Archive for 2010

Botanists Develop 'Antifreeze' Spray for Plants

Posted on Thursday, September 16, 2010 by sai kiran reddy


Every year, Americans spend more than $38 billion on their lawns and gardens. No matter what you're growing, a sudden frost or freeze can spell serious trouble. Soon, science could come to the rescue with antifreeze for plants.
After 21 years in the nursery business, Margaret Brown knows cold can kill.
"We keep [our] fern houses on about 28 so they can take down a little below freezing," Brown said. Greenhouses keep Brown in business through the winter. For customers who spend hundreds -- even thousands -- on shrubs and flowers, the threat of a freeze is a serious issue.
"The phone rings constantly," Brown said. "I feel like a weatherman in the fall, because everybody wants to know what the weather's going to do."
"At minus 6.6 or minus 6.3 centigrade, plant tissues freeze solid, and we have to deal with that solidity, that freezing," said David Francko, Ph.D., a botanist at the University of Alabama in Tuscaloosa, Ala. Dr. Francko developed a solution that works like antifreeze for plants. It lowers the plants' freezing temperatures and enhances the plants' natural mechanisms to resist freeze damage.
"The ability to reduce the freezing point of water that's inside the tissues of that plant and also, once that water freezes, to allow that plant to survive freezing temperatures [helps]," Dr. Francko said. "It can be frozen solid and still be viable."
A freezing chamber put his freeze-proof solution to the test. Untreated, plant after plant couldn't make it below 30 degrees. Plants sprayed with the antifreeze solution survived the freeze with vital structures still intact. "It's like moving your whole home landscape about 200 miles farther south," Dr. Francko said. "That's about the effect that you get, anywhere from three to 10 degrees more cold tolerance."
As temperatures fall, a dose of antifreeze could buy gardeners and growers a little more time and a little more green. Dr. Green expects the product to be on the market for home and agricultural use by sometime this winter.
WHAT IS FREEZE PRUF? Freeze-Pruf combines five ingredients into a liquid spray to protect against cold damage in plants. The ingredients have a synergistic effect that exceeds the sum of what they would do individually. The ingredients include an antifreeze-like substance that is present in animals, another that helps to lower the freezing point of plant cells by dehydrating them, one that strengthens cell walls, another that helps the solution penetrate leaves, and one to resist washing away by rain and snow. The protection lasts about 4-6 weeks, and the best times to use it are the late fall and early spring.
WHAT IS FROST, AND HOW DOES IT FORM? Tiny frozen water droplets in the air make frost. When water changes to ice (or to steam, when heated) this is a process known as a "phase transition." When water reaches freezing temperature, it will turn into ice. Different materials freeze at different temperatures, but water at sea level will freeze at 32 degrees Fahrenheit. Humidity measures how much vapor is present in the air at any given time. Clear, calm fall nights, when the air mass is especially humid, are the best conditions for frost to form.
Frost is the frozen version of dew, and, like snow, it results from the presence of too much water vapor in already-saturated air. It is a very thin deposit of tiny ice crystals. Frost forms when water vapor in the air condenses directly into ice, instead of condensing first into a liquid, then into ice. Condensation typically occurs when the temperature drops sufficiently for the air to become saturated with water vapor. The excess vapor condenses onto surfaces colder than the air. If the surface temperature is above 32 degrees Fahrenheit, dew will form; if it is below 32 degrees Fahrenheit, frost will form.Frost forms on the inside surface of windowpanes when the air inside has lower humidity than the air outside. If it didn't, the water vapor would first condense into small drops before freezing into clear ice.

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Oral Biologists Use Chemistry To Formulate Cavity Fighting Mints

by sai kiran reddy


Sodas, candy and processed foods are packed with tooth-decaying, cavity-causing sugar. For the past 40 years, experts have seen a decrease in the amount of tooth decay in children; but according to Centers for Disease Control statistics, the trend is reversing. To tackle the problem, one dental scientist has found a way to use candy to help prevent cavities.
Tooth decay in kids has increased 28 percent in the past eight years. Experts believe too many sugary, processed foods and not enough brushing are to blame. A key factor in fighting cavities is found in your mouth.
"Saliva is the great protector against cavities," said Israel Kleinberg, D.D.S., Ph.D., an oral biologist at Stony Brook University in Stony Brook, N.Y.
Dr. Kleinberg says 40 years of research and more than $1 billion has been spent trying to figure out what saliva has that fights tooth decay.
"I'm one of the pioneers in that as a whole new science," Dr. Kleinberg said. "It's where one mixes dentistry and biochemistry."
Dr. Kleinberg discovered how saliva's chemistry helps teeth neutralize the acidity created from eating food by balancing the pH levels in the mouth.
"[It's] like if you've got a swimming pool," Dr. Kleinberg said. "You have got to get the pH right. If you've got a neutral pH, you've got the ideal condition."
He developed a candy to fight cavities. The candy is fluoride-free and protects teeth in two ways. First, it raises pH levels to neutralize more acid than saliva alone. Second, it protects the minerals in tooth enamel. Arginine, an amino acid, combines with calcium in Cavistat, the candy's main ingredient, and sticks to teeth -- leaving behind a layer of protection.
Kids who ate two mints twice a day for one year had 68 percent fewer cavities in their molars than children who didn't chew the mints.
"The number of cavities, we think that ultimately is going to get to almost zero," Dr. Kleinberg said.
That would bring a smile to just about everyone's face.
All the ingredients in the mints are natural and considered foods, so the product doesn't need FDA approval.
WHAT DOES IT DO? BasicMints contain Cavistat, a cavity-fighting agent that includes two major components. Cavistat disrupts oral chemistry and biology in two ways. First, it introduces an amino acid called arginine to the mouth. When bacteria in the mouth break the arginine down, it neutralizes the acid generated by sugars in food, which reduces the amount of acid in the mouth and helps prevent damage to teeth. Additionally the Cavistat adds other chemical compounds that protect the minerals that make up teeth from dissolving.
ANATOMY OF A TOOTH: We think of teeth as being the part visible above the gum, but this is only the tip, or crown, of a tooth. There is also a neck that lies at the gum line, and a root, located below the gum. The crown of each tooth has an enamel coating to protect the underlying dentine. Enamel is even harder than bone, thanks to rows of tightly packed calcium and phosphorus crystals. The underlying dentine is slightly softer, and contains tiny tubules that connect with the central nerve of the tooth within the pulp. The pulp forms the central chamber of the tooth, and is made of soft tissue containing blood vessels that carry nutrients to the tooth. It also contains nerves so teeth can sense hot and cold, as well as lymph vessels to carry white blood cells to fight bacteria.

