October 11, 2007, 4:04 AM CT

Surprise in the organic orchard

The discovery was reported by a team of insect virologists and geneticists from the Agricultural Service Centre of Rhineland-Palatinate (DLR Rheinpfalz), the German Federal Biological Research Centre (BBA Darmstadt), the University of Hohenheim, and the Max Planck Institute for Chemical Ecology (MPICE Jena). Starting in 2005, codling moths collected from 13 organic orchards in southwest Gera number of were tested in the laboratory to confirm that the insects could tolerate granulovirus amounts more than a thousand times higher than previously. Genetic studies showed that the resistance could be transmitted from parents to offspring via one of the sex chromosomes - which helps to explain how the resistance increased so quickly.

The sex chromosomes in humans are called X and Y, with XX females and XY males. This is reversed in moths, where the sex chromosomes are called Z and W, with ZZ males and ZW females. The scientists observed that the gene for granulovirus resistance occurs on the Z chromosome. Female caterpillars need only a single copy of the resistance gene to be nearly 100,000 times less susceptible to granulovirus infection. They stay healthy and survive to reproduce, when most others have been killed.

Sons from matings between these highly resistant females and susceptible males carry a virus resistance gene on just one of their two Z chromosomes. "Our research has shown that such males can pupate normally if they encounter a low dose of the virus" reports Dr. Johannes Jehle of the DLR Rheinpfalz. They survive and pass on their resistance gene to the next generation. "In later generations, there are also males carrying the resistance gene on both Z chromosomes, and these can survive even higher virus concentrations" explains the leader of the research team......... Posted by: Erica      Read more         Source

October 10, 2007, 7:23 PM CT

Key Component In The Disease-fighting Process

Researchers have finally identified a key component in the disease-fighting process in plants that activates plant-wide defenses after a pathogen attack.

It has long been known that plants often develop a state of heightened resistance, called systemic acquired resistance, following pathogen infection; this phenomenon requires the movement of a signal from the infected leaf to uninfected parts of the plant. Until now, however, no one knew what that signal was.

Now, scientists at the Boyce Thompson Institute for Plant Research (BTI) have identified methyl salicylate (MeSA), an aspirin-like compound, as a signal that alerts a plant's immune system to shift into high gear. This research, which was funded by the National Science Foundation (NSF), is reported in the Oct. 5, 2007, issue of Science.

"Now that we have identified a signal that activates defenses throughout the plant, as well as the enzymes that regulate the level of this signal, we may be able to use genetic engineering to optimize a plant's ability to turn on those defenses," said Daniel F. Klessig of BTI, who heads the research team. "This approach could boost crop production and reduce the use of pesticides, which are potentially harmful to people and/or the environment".

Prior studies conducted by the BTI scientists and others had revealed that after a plant is attacked by a pathogen, it produces a disease-fighting hormone called salicylic acid (SA) at the infection site. Some of this SA activates defenses locally, and some of this SA is converted to MeSA, which is biologically inactive since it cannot induce immune responses......... Posted by: Erica      Read more         Source

October 10, 2007, 7:19 PM CT

Genetically Engineered Corn May Harm Stream Ecosystems

A new study indicates that a popular type of genetically engineered corn--called Bt corn--may damage the ecology of streams draining Bt corn fields in ways that have not been previously considered by regulators. The study, which was funded by the National Science Foundation, appears in the Oct. 8 edition of The Proceedings of the National Academy of Sciences.

This study provides the first evidence that toxins from Bt corn may travel long distances in streams and may harm stream insects that serve as food for fish. These results compound concerns about the ecological impacts of Bt corn raised by prior studies showing that corn-grown toxins harm beneficial insects living in the soil.

Licensed for use in 1996, Bt corn is engineered to produce a toxin that protects against pests, especially the European corn borer. Bt corn now accounts for approximately 35 percent of corn acreage in the U.S., and its use is increasing.

"As part of the licensing process for genetically modified crops, the U.S. Environmental Protection Agency (EPA) was responsible for testing and identifying potential environmental consequences from the planting of Bt corn," says Jennifer Tank, who is from the University of Notre Dame and is a member of the team studying Bt corn.

