March 12, 2007, 9:14 PM CT

Disease opened door to invading species

Plant and animal diseases can play a major and poorly appreciated role in allowing the invasion of exotic species, which in turn often threatens biodiversity, ecological function and the world economy, researchers say in a new report.

In particular, a plant pathogen appears to have opened the gate for the successful invasion of non-native grasses into much of California, one of the world's largest documented cases of invading species and one that dramatically changed the history and ecology of a vast grassland ecosystem.

The study, published recently in Proceedings of the National Academy of Sciences, a professional journal, should improve the understanding of invasive species and possibly suggest new tools to combat them, said researchers at Oregon State University.

"Even if we can't control all the diseases that help species invade, at least now we know to consider diseases when studying invasion," said Elizabeth Borer, an assistant professor of zoology at OSU. "In analyzing the ecology of exotic plant or animal species, it's clear that diseases are one part of the equation".

About 50,000 exotic species have been introduced into the United States, and the havoc they wreak upon agricultural crops, wildlife, ranch animals, forests and grasslands costs about $137 billion a year, scientists say. Invading species are also responsible for about half of all native species that go extinct, studies show......... Posted by: Ashley      Read more         Source

March 12, 2007, 9:07 PM CT

About Caribbean extinctions

Smithsonian scientists and colleagues report a new study that may shake up the way paleontologists think about how environmental change shapes life on Earth. The researchers summarized the environmental, ecological and evolutionary consequences for Caribbean shallow-water marine communities when the Isthmus of Panama was formed. They concluded that extinctions resulting when one ocean became two were delayed by 2 million years.

Researchers from the Smithsonian Tropical Research Institute, Scripps Institution of Oceanography and London's Natural History Museum report their study in the Proceedings of the National Academy of Sciences on March 12.

Three to 4 million years ago, the Isthmus of Panama land bridge rose to connect North and South America, and divided one vast ocean into two. In response, a major extinction of marine animals that had flourished under open seaway conditions occurred on the Caribbean side of the new Isthmus.

"We may be way off-track when we search for the causes of extinctions by looking only at the time the extinctions occur in the fossil record, which is what paleontologists normally do," said Aaron O'Dea, postdoctoral fellow at the Smithsonian Tropical Research Institute and Scripps Institution of Oceanography. "In our case, we see that most coral and snail species died off a good 2 million years after the environmental change that caused their demise"......... Posted by: William      Read more         Source

March 11, 2007, 8:43 PM CT

Magnetic Field In A Turbulent Fluid

Understanding the origin and behavior of the magnetic fields of planets and stars is the goal of research being carried out by a number of teams from all over the world. The VKS1 collaboration (CEA2, CNRS3,4, Ecole normale suprieure in Lyon3, Ecole normale suprieure in Paris4) has succeeded in creating in the laboratory a magnetic field in a highly turbulent flow of liquid sodium. Eventhough the extreme conditions specific to astrophysical and geophysical environments cannot all be reproduced in the laboratory, the magnetic field observed shows remarkable similarities with magnetic fields observed in the cosmos. The findings represent a significant advance in the understanding of the mechanisms at work in the formation of natural magnetic fields. They are published in Physical Review Letters dated 26 January 2007.

Most of the astrophysical objects which surround us (planets, stars and galaxies) have a magnetic field, whose origin is poorly understood. Such magnetic fields can play a major role in the evolution of various structures throughout the Universe. The Earth's magnetic field, which is very probably caused by the movement of liquid iron in the core, not only makes compass needles point north, but also protects us from the harmful effects of cosmic rays and the solar wind......... Posted by: Kevin      Read more         Source

March 11, 2007, 8:13 PM CT

These legs were made for fighting

Ape-like human ancestors known as australopiths maintained short legs for 2 million years because a squat physique and stance helped the males fight over access to females, a University of Utah study concludes.

"The old argument was that they retained short legs to help them climb trees that still were an important part of their habitat," says David Carrier, a professor of biology. "My argument is that they retained short legs because short legs helped them fight".

The study analyzed leg lengths and indicators of aggression in nine primate species, including human aborigines. It is in the recent issue of the journal Evolution.

Creatures in the genus Australopithecus immediate predecessors of the human genus Homo had heights of about 3 feet 9 inches for females and 4 feet 6 inches for males. They lived from 4 million to 2 million years ago.

"For that entire period, they had relatively short legs longer than chimps' legs but shorter than the legs of humans that came later," Carrier says.