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Plant Biologists And Immunochemists Develop Hypoallergenic Alternative To Latex

by sai kiran reddy


Since the 1980s, latex gloves have been an important part of preventing the spread of infectious diseases like MRSA, HIV and AIDS. In fact, ten billion latex gloves are used every year in the United States. As we use more latex, more people are developing dangerous allergies to it. Scientists have developed a new, natural alternative that may solve the problem.
Faith, Lamar and David Ryberg love games -- but that's not all they have in common. They all have Spina Bifida. Like 68 percent of kids with this birth defect, all three have dangerous allergies to latex.
"You just get kind of nervous you could stop breathing at any moment," Lamar said.
Three million Americans and as many as 17 percent of healthcare workers in the United States have latex allergies. Reactions range from skin irritations and wheezing to a sudden drop in blood pressure, anaphylactic shock and even death. Scientists say a desert plant called guayule offers a new, natural rubber alternative without the proteins that trigger allergic reactions.
Katrina Cornish, Ph.D., a plant biologist and immunochemist at the Yulex Corporation in Maricopa, Ariz., says the key to processing guayule is to release the rubber contained in the plant. It starts with a sort of guayule milkshake.
"We take the whole shrub and grind it up to release the rubber particles, which are made in the bark into an aqueous medium," said Dr. Cornish.
Rubber particles in the mixture are slightly lighter than water. By spinning the solution in a centrifuge, the rubber separates, forming a liquid that rises to the top. Dr. Cornish says not only is this latex alternative, called Yulex, safer for those with allergies -- products made with it are more flexible and stronger than latex. In this test, the Yulex on the left stood up to nearly twice as much force as the purple latex on the right.
Uses for guayule latex are virtually endless.
"So far, we haven't found anything made out of rubber that we can't make with guayule," Dr. Cornish said. It's a new kind of rubber that might just fit like a glove for the millions with latex allergies, like Lamar.
"It would be very, very good!" Lamar exclaimed.
Yulex recently received FDA approval for a medical examination glove. Researchers say it's comparable in price to high-end synthetic latex. Because over 50 percent of rubber products now available are petroleum-based, Yulex could become even more attractive as oil prices increase.
WHAT IS GUAYULE? Guayule is a plant native to North America that grows well in arid areas of the southwestern United States and in Mexico. The plant produces resins that act as natural pesticides, making guayule resistant to many pests and diseases. The bark of the guayule contains rubber, but it does not contain the allergy-causing proteins present in the plants that are used to make latex. Guayule rubber has comparable strength to that of synthetic latex, but is softer and more elastic.
WHAT ARE ALLERGIES? Every year, when spring rolls around, millions of Americans start sneezing and coughing. Allergies are the culprit. An allergy is simply a negative reaction to a substance that enters the body that is not toxic in itself, yet for some reason causes a bad reaction in the body. Just about anything can be an allergen: dust mites, pollen, cats, dogs, wasps or bees, milk, eggs, peanuts, and even fruits are the most common.
A normal immune system is the body's defense against invading bacteria and viruses. It senses potential invaders and attacks them by producing antibodies. But sometimes a person's immune system mistakes a common allergen as harmful. So it produces antibodies to attack them, and this triggers other cells to release chemicals called histamines, causing allergic symptoms. The most common symptoms of an allergic reaction include sneezing, swelling, itchy eyes, sinus pain, a runny nose, rashes or hives, coughing, and in some cases, vomiting. In extreme cases, an allergen can cause difficulty in breathing. This is called an anaphylactic reaction, and a severe attack can be fatal if not treated quickly.

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Biogeochemists Map Out Carbon Dioxide Emissions In The U.S.

by sai kiran reddy


The Environmental Protection Agency estimates emissions in the United States rose almost 15 percent between 1990 and 2006, and the number will continue to rise. Carbon dioxide is mainly responsible for the increase. A new high-tech map reveals the areas in the country most responsible for the carbon dioxide problem.
Carbon dioxide (CO2) is the most abundant greenhouse gas in our atmosphere. Its sources can be found almost everywhere -- from cars, to cows, to power plants -- but scientists are still trying to figure out which parts of the country are pumping out the most CO2.
In the past, CO2 levels have been calculated based on population, putting the Northeast at the top of the list. Now, a new map called Vulcan reveals for the first time where the top carbon dioxide producers are in the country. The answer surprised Kevin Gurney, Ph.D., a biogeochemist at Purdue University in West Lafayette, Ind.
"There are a lot more emissions in the Southeast than we previously thought, and a lot of that is because it's not necessarily associated with where people live directly, but actually where industry and activities are," said Dr. Gurney.
The high-resolution map shows 100 times more detail than ever before and zooms in to show greenhouse gas sources right down to factories, power plants and even roadways. An animated version of Vulcan reveals huge amounts of greenhouse gas gets blown toward the North Atlantic region.
"We've never had a map with this much detail and accuracy that everyone can view online," Dr. Gurney said.
The map helps scientists better visualize and target the areas where CO2 emissions are the highest and help those areas reduce their negative impact on Earth. It can be downloaded for free online from the Purdue University Vulcan Project Web site.
ABOUT CARBON DIOXIDE: The concentration of carbon dioxide in the atmosphere has increased by about 30 percent since the beginning of the industrial revolution in the late 1800's. Most of this increase comes from using fossil fuel -- coal, oil and natural gas -- for energy, but approximately 25 percent of the carbon came from changes in land use, such as the clearing of forests and the cultivation of soils for food production. Natural sources of atmospheric carbon include gases emitted by volcanoes, and respiration of living things. We breathe in oxygen, and breathe out carbon dioxide.
ABOUT AIR POLLUTION: Air pollution is made up of many kinds of gases, droplets and particles that can remain suspended in the air. This makes the air dirty. The easiest way to visualize airborne particles (also called aerosols) is to exhale outside on a cold day and watch the fog come out of your mouth as water vapor forms into water droplets. The same thing happens in the atmosphere, but for different reasons. Under certain conditions individual molecules come together and form particles -- a chemical soup. In the city, air pollution may be caused by cars, buses and airplanes, as well as industry and construction. Ground-level ozone is created when engine and fuel gases already released into the air interact when sunlight hits them. Ozone levels increase in cities when the air is stil

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CRISPR Critters: Scientists Identify Key Enzyme in Microbial Immune System

