April 21, 2009, 5:19 AM CT

How cells change gears

Bioinformatics scientists from UC San Diego just moved closer to unlocking the mystery of how human cells switch from "proliferation mode" to "specialization mode." This computational biology work from the Jacobs School of Engineering's bioengineering department could lead to new ideas for curbing unwanted cell proliferationincluding some cancers. This research, published in Nature Genetics, could also improve our understanding of how organs and other complex tissues develop.

The UC San Diego bioengineers are part of a Japan-based global research consortium, the Genome Network Project, which generated one of the first close-to-comprehensive looks at a human cell's entire network of proteins called "transcription factors." Each human cell contains approximately 2,000 transcription factors, which are proteins that bind to specific locations on the cell's DNA. Once bound to DNA, transcription factors work to either encourage or prevent "transcription"the process by which messenger RNA is generated from DNA. These messenger RNA strands then travel to cellular factories called ribosomes which churn out proteins based on the specifications of the mRNA.

"Transcription is one of the most important events in the cellit determines cell morphology and cell function," said Timothy Ravasi, a UC San Diego research scientist from the bioengineering department and author on the new Nature Genetics paper......... Posted by: Janet      Read more         Source

April 20, 2009, 9:54 PM CT

Nitrogen-fixing bacteria protect soybeans

An invasion of soybean aphids poses a problem for soybean farmers requiring application of pesticides, but a team of Penn State entomologists thinks a careful choice of nitrogen-fixing bacteria may provide protection against the sucking insects.

Soybeans are legumes, plants that can have a symbiotic relationship with nitrogen-fixing bacteria - rhizobia - and therefore do not need additional nitrogen fertilizer. Each type of legume - peas, beans, lentils, alfalfa - have their own rhizobia.

"Soybeans are from Asia and so there were originally no nitrogen-fixing bacteria that would colonize soybeans in U.S. soils," said Consuelo De Moraes, associate professor of entomology. "The rhizobia had to be transferred here".

The soybean aphid is also not native to North America. This pest only began to infest soybean fields about 10 years ago but are now fully established pests requiring pesticide applications to avoid the loss of as much as 40 percent of the crop. The scientists investigated the relationship between the type of rhizobia colonizing soybean plants and the plants' infestation with the aphids.

"Our results demonstrate that plant-rhizobia interactions influence plant resistance to insect herbivores and that some rhizobia strains confer greater resistance to their mutualist partners than do others," the scientists report in the journal Plant and Soil online......... Posted by: Janet      Read more         Source

April 20, 2009, 9:42 PM CT

New Chemical Reaction for DNA Production

A team of scientists has discovered a new chemical reaction for producing one of the four nucleotides, or building blocks, needed to build DNA. The reaction includes an unusual first step, or mechanism, and unlike other known reactions that produce the DNA building block, uses an enzyme that speeds up, or catalyzes, the reaction without bonding to any of the compounds, or substrates, in the reaction.

The chemical reaction discovered by the scientists uses an enzyme called flavin-dependent thymidylate synthase, or FDTS. The enzyme is coded by the thyX gene and has been found primarily in bacteria and viruses, including several human pathogens and biological warfare agents. In the future, researchers may use this knowledge for the development of new antibacterial and antiviral drugs.

Supported with partial funding from the National Science Foundation (NSF) and led by Amnon Kohen, an associate professor in the departments of chemistry and molecular and cellular biology at the University of Iowa, the team reports their findings in the April 16, 2009, issue of Nature, Letters section.

Previous to the team's discovery, it was thought that thymidylate synthase, or TS, was the primary enzyme catalyzing a reaction that produced one of the four DNA building blocks called deoxy-thymidine monophosphate......... Posted by: Janet      Read more         Source

April 20, 2009, 9:37 PM CT

Unusual Antarctic Microbes Lived in Extreme Conditions

An unmapped reservoir of briny liquid chemically similar to sea water, but buried under an inland Antarctic glacier, appears to support unusual microbial life in a place where cold, darkness and lack of oxygen would previously have led researchers to believe nothing could survive, as per newly published research.

After sampling and analyzing the outflow from below the Taylor Glacier, an outlet glacier of the East Antarctic Ice Sheet in the otherwise ice-free McMurdo Dry Valleys of Antarctica, scientists think that, lacking enough light to make food through photosynthesis, the microbes have adapted over the past 1.5 million years to manipulate sulfur and iron compounds to survive.