"So the question is, why did australopiths retain short legs for 2 million years? Among experts on primates, the climbing hypothesis is the explanation. Mechanically, it makes sense. If you are walking on a branch high above the ground, stability is important because if you fall and you're big, you are going to die. Short legs would lower your center of mass and make you more stable"......... Posted by: William      Read more         Source

March 8, 2007, 8:03 AM CT

Hurricane Can Form New Eyewall

Hurricanes can gain or lose intensity with startling quickness, a phenomenon never more obvious than during the historic 2005 hurricane season that spawned the remarkably destructive Katrina and Rita.

Scientists flew through Rita, Katrina and other 2005 storms trying to unlock the key to intensity changes. Now, data from Rita is providing the first documented evidence that such intensity changes can be caused by clouds outside the wall of a hurricane's eye coming together to form a new eyewall.

"The comparison between Katrina and Rita will be interesting because we got excellent data from both storms. Rita was the one that showed the eyewall replacement," said Robert Houze Jr., a University of Washington atmospheric sciences professor and lead author of a paper detailing the work in the March 2 edition of the journal Science.

"The implication of our findings is that some new approaches to hurricane forecasting might be possible," he said.

Houze and Shuyi Chen, an associate professor of meteorology and physical oceanography at the University of Miami Rosenstiel School of Marine and Atmospheric Science, lead a scientific collaboration called the Hurricane Rainband and Intensity Change Experiment. The project is designed to reveal how the outer rainbands interact with a hurricane's eye to influence the storm's intensity. Chen is a co-author of the Science paper, as are Bradley Smull of the UW and Wen-Chau Lee and Michael Bell of the National Center for Atmospheric Research in Boulder, Colo......... Posted by: Tyler      Read more         Source

March 8, 2007, 7:58 AM CT

Exploring Earth's Deepest Sinkhole

Researchers return this week to the world's deepest known sinkhole, Cenote Zacaton in Mexico, to resume tests of a NASA-funded robot called DEPTHX, designed to survey and explore for life in one of Earth's most extreme regions and potentially in outer space.

If all goes well with this second round of testing and exploration, the team will return in May for a full-scale exploration of the Zacaton system.

Sinking more than 1,000 feet, Zacaton has only been partially mapped and its true depth remains unknown.

During eight years of research, doctoral student Marcus Gary and hydrogeology professor Jack Sharp from The University of Texas at Austin's Jackson School of Geosciences discovered the system's unusual hydrothermal nature is analogous to liquid oceans under the icy surface of Jupiter's moon Europa.

Technology developed to explore the sinkholes could be applied to future space probes of Europa, where researchers think that deep cracks and holes in the ice offer a chance of finding extraterrestrial life.

The technology could also be used to explore Earth's ice-bound polar lakes, which hold clues to the origins of life on Earth.

Microbes which appear to be new to science have been discovered floating in deep water and lining rocks in Zacaton. Far below sunlight's ability to penetrate, they may get their energy from nutrients welling up from hot springs. Gary and others speculate that previously undocumented life may await discovery in the murky depths......... Posted by: Tyler      Read more         Source

March 6, 2007, 3:55 PM CT

New Way to Fight Autoimmune Diseases

Multiple sclerosis, diabetes, and arthritis are among a variety of autoimmune diseases that are aggravated when one type of white blood cell, called the immune regulatory cell, malfunctions. In humans, one cause of this malfunction is when a mutation in a gene called FOXP3 disables the immune cells' ability to function. In a new study published online next week in the Proceedings of the National Academy of Sciences, researchers at the University of Pennsylvania School of Medicine have discovered how to modify enzymes that act on the FOXP3 protein, in turn making the regulatory immune cells work better. These findings have important implications for treating autoimmune-related diseases.

"We have uncovered a mechanism by which drugs could be developed to stabilize immune regulatory cells in order to fight autoimmune diseases," says senior author Mark Greene, MD, PhD, the John Eckman Professor of Pathology and Laboratory Medicine. "There's been little understanding about how the FOXP3 protein actually works." First author Bin Li, PhD, a research associate in the Greene lab has been working on elucidating this process since FOXP3's discovery almost five years ago.

Li discovered that the FOXP3 protein works via a complex set of enzymes. One set of those enzymes are called histone deacetylases, or HDACs. These enzymes are linked to the FOXP3 protein in association with another set of enzymes called histone acetyl transferases that modify the FOXP3 proteins......... Posted by: Sean      Read more         Source

March 6, 2007, 3:38 PM CT

Amazonian Basin Not Well-Populated

There's a scholarly debate brewing about whether pre-Columbian Amazonian populations settled in large numbers across Amazonia and created the modern forest setting that a number of conservationists take to be 'natural.'.

