December 11, 2008, 10:35 PM CT

Missing: 2,000 elephants

Elephants in Zakouma National Park, the last stronghold for the savanna elephants of Central Africa's Sahel region, now hover at about 1,000 animals, down from an estimated 3,000 in 2006. Ivory poachers using automatic weapons have decimated elephant populations especially when herds venture seasonally outside of the park.

Civil unrest in has made conservation exceedingly difficult in Chad. Several park guards have been shot and killed in recent years. However, safety conditions have recently improved somewhat and WCS is optimistic that it can increase on-the-ground elephant conservation work in and around Zakouma to protect the remaining population.

"The situation in Zakouma is dire, but there is still time to save the park's remaining elephants provided we can marshal the forces we need to stop poaching," said WCS President and CEO Dr. Steven E. Sanderson. "We need to continue to work closely with Zakouma's dedicated park guards and give them what they need to do their jobs, while our own field staff provide aerial reconnaissance and technical support".

WCS has established a fund to help save Zakouma's surviving elephants. Members of the public can support this critical effort by going to: www.wcs.org/elephants.

History has shown that elephants can recover in Zakouma. Until this recent spate in poaching, elephant numbers have rebounded from an estimated 1,100 in 1985 to as a number of as 3,500 in early 2006......... Posted by: Kelly      Read more         Source

December 9, 2008, 10:31 PM CT

Secret Ingredient For The Health of Tropical Rainforests

A team of scientists led by Princeton University researchers has found for the first time that tropical rainforests, a vital part of the Earth's ecosystem, rely on the rare trace element molybdenum to capture the nitrogen fertilizer needed to support their wildly productive growth. Most of the nitrogen that supports the rapid, lush growth of rainforests comes from tiny bacteria that can turn nitrogen in the air into fertilizer in the soil.

Until now, researchers had thought that phosphorus was the key element supporting the prodigious expansion of rainforests, as per Lars Hedin, a professor of ecology and evolutionary biology at Princeton University who led the research. But an experiment testing the effects of various elements on test plots in lowland rainforests on the Gigante Peninsula in the Barro Colorado Nature Monument in Panama showed that areas treated with molybdenum withdrew more nitrogen from the atmosphere than other elements.

"We were surprised," said Hedin, who is also a professor in the Princeton Environmental Institute. "It's not what we were expecting".

The report, detailed in the Dec. 7 online edition of Nature Geoscience, will be the journal's cover story in its print edition.

Molybdenum, the team found, is essential for controlling the biological conversion of nitrogen in the atmosphere into natural soil nitrogen fertilizer, which in turn spurs plant growth. "Just like trace amounts of vitamins are essential for human health, this exceedingly rare trace metal is indispensable for the vital function of tropical rainforests in the larger Earth system," Hedin said. Molybdenum is 10,000 times less abundant than phosphorus and other major nutrients in these ecosystems......... Posted by: Erica      Read more         Source

December 9, 2008, 9:15 PM CT

Application quantifies carbon sequestration of urban trees

U.S. Forest Service researchers at the Center for Urban Forest Research are providing online software that can show users how much carbon dioxide an urban tree in California has sequestered in its lifetime and the past year.

The Tree Carbon Calculator is free and programmed in a Microsoft Excel spreadsheet that provides carbon-related information for a single tree in one of six California climate zones. It is the only tool approved by the California Climate Action Registry's Urban Forest Project Reporting Protocol for quantifying carbon dioxide sequestration from tree planting projects.

It can be found at the U.S. Forest Service Climate Change Resource Center Web site, http://www.fs.fed.us/ccrc/topics/urban-forests/.

In addition, the tool is available on the Center for Urban Forest Research Web site, http://www.fs.fed.us/psw/programs/cufr/.

Users enter information such as a tree's climate zone, species name, size or age. The program then estimates how much carbon dioxide the tree has sequestered in the past year and its lifetime. It also calculates the dry weight of the biomass that would be obtained if it were removed.

Trees planted near buildings to cut heating and cooling costs require additional inputs because they also reduce the greenhouse gases power plants emit while generating electricity. The Tree Carbon Calculator automatically calculates power plant reductions using emission factors for local utilities......... Posted by: Erica      Read more         Source

December 8, 2008, 10:13 PM CT

Why do some bird species lay only 1 egg?

Why do some species of birds lay only one egg in their nest, while others lay 10 or more?

A global study of the wide variation among birds in this trait, known as the "clutch size," now provides biologists with some answers. The study, reported in the current issue of the journal PLoS Biology, combined data on the clutch sizes of 5,290 species of birds with information on the biology and environment of each of these species.