To fulfill this requirement, EPA completed studies that assumed that plant parts would remain in fields without being carried away by streams draining agricultural lands, says Tank. In addition, EPA only tested the impacts of Bt corn on small lake organisms that are typically used to test the impacts of chemicals on aquatic ecosystems......... Posted by: Erica      Read more         Source

October 10, 2007, 6:54 PM CT

Bat and mouse game

This image by MIT researchers, based on a computer model of a bat in flight, won first place in the Informational Graphics category of the 2007 International Science and Technology Visualization Challenge.

"When viewed in slow motion, bat flight is beautiful and complex. The goal of this illustration is to capture that beauty while also adding scientific merit," David J. Willis, a research scientist in the Department of Aeronautics and Astronautics, told Science magazine. The competition is sponsored by Science, published by the American Association for the Advancement of Science, and the National Science Foundation.

Willis created the winning image with Professor Jaime Peraire of aeronautics and astronautics and several colleagues from Brown University led by Professor Kenneth Breuer.

For the contest, illustrators, photographers, computer programmers, and graphics specialists from around the world were invited to submit visualizations that would intrigue, explain and educate. More than 200 entries were received from 23 countries, representing every continent except the Arctic and Antarctica.

"Breakthroughs in science and engineering are often portrayed in movies and literature as 'ah-ha!' moments. What these artists and communicators have given us are similar experiences, showing us how bats fly or how nicotine becomes physically addictive," said Jeff Nesbit, director of NSF's Office of Legislative and Public Affairs. "We look at their visualizations, and we understand"......... Posted by: Kelly      Read more         Source

October 10, 2007, 5:03 AM CT

Humans unknowing midwives for pregnant moose

When its time for moose to give birth in the Greater Yellowstone Ecosystem, they head to where it is safest from predators namely closer to people, as per a new study by the Wildlife Conservation Society. Reported in the Royal Societys journal Biology Letters, the study says that moose avoid predation of their calves by grizzly bears by moving closer to roads and other infrastructure previous to giving birth.

Wildlife Conservation Society scientists tracked both moose and bears, finding that pregnant moose in Greater Yellowstone have shifted their movements each year for the past decade about 125 meters closer to roads during calving season, specifically to avoid road-shy brown bears, which can prey heavily on moose calves.

Given that brown bears avoid areas within approximately 500 meters of roads in Yellowstone and elsewhere, moose mothers have apparently buffered against predation on offspring using roadside corridors, said Wildlife Conservation Society biologist Dr. Joel Berger, the studys author.

Berger also cited similar examples where prey species tend to use humans as cover from predation, including vervet monkeys in Kenya and axis deer in Nepal that avoiding big cats by staying close to ranger stations.

The studys results indicate that moose and other prey species find humans more non-malignant and hence move to humans for safety whereas predators do not because we humans tend to be less kind to predators, Berger added......... Posted by: Kelly      Read more         Source

October 8, 2007, 11:16 AM CT

Studying component parts of living cells

Carbon nanotubes (CNTs) have shown great potential for use as cellular probes. As nanopipes they can be used to transport liquids to or from cells and inject solutions or drugs directly into individual cells and individual organelles within the cells. In addition, because of the small diameters of the carbon nanotubes induce little damage to cells upon penetration. By making these probes able to sense within the cells, information about chemical interactions within the cells could be found. Surface-enhanced Raman Spectroscopy (SERS) has this capability.

A journal article just released on the nanotechnology website AZoNano examines making carbon nanotubes SERS active by functionalization with SERS active nanoparticles. This creates the possibility of extremely sensitive study and identification of components of cells. In addition, the nanotubes can be applied to a nanofluidic device where they can serve as an intercorrelation between a fluid reservoir and the cell, to both deliver and extract fluids. The effects of the fluids on the cells could be studied in situ.

The paper by Alia Sabur from Drexel University has been released as part of the open access journal, AZoJono*. The research observed that carbon nanotubes and nanopipes can be used as SERS probes by two different methods that achieved identical results. Combining these SERS active nanotubes with already existing nano-probing techniques could enable the study of cells with single-molecule sensitivity......... Posted by: Janet      Read more         Source

October 8, 2007, 11:15 AM CT

Fair Play in Chimpanzees

In the ultimatum game - which was developed by another German, Werner Güth, now at the Max Planck Institute for Economics in Jena - one person, the proposer, is given money by an experimenter. That proposer can then divide the "manna from heaven" with a second person, the responder. The responder is not powerless - if he accepts the division, both people take home the offered amounts. But if he rejects it, both get nothing. The fear of having an unfair offer rejected causes the proposer to make a fair offer. People typically make offers of close to 50%. Anything less is likely to be rejected. Sensitivity to unfair offers and a willingness to pay a cost to punish someone contradicts economic models of pure self-interest, and they have been claimed to be unique to humans.

