April 8, 2009, 5:24 AM CT

Studying migration of threatened whale sharks

Whale sharks -- giants of the fish world that strike terror only among tiny creatures like the plankton and krill they eat -- are imperiled by over-fishing of the species in parts of its ocean range.

That threat is underscored in a newly released study from geneticists led by Jennifer Schmidt, University of Illinois at Chicago associate professor of biological sciences, reported online April 7 in the journal PLoS One

Schmidt and her colleagues studied the DNA of 68 whale sharks from 11 locations across the Indian and Pacific Oceans and the Caribbean Sea -- an area that covers most of the shark's known range. Results showed little genetic variation between the populations, which indicates migration and interbreeding among far-flung populations of the big fish.

"Our data show that whale sharks found in different oceans are genetically quite similar, which means that animals move and interbreed between populations," said Schmidt. "From a conservation standpoint, it means that whale sharks in protected waters cannot be assumed to stay in those waters, but may move into areas where they appears to be in danger".

A tropical fish that can grow 50 feet or longer and weigh over 20 tons, a whale shark's range can span oceans. They do not breed until they are about 25 to 30 years old, so it will take a long time for the species to recover from recent population declines......... Posted by: Kelly      Read more         Source

April 8, 2009, 5:17 AM CT

Human impacts on coral reefs

Results of a newly released study shed light on how threats to the world's endangered coral reef ecosystems can be more effectively managed.

In the current issue of the journal Coral Reefs, authors Kimberly Selkoe and Benjamin Halpern, both of the National Center for Ecological Analysis and Synthesis (NCEAS) at the University of California at Santa Barbara, explain how maps of the Northwestern Hawaiian Islands (NWHI)--a vast area stretching across more than 1,200 miles of Pacific Ocean--can be used to make informed decisions about protecting the world's fragile coral reefs.

"Our maps of cumulative human impacts are a powerful tool for synthesizing and visualizing the state of the oceans," said Selkoe, who is also affiliated with Hawaii Institute of Marine Biology at the University of Hawaii.

"The maps can aid in zoning uses of the oceans in an informed way that maximizes commercial and societal benefits, while minimizing further cumulative impact".

President George W. Bush declared the Northwestern Hawaiian Islands a National Monument in 2006, "in part because it is one of the last places in the oceans that have not been heavily altered by human activities," said Halpern.

"Despite the islands' extreme isolation, however, humans are already significantly impacting this area," he said. "A number of of the key threats, such as those linked to climate change, are not mitigated with Monument designation"......... Posted by: Janet      Read more         Source

April 8, 2009, 5:15 AM CT

Switch one dietary poison for another

As the U.S. Southwest grew warmer between 18,700 and 10,000 years ago, juniper trees vanished from what is now the Mojave Desert, robbing woodrats of their favorite food.

Now biologists have narrowed the hunt for detoxification genes that let the rodents eat the toxic creosote bushes that replaced junipers.

"It was either eat it or move out," says biologist Denise Dearing of the University of Utah, main author of a paper detailing the results, published on-line on April 7, 2009, in the journal Molecular Ecology

"This is an excellent example of research that bridges the fields of ecology and physiology," says Mary Chamberlin, acting deputy division director of the National Science Foundation (NSF)'s Division of Integrative Organismal Systems, which funded the research.

"It underscores the importance of studying organismal biology in order to understand how animals may or may not adapt to changes in their ecosystems".

During the study, eight woodrats were captured from each of two western regions: the Mojave Desert and the cooler Great Basin. Rats from both areas were fed rabbit chow mixed with either creosote or juniper.

The researchers then scanned the rodents' genetic blueprints to look for active genes known as "biotransformation genes" because they produce liver enzymes to detoxify the poisons in creosote and the less-toxic juniper......... Posted by: Kelly      Read more         Source

April 6, 2009, 9:48 PM CT

The fragility of the world's coral reserve

A newly released study by scientists from UC Santa Barbara's National Center for Ecological Analysis and Synthesis (NCEAS) sheds light on how threats to the world's endangered coral reef ecosystems can be more effectively managed.

In a recent issue of the journal Coral Reefs, main authors Kimberly A. Selkoe and Benjamin S. Halpern, both of NCEAS, explain how their maps of the Northwestern Hawaiian Islands (NWHI) a vast area stretching over 1,200 miles can be used to make informed decisions about protecting the world's fragile reefs.