The microbes also are remarkably similar in nature to species found in marine environments, leading to the conclusion that the populations under the glacier are the remnants of a larger population of microbes that once occupied a fjord or sea that received sunlight. A number of of these marine lineages likely declined, while others adapted to the changing conditions when the Taylor Glacier advanced, sealing off the system under a thick ice cap.

The research would be reported in the April 17 edition of the journal Science.

The research answers some questions and raises others about the persistence of life in extreme environments such as under glaciers, or even in liquid lakes trapped kilometers under the Antarctic ice sheet, environments that until recently researchers would not have believed could support living creatures......... Posted by: Janet      Read more         Source

April 20, 2009, 5:15 AM CT

Antioxidant benefits of tart cherries

Eating just one and a half servings of tart cherries could significantly boost antioxidant activity in the body, according to new University of Michigan research reported at the 2009 Experimental Biology meeting in New Orleans.¹ In the study, healthy adults who ate a cup and a half of frozen cherries had increased levels of antioxidants, specifically five different anthocyanins the natural antioxidants that give cherries their red color.

Twelve healthy adults, aged 18 to 25 years, were randomly assigned to eat either one and a half cups or three cups of frozen tart cherries. Researchers analyzed participants' blood and urine at regular intervals after they ate the cherries and found increased antioxidant activity for up to 12 hours after eating cherries.

"This study documents for the first time that the antioxidants in tart cherries do make it into the human bloodstream and is coupled with increased antioxidant activity that could have a positive impact," said Sara L. Warber, MD, Co-Director of University of Michigan Integrative Medicine and principal investigator of the study. "And, while more research is needed, what's really great is that a reasonable amount of cherries could potentially deliver benefits, like reducing risk factors for heart disease and inflammation." ......... Posted by: Erica      Read more         Source

April 17, 2009, 5:22 AM CT

Museum specimens aid conservation efforts

There is a new tool for those developing conservation strategies for threatened species and landscapes: museum specimens. Richard Pearson and Christopher Raxworthy of the American Museum of Natural History dusted off many collections from Madagascar and used the location information linked to each species to test different ideas regarding the evolution of locally distributed endemism (unique species confined to small regions). The research paper published this month in Evolution found support for alternative hypotheses, suggesting that multiple processes develop local endemism. This improved knowledge of the processes that lead to endemism can help to identify priorities in conservation planning.

"Museum records can be used for conservation purposes, particularly because they tie together generations of data," says Pearson, a Biodiversity Scientist at the Museum's Center for Biodiversity and Conservation. "Madagascar is a unique natural laboratory for this project because of the large amount of local endemism and because the government's decision to set aside land has spurred an effort to prioritize the location of reserves within the landscape".

Madagascar is an island nation in the Indian Ocean that has been completely isolated from other land masses for the last 80 million years. Isolation has led to a high number of unique species like chameleons (Furcifer petteri), lemurs (Lemur catta), and day geckos (Phelsuma madagascariensis) which, in turn, has led Madagascar to be labeled a biodiversity "hotspot" by conservation groups. The Malagasy government pledged to set aside 10 percent of the land for conservation purposes as part of the 2003 World Parks Congress in Durban. Prior research papers have attempted to use species location records to determine which areas of the island would conserve the largest number of species......... Posted by: Kelly      Read more         Source

April 17, 2009, 5:20 AM CT

Size and suitability as a mate

A new study by scientists at the University of Alaska Fairbanks offers evidence that in one breed of northern seabird, the size of males' feather crests appears to be more than simple ornamentation.

Their study, published this month in of the Journal of Comparative Physiology B, shows that crest size appears to be a physical indicator of a male crested auklet's quality as a mate.

Researchers have long noted that female auklets prefer males with larger crests. But until recently, they did not know why. Low levels of stress hormones in males with larger crests indicate that they cope better with the stresses of reproduction, such as finding food, competing with thousands of other birds for mates and nest sites, and helping rear chicks.

"Females will divorce shorter-crested mates for the opportunity to mate with longer-crested males. Our study suggests that longer-crested males could contribute more to reproductive success because they have greater capacity to meet the social and physiological costs," said Hector Douglas, assistant professor of biology at the Kuskokwim Campus in Bethel.

