February 13, 2006, 11:23 PM CT

Mice Lacking Social Memory Molecule

The social avoidance that normally develops when a mouse repeatedly experiences defeat by a dominant animal disappears when it lacks a gene for a memory molecule in a brain circuit for social learning, researchers funded by the National Institutes of Health's (NIH) National Institute of Mental Health (NIMH) have discovered. Mice engineered to lack this memory molecule continued to welcome strangers in spite of repeated social defeat. Their unaltered peers subjected to the same hard knocks became confirmed loners - unless the scientists treated them with antidepressants.

"For both mice and men, social status is important; for mice, losing to a dominant mouse commonly means that they avoid the dominant and they avoid social situations," explained NIMH director Dr. Thomas Insel. "These new findings add to a growing literature on the molecular basis of social behavior, helping us to know where as well as how social information is encoded in the brain".

The results reveal neural mechanisms by which social learning is shaped by psychosocial experience and how antidepressants act in this particular brain circuit. They also suggest new strategies for treating mood disorders such as depression, social phobia and post-traumatic stress disorder, in which social withdrawal is a prominent symptom. Drs. Olivier Berton and Eric Nestler, University of Texas Southwestern Medical Center (UTSMC), and his colleagues, report on their study in the February 10, 2005 issue of Science.........

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February 12, 2006, 10:08 PM CT

Introduced Foxes Throw A Wrench In The Food Web

In an extensive study, scientists from the University of Montana, University of California - Santa Cruz, and the University of California - Davis have shown that a top predator strongly affected plants and animals at the bottom of an island food web by eating organisms that transport nutrients between ecosystems. "An introduced predator alters Aleutian island plant communities by thwarting nutrient subsidies," is reported in the recent issue of Ecological Monographs.

As any biologist can attest, cells, organelles, and organisms maintain specific surface to area ratios to ensure life. Similar relations have been observed in regard to an island's size and nutrient deposition. In a number of cases, a small island with a large perimeter touching the sea receives more nutrients from marine ecosystems than a large island due to the differences in surface-to-area ratios. In a new study by John Maron, James Estes, Donald Croll, Eric Danner, Sarah Elmendorf, and Stacey Bucklelew, researchers have discovered that the introduction of a top predator has even affected this system.

"Our results show that the ecological effects of fox introductions extended well beyond the direct reductions of bird populations. We have clear evidence that foxes influence the terrestrial plant community and ecosystem dynamics through one particular route," state the scientists in their study.........

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February 12, 2006, 9:58 PM CT

Dozens of New Species in the "Lost World"

An expedition to one of Asia's most isolated jungles - in the mist-shrouded Foja Mountains of western New Guinea - discovered a virtual ``Lost World" of new species, giant flowers, and rare wildlife that was unafraid of humans.

The December 2005 trip by a team of U.S., Indonesian, and Australian researchers led by Conservation International (CI) found dozens of new species including frogs, butterflies, plants, and an orange-faced honeyeater, the first new bird from the island of New Guinea in more than 60 years.

Conservation International and the Indonesian Institute of Science (LIPI) sponsored the expedition, with financial support from the Swift Foundation, the Gordon and Betty Moore Foundation, the National Geographic Society and the Global Environment Project Institute.

The team captured the first photos ever seen of exotic birds such as a male Berlepsch's Six-Wired Bird of Paradise (Parotia berlepschi). It also found a new large mammal for Indonesia - the Golden-mantled Tree Kangaroo (Dendrolagus pulcherrimus), formerly known from only a single mountain in neighboring Papua New Guinea.

"It's as close to the Garden of Eden as you're going to find on Earth," marveled Bruce Beehler, vice president of CI's Melanesia Center for Biodiversity Conservation and a co-leader of the expedition. "The first bird we saw at our camp was a new species. Large mammals that have been hunted to near extinction elsewhere were here in abundance. We were able to simply pick up two Long-Beaked Echidnas, a primitive egg-laying mammal that is little known".........

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February 9, 2006, 10:59 PM CT

Microbes Strengthen Inside Animals' Protozoa

In an animal research "first," disease-causing bacteria have been found to gain strength from interaction with single-celled organisms called protozoa that are naturally present inside animals. This finding suggests that the protozoa in animals' digestive tracts may be a place where dangerous bacteria can lurk and develop.

