Thursday, July 16, 2009

VIRUS-RESISTANT GRAPEVINES

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A good wine needs to ripen. But it's a long way to the barrel. Even before the harvest, the grapevines have to overcome all kinds of obstacles. Extremely hot or rainy periods can destroy entire crops, not to mention the wide variety of pests that can appear on the scene. Bugs such as the vine louse or the rust mite, fungi such as mildew, or viruses such as the "Grapevine fanleaf virus" (GFLV for short) can give the vines a hard time. The GFLV infects the grapevine and causes fanleaf disease, resulting in deformed and very yellowed leaves, smaller grapes and crop loss.

However, there will soon be a cure for GFLV infections: Researchers at the Fraunhofer Institute for Molecular Biology and Applied Ecology IME in Aachen are making certain plants resistant to the GFLV by genetic engineering. "Our modified plants produce antibodies," explains Dr. Stefan Schillberg, head of department at the IME. "These antibodies 'recognize' the viruses and prevent them from spreading in the plant and causing damage." To enable the plant to produce the antibodies, the scientists have to modify its genotype and channel genetic information for the antibodies into it. This task is performed by tiny helpers called agrobacteria, which genetic engineers have been using for over twenty years. These are soil bacteria that inherently transfer parts of their own genome to that of the plant. Using simple routine processes, the researchers introduce the antibody gene into the bacteria, which then act as a transport vehicle and carry it over to the vine.

The researchers are still testing this process on model plants, and the first results show that their modified versions are up to 100 percent resistant to the virus. "The antibody is produced very effectively inside the plants," says Schillberg. "The next step on the agenda is to test the method on actual grapevines and then to carry out field tests." The scientists' long-term goal is to curb the use of pesticides. "Certain pesticides are necessary to fight GFLV infections," Schillberg explains. But they often only have a limited effect. They are also harmful to the environment and therefore banned in many regions. Countries like Chile, for example, which depend strongly on their winegrowing business, could benefit enormously from the pathogen-resistant grapevines and improve their crop yields.

(Photo: Fraunhofer IME)

Fraunhofer-Gesellschaft

DESERT RHUBARB -- A SELF-IRRIGATING PLANT

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Researchers from the Department of Science Education-Biology at the University of Haifa-Oranim have managed to make out the "self-irrigating" mechanism of the desert rhubarb, which enables it to harvest 16 times the amount of water than otherwise expected for a plant in this region based on the quantities of rain in the desert. This is the first example of a self-irrigating plant worldwide.

The desert rhubarb grows in the mountains of Israel's Negev desert, where average precipitation is particularly low (75 mm per year). Unlike most of the other desert plant species, which have small leaves so as to minimize moisture loss, this plant is unique in that its leaves are particularly large; each plant's rosette of one to four leaves reaches a total diameter of up to one meter. Prof. Simcha Lev-Yadun, Prof. Gidi Ne'eman and Prof. Gadi Katzir came across this unique plant growing in the desert while studying the field area with students of the Department of Science Education-Biology of the University of Haifa-Oranim, and noticed that its leaves are unusually large and covered with a waxy cuticle. They observed an exceptionally ridged structure on each leaf, forming a leaf structure that resembles the habitat's mountainous topography.

The scientists explained that these deep and wide depressions in the leaves create a "channeling" mountain-like system by which the rain water is channeled toward the ground surrounding the plant's deep root. Other desert plants simply suffice with the rain water that penetrates the ground in its immediate surroundings.

The findings have shown that the natural selection process has resulted in the evolution of this plant's extremely large leaves, which improved its ability to survive in the arid climate of the desert. The results of experiments and analysis of the plant's growth - in an area with an average annual rainfall of 75 mm - showed that the desert rhubarb is able to harvest quantities of water that are closer to that of Mediterranean plants, reaching up to 426 mm per year. This is 16 times the amount of water harvested by the small-leafed plants of the Negev desert region. When the research team watered the plant artificially, they observed how the water flows along the course of the leave's depressed veins to the ground surrounding the plant's single root and then penetrates the ground to a depth of 10 cm or more. Under the experimental conditions, water penetrated the ground only as deep as 1 cm.

"We know of no other plant in the deserts of the world that functions in this manner," the researchers concluded.

(Photo: Prof. Gidi Ne'eman, University of Haifa)

University of Haifa

SUPER-SLEEPERS COULD HELP SUPER-SIZERS!