Posted on Wednesday, September 15, 2010 by sai kiran reddy


Through the combination of CRISPR and squads of CRISPR-associated -- "Cas" -- proteins, microbes are able to utilize small customized RNA molecules to silence critical portions of an invader's genetic message and acquire immunity from similar invasions in the future. To better understand how this microbial immune system works, scientists have needed to know more about how CRISPR's customized small RNA molecules get produced. Answers have now been provided by a team of researchers with the Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California (UC) Berkeley.
In a study led by biochemist Jennifer Doudna, the research team used protein crystallography beamlines at Berkeley Lab's Advanced Light Source to produce an atomic-scale crystal structure model of an endoribonuclease called "Csy4." Doudna and her colleagues have identified Csy4 as the enzyme in prokaryotes that initiates the production of CRISPR-derived RNAs (crRNAs), the small RNA molecules that target and silence invading viruses and plasmids.
"Our model reveals that Csy4 and related endoribonucleases from the same CRISPR/Cas subfamily utilize an exquisite recognition mechanism to discriminate crRNAs from other cellular RNAs to ensure the selective production of crRNA for acquired immunity in bacteria," Doudna says. "We also found functional similarities between the RNA recognition mechanisms in Cys4 and Dicer, the enzyme that plays a critical role in eukaryotic RNA interference."
Doudna is a leading authority on RNA molecular structures who holds joint appointments with Berkeley Lab's Physical Biosciences Division and UC Berkeley's Department of Molecular and Cell Biology and Department of Chemistry. She is also an investigator with the Howard Hughes Medical Institute (HHMI). The results of this latest research on CRISPR are reported in the journal Science in a paper titled "Sequence- and structure-specific RNA processing by a CRISPR endonuclease." Co-authoring the paper with Doudna were Rachel Haurwitz, Martin Jinek, Blake Wiedenheft and Kaihong Zhou.
CRISPR is a unit of DNA, usually on a microbe's chromosome, made up of "repeat" elements, base-pair sequences ranging from 30 to 60 nucleotides in length, separated by "spacer" elements, variable sequences that are also from 30 to 60 nucleotides in length. CRISPR units are found in about 40-percent of all bacteria whose genomes have been sequenced, and about 90-percent of archaea. A microbe might have several CRISPR loci within its genome and each locus might contain between four and 100 CRISPR repeat-spacer units. Doudna and her colleagues studied CRISPR in Pseudomonas aeruginosa, a common bacterium that is ubiquitous in the environment.
Rachel Haurwitz, a graduate student in Doudna's research group and the first author on the Science paper, explains how the CRISPR/Cas immunity system works.
"When a bacterium recognizes that it has been invaded by a virus or a plasmid, it incorporates a small piece of the foreign DNA into one of its CRISPR units as a new spacer sequence. The CRISPR unit is then transcribed as a long RNA segment called the pre-crRNA. The Csy4 enzyme cleaves this pre-crRNA within each repeat element to create crRNAs about 60 nucleotides long that will contain sequences which match portions of the foreign DNA. Cas proteins will use these matching sequences to bind the crRNA to the invading virus or plasmid and silence it."
Haurwitz says the CRISPR/cas system for silencing foreign DNA in prokaryotes is analogous to the way in which short interfering or siRNAs correct genetic problems in eukaryotes. Over time, the CRISPR/cas system will build up inheritable DNA-encoded immunity from future invasions by the same types of viruses and plasmids.
With their crystal structure model of the Csy4 enzyme bound to its cognate RNA, which features a resolution of 1.8 Angstroms, the Berkeley CRISPR research team has shown that Csy4 makes sequence-specific interactions in the major groove of the CRISPR RNA repeat stem-loop. Together with electrostatic contacts to the phosphate backbone, these interactions enable Csy4 to selectively bind to and cleave pre-crRNAs using phylogenetically conserved residues of the amino acids serine and histidine in the active site.
"Our model explains sequence- and structure-specific processing by a large family of CRISPR-specific endoribonucleases," Doudna says.
Doudna and her colleagues produced their 1.8 Angstrom resolution crystallographic structure using the experimental end stations of Beamlines 8.2.1 and 8.3.1 at Berkeley Lab's Advanced Light Source (ALS). Both beamlines are powered by superconducting bending magnets -- "superbends" -- and both feature state-of-the-art multiple-wavelength anomalous diffraction (MAD) and macromolecular crystallography (MX) capabilities. Beamline 8.2.1 is part of the suite of protein crystallography beamlines that comprise the Berkeley Center for Structural Biology.
"The ALS and its protein crystallography beamlines continue to be a critical resource for our research, " Doudna says.
The crRNAs used by the CRISPR/cas system for the targeted interference of foreign DNA join the growing ranks of small RNA molecules that mediate a variety of processes in both eukaryotes and prokaryotes. Understanding how these small RNA molecules work can improve our basic understanding of cell biology and provide important clues to the fundamental role of RNA in the evolution of life.
Says Doudna, "By investigating how bacteria produce and use small RNAs for selective gene targeting, we hope to gain insight into the fundamental features of the pathways that have proven evolutionarily useful for genetic control, both in the bacterial world and in the world of eukaryotes. Right now it looks like bacteria and eukaryotes have evolved entirely distinct pathways by which RNAs are used for gene regulation and that is pretty amazing!"
This work was supported in part by grants from the National Science Foundation and from the Bill and Melinda Gates Foundation.

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Protein Clamps Tight to Telomeres to Help Prevent Aging and Support Cancer

