scientists brought eight-million-year-old microbes back to life—simply by thawing them.

The ancient bacteria were found frozen in the world's oldest known tracts of ice, the debris-covered glaciers of Antarctica.

"We think that they were pretty much locked in a frozen, inanimate state for that period of time," said lead study author Kay Bidle, a marine microbiologist at Rutgers University in New Brunswick, New Jersey.

It's also possible that some of the microbes were capable of maintaining their metabolism within tiny droplets of water suspended in the ice, Bidle said.

Bidle and colleagues retrieved and revived two samples of bacteria from the glacial ice. The first was a hundred thousand years old, and the second was around eight million years old.

The eight-million-year-old bacteria were alive, but barely.

Their genes were severely damaged from long exposure to cosmic radiation, which is higher at Earth's poles.

The radiation bombarded the bacteria's DNA with high-energy particles, which broke apart the DNA's chemical bonds and hacked it into shorter pieces.

Big Bacterial Thaw

Most of the bacteria in the samples probably blew over from African deserts, said study co-author Paul Falkowski, a biochemist at Rutgers.

Once the bacteria landed on the glacier's snowy surface, they were compressed with the snow to form ice.

"These ices are literally gene banks," he added.

That's because bacteria are able to incorporate foreign DNA into their own genetic makeup in a process called horizontal gene transfer.

This gives bacteria a way to pick up new advantageous traits, which in turn speeds up their evolution.

Falkowski likens the Antarctic ice to a "genetic popsicle."

As glaciers and ice caps melt as a result of the current trend of global warming, vast amounts of bacterial genetic material might be flushed into the ocean.

"You basically have this mechanism by which you're freeing up encased DNA and microbes that may be viable," lead author Bidle said.

Scraps of bacterial DNA might get incorporated into today's marine microbes, or viable bacteria released from the ice might also grow and impact the ecosystem.

"How that's going to play out, we don't know," Bidle said. He and Falkowski plan to focus future work on how current ice melting impacts modern microbes' genetic diversity.

The study appears in this week's journal Proceedings of the National Academy of Sciences.

Meaning for Mars?
The finding also lends hope to the possibility that microbes could lie in a similar suspended state in ancient Martian ice.

But it also nixes the idea that life could hitch a ride on comets between solar systems.

"Each solar system is an island of life," Falkowski said. Microbes on comets would be exposed to lethal doses of cosmic radiation for millions of years during their journey, he said.

"Under those conditions you would be sterilizing comets."