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Many species of animals go through a period of torpor to conserve energy when resources are scarce. But when it comes to switching to energy-saving mode, the champion by far among vertebrates is the burrowing frog (Cyclorana alboguttata), which can survive for several years buried in the mud in the absence of any food or water. How do they accomplish this feat?

A team of scientists at the University of Queensland have discovered that the metabolism of their cells changes radically during the dormancy period allowing the frogs to maximise the use of their limited energy resources without ever running on empty. This discovery could prove to have important medical applications in the long term. "It could potentially be useful in the treatment of energy-related disorders such as obesity", explains Ms. Sara Kayes.

When the operation efficiency of the mitochondria, the tiny "power plants" of the cell, was measured during the dormancy period, it was found to be significantly higher compared to that observed in active animals. This trick , known as mitochondrial coupling, allows these frogs to be extremely efficient in the use of the limited energy stores they have by increasing the total amount of energy obtained per unit consumed, allowing them to easily outperform other species whose energy production efficiency remains essentially the same even when they happen to be inactive for extended periods.

If this is such an efficient way to use energy resources during dormancy, how come that it is not more widespread in the animal kingdom? The researchers speculate that a potential drawback may be the increased production of reactive oxygen species, which may in turn lead to oxidative stress. Since these small molecules are believed to cause most of the damage during periods of re-awakening, increasing mitochondrial coupling does not seem to be a particularly good idea for animals that tend to exhibit short periods of spontaneous arousal during the dormancy period, in some cases even daily. Burrowing frogs, on the other hand, are believed to remain deeply asleep during the entire period of dormancy. Furthermore, being cold-blooded, they don't have the need to maintain a basal level of heat production, minimizing their energy needs.

(Photo: Sara M. Kayes)

Society for Experimental Biology

WHAT MAKES A GREAT FOOTBALLER?

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While most fans are in awe of what their football heroes can do with a football, the source of their remarkable skill remains strangely mysterious. Although being in excellent physical condition undoubtedly helps, few people actually believe that intense physical training alone can turn an average bloke into a Ronaldo. Now, scientists from the University of Queensland have decided to study what this "something else" might

Dr. Robbie Wilson believes that this type of research may have applied outcomes for football clubs: "Our analyses suggest that unambiguous metrics of a player's skill components should be used to help in the selection and identification of new talent. Our studies could help to streamline selection criteria and efficiency by providing a rank ordering of individuals based upon competitive one-on-one tasks. In addition, the relative importance of each type of skill component could be tailored to each player's position and the club's immediate and future requirements."

Members of the semi-professional University of Queensland Football Club (UQFC) were recruited as experimental subjects, and they were made to compete against each other in one-on-one "football tennis" games, which require very similar athletic and skill sets to that required for regular football games. In parallel, the same players were evaluated for overall athleticism and skill in sixteen different tasks. "There was no evidence of any correlations between maximal athletic performance and skill", explains Dr. Wilson. "Our studies suggest that skill is just as important, if not more important, than athletic ability in determining performance of complex traits, such as performance on the football field".

Interestingly, the researchers are hoping that focusing on footballing ability in humans will also provide them with insight into the role that individual skills play in other species, for example during aggression, prey capture or escape from a predator. Dr. Wilson argues that the importance of skill for the evolution of vertebrate physical performance is currently unknown and largely treated by researchers as a difficult 'black box' to understand. "To develop an understanding of the evolution and function of complex performance traits, we need to investigate the role of individual skill".

Society for Experimental Biology

TRIANGLES GO UNDERWATER AND SUPERSONIC

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The first study to systematically compare the hydrodynamic properties of the flippers of several kinds of dolphins, porpoises and whales has concluded that the swept back, triangular flippers help the animal move efficiently through the water in much the same way that the jet’s delta wings provide lift in the air.

The study was carried out by Duke University engineers and researchers from the U.S. Naval Academy and West Chester University.

By creating models based on real flippers and testing them in water tunnels, the researchers were able to calculate the characteristics of flippers from seven different animals – Amazon River dolphin, striped dolphin, harbor porpoise, Atlantic white-sided dolphin, bottlenose dolphin, common dolphin and pygmy sperm whale.

“We found that flippers of similar shape had similar hydrodynamic performance properties,” said Paul Weber, a graduate student in mechanical engineering and materials science at Duke’s Pratt School of Engineering. He, and senior researcher Laurens Howle, Duke associate professor of mechanical engineering and materials science, reported the results of their experiments in the June 26 issue of the Journal of Experimental Biology.

The researchers focused on two important forces experienced by flippers during movement – lift and drag. Lift is the upward force exerted on the flipper, while drag is the rearward force.

For their experiments, the researchers collected flippers from dead, stranded animals and performed complete computed tomography (CT) scans on them. Using computer software developed at Duke, the researchers turned the CT data into 3-D renderings, which became the basis for the creation of scale-model flippers.

“The CT scans allowed us to recreate as closely as possible the shape, structure and surface of the each of the flippers,” Weber said.

After categorizing each flipper as either triangular, swept-pointed, or swept-rounded, the scale models were put through their paces in water tunnels at the Naval Academy in Annapolis, Md. The researchers measured the hydrodynamic forces as the flippers’ orientation and water speeds were changed.

When the researchers plotted the results of their experiments in graph form, they found that the lift and drag curves exhibited by the flippers were quite similar to those of hydrofoil surfaces designed by engineers.

“Unexpectedly, we also found a unique lift curve for animals with swept-wing-like flippers,” Weber said. “The same phenomenon occurs in aircraft with delta wings.”

A delta wing is basically a large triangle, named after the uppercase Greek letter “delta,” which in the case of the Concorde generates sufficient lift at low speeds and is highly efficient at high speeds.

Animals such as the Amazon River dolphin have larger flippers, since maneuverability -- not speed -- is essential in its world of rivers and flooded forests. On the other hand, the bottlenose dolphin has smaller, swept flippers for speed in the open ocean.

“Our work represents a first step toward the understanding of the association between the three-dimensional form of the flippers and each animal’s ability to exist in its environment to get food, escape from predators or mate,” Howle said. “While some studies have focused on flippers of individual species, there hasn’t to date been any comparative study.

“Many factors, including ecology, body shape and performance requirements, have influenced the evolution of cetacean flippers, and these factors are all linked to hydrodynamic characteristics of the flippers we see today,” Howle said. “As we continue to evaluate more animals, we will be better able to link these factors together.”

(Photo: Duke U.)

Duke University

LIKE BURRS ON YOUR CLOTHES, VIRUS-SIZE CAPSULES STICK TO CELLS TO TARGET DRUG DELIVERY

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It is now possible to engineer tiny containers the size of a virus to deliver drugs and other materials with almost 100 percent efficiency to targeted cells in the bloodstream.

According to a new Cornell study, the technique could one day be used to deliver vaccines, drugs or genetic material to treat cancer and blood and immunological disorders. The research is published online at the Web site of the journal Gene Therapy.

"This study greatly extends the range of therapies," said Michael King, Cornell associate professor of biomedical engineering, who co-authored the study with lead author Zhong Huang, a former Cornell research associate who is now an assistant professor at the Shenzhen University School of Medicine in China. "We can introduce just about any drug or genetic material that can be encapsulated, and it is delivered to any circulating cells that are specifically targeted," King added.

The technique involves filling the tiny lipid containers, or nanoscale capsules, with a molecular cargo and coating the capsules with adhesive proteins called selectins that specifically bind to target cells. A shunt coated with the capsules is then inserted between a vein and an artery. Much as burrs attach to clothing, the selectin-coated capsules adhere to targeted cells in the bloodstream. After rolling along the shunt wall, the cells break free from the wall with the capsules still attached and ingest their contents.

The technique mimics a natural immune response that occurs during inflammation, which stimulates cells on blood vessel walls to express selectins, which quickly form adhesive bonds with passing white blood cells. The white blood cells then stick to the selectins and roll along the vessel wall before leaving the bloodstream to fight disease or infection. Selectin proteins may be used to specifically target nucleated (cells with a nucleus) cells in the bloodstream.

The study shows that since only the targeted cells ingest the contents of the nanocapsules, the technique could greatly reduce the adverse side effects caused by some drugs.

In a previous paper, King showed how metastasizing cancer cells circulating in the blood stream can stick to selectin-coated devices containing a second protein that programs cancer cells to self-destruct.

Said King, "We've found a way to disable the function of cancer cells without compromising the immune system," which is a problem with many other therapies directed against metastasis.

The current study demonstrates that genetic material can be delivered to targeted cells to turn off specific genes and interfere with processes that lead to disease. The researchers filled nanocapsules with a small-interfering RNA (siRNA) and targeted them to specific circulating cells. When the targeted cells ingested the capsules, the siRNA turned off a gene that produces an enzyme that contributes to the degradation of cartilage in arthritis.

In a similar manner, the method could be used to target the delivery of chemotherapy drugs, vaccine antigens to white blood cells, specific molecules that mitigate auto-immune disorders and more, King said.

(Photo: Zhong Huang/Cornell University)

Cornell University

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