by sai kiran reddy


While the nature of this portion of Cdc13 had previously eluded scientists, the Wistar researchers found that two copies of the protein bind together to form what is called a "dimer," and how that dimer physically interacts with DNA, regulating how enzymes called telomerases access and lengthen the telomeres. The study was performed using the yeast gene, however, this essential life process has changed little through evolution, and evidence suggests that the human equivalent of this protein may make a good target for future anticancer drugs.
They present their findings in the journal Molecular and Cellular Biology, available online now, ahead of print.
"Cdc13 has a crucial support role in maintaining and lengthening telomeres, which are reduced in length through every round of DNA replication," said Emmanuel Skordalakes, Ph.D., assistant professor in Wistar's Gene Expression and Regulation Program and senior author of the study. "We know that disabling this protein in humans will most likely lead to senescence, which is of particular interest in cancer, because telomere lengthening is one of the ways cancer cells obtain their immortality."
In the present study, Skordalakes and his colleagues detail how Cdc13 serves a dual function in telomere replication. First, it keeps the cells' natural DNA repair mechanisms from mistaking the telomere for a broken stretch of DNA, which could cause genetic mayhem if such repair proteins fuse the ends of two chromosomes together, for example. Secondly, Cdc13 recruits telomerase and related proteins to place in order to lengthen the telomeres.
When the researchers introduced mutations into Cdc13 that prevented the protein from forming a dimer, it caused the telomeres to shorten, which would hasten the demise of the yeast cells. When they created mutations that prevented Cdc13 dimers from binding to DNA, it had the effect of excessively lengthening telomeres, an act the researchers attribute to the notion that Cdc13 helps regulate the ability of DNA-replication enzymes to access telomeres. "The complex role of Cdc13 underscores the unique nature of telomeres and the fine balance between normal cell division and cancer," said Skordalakes.
Telomeres are important to cell division because they serve as sort of a timing mechanism that can, in effect, limit the number of times a normal cell can divide. As each cell divides, it must first replicate -- or copy -- the DNA of its chromosomes in exacting detail.
However, the proteins in cells that make this replication possible physically cannot copy the last few base units of DNA at the tips of the chromosomes, which effectively shortens the telomere each time a chromosome is copied. Without telomeres to serve as a buffer, a chromosome could conceivably lose a functioning gene as it is copied. This natural "lifespan" of cells was first identified in the 1960s as the Hayflick Limit, named after its discoverer, Leonard Hayflick, Ph.D., then a Wistar scientist.
In 2008, the Skordalakes laboratory was the first to determine the 3-D structure of the catalytic subunit of the enzyme telomerase, which functions to tack on the short stretches of DNA at the telomeres that the cell's main DNA-replicating enzymes miss. The act of preserving telomeres through telomerase is a hallmark of only certain cells, particularly those in developing embryos. In adults, telomerase is active in stem cells, certain immune system cells and, most notably, cancer cells.
According to Skordalakes, the discovery of the dimeric nature of Cdc13 sheds light into the core function of this protein, the recruitment of telomerase (which is also a dimer) to the telomeres. Within the Cdc13 dimer are multiple sites that can bind to DNA with varying degrees of affinity. This allows Cdc13 to straddle the DNA so that one section grips tightly to DNA, while another section -- with a more relaxed grip -- can bind nearer the tail end of the DNA strand and where telomerase binds. This feature of Cdc13 also assists in recruiting telomerase, summoning the enzyme into place above the telomere.
"You can think of Cdc13 as if it were you hanging on to the edge of a cliff, with one grip stronger than the other," Skordalakes said. "You're going to keep that strong hand on the cliff's edge while your weaker hand reaches into your pocket for your phone."
When Cdc13 interacts with telomerase, Skordalakes says, its weaker hand lets go of DNA, allowing the telomerase to access the telomere while the "strong hand" keeps the telomerase-Cdc13 complex firmly attached to the chromosome end. "It effectively serves as both a protective placeholder and a means of guiding telomerase activity," Skordalakes said.
The Skordalakes laboratory continues to explore the complex biology of telomeres, as well as the numerous other proteins necessary for telomere lengthening to occur. Meanwhile, they are investigating the potential of small molecule inhibitors to serve as viable therapeutics against cancer by blocking telomerase and their related proteins.
Co-authors from The Wistar Institute include David W. Speicher, Ph.D., a Wistar professor, and laboratory staff Meghan Mitchell (a former research assistant under Skordalakes), Mark Mason (a graduate student under Skordalakes), and Sandy Harper (a technician under Speicher ). They were joined by Jasmine S. Smith and F. Brad Johnson, M.D., Ph.D., from the University of Pennsylvania School of Medicine's Department of Pathology and Laboratory Medicine.
The research was supported by grants from the Pennsylvania Department of Health, The Ellison Medical Foundation, The Emerald Foundation, Inc., and the National Institute on Aging of the National Institutes of Health.

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Nature's Gift for Gardening May Hold Key to Biodiversity

by sai kiran reddy


DNA analysis of wild evergreen rhododendrons in the Himalayas has suggested that hundreds of species of the plant could be derived from hybrids -- cross-breeds between different species.
Their findings may help explain the rich biodiversity of the natural world, as it shows how random pairings of wild plants millions of years ago has led to the development of hundreds of new species that exist today.
While scientists have long known that single species can derive from hybrid origins, this latest finding offers rare evidence that whole groups of species can be developed from a hybrid ancestor.
Scientists sampled the DNA of 79 species of rhododendron and used the results to analyse how each species was related.
They found that although most Himalayan rhododendrons were descended from the same ancestral line, three rogue species showed traces of a second, distantly related ancestor. This species, now extinct, may have arrived in the Himalayas within the last 10 million years, and interbred with species already there.
The discovery suggests that much of the diversity found in rhododendrons -- and perhaps many other species -- is a result of ancient cross-breeding, which has enabled a diverse range of offspring over many successive generations.
The joint study with Royal Botanic Garden Edinburgh, published in the Journal of Plant Systematics and Evolution, was supported by the Natural Environment Research Council.
Dr Richard Milne of the University of Edinburgh's School of Biological Sciences, who led the research, said: "Nature seems to be more creative than the most gifted of gardeners. Cross-breeding in the wild may have played a significant part in contributing to the wealth of species on Earth today -- but more work is needed to investigate the significance of this.

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Scots Pine Shows Its Continental Roots

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The research was carried out by an international team from the Centre for Ecology & Hydrology, the Polish Academy of Sciences, the University of Edinburgh and the Macaulay Land Use Research Institute.
Today's Scots Pine forests are remnants of the ancient, much larger Caledonian forest that covered the northern parts of Britain from the end of the last Ice Age until many trees were lost due to over-exploitation and agriculture more than 400 years ago.
It has previously been thought that as the trees were lost so was much of the genetic diversity contained within them. Without sufficient genetic diversity the remaining pine tree populations may not be able to adapt and survive under new conditions, for example as the climate changes.
By studying the remnant Scottish populations the researchers were able to see how much genetic variation remains and also how these trees compare to the intact Scots Pine forests of continental Europe and Asia.
The good news is that Scottish populations turn out to be at least as genetically diverse as their continental cousins. This suggests that despite the huge losses they have suffered, the last fragments of the Caledonian Pine forest in Scotland still harbour genetic variation that could help regenerate future populations.
"Despite its Scottish image, the Scots Pine owes much to its European roots." said paper co-author Dr Stephen Cavers, an ecologist based at the Centre for Ecology & Hydrology's Edinburgh site, "By looking at the trees' DNA we have learnt much about how the forests grew up after the Ice Age. Given the severe fragmentation of the current population, our results are key to understanding how these forests will cope with future change."
Where the genetic diversity comes from is another question. Given the great age that these trees can reach -- as much as 700 years in some cases -- the forests present today may be no more than a few tens of generations removed from the first migrants to reach these shores after the ice retreated. DNA evidence suggests that these early arrivals came in two waves: one, which reached the far north-western Highlands very soon after the ice retreated, possibly via Ireland, and another, which settled in the eastern Highlands, from central Europe.
Dr Cavers added, "We plan to continue the study, to try and discover if there are particular genes which let the Highland trees tolerate the harsh Scottish climate."