Coral reef ecosystems are at risk due to the direct and indirect effects of human activities. This study was designed to help natural resource managers make decisions on issues such as surveillance priorities, granting of permits for use, and discernment of which areas to monitor for climate change effects.

"Our maps of cumulative human impact are a powerful tool for synthesizing and visualizing the state of the oceans," said first author Selkoe, who is also affiliated with Hawaii Institute of Marine Biology at the University of Hawaii. "The maps can aid in strategically zoning uses of oceans in an informed way that maximizes commercial and societal benefits while minimizing further cumulative impact".

"President (George W.) Bush declared the Northwestern Hawaiian Islands a National Monument in 2006, in part because it is one of the last places in the oceans that have not been heavily altered by human activities," said Halpern. "Our maps of cumulative human impact on these islands show that, despite their extreme isolation, humans are already significantly impacting this special place, and that a number of of the key threats, such as those linked to climate change, are not mitigated with Monument designation. We must continue to act to protect these islands and coral atolls if we hope to preserve them for future generations"......... Posted by: Janet      Read more         Source

April 6, 2009, 9:32 PM CT

Male flower parts responsible for potent grapevine perfume

University of British Columbia researchers have traced the fragrant scent of grapevine flowers to pollen grains stored in the anthers, contrary to common perception that petals alone produce perfume.

While studying grapes used to produce Cabernet Sauvignon from the Okanagan region of British Columbia, scientists from UBC's Wine Research Centre and Michael Smith Laboratories identified a gene that produces and regulates fragrance from the vines' tiny clusters of green blossoms.

"This was a surprise in fundamental plant biology," says Joerg Bohlmann, a Distinguished University Scholar and professor in the Michael Smith Laboratories who directed the study. "This discovery gives us strong clues to the origin and evolution of fragrant flowers".

Details of the study are published in this week's Proceedings of the National Academy of Sciences Online Early Edition.

Researchers believe plants have evolved to produce perfume in order to attract specific types of pollinators while fending off herbivores and pathogens.

"If you ask people where the perfume of a flower comes from, they'll likely say the female parts or the petals," says Bohlmann. While flowers such as roses and snapdragons rely on their petals to produce perfume and attract insects, few other species have been so closely studied......... Posted by: Erica      Read more         Source

April 2, 2009, 5:21 AM CT

Sexy or Repulsive?

Butterflies seem able to both attract mates and ward off predators using different sides of their wings, as per new research by Yale University biologists.

Trying to find the balance between these two crucial behaviors is one of nature's oldest dilemmas, as per Jeffrey Oliver, a postdoctoral associate in Yale's Department of Ecology and Evolutionary Biology and main author on the study, which appears online today in the journal Proceedings of the Royal Society B: Biological Sciences.

"You want to be noticeable and desirable for mates, but other onlookers, including predators, are paying attention to those signals as well".

Oliver was interested in whether the eyespots on the upperside of butterflies' wings - specifically, those of bush brown butterflies - serve a different purpose than the ones on the underside. Ever since Darwin's time, biologists (including Darwin himself) have postulated whether the upperside patterns could be used to attract mates, while at the same time, those on the underside could help avoid predators.

Working with Yale biologist Antonia Monteiro, Oliver used new tools to put the old theory to the test. Using different evolutionary models, he observed that the eyespots on the upperside of the butterflies' wings appear to evolve much more quickly than those on the underside, meaning they appear and disappear frequently through the course of evolution. The result is consistent with the theory that these are used to attract mates, as signals used for sexual selection tend to evolve faster than others......... Posted by: Kelly      Read more         Source

April 2, 2009, 5:18 AM CT

The mysterious Green Glow of the Sea

A number of longtime sailors have been mesmerized by the dazzling displays of green light often seen below the ocean surface in tropical seas. Now scientists at Scripps Institution of Oceanography at UC San Diego have uncovered key clues about the bioluminescent worms that produce the green glow and the biological mechanisms behind their light production.

Marine fireworms use bioluminescence to attract suitors in an undersea mating ritual. Research conducted by Scripps marine biologists Dimitri Deheyn and Michael Latz reveals that the worms also may use the light as a defensive measure. The report, published as the cover story of the current issue of the journal Invertebrate Biology, provides insights into the function of fireworm bioluminescence and moves researchers closer to identifying the molecular basis of the light.

