May 19, 2008, 7:35 PM CT

New recommendations for grape growers

The inland areas of the Pacific Northwest, where rainfall averages only 4 to 12 inches per year, present growing challenges for vineyard owners and wine grape producers. The arid conditions in this part of the country have not been conducive for vineyard owners who produce and market high-quality wine grapes.

To promote healthy grape production when nature fails to deliver, vineyard managers in the area typically employ an irrigation practice known as regulated deficit irrigation. More than 60% of the wine grapes in the state of Washington are grown using this drip irrigation method. Unfortunately, the current irrigation methods are replete with problems that can cause over-irrigation and compromised grape quality.

Recently, scientists at Washington State Universitys Irrigated Agriculture Research and Extension Center completed a study that should provide vineyard managers new techniques for producing healthy and long-lasting grape crops. Joan R. Davenport was the lead author of the study reported in the February 2008 issue of HortScience. Explaining the impetus behind the research, Davenport said: Most of these vineyards use drip irrigation to supply supplemental water. Soil moisture is often measured to determine when to apply irrigation. However, without knowing the pattern of moisture under these conditions, the best place to check soil moisture content to mimic what the plant root sees was not understood. Our objective was to establish the soil moisture zone in this system......... Posted by: Erica      Read more         Source

May 18, 2008, 10:26 PM CT

Wanted: a reason to divorce

Divorce is widespread, not only in humans, but also in socially monogamous birds like the blue tit. Behavioural ecologists Mihai Valcu and Bart Kempenaers from the Max Planck Institute for Ornithology in Seewiesen found divorce rates of up to 50% in a long-term study of this species. But why do partners split up? To answer this question, it helps to know who suffers and who benefits from the separation (Animal Behaviour, April 23, 2008).

Prior studies on small passerine birds, such as blue tits, have shown that females do better after divorce. This is because they had more offspring with a new partner. "These findings have led to the suggestion that the females should take the initiative to leave their partner", says Bart Kempenaers, Director of the Department Behavioural Ecology and Evolutionary Genetics at the Max Planck Institute for Ornithology in Seewiesen.

In their study however, Kempenaers and his colleague Mihai Valcu obtained evidence that the increased reproductive success of divorced females may not be caused by getting a better partner, but by leaving the prior home and moving to a better place. Such breeding dispersal is common in females, in contrast to males, who rarely leave their territory after a divorce.

To separate the effects of territory change and partner change, the Max Planck scientists investigated what happens to the divorced females that stay in or close to their former breeding area. They observed that in this case males, but not females, increased their fitness: they mated with larger females and had a higher breeding success in comparison to their former partner......... Posted by: Kelly      Read more         Source

May 18, 2008, 9:40 PM CT

Explorers marvel at 'Brittlestar City' on seamount

Census of Marine Life-affiliated scientists, plumbing the secrets of a vast underwater mountain range south of New Zealand, captured the first images of a novel Brittlestar City established against daunting odds on the peak of a seamount an underwater summit taller than the worlds tallest building.

Its cramped starfish-like inhabitants, tens of millions living arm tip to arm tip, owe their success to the seamounts shape and to the swirling circumpolar current flowing over and around it at roughly four kilometers per hour. It allows Brittlestar Citys underwater denizens to capture passing food simply by raising their arms, and it sweeps away fish and other hovering would-be predators.

Discovery of this marine metropolis, announced recently along with important new insights into seamount geology and physics, highlighted a month-long April expedition to survey the Macquarie Ridge aboard the Research Vessel Tangaroa of New Zealands National Institute of Water & Atmospheric Research, host of the Census of Marine Life seamount programme, CenSeam. The voyage was largely funded by the New Zealand Foundation for Research, Science and Technology.

Formed at least 12.5 million years ago, Macquarie Ridge stretches 1,400 km south from New Zealand to just above the Antarctic Circle. A multi-disciplinary scientific team from New Zealand and Australia extensively sampled this intriguing ecosystem deep beneath waves familiar to fishing trawlers but rarely reached by scientists......... Posted by: Janet      Read more         Source

May 15, 2008, 8:02 PM CT

Simple Model Cell is Key to Understanding Cell Complexity

A team of Penn State scientists has developed a simple artificial cell with which to investigate the organization and function of two of the most basic cell components: the cell membrane and the cytoplasm--the gelatinous fluid that surrounds the structures in living cells. The work could lead to the creation of new drugs that take advantage of properties of cell organization to prevent the development of diseases. The team's findings will be published later this month in the Journal of the American Chemical Society.