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Human Development Scientists And Computer Game Developers Design Video Game That Teaches Conflict Resolution To Kids

Posted on Tuesday, September 14, 2010 by sai kiran reddy


Amid growing concern surrounding the effects violent video games have on children, a new computer game could be the alternative parents have been waiting for.
Kids who play together also argue together. Fights over games, toys and friendships are common, but when arguments heat up, it's time to solve them before things get out of hand. A new computer game teaches kids how to solve playground and classroom quarrels that kids face every day in a positive way -- without fists and fights.
"It helps them resolve conflicts by giving them a chance to think about what happens in the course of an actual conflict episode," said Melanie Killen, Ph.D., a human development expert at the University of Maryland in College Park, Md.
The game, called "Cool School: Where Peace Rules" -- designed by a team of human development scientists, teachers, government mediators, computer game developers and animators -- helps kids solve school violence and bullying while still having fun.
"You're learning things, but at the same time it's having fun with it," said student Ellen Yaffe.
Animated objects come to life and depict common conflicts. Kids experiment on how to settle each argument. Players have the option of threatening the peer, telling the teacher, forgetting about it or talking things through.
Players are rewarded for choosing positive solutions to resolve conflicts with letters they collect to win.
"What this game is doing is it's empowering children to make choices and decisions and to see what unfolds based on their own decisions," Dr. Killen said.
Parents and teachers praise the new game, and kids love it for their own reasons.
"I think they make it very realistic with like the names and how the school looks," student Jacob Tycko told Ivanhoe.
The best part is the game is totally free. You can download it online by visiting http://www.curriki.com and searching for "cool school."
ABOUT THE GAME: "Cool School: Where Peace Rules" came about when the Federal Mediation and Conciliation Service asked a Human Development professor to help them design a videogame to help five to seven year old children deal with conflicts in a peaceful manner. The project relied on animators to create the visual environments, and for the professor to create scenarios that will help kids learn to resolve problems without resorting to violence. The game uses a wide variety of charactersýfrom erasers to desks to books and basketballsýto lead players through 52 different scenarios.To learn more about the game or to play it go to (http://www.rtassoc.com/gm_coolschool.html).
TIPS ON STOPPING BULLIES: This list is adapted from material on the website of the United States Health Resources and Services Administration.http://stopbullyingnow.hrsa.gov/
DO:
  • Tell an adult
  • Join clubs and groups where you will meet other kids
  • Support someone else who is being bullied
DO NOT:
  • Think it's your fault.
  • Fight back or bully a person back.
  • Reply to online bullying
The American Sociological Association contributed to the information contained in the TV portion of this report.

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Kinesiologists Design Tiny Treadmill To Help Balance Baby Steps In Down Syndrome Infants

by sai kiran reddy


Down syndrome affects one in every 800 babies. It's a genetic condition that causes delays in intellectual and physical development. Researchers have now developed a treadmill for Down's babies to help them walk earlier than ever before.
Six-year-old Evan keeps his big brothers busy. Nothing can slow him down, and that's just the way his mom likes it. "He loves to run and play with his brothers," mother Jeanette Kurnik said.
Evan has Down syndrome, a genetic disorder caused when a fetus has 47 chromosomes instead of the usual 46. Typical kids learn to walk at 12 months. Babies with Down syndrome learn at 24 to 28 months.
Kinesiologist Dale Ulrich, Ph.D., of the University of Michigan in Ann Arbor, Mich., studies human movement and led the team who developed a tiny treadmill specifically for children with Down syndrome.
"The idea is we want to support this underlying pattern of coordination in their legs, this alternating stepping," Dr. Ulrich said.
The treadmill training helps babies with Down learn to balance earlier. Signe Newcomb helps her daughter Lauren use the treadmill at home for eight minutes every day. "She likes to stand more and is building her core muscle strength," Newcomb said.
Once the babies take eight to ten steps by themselves, they are evaluated at the Gait Laboratory where information from light-reflecting markers attached to the child is recorded on cameras.
"Basically, we know how long their step is, how wide they walk and how fast they walk," Rosa Angulobarroso, a research scientist at the University of Michigan, said.
Studies show the babies learn to walk six months earlier than kids without treadmill training, and the quality of their walking is much better. It doesn't sound like much, but it can mean a world of difference.
"Once locomotion occurs, it really advances cognitive development, social skill development and language, so the sooner you get them walking, [the sooner] they can explore their environment," Dr. Ulrich said.
Babies can start their treadmill training as early as eight to 10 months of age.
WHAT CAUSES ABNORMAL NUMBERS OF CHROMOSOMES? Chromosomes are tiny structures in the cells of the human body that contain roughly 30,000 to 35,000 gene pairs. The genes determine traits like eye and hair color, and also how our bodies grow and develop in the womb. Each person normally has 23 pairs of chromosomes (46 in all), inheriting one chromosome per pair from each parent. Unlike other cells in the body, sperm and egg cells only have 23 unpaired chromosomes; when a sperm and egg unite, they form a fertilized egg with all 46 chromosomes. But sometimes, in the process of cell division, an error occurs, so that a sperm or egg cell has too many or too few chromosomes. Scientists don't know what exactly causes this, but the resulting embryo has a chromosomal abnormality. About 70 percent of such pregnancies result in a miscarriage, but if carried to term, the baby could have any number of disorders because of the abnormality.
ABOUT DOWN SYNDROME AND CHROMOSOMAL ABNORMALITIES: Down syndrome is the most common of these disorders, affecting about 1 in every 800 to 1,000 live-born babies. Babies with Down syndrome have three copies of a particular chromosome instead of two. Children with Down syndrome can suffer from intellectual and developmental disabilities as well as heart defects. Babies born with extra copies of other chromosomes can be severely retarded with many physical birth defects; most die before their first birthday. Other chromosomal abnormalities include small missing sections of the chromosome; a missing single gene; a section of one chromosome attaching itself to another; and a chromosome that is somehow snipped out and reinserted upside down in the sequence.
HOW WE WALK: Walking is different from a running gait because only one foot at a time lifts off the ground. During forward motion, the leg that leaves the ground swings forward from the hip, like a pendulum. Then the leg strikes the ground with the heel and rolls through the toe in a motion similar to an inverted pendulum. The motion of the two legs is coordinated so that one foot or the other is always in contact with the ground -- a so-called 'double pendulum' strategy. The process of walking recovers about 60 percent of the energy expended thanks to the pendulum dynamics and the ground reaction force. The legs act as long levers that transfer ground reaction force to the spine