"This is another step toward understanding the biology of the bioluminescence in fireworms, and it also brings us closer to isolating the protein that produces the light," said Deheyn, a scientist in the Marine Biology Research Division at Scripps. "If we understand how it is possible to keep light so stable for such a long time, it would provide opportunities to use that protein or reaction in biomedical, bioengineering and other fields-the same way other proteins have been used"......... Posted by: Janet      Read more         Source

April 2, 2009, 5:07 AM CT

Tropical forest seed banks

Seeds of some tree species in the Panamanian tropical forest can survive for more than 30 years before germinating.

That is 10 times longer than most field botanists had believed.

Using the Lab's Center for Accelerator Mass Spectrometry to measure the amount of carbon 14 in seeds of the trees Croton billbergianus (Euphorbiaceae), Trema micrantha (Celtidaceae) and Zanthoxylum ekmannii ( Rutaceae), Lawrence Livermore National Laboratory scientist Tom Brown and University of Illinois at Urbana-Champaign colleague James Dalling observed that seeds survived in the soil for 38, 31 and 18 years, respectively.

Prior demographic studies of pioneer tree species showed that seed persistence (the ability to survive in soil, awaiting favorable conditions for germination) is short, lasting only for a few years at most.

But in the tropical forests of Barro Colorado Island (BCI), Panama, Brown and Dalling found the seeds of some pioneer trees remain viable for a number of years.

"This is part of nature that wasn't really what people in the field thought was going on," Brown said. "It turns out these seeds in soil just a few centimeters below the surface can survive a lot longer than anyone ever thought was possible".

To increase the probability of encountering "old" seeds, Brown and Dalling used data from a forest plot to target sites in the forest occupied 20 years previously by species they suspected were capable of long-term persistence......... Posted by: Erica      Read more         Source

March 31, 2009, 2:48 PM CT

Magnetic nano-'shepherds' organize cells

The power of magnetism may address a major problem facing bioengineers as they try to create new tissue -- getting human cells to not only form structures, but to stimulate the growth of blood vessels to nourish that growth.

A multidisciplinary team of researchers from Duke University, Case Western Reserve University and the University of Massachusetts, Amherst created an environment where magnetic particles suspended within a specialized solution act like molecular sheep dogs. In response to external magnetic fields, the shepherds nudge free-floating human cells to form chains which could potentially be integrated into approaches for creating human tissues and organs.

The cells not only naturally adhere to each other upon contact, the scientists said, but the aligned cellular configurations may promote or accelerate the creation and growth of tiny blood vessels.

"We have developed an exciting way of using magnetism to manipulate human cells floating freely in a solution containing magnetic nanoparticles" said Randall Erb, fourth-year graduate student in the laboratory of Benjamin Yellen, assistant professor of Mechanical Engineering and Materials Science, at Duke University's Pratt School of Engineering. "This new cell assembly process holds much promise for tissue engineering research and offers a novel way to organize cells in an inexpensive, easily accessible way"......... Posted by: Janet      Read more         Source

March 31, 2009, 5:14 AM CT

Why a chimp is so strong?

February's brutal chimpanzee attack, during which a pet chimp inflicted devastating injuries on a Connecticut woman, was a stark reminder that chimps are much stronger than humansas much as four-times stronger, some scientists believe. But what is it that makes our closest primate cousins so much stronger than we are? One possible explanation is that great apes simply have more powerful muscles. Indeed, biologists have uncovered differences in muscle architecture between chimpanzees and humans. But evolutionary biologist Alan Walker, a professor at Penn State University, thinks muscles may only be part of the story.

In an article to be reported in the recent issue of Current Anthropology, Walker argues that humans may lack the strength of chimps because our nervous systems exert more control over our muscles. Our fine motor control prevents great feats of strength, but allows us to perform delicate and uniquely human tasks.

Walker's hypothesis stems partly from a finding by primatologist Ann MacLarnon. MacLarnon showed that, relative to body mass, chimps have much less grey matter in their spinal cords than humans have. Spinal grey matter contains large numbers of motor neuronsnerves cells that connect to muscle fibers and regulate muscle movement.

More grey matter in humans means more motor neurons, Walker proposes. And having more motor neurons means more muscle control......... Posted by: Kelly      Read more         Source