This view has become fashionable among a number of archaeologists and anthropologists, and is challenged in a recent paper from Dr. Mark Bush of the Florida Institute of Technology. The findings of Bush's research may rekindle a debate has major implications for land use and policy-setting in the rain forest.

"We don't contradict that there were major settlements in key areas flanking the Amazon Channel -- there could have been millions of people living there," says Mark Bush, a British-born paleo-ecologist who travels to extremely remote rain forest locations to collect core samples from ancient lakes. He then analyzes those samples for pollen and charcoal and thus is able to conclude with a high degree of accuracy the extent of human settlement in that region.

"What we do say is that when you start to look away from known settlements, you may see very long-term local use," he says. "These people didn't stray very far from home, or from local bodies of water for several thousands of years. We looked at clusters of lakes and landscapes where people lived, and asked, did they leave their homesite to farm around other nearby lakes? No they didn't. These findings argue for a very localized use of Amazonian forest resources outside the main, known, archaeological areas"......... Posted by: Tyler      Read more         Source

March 5, 2007, 10:05 PM CT

How buddies help alpha males get the girl

Why do some individuals sacrifice their own self-interest to help others? The evolution and maintenance of cooperative behavior is a classic puzzle in evolutionary biology. In some animal societies, cooperation occurs in close-knit family groups and kin selection explains apparently selfless behavior. Not so for the lance-tailed manakin. Males of this little tropical bird cooperate in spectacular courtship displays with unrelated partners, and the benefits of lending a helping wing may only come years down the line. Instead of fighting over females, pairs of male lance-tailed manakins team up to court prospective mates. Two males dance together for interested females, using tightly synchronized 'leapfrog' and flight displays to impress the opposite sex. But when the dance is over, only the dominant male, the alpha, gets the chance to mate. Emily DuVal, of UC Berkeley's Museum of Vertebrate Zoology, studied these birds to answer the question of why subordinate beta males cooperate. Starting in 1999, DuVal color-banded and observed wild lance-tailed manakins in Panam to follow changes in status over multiple years. Then she used genetic analyses to determine chicks' paternity and genetic relationships among adults.

The results of DuVal's work, would be published in the recent issue of The American Naturalist, showed that male partners were unrelated, and betas rarely sired chicks, ruling out two of the major hypotheses explaining males' cooperative behavior. Following males across years showed that betas became alphas more often than other males, but not necessarily at the same territory where they were betas. Even when the local alpha slot was empty, some betas moved to be helpers elsewhere rather than take over the vacant position. "Without being an alpha, there's essentially no chance for these males to reproduce," says DuVal. "My results suggest that betas could actually benefit from staying betas for a while, for example by gaining courtship skills during a sort of apprenticeship or by forming alliances with other males who later act as their betas." These results contrast with those from studies of other birds with cooperative courtship displays: wild turkeys strut cooperatively with close relatives, and ruffs (a shorebird) form alliances of males that often both mate while they are partners. These contrasts are interesting because they show that similar behavior can result from very different social and selective environments. DuVal is now a postdoctoral researcher at the Max Planck Institute for Ornithology, Germany, where she is investigating how female lance-tailed manakins choose their mates......... Posted by: Ashley      Read more         Source

March 5, 2007, 9:46 PM CT

BMI often not an accurate indicator of body fat

Body mass index, or BMI, long considered the standard for measuring the amount of fat in a person's body, may not be as accurate as originally thought, according to new research.

A research team from Michigan State University and Saginaw Valley State University measured the BMI of more than 400 college students - some of whom were athletes and some not - and found that in most cases the student's BMI did not accurately reflect his or her percentage of body fat.

The research is published in the recent issue of Medicine and Science in Sports and Exercise, the official journal of the American College of Sports Medicine.

BMI is determined by this equation: A person's weight divided by his or her height squared. Generally a BMI of 25 or above indicates a person is overweight; 30 or above indicates obesity. A person with a higher BMI is thought to be at a greater risk of heart disease, diabetes and other weight-related problems.

"The overlying issue is the same criteria for BMI are used across the board," said Joshua Ode, a Ph.D. student in the MSU Department of Kinesiology and an assistant professor of kinesiology at Saginaw Valley. "Whether you're an athlete or a 75-year-old man, all the same cut points are used".

"BMI should be used cautiously when classifying fatness, especially among college-age people," said Jim Pivarnik, an MSU professor of kinesiology and epidemiology. "It really doesn't do a good job of saying how fat a person really is"......... Posted by: Sean      Read more         Source