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Sociologists Weigh In On Obesity Increasing The Length Of Hospital Stays

by sai kiran reddy


The numbers on our nation's scales are going up. A recent study puts Mississippi at the top of the list with the highest rate of adult obesity in the country. New research shows how extra weight is adding up to longer hospital stays.
Annette Armstead knows what it takes to stay healthy. Before she started exercising, she weighed 225 pounds.
"I was tired of people telling fat jokes," said Armstead. "I was in pain all the time. I was so heavy that my knees would give out on me, and I was always falling down."
Obesity is linked with increased risk of heart disease, stroke, diabetes and other illnesses.
"I had problems with arthritis and different health problems, and everything they were saying [indicated] I was too heavy and I needed to lose weight," Armstead said. A new study by sociologists at Purdue University found obesity also leads to more frequent and longer hospital stays.
"Obese people, on average, stay at least one to one and a half days longer than a normal-weight individual," said Ken Ferraro, Ph.D., a sociologist at Purdue University in West Lafayette, Ind.
The main reason for extra hospitalizations is disease. Forty-six percent of obese adults in the study had high blood pressure, and obese adults who have been overweight since childhood and carried extra weight into adulthood pay the highest price for being heavy.
"The longer the person is obese, the longer their stay in the hospital," Dr. Ferraro said.
Tackling obesity at a young age is crucial to staying out of the hospital later on.
"If you can tell other people that you're on a diet, a lot of them actually might help you to stay on that diet, but if you're silent to your friends, then obviously they can't support you," Dr. Ferraro advised.
Armstead credits her weight loss to diet and exercise and has never felt better.
"I feel healthier at 55 than I did at 25," she said.
ABOUT TYPE II DIABETES: Type II diabetes is the most common form of diabetes. In this form of the disease, either the body does not produce enough insulin, or the cells in the body ignore insulin. This can stop glucose from moving out of the bloodstream and into cells. Cells need the energy that glucose provides, and too much sugar in the blood can cause damage to the eyes, nerves, kidneys, or heart. These complications are very similar to the threats from type I diabetes, though type II can sometimes be treated with medications and diet instead of insulin (obtained through injections or in an inhaled form).
WHAT IS BLOOD PRESSURE: Blood pressure is the force in the arteries when the heart beats, and when the heart is at rest. When blood pressure is high, there is an increased risk of heart disease (which leads to heart attack) and stroke. It is most common in adults over age 35, and is especially prevalent in African Americans, the middle-aged and elderly, obese people, heavy drinkers, and women who are taking birth control pills. Those with diabetes, gout or kidney disease are also prone to suffer from high blood pressure.
WHAT CAUSES HEART ATTACKS: Heart attack is the leading cause of death in North and South America and in Europe. It is usually the result of prolonged hardening and narrowing of the arteries that direct blood into the heart. When blood vessels are healthy, oxygen-rich blood flows easily to all the muscles and organs of the body. But if they become clogged by the buildup of fatty deposits on vessel walls, blood can be cut off, killing heart muscle cells. This is called coronary heart disease, and it can lead to heart attacks or strokes.
The American Sociological Association contributed to the information contained in the TV portion of this report.

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A Biochemist Explains The Chemistry Of Cooking

by sai kiran reddy


You love to cook, but have you whipped up some disasters? Even the best recipes can sometimes go terribly wrong. A nationally recognized scientist and chef says knowing a little chemistry could help.
Long before she was a cook, Shirley Corriher was a biochemist. She says science is the key to understanding what goes right and wrong in the kitchen.
"Cooking is chemistry," said Corriher. "It's essentially chemical reactions."
This kind of chemistry happens when you put chopped red cabbage into a hot pan. Heat breaks down the red anthocyanine pigment, changing it from an acid to alkaline and causing the color change. Add some vinegar to increase the acidity, and the cabbage is red again. Baking soda will change it back to blue.
Cooking vegetables like asparagus causes a different kind of reaction when tiny air cells on the surface hit boiling water.
"If we plunge them into boiling water, we pop these cells, and they suddenly become much brighter green," Corriher said.
Longer cooking is not so good. It causes the plant's cell walls to shrink and release acid.
"So as it starts gushing out of the cells, and with acid in the water, it turns cooked green vegetables into [a] yucky army drab," Corriher said.
And that pretty fruit bowl on your counter? "Literally, overnight you can go from [a] nice green banana to an overripe banana," Corriher said.
The culprit here is ethylene gas. Given off by apples and even the bananas themselves, it can ruin your perfect fruit bowl -- but put an apple in a paper bag with an unripe avocado, and ethylene gas will work for you overnight.
"We use this as a quick way to ripen," Corriher said. Corriher says understanding a little chemistry can help any cook.
"You may still mess up, but you know why," she said. When it works, this kind of chemistry can be downright delicious.
WHAT ARE ACIDS AND BASES? An acid is defined as a solution with more positive hydrogen ions than negative hydroxyl ions, which are made of one atom of oxygen and one of hydrogen. Acidity and basicity are measured on a scale called the pH scale. The value of freshly distilled water is seven, which indicates a neutral solution. A value of less than seven indicates an acid, and a value of more than seven indicates a base. Common acids include lemon juice and coffee, while common bases include ammonia and bleach.
WHY DOES FOOD SPOIL? Processing and improper storage practices can expose food items to heat or oxygen, which causes deterioration. In ancient times, salt was used to cure meats and fish to preserve them longer, while sugar was added to fruits to prevent spoilage. Certain herbs, spices and vinegar can also be used as preservatives, along with anti-oxidants, most notably Vitamins C and E. In processed foods, certain FDA-approved chemical additives also help extend shelf life.


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Radiologists Develop Asthma Imaging Method

Posted on Monday, September 13, 2010 by sai kiran reddy

Radiologists developed a new method for viewing the lungs of asthma sufferers. The method uses a polarized helium-3 gas--making it visible during an MRI. The patient inhales the helium-3 and undergoes an MRI, where doctors can see how far the atoms in the gas can travel in the lungs. This gives an image of what airways are blocked and what parts of the lungs ventilate. The black areas of the image indicate portions of the lung where air does not reach--areas where the helium-3 atoms could not travel.