In a study reported in Science on October 5th, the scientists confronted our closest living relatives, chimpanzees, to a simplified version of the ultimatum game. The proposer would propose an offer of raisins to the responder by partially pulling out a tray of raisins as far as he could. If the responder accepted the division of raisins, he would pull the tray the rest of the way and the two would be able eat. However, if the responder did not like what he saw, he would not pull the tray and neither of them would get anything to eat......... Posted by: Kelly      Read more         Source

October 8, 2007, 11:12 AM CT

Genes from the father forms new species

The two closely related bird species, the collared flycatcher and the pied flycatcher, can reproduce with each other, but the females are more strongly attracted to a male of their own species. This has been shown by an international research team directed by Anna Qvarnstrm at Uppsala University in todays Net edition of Science. They demonstrate that the gene for this sexual preference is found on the sex chromosome that is inherited from the father and that only females have a copy of. The discovery sheds new light on how new species are formed.

The formation of new species takes millions of years. It often happens when a population (group of individuals) is divided and separated geographically and then adapts to disparate environments over thousands of generations. For instance, the earths ice ages have led to many such population splits. But divided populations often come into contact with each other before they have had time to become entirely sexually isolated from each other. When individuals mate with each other from such split populations that have not quite become separate species, their offspring (so-called hybrids) often have limited viability.

Anna Qvarnstrms research team from Uppsala University in Sweden, working with scientists from Norway, the Czech Republic, the US, and Holland, have studied natural hybridization between two closely related bird species, the collared flycatcher and the pied flycatcher. The two flycatcher species (or quasi species) have come into contact with each other after having been separated during the last ice age. The question they addressed was whether the flycatchers will conclude the species formation that is under way and become entirely sexually isolated from each other or, instead, if they will meld into the same species again......... Posted by: Janet      Read more         Source

October 8, 2007, 11:10 AM CT

Fungus genome yielding answers

Why a pathogen is a pathogen may be answered as researchers study the recently mapped genetic makeup of a fungus that spawns the worst cereal grains disease known and also can produce toxins potentially fatal to people and livestock.

The fungus, which is particularly destructive to wheat and barley, has resulted in an estimated $10 billion in damage to U.S. crops over the past 10 years. The researchers who sequenced the fungus' genes said that the genome will help them discover what makes this particular pathogen so harmful, what triggers the process that spreads the fungus and why various fungi attack specific plants.

These investigations also may lead to producing plants that are completely resistant to the fungus Fusarium graminearum, something that hasn't been possible previously, said Jin-Rong Xu, a Purdue University molecular biologist. He is pinpointing which genes enable the fungus to cause the disease Fusarium head blight, or scab.

In a recent issue of the journal Science, Xu and an international scientific team reported that certain chromosomal regions in Fusarium graminearum appear to dictate plant and fungus molecular interactions that allow the fungus to contaminate crops and cause disease.

The scientists located all of the genes on the fungus' chromosomes and then determined the genes' chemical makeup, or sequence......... Posted by: Janet      Read more         Source

October 4, 2007, 5:10 AM CT

Crocodile Tears Are Real

When someone feigns sadness they "cry crocodile tears," a phrase that comes from an old myth that the animals cry while eating.

Now, a University of Florida researcher has concluded that crocodiles really do bawl while banqueting - but for physiological reasons rather than rascally reptilian remorse.

UF zoologist Kent Vliet observed and videotaped four captive caimans and three alligators, both close relatives of the crocodile, while eating on a spit of dry land at Florida's St. Augustine Alligator Farm Zoological Park.

He observed that five of the seven animals teared up as they tore into their food, with some of their eyes even frothing and bubbling.

"There are a lot of references in general literature to crocodiles feeding and crying, but it's almost entirely anecdotal," Vliet said. "And from the biological perspective there is quite a bit of confusion on the subject in the scientific literature, so we decided to take a closer look".

A paper about the research appears in the latest edition of the journal BioScience.

Vliet said he began the project after a call from D. Malcolm Shaner, a consultant in neurology at Kaiser Permanente, West Los Angeles, and an associate clinical professor of neurology at the University of California, Los Angeles......... Posted by: Kelly      Read more         Source