Douglas and collaborator Alexander Kitaysky, an associate professor at the UAF Institute of Arctic Biology, say their results fit into a larger theory about animal societies......... Posted by: Kelly      Read more         Source

April 17, 2009, 5:17 AM CT

What life may have been like for dinosaurs?

During the last 540 million years, the earth's oxygen levels have fluctuated wildly. Knowing that the dinosaurs appeared around the time when oxygen levels were at their lowest at 12%, Tomasz Owerkowicz, Ruth Elsey and James Hicks wondered how these monsters coped at such low oxygen levels. But without a ready supply of dinosaurs to test their ideas on, Owerkowicz and Hicks turned to a modern relative: the alligator. 'We knew testing the effects of different oxygen levels would work with alligators,' Owerkowicz explains, 'because crocodilians have survived in their basic shape and form for 220 million years. They must be doing something right to have survived the oxygen fluctuations.' Choosing to start at the beginning of alligator development, the trio decided to try incubating alligator eggs at different oxygen levels, to find out how the youngsters grew and developed and publish their results on April 17 2009 in The Journal of Experimental Biology at http://jeb.biologists.org.

Receiving newly laid alligator eggs from Elsey at the Rockefeller Wildlife Refuge, Owerkowicz divided the eggs into groups incubated at 12% (low) oxygen, 21% (normal) oxygen and 30% (high) oxygen, and waited to see what would happen. After almost 10 weeks of waiting, the eggs began hatching and Owerkowicz could see that there were no obvious differences between the alligators that developed in normal and high oxygen atmospheres......... Posted by: Kelly      Read more         Source

April 16, 2009, 5:26 AM CT

Red pandas and sweet tooth

PHILADELPHIA (April 15, 2009) -- Scientists from the Monell Center report that the red panda is the first non-primate mammal to display a liking for the artificial sweetener aspartame. This unexpected affinity for an artificial sweetener may reflect structural variation in the red panda's sweet taste receptor.

The findings may shed light on how taste preferences and diet choice are shaped by molecular differences in taste receptors.

"The red panda's unique taste receptor gives us a tool to broaden our understanding of how we detect sweet taste," said the paper's senior author, Joseph G. Brand, PhD, a biophysicist at Monell. "Greater insight into why we like artificial sweeteners could eventually lead to the development of more acceptable sugar substitutes, potentially benefiting diabetics and other individuals on sugar-restricted diets".

A number of species like sweet-tasting foods, but there are some exceptions. In an earlier study, Brand and Monell comparative geneticist Xia Li, PhD, reported that cats both domestic and wild can not taste sweets due to a defect in one of the genes that codes for the sweet taste receptor.

The current research extended those findings by relating sweet preferences to genetic analyses of sweet receptor structure in six related species. Like the cat, each of the species tested -- red panda, ferret, genet, meerkat, mongoose, and lion -- belongs to the Order Carnivora......... Posted by: Kelly      Read more         Source

April 16, 2009, 5:23 AM CT

Researcher names lichen after President Obama

A researcher at UC Riverside has discovered a new species of lichen a plant-like growth that looks like moss or a dry leaf and named it after President Barack Obama.

"I discovered the new species in 2007 while doing a survey for lichen diversity on Santa Rosa Island in California," said Kerry Knudsen, the lichen curator in the UCR Herbarium. "I named it Caloplaca obamae to show my appreciation for the president's support of science and science education".

Knudsen published his discovery in the recent issue of the journal Opuscula Philolichenum

"I made the final collections of C. obamae during the suspenseful final weeks of President Obama's campaign for the United States presidency, and this paper was written during the international jubilation over his election," Knudsen said. "Indeed, the final draft was completed on the very day of President Obama's inauguration".

C. obamae, the first species of any organism to be named in honor of President Obama, grows on soil and almost became extinct during the days of cattle ranching that spanned nearly a hundred years on Santa Rosa Island.

"This species barely survived the intensive grazing of cattle, elk and deer on Santa Rosa Island," Knudsen said. "But with cattle now removed, it has begun to recover. With future removal of elk and deer both of which were introduced to the island it is expected to fully recover"......... Posted by: Janet      Read more         Source