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Mechanical Engineers Rock Out On Guitars They Construct Themselves

by sai kiran reddy


Mechanical engineers combined their skills with that of electrical engineering and computer science to create a college class inspired by the Guitar Hero game. The hands-on course requires students to build their own guitar. To do this, students choose a shape for the guitar, which is cut out of lumber by a computer. Located under the guitar strings, magnets detect vibrations and wire coils send an electronic signal to an amplifier and speaker. Effects pedals can also distort the sound and add special effects.

Skills from mechanical engineering, electrical engineering and computer science come together to form a cool kind of class that's a hit with students.
The video game Guitar Hero is a chart-busting hit. It was the inspiration that mechanical engineering graduate student and teacher Gavin Garner needed for a class assignment.
"I realized the students enjoyed pretending they were actual guitar players, and I thought, 'Why not have them actually build the real thing in the lab?'" said Garner, of the University of Virginia in Charlottesville, Va.
Garner's class isn't a music class. It's a new hands-on course combining skills from mechanical, electrical and software engineering called mechatronics. Mechanical engineering student Brad Nichols' guitar rocks.
"I was thrilled with the guitar," Nichols said. "I thought it looked great for something that was made with two by fours by students in a lab in two or three weeks. It actually sounds pretty good."
Students pick the shape and a computer automatically cuts the guitar from lumber. Basic magnets, nails and wire coils are mounted under the strings. The magnets pick up the vibrations of the strings and the wire coils send an electronic signal to an amplifier and speaker to produce sound.
"Then, the electrical signal travels down through into these effects pedals which distort the sound and add special effects, which changes the tone of the music," Garner said.
The designs show the creativity that went into the guitars, and the sound shows the science skills that created fun, useable objects that students love. "When I want to appreciate what I learned in school, I'll plug that in and strum around on it a little bit," Nichols said.
Another class assignment had students design a Mech-E-Mouse, a robot programmed to navigate through mazes to find a piece of electronic cheese.
WHAT IS PITCH: Sound waves are pressure waves. A vibrating object creates a disturbance in the surrounding air, much like a stone cast in a quiet pond will cause waves to ripple outward from the spot where the stone hit. All sound waves have wavelength and frequency. Objects that vibrate very quickly create short wavelengths and a high-pitched sound. Objects that vibrate very slowly create long wavelengths and a low-pitched sound. Frequency measures the speed of vibration in a unit called a Hertz (Hz), and 1 Hz is equivalent to 1 vibration per second. Pluck a string on a guitar, and it might vibrate 500 times per second, so the sound wave's frequency would be 500 Hertz. Pitch simply denotes those frequencies within the range of human hearing (from about 20 Hz to 20,000 Hz). The faster the rate of vibration, the higher the pitch; the slower the rate of vibration, the lower the pitch.
WHAT MAKES ELECTRIC GUITARS LOUD? Essentially this is possible because of two items: an amplifier and a pick-up. Amplifiers, as you may expect, increase the amplitude or volume of sound and other signals. For audio amplifiers that means a sound must be turned into an electric signal, and sent into the amplifier before it emerges many times louder than the level at which it was originally produced. It is essentially a speaker whose source can be a guitar, a CD, a microphone, or many other items. A pick-up transforms the movement of guitar strings into an electrical signal that can be transmitted to amplifiers or recording equipment. Some use magnets wrapped inside a coil of wire, while others use alternate methods, such as piezoelectric crystals (which respond to physical stress or deformity by creating electrical energy).

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Embryonic Cell and Adult Pig Islet Transplants Cure Diabetes in Rats

Posted on Wednesday, June 30, 2010 by sai kiran reddy


The rats adopted the pig transplants as their own and produced enough insulin to control their blood sugar -- all without the need for anti-rejection drugs. The researchers report their findings online in the American Journal of Pathology.
Using a two-step approach, the researchers first transplanted a cluster of embryonic pig pancreatic cells into diabetic rats. These cells grow to become the pancreas, which houses the islet cells that produce insulin. The embryonic cells primed the rats' immune system to accept a second implant of islets from adult pigs several weeks later.
The new research -- the first long-term, successful cross-species transplant of pig islets without immune suppression -- raises the prospect that it may one day be possible to cure diabetes in humans using a similar strategy. Pig cells could overcome the shortage of human islets available from deceased donors and the need for transplant patients to take anti-rejection drugs for life.
"While human islet transplants have cured diabetes in some people, there are so few donors that only a small percentage of patients get transplants," says senior author Marc Hammerman MD, the Chromalloy Professor of Renal Diseases in Medicine. "Moreover, those who receive human islet transplants must take anti-rejection drugs for the rest of their lives, so essentially they are trading daily insulin shots for immune-suppression drugs, which carry their own risks. Our research paves the way for a new approach to treating diabetes, one that features a virtually unlimited supply of islets and no need for immune suppression."
Pig insulin has been used to treat diabetes in humans, making the animals potentially good islet donors for humans with the disease. Insulin from pigs was routinely given to patients with diabetes until the 1980s, when DNA technology enabled pharmaceutical companies to manufacture human insulin.
In the new study, the researchers transplanted clusters of embryonic pig pancreatic cells into 10 diabetic rats that could not produce any insulin on their own and had very high glucose levels. The cells were retrieved from the pig embryos early in their development, which is believed to make them "invisible" to the rats' immune system or induce a state of immune tolerance.
As the immature pancreatic cells developed, they began to produce insulin, significantly lowering blood glucose in the rats, though not to normal levels. Then, eight weeks later, some of the rats underwent a second transplant of islet cells from adult pigs. Other diabetic rats in a control group did not receive any embryonic pancreatic cells but only adult pig islets.
After 12 weeks and for the several months that followed, the rats that got both the embryonic pig pancreatic cells and the islets had normal blood glucose levels, a strong indicator that the pig islet cells were producing ample insulin. The rats in the control group that received only embryonic pancreatic cells continued to have higher-than-normal glucose levels.
The researchers determined by multiple methods that the successfully transplanted pig islets had become established in the rats that had earlier received embryonic pancreatic cell transplants. In contrast, the pig islet cells underwent immune rejection in the rats that did not get the embryonic pancreatic cell transplants.
"This is a major advance and a completely new way to employ pig islets for the treatment of diabetes," Hammerman says. "In essence, first transplanting embryonic pig pancreatic cells enables adult pig islet implants to cure diabetes in rats without immune suppression drugs. We are now carrying out experiments to test whether the same transplant strategy works in diabetic non-human primates without using immune suppression drugs. If it does, we hope to evaluate pig cell transplants in people with diabetes."
In earlier research, Hammerman and his colleagues demonstrated they could cure diabetes in rats using larger quantities of embryonic pig pancreatic cell clusters alone, without the need for immune suppression drugs. But they hit a roadblock when they attempted the same transplant procedure in non-human primates. The embryonic pig pancreatic cells engrafted in the primates and lowered their blood sugar levels but not enough to wean the animals completely off insulin injections.
"Primates are much larger than rats, and we learned we would need to give them massive amounts of embryonic pig pancreatic tissues, which is not practical," Hammerman says. "Adult pig islets provide a more concentrated source of insulin and are easier to obtain. We are hopeful their ability to effectively control blood sugar levels in rats without an immune suppression requirement will carry over to non-human primates and eventually to humans."
Hammerman and lead author Sharon Rogers, research instructor of medicine, are leaders in the emerging field of organogenesis, which focuses on growing organs from stem cells and other embryonic cell clusters known as organ primordia. Unlike stem cells, which can become virtually any cell type, primordia are locked into becoming a particular cell type or set of cell types that make up an organ.
Funding from the Juvenile Diabetes Research Foundation and the National Institutes of Health (to Washington University's George M. O'Brien Center for Kidney Disease Research) supported the work.