In studies at the Agricultural Research Service (ARS) National Animal Disease Center (NADC) in Ames, Iowa, veterinary medical officer Steven Carlson and microbiologist Mark Rasmussen discovered that an antibiotic-resistant strain of Salmonella becomes particularly virulent when tucked inside protozoa in the rumen, or first stomach, of cattle.

Until now, protozoa had never been thought of as reservoirs of disease in animals, as per Rasmussen.

The scientists set out to study the relationship between rumen protozoa and Salmonella's virulence and resistance to antibiotics. They focused on an S. enterica strain named DT104 that's a foodborne pathogen thought to bemore virulent than its antibiotic-sensitive counterparts.

In animals, salmonellosis is commonly a diarrheal disease that the animals recover from without requiring antimicrobial treatment. But antibiotics are needed when severe diarrhea or systemic infections occur. Unfortunately, a number of Salmonella strains have become resistant to a number of antibiotics, as per Carlson.........

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February 5, 2006, 10:55 PM CT

From Lions To Honey Badgers

It may still be "king of the beasts," but the African lion's kingdom is dwindling, as per a new report released by the New York-based Wildlife Conservation Society (WCS) that says these emblematic big cats have disappeared from 82 percent of their historic distribution over the past several decades. The 200-page report looked at the conservation status of the 20 largest species of African carnivores and examined priorities to help ensure that they persist on the continent.

WCS researchers ranked all 20 species using a variety of external factors, from the state of current knowledge on the species, to the threats facing each of them. They also looked at which areas in Africa have retained their full complement of large carnivore species and which areas need more conservation action.

Populations of the lion, listed in the report as "most vulnerable" have dropped steadily in recent decades, primarily due to conflicts with humans, destruction of habitat, and the loss of prey, as per the report. Also making the most-vulnerable list are cheetahs and African wild dogs, which have vanished from 75 and 89 percent of their historical habitat respectively, and Ethiopian wolves which have vanished from an astonishing 98 percent of their range. Other species of concern included the leopard, spotted hyena, and golden cat, all of which suffer from the combined key threats of habitat loss and conflict with people over predation on domestic animals.........

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February 2, 2006, 8:32 PM CT

Anthrax Toxins Harmful To Fruit Flies

Deadly and damaging toxins that allow anthrax to cause disease and death in mammals have similar toxic effects in fruit flies, as per a research studyconducted by biologists at the University of California, San Diego.

Their findings, which appear this week in an early online edition of the journal Proceedings of the National Academy of Sciences, show that fruit flies can be used to study the link between the biochemical activities and physiological effects of anthrax toxins.

Learning how these toxins attack developing and adult tissues is important because it can help researchers understand how they function at the molecular level and may lead to new therapeutic strategies for neutralizing their effects in humans.

Annabel Guichard, a biologist at UCSD and lead author of the study, tracked the ways that two active anthrax toxins, known as lethal factor, or LF, and edema factor, EF, cause cellular damage and death in the fruit fly Drosophila melanogaster. These toxins are mandatory for the anthrax bacterium Bacillus anthracis to evade the host immune system and cause disease.

Using a combination of biochemical, genetic and cell biological approaches, the biologists tested whether or not the anthrax toxins were active in living Drosophila and, if so, whether they acted in the same way as they do in humans. The biologists found that anthrax toxins do alter the same signaling pathways used for cell communication in fruit flies and humans.........

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January 31, 2006, 0:16 AM CT

Better Way To Scrub Milking Hardware

Scientists at Penn State have devised a novel way to clean and disinfect milking equipment, using little more than salt water. The new method could be a safer and cheaper alternative to conventional cleaning systems.

"Concentrated chemicals used in the conventional cleaning are stored on the farm and on contact, they can cause serious burns in the eyes and on skin," says Dr. Ali Demirci, associate professor of agricultural and biological engineering. And, he says the chemicals are also expensive.

Most farms across the United States use some form of mechanized system to milk cows. The set-up basically comprises a rubber-lined suction cup that milks the cow and transfers the milk to a central refrigerating tank, through a series of pipes.

