September 28, 2008, 8:40 PM CT

Gene that may contribute to improved rice yield

A team of scientists, including Penn State Distinguished Professor of Biology Hong Ma, has identified a gene in rice that controls the size and weight of rice grains. The gene may prove to be useful for breeding high-yield rice and, thus, may benefit the vast number of people who rely on this staple food for survival. "Our work shows that it is possible to increase rice's yield by enhancing the expression of a particular gene," said Ma. The team's results will be published on 28 September 2008 in an early online edition of the journal Nature Genetics, and in the November print issue of the journal.

The scientists first searched for and identified mutant strains of rice that exhibited underweight grains. "We found a particular mutant that is defective in its ability to produce normal-sized grains," said Zuhua He, a biology professor at the Chinese Academy of Sciences and the leader of the team. The group then examined the mutant and observed that it carried a mutation within the GIF1 gene. "The GIF1 gene is responsible for controlling the activity of the enzyme invertase, which is located in the cell wall and converts sucrose to substances that then are used to create starch," said He. "Invertase is important in the formation of starch within developing grains of rice. If invertase is not active, the rice plant cannot produce edible grains"......... Posted by: Erica      Read more         Source

September 28, 2008, 8:38 PM CT

Reversible 3-D cell culture gel invented

Singapore's Institute of Bioengineering and Nanotechnology (IBN), which celebrates its fifth anniversary this year, has invented a unique user-friendly gel that can liquefy on demand, with the potential to revolutionize three-dimensional (3D) cell culture for medical research.

As reported in Nature Nanotechnology (Y.S. Pek, A. C. A. Wan, A. Shekaran, L. Zhuo and J. Y. Ying, "A Thixotropic Nanocomposite Gel for Three-Dimensional Cell Culture"), IBN's novel gel media has the unique ability to liquefy when it is subjected to a moderate shear force and rapidly resolidifies into a gel within one minute upon removal of the force. This phenomenon of reverting between a gel and a liquid state is known as thixotropy.

IBN's thixotropic gel is synthesized from a nanocomposite of silica and polyethylene glycol (PEG) under room temperature, without special storage conditions. This novel material facilitates the safe and convenient culture of cells in 3D since cells can be easily added to the gel matrix without any chemical processes.

As per IBN Executive Director Jackie Y. Ying, Ph.D., "Cell culture is conventionally performed on a flat surface such as glass slides. It is an essential process in biological and medical research, and is widely used to process cells, synthesize biologics and develop therapys for a large variety of diseases......... Posted by: Janet      Read more         Source

September 18, 2008, 9:56 PM CT

GenesControlling Rhythmic Plant Growth

A team of biologists from UC San Diego, the Salk Institute for Biological Studies and Oregon State University has identified the genes that enable plants to undergo bursts of rhythmic growth at night and allow them to compete when their leaves are shaded by other plants.

The scientists report in this week's issue of the journal PLoS Biology that these genes control the complex interplay of plant growth hormones, plant light sensors and circadian rhythms that permit plants to undergo rhythmic growth spurts at specific times of the day or year in response to varying levels of light and other environmental conditions.

Their discovery of the genetic underpinnings of the rhythmic plant movements that enthralled Charles Darwin more than a century ago could eventually allow researchers to design crops that can grow substantially faster and produce more food than the most productive varieties today.

"This paper builds on our prior findings that almost all plant genes are expressed only at a particular time of the day," said Howard Hughes Medical Institute investigator Joanne Chory, a professor in the Salk Institute's Plant Biology Laboratory.

"What we found is a whole raft of genes that could be the actual molecular switches that define plant