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Plant Pathogen Genetically Tailors Attacks to Each Part of Host

Posted on Sunday, April 18, 2010 by sai kiran reddy


 A tumor-causing maize fungus with the unsavory-sounding name "corn smut" wields different weapons from its genetic arsenal depending on which part of the plant it infects. The discovery by Stanford researchers marks the first time tissue-specific targeting has been found in a pathogen.
The finding upends conventional notions of how pathogens attack and could point the way to new approaches to fighting disease not only in plants but also in people, according to Stanford researchers. Corn smut is a plant cancer.
A maize tassel infected with corn smut. The tumors are the large white, bulbous growths, some of which have turned yellow or brown. (Credit: Linda A. Cicero, Stanford University News Service)

"This establishes a new principle in plant pathology, that a pathogen can tailor its attack to specifically exploit the tissue or organ properties where it is growing," said Virginia Walbot, professor of biology and senior author of a paper published inScience detailing the study. A summary of the study will be published in the May issue of Nature Cancer Reviews as a Research Highlight.
"It would be as if a pathogen of a human could recognize whether it is in muscle or kidney or skin, and activate different genes to exploit the host more effectively," she said.
Up until now, pathologists had always assumed that when a pathogen went on the attack, it used every weapon it had, no matter which part of an organism it was infecting. But Walbot's team found that only about 30 percent of the genes in the corn smut genome are always activated, or "expressed," regardless of whether it is in seedlings, adult leaves or the tassel.
The other 70 percent of the genome is what the fungus would pick and choose from, depending on the tissue it was infecting. Some of those genes were expressed in only one of the three organs the researchers studied; the others were activated in two of the three.
"This is a revolutionary finding," Walbot said.
Her team also discovered that different parts of the maize plant activated different genes in response to being attacked.
"We hope that other people working on pathogens of all types will go back now and ask, 'when the pathogen is found in different parts of the body, is it actually using different weapons?'" Walbot said. "We think this discovery will stimulate many new experiments with existing pathogens."
Pathologists generally collect their samples from the same, characteristic place on the organism they are studying. For a plant, that is typically the leaves or fruit, while in an animal, it is usually a spot where the pathogen of interest is clearly flourishing. But as a result, Walbot said, when researchers happen to find the pathogen in another place in the organism, they generally don't test whether the pathogen is doing different things.
"It may be just the specialization of modern pathology which has resulted in the 'whole organism' context being overlooked," she said.
Walbot hopes that her team's work on corn smut will also inspire new experiments on human disease such as cancer.
"Medicine has made the same assumption that pathogens use all of their weapons wherever they are attacking a human," Walbot said.
But it may be that human pathogens are also situationally selective, genetically modulating the nature of their attack to whatever part of the body they are infecting.
"If that is the case, then we could develop drugs that are specific for the particular organ or tissue where the pathogen is found," Walbot said. "I think that holds great promise for reducing the damage done to the patient in the course of drug treatment."
Walbot got interested in researching the possibility that pathogens might vary their attack while doing fieldwork on a different project for which she was evaluating some mutant strains of maize. She noticed that certain kinds of mutants were resistant to corn smut.
Through a series of experiments with different maize mutants, she determined that the key factor in determining whether -- or how intensely -- corn smut infected a given part of a plant was the potential for growth of that particular type of tissue. Greater potential for continued growth correlated with more intense infections of corn smut and bigger, more plentiful tumors.
The key aspect was the potential -- if a mutant grew only small leaves and then quickly stopped growing, the corn smut wasn't interested, even if there was sufficient area to host some tumors.
Walbot tested how various mutant strains of corn smut behaved when infecting normal maize plants. She discovered that a strain that was highly effective in causing tumors in, say, the tassels might be completely ineffective in triggering tumors in a seedling. That told her that different genes in the fungus were involved depending on which part of the maize the fungus was attacking.
"We found genetic evidence from both the pathogen and the host that depending on the growth potential, in an organ-specific way, of both the pathogen and the host, you could modulate the number of tumors," Walbot said.
The team then set to work with DNA microarrays, lab tools that can screen thousands of genes at a time and determine which ones are active and which are not. The microarray work confirmed and quantified the results of their earlier experiments -- corn smut was indeed situationally selective, to a high degree. Less than a third of its genes were consistently activated regardless of which organ of the maize plant it was infecting.
"We had proof from the microarray that paralleled the genetic proof; that is, that there is organ-specific expression by maize in response to corn smut, and corn smut expresses a specific suite of genes depending on where it is in the plant," Walbot said.
Corn smut, though a common pathogen, does not devastate maize crops and so relatively little work had been done by plant pathology researchers to study it. In Mexico, the fungus is called "huitlacoche," and the tumors, which are used in cooking, are sometimes purposely grown on ears of corn.
"If you order a mushroom omelet in Mexico, the fungus that you are eating is Ustilago maydis, or corn smut," Walbot said.
Though the new findings may not have much impact on those who savor corn smut for its culinary delights, Walbot said researchers are likely to take note.
"That is just a prediction," she said, "but I think pathologists will be quick to pounce on this."
Coauthors of the paper include David Skibbe, a postdoctoral fellow in biology, and John Fernandes, a bioinformaticist and research assistant in biology, both at Stanford. Coauthor Gunther Doehlemann is a research group leader in terrestrial microbiology at the Max Planck Institute for Terrestrial Microbiology, Marburg, Germany

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