"A number of researchers are trying to understand cells by turning off genes, one at a time, and are observing the effects on cell function, but we're doing the opposite," said Associate Professor of Chemistry Christine D. Keating, who led the research. "We're starting from scratch, adding in components to find out what is needed to simulate the most basic cell functions. Our goal is to find out how much complexity can be observed in very simple collections of molecules".

Building on prior work that was reported in the 16 January 2008 issue of Journal of the American Chemical Society, Keating and her colleagues built a model cell using as the cytoplasm a solution of two different polymers: polyethyleneglycol (PEG) and dextran. The scientists encapsulated this polymer solution inside a cell membrane and, because the two polymers do not mix, one of the phases surrounded the other like the white of an egg around a yolk. The team then exposed the cell to a concentrated solution of sugar. Through a process known as osmosis--in which water diffuses across a cell membrane from a region of higher water concentration to a region of lower water concentration--water traveled from the relatively diluted polymer solution inside the cell to the more concentrated sugar solution outside the cell. As a result, the volume of the polymer solution inside the membrane was reduced......... Posted by: Janet      Read more         Source

May 15, 2008, 7:29 PM CT

Gravity-defying bird beak mystery

As Charles Darwin showed nearly 150 years ago, bird beaks are exquisitely adapted to the birds' feeding strategy. A team of MIT mathematicians and engineers has now explained exactly how some shorebirds use their long, thin beaks to defy gravity and transport food into their mouths.

The phalarope, usually found in western North America, takes advantage of surface interactions between its beak and water droplets to propel bits of food from the tip of its long beak to its mouth, the research team reports in the May 16 issue of Science.

These surface interactions depend on the chemical properties of the liquid involved, so phalaropes and about 20 other birds species that use this mechanism are extremely sensitive to anything that contaminates the water surface, particularly detergents or oil.

"Some species rely exclusively on this feeding mechanism, and so are extremely vulnerable to oil spills," said John Bush, MIT associate professor of applied mathematics and senior author of the paper.

Wildlife biologists have long noted the unusual feeding behavior of phalaropes, which spin in circles on the water, creating a vortex that sweeps small crustaceans up to the surface, just like tea leaves in a swirling tea cup.

The birds peck at the surface, picking up millimetric droplets of water with their prey trapped inside. Since the birds point their beaks downward during the feeding process, gravity must be overcome to get those droplets from the tip of the bird's long beak to its mouth. Until now, researchers have been puzzled as to how that happens......... Posted by: Kelly      Read more         Source

May 14, 2008, 9:24 PM CT

Deep sea methane scavengers captured

Researchers of the Helmholtz Centre for Environmental Research (UFZ) in Leipzig and the California Institute of Technology (Caltech) in Pasadena succeeded in capturing syntrophic (means "feeding together") microorganisms that are known to dramatically reduce the oceanic emission of methane into the atmosphere. These microorganisms that oxidize methane anaerobically are an important component of the global carbon cycle and a major sink for methane on Earth. Methane -- a more than 20 times stronger greenhouse gas than carbon dioxide -- constantly seeps out large methane hydrate reservoirs in the ocean floors, but 80 percent of it are immediately consumed by these microorganisms. The importance of the anaerobic oxidation of methane for the Earth's climate is known since 1999 and various international research groups work on isolating the responsible microorganisms, so far with little success. Pernthaler and co-workers developed a new molecular technique to selectively separate these microorganisms from their natural complex community, and subsequently sequenced their genome. The findings were exciting: Besides identifying all genes responsible for the anaerobic oxidation of methane, new bacterial partners of this syntrophic association were discovered and the ability to fix N2 could be demonstrated. The work has been reported in the current issue of the renowned Journal Proceedings of the National Academy of Sciences (PNAS)......... Posted by: Janet      Read more         Source

May 14, 2008, 8:54 PM CT

Monarch butterflies help explain why parasites harm hosts

It's a paradox that has confounded evolutionary biologists since Charles Darwin published On the Origin of Species in 1859: Since parasites depend on their hosts for survival, why do they harm them?

A new University of Georgia and Emory University study of monarch butterflies and the microscopic parasites that hitch a ride on them finds that the parasites strike a middle ground between the benefits gained by reproducing rapidly and the costs to their hosts. The study, reported in the early online edition of the journal Proceedings of the National Academy of Sciences, provides the first empirical evidence in a natural system of what's called the "trade-off hypothesis".

"Parasites have to harm their host to replicate and be transmitted," said lead author Jacobus de Roode, a former post-doctoral researcher at UGA and now an assistant professor at Emory University. "But what this study found is that if they harm their host too much, they'll suffer too. Conversely, this study also shows that it does not benefit the parasite to be maximally benign, because those parasites don't replicate enough to be effectively transmitted".