At day's end, the whole system is cleaned in a four-step process: first the pipes are rinsed with warm water to remove the milk. Then they are flushed with a chlorinated detergent at high temperature to remove soils such as fat and protein deposits, and then with a weak acid to neutralize the detergent and remove mineral deposits.

Finally, the pipes have to be sanitized with an EPA-registered sanitizing agent before they can be used again.

Demirci and colleagues tried to clean the milk pipes using electrolyzed oxidizing water, as other scientists had shown its effectiveness in cleaning fresh produce, eggs, etc.........

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January 25, 2006, 9:41 PM CT

Ability To Capture Large Prey

Animal behaviorist Sean O'Donnell was having an afternoon cup of coffee when a giant earthworm exploded out of the leaf litter covering the jungle floor in an Ecuadorean nature preserve. The worm, later measured at nearly 16 inches long, was pursued by a column of hundreds of raiding army ants that quickly paralyzed or killed it.

That sighting, and another involving what turned out to be the same species of army ant feeding on the carcass of a snake, has led O'Donnell of the University of Washington and several colleagues to offer a new theory on the origin of cooperative hunting behavior in army ants, which are among the most socially complex animals known.

Writing in the current issue of the journal Biotropica, O'Donnell and biologists Michael Kaspari of the University of Oklahoma and John Lattke of Universidad Central de Venezuela, propose that mass cooperative food foraging, a key element in the behavior of army ants, may have begun as a way to subdue large prey.

The species that O'Donnell observed is called Cheliomyrmex andicola and it lives mainly underground in New World tropical rainforests. It had been previously identified, but little was known about its behavior or prey until the two chance encounters at the Tiputini Biodiversity Station, an ecological preserve in eastern Ecuador.........

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January 24, 2006, 4:19 PM CT

How Do Boxers Differ From Poodles?

As any dog lover knows, no two breeds are identical. Some dogs are perfect for sloppy kisses. Others make fierce guardians. Still others resemble tiny, fluffy toys. Now, two new studies by researchers at The Institute for Genomic Research (TIGR) and collaborators reveal the genomic differences beneath such canine characteristics.

In the recent issue of Genome Research -a special issue devoted to dog genomes-TIGR scientists Ewen Kirkness and Wei Wang compared the genome sequences of two dogs, a standard poodle and a boxer. Finding key genetic differences between the two dogs, the scientists went on to compare those telltale genetic variations in the genomes from nine additional dog breeds--beagle, Labrador retriever, German shepherd, Italian greyhound, English shepherd, Bedlington terrier, Portuguese water dog, Alaskan malamute, and rottweiler--and five genomes of wild canids (four types of wolves and a coyote).

"This work demonstrates a significant amount of variation that you can see between individual dogs at the genomic level," says Kirkness, lead investigator of the project, funded by TIGR. "That variation can now be exploited to study the differences between dogs, their diseases, development and behaviors." More broadly, Kirkness adds, the comparisons illustrate evolutionary influences that can shape mammalian genomes.........

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January 23, 2006, 6:46 PM CT

Relationship between ants and bacteria

Ants that tend and harvest gardens of fungus have a secret weapon against the parasites that invade their crops: antibiotic-producing bacteria that the insects harbor on their bodies.

Writing today in the journal Science, an international team led by UW-Madison bacteriologist Cameron Currie illustrates the intricate and ancient nature of this mutualistic relationship. The scientists found that the ants house the bacteria in specialized, highly adapted cavities and nourish them with glandular secretions-an indication that the ants, bacteria, fungus and parasites have likely been evolving together for tens of millions of years.

"Every ant species [that we have examined] has different, highly modified structures to support different types of bacteria," says Currie. "This indicates the ants have rapidly adapted to maintain the bacteria. It also indicates that the co-evolution between the bacteria and the ants, as well as the fungus and parasites, has been occurring since very early on, apparently for tens of millions of years."

Furthermore, Currie says, the fact that the species have coexisted for so long means there might be a mechanism in place to decrease the rate of antibiotic resistance - which could help address a significant problem facing modern medicine. "We can learn a lot about our own use of antibiotics from this system," he says.........

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