"With this approach, we were able to explain a major proportion of the global variation in clutch size and also to predict with high confidence the average clutch size for types of birds living and breeding in certain environments," said Walter Jetz, an associate professor of biology at UC San Diego and the senior author of the study. "For example, cavity nesters, such as woodpeckers, have larger clutches than open-nesting species. And species in seasonal environments, particularly those living at northern latitudes, have larger clutches than tropical birds".

Clutch size in birds and reptiles has long been studied by biologists, who have found generally that species that are short-lived or have a low survival rate among their offspring tend to lay more eggs at one time to increase the chances of having surviving offspring. In contrast, longer-lived species or those with a higher survival rate among offspring tend to lay fewer eggs in their nests and invest more time and effort in raising their offspring. However, the reasons why one species of bird may lay one egg and another 10 are more complex because clutch sizes can vary widely between closely related species due to variations in their environment, nutrition, health and predation......... Posted by: Kelly      Read more         Source

December 6, 2008, 4:14 PM CT

Insight on wonder of cell division

Biologists have discovered a mechanism that is critical to cytokinesis -- nature's completion of mitosis, where a cell divides into two identical daughter cells.

The researchers have opened a new window on the assembly and activity of a ring of actin and myosin filaments that contract to pinch a cell at just the right time. They focused on key proteins whose roles drive signaling mechanisms that promote the production of both linear and branching microfilaments along the inside surface membrane of a dividing cell. By down-regulating the production of branched microfilaments at the right time, the membrane may be more malleable and better able to pinch inward and complete cytokinesis.

The findings-- detailed in the Dec. 5 issue of the journal Science -- come from basic research using Caenorhabditis elegans (roundworm) embryos. The discovery provides more basic insight than immediate biomedical application, but the implications could lead to a fine-tuning of anti-cancer drug therapies or to isolating new targets for drugs to stop cancerous cell division, said Bruce Bowerman, professor of biology in the University of Oregon's Institute for Molecular Biology.

Bowerman and Karen Oegema of the Ludwig Institute for Cancer Research at the University of California, San Diego, were principal scientists of a seven-member team funded by the National Institutes of Health......... Posted by: Janet      Read more         Source

December 1, 2008, 6:36 PM CT

Gaps in adhesion

Chemists can learn from some shellfish. Mussels, for example, produce an adhesive that sticks strongly to metal and stone, even under water. Chemists have reproduced the protein responsible for this in a synthetic material that contains the same adhesive elements. Irrespective of whether the adhesive is completely made up of these elements or whether they represent just a tenth of its make-up, adhesion is equally good. These findings were made by scientists at the Max Planck Institute for Polymer Research and at the Johannes Gutenberg University in Mainz. It might be possible to use the 90% of the polymers that are not necessary to create a good bond for other functions by providing them with chemical adjuncts which will allow them to adhere to surfaces other than metal or stone.

Some shellfish have a hard life: when they settle at the bottom of the sea close to the coast, the constant surging to and fro of the surf pulls at them. So that they are not washed away by the waves, the shellfish use special proteins to attach themselves firmly to a foundation - an ability that engineers still find difficult to achieve: adhesion under water. The shellfish can do this thanks to the amino acid dihydroxyphenylalanine, also known as dopa. Its chemical structure allows it to form very stable bonds with metals and minerals and is contained in the adhesion proteins with which shellfish attach themselves to the sea bed......... Posted by: Kelly      Read more         Source

December 1, 2008, 6:19 PM CT

Endangered sawfish focus of national collection

The University of Florida, keeper of the world's shark attack records, is also now overseeing a national records collection for another toothy marine predator: the sawfish.

Distinguished by a long rostrum or "saw" that makes it a popular curio item and gives it its name, the sawfish has become a historical and cultural icon that is rapidly disappearing, said George Burgess, a UF ichthyologist and curator of both the International Shark Attack File and the newly expanded National Sawfish Encounter Database.

"Postcards from the turn of the 20th century often depicted this so-called monster that inhabited Florida waters, and if one goes back and looks at newspaper accounts from places outside Florida, every time a sawfish was caught it made the papers," he said. "Today, it's difficult to find a bar in South Florida that doesn't have a sawfish 'saw' hanging on the wall".

An important part of Florida's fauna, the sawfish once swam in bays, lagoons and rivers extending from New York to the Rio Grande, Burgess said. Today, its American range has shrunk to Florida and its declining numbers have made it the first species of marine fish to be placed on the list of federally endangered species, he said.

Burgess and a team of researchers at the Florida Museum of History on the UF campus plan to use information from the sawfish database to further enhance a management plan developed to help speed the species' recovery......... Posted by: Kelly      Read more         Source

November 27, 2008, 5:28 AM CT

Land iguanas under continuing threat

The Galpagos Islands, which provided impetus and inspiration for Charles Darwin's seminal work, "On the Origin of Species", are home to unique populations of reptiles. Since the time of man's first visit in the 16th century to this crucial incubator for evolutionary theory, the islands' native plants and animals have faced grave challenges, including severe pressures from introduced species, habitat destruction and predation by man himself.

In some instances, this has led to reduced populations and even extinction. In the 20th century, conservation efforts began, but as per new research published this week in the scientific journal Molecular Ecology considerably more must be done to insure the long-term survival of land-dwelling iguanas on the archipelago.

In their new article, "Galapagos Land Iguanas Remnant Populations," an international coalition of scientists, led by Michel Milinkovitch, from the University of Geneva, Switzerland, detail their near-decade-long effort to assess the population genetics of land iguanas on the six islands where the reptiles occur today.

Population genetics is a cornerstone of modern evolutionary synthesis. It employs principles of molecular genetics and sophisticated data analysis to identify populations and characterize the genetic diversity within and the levels of genetic differentiation among these evolutionarily significant groups. Changes are influenced by the evolutionary forces of natural selection, genetic drift, mutation and gene flow. Researchers obtain blood or tissue samples from subjects and examine multiple loci across their genome. In so doing, scientists are able to draw conclusions regarding relationships, genetic diversity and genetic drift among various populations......... Posted by: Kelly      Read more         Source

November 27, 2008, 5:13 AM CT

Humpback whales' dining habits

As most American families sit down to Thanksgiving dinner, a University of British Columbia researcher is revealing how one of the largest animals on earth feasts on the smallest of prey and at what cost.

Some large marine mammals are known for their extraordinarily long dive times. Elephant seals, for example, can stay underwater for an hour at a time by lowering their heartbeat and storing large amounts of oxygen in their muscles.

"Weighing up to 40 tons, humpback whales and their close relatives have relatively short dive times given their large body size," says UBC zoology PhD candidate Jeremy Goldbogen, whose study is featured on the cover of the current issue of The Journal of Experimental Biology "Our study suggests that this has to do with the enormous energy costs of its unique foraging behaviours".

Humpbacks belong to a group of whales called rorquals that includes the fin whale and the blue whale, the largest animal that has ever lived. Characterized by an accordion-like blubber layer that goes from the snout to the naval, these whales take deep dives in search of dense patches of tiny zooplankton, such as krill or copepods.

While foraging, the whales literally drop their jaws during a high-speed dive called a lunge creating enormous drag akin to a race car driver opening a parachute. The drag forces the blubber to expand around a large volume of prey-laden water, which is then filtered out through a comb-like structure called baleen when the mouth closes......... Posted by: Kelly      Read more         Source

November 25, 2008, 10:25 PM CT

Synthetic virus supports a bat origin for SARS

SARS severe acute respiratory syndrome alarmed the world five years ago as the first global pandemic of the 21st century. The coronavirus (SARS-CoV) that sickened more than 8,000 people and killed nearly 800 of them may have originated in bats, but the actual animal source is not known.

In an effort to understand how SARS-CoV may have jumped from bats to humans, a team of researchers from Vanderbilt University Medical Center and the University of North Carolina at Chapel Hill has now generated a synthetic SARS-like bat coronavirus. The virus the largest replicating synthetic organism ever made is infectious in cultured cells and mice, the scientists report in the Proceedings of the National Academy of Sciences

The findings identify pathways by which a bat coronavirus may have adapted to infect humans. The studies also provide a model approach for rapid identification, analysis and public health responses to future natural or intentional virus epidemics.

Zoonotic viruses animal pathogens that can cause disease in humans pose a serious threat to public health, said Mark Denison, M.D., professor of Pediatrics at Vanderbilt and a co-leader of the research with Ralph Baric, Ph.D., professor of Epidemiology at UNC.

"It's becoming more and more clear that new human epidemics will continue to originate in animals," said Denison, who is also an associate professor of Microbiology & Immunology. "However, the mechanisms of trans-species movement and adaptation of viruses from animals to humans remain poorly understood"......... Posted by: Kelly      Read more         Source