In a painstaking, three-year study conducted in the laboratory of Sonia Altizer, assistant professor in the UGA Odum School of Ecology, scientists infected monarch caterpillars with varying levels of spores from a protozoan parasite usually found in wild populations. After the adult butterflies emerged, females were mated and placed in outdoor mesh cages. The butterflies spread the parasites when they deposit spores onto eggs or leaves of the milkweed plants that caterpillars feed on. These spores are then consumed by caterpillars as they feed. Each butterfly had one stalk of milkweed in its cage, and every day for up to 30 days the scientists gave the butterflies a new stalk while taking the prior stalk back to the lab for analysis. The spores on the eggs and on the milkweed were counted, which is no easy task considering that each spore is 1/100th the size of the powdery scales on butterfly wings. A single egg can have more than 1,000 spores on it......... Posted by: Kelly      Read more         Source

May 14, 2008, 8:43 PM CT

Likely causative gene for Alzheimer's

The genetic profile of two large Georgia families with high rates of late-onset Alzheimer's disease points to a gene that may cause the disease, scientists say.

Genetic variations called single nucleotide polymorphisms, or SNPs, are common in DNA, but this pattern of SNPs shows up in nine out of 10 affected family members, says Dr. Shirley E. Poduslo, neuroscientist in the Medical College of Georgia Schools of Medicine and Graduate Studies and the Charlie Norwood Veterans Affairs Medical Center in Augusta.

The 10th family member had half the distinctive pattern. The SNPs also were found in the DNA of 36 percent of 200 other late-onset patients stored in the Alzheimers' DNA Bank.

"We were shocked; we had never seen anything like this before," Dr. Poduslo says of findings published online in the American Journal of Medical Genetics. "If we looked at unaffected spouses, their SNPs were all different. The variants consistently found in affected siblings are suggesting there is something in this gene. Now we have to go back and find what is in this gene that is making it so unique for Alzheimer's patients".

The variation was in the TRPC4AP gene, part of a large family of genes that is not well-studied but is believed to regulate calcium. Calcium is needed throughout the body but its dysregulation can result in inflammation, nerve cell death and possibly plaque formation as well, she says......... Posted by: Kelly      Read more         Source

May 14, 2008, 8:39 PM CT

Mouse can do without man's most treasured genes

The mouse is a stalwart stand-in for humans in medical research, thanks to genomes that are 85 percent identical. But identical genes may behave differently in mouse and man, a study by University of Michigan evolutionary biologists Ben-Yang Liao and Jianzhi Zhang reveals.

Their results, which have implications for the use of mouse models in studying human disease, appear in the current issue of the journal Proceedings of the National Academy of Sciences (PNAS).

"Everyone assumes that deletion of the same gene in the mouse and in humans produces the same phenotype (an observable trait such as presence or absence of a particular disease). That's the basis of using the mouse to study human disease," said Zhang, an associate professor of ecology and evolutionary biology. "Our results show that may not always be the case".

Zhang and his graduate student Liao focused their study on so-called essential genes-genes which, through their effects on survival or fertility, are necessary for organisms to reach sexual maturity and reproduce. They then homed in on 120 essential human genes for which the mouse has an identical counterpart that also has been studied. Next they consulted a database that catalogs the results of experiments in which the mouse equivalents of human genes are deleted, or "knocked out"......... Posted by: Kelly      Read more         Source

May 14, 2008, 8:25 PM CT

Window of opportunity for restoring oaks small

Communities of Oregon white oak were once widespread in the Pacific Northwests western lowlands, but, today, they are in decline. Fire suppression, conifer and invasive plant encroachment, and land use change have resulted in the loss of as much as 99 percent of the oak communities historically present in some areas of the region.

A new technical report titled "Evaluation of Landscape Alternatives for Managing Oak at Tenalquot Prairie, Washington" outlines the findings of a study aimed at determining the success of different management scenarios in restoring the regions oak communities. The studys findings indicated that if oaks are to be successfully restored, more aggressive management is needed within the next several decades.

In areas where conifers have encroached into oak woodlands and savannas, about two-thirds of the remaining oaks were predicted to die over a 50-year period unless the conifers are removed, said Peter Gould, a research forester and lead author of the report.

Gould and colleagues conducted a landscape-level analysis of a portion of Fort Lewis, Washington, that is the site of a number of of the Puget Sounds last remaining oak communities. Using geographic information system technology, a forest growth model, and landscape visualization software, the scientists simulated the effects of five different management scenarios on the extent and condition of oaks. The scenarios ranged from no management at all to restoration of the historical extent of oak prairies typical of 1853......... Posted by: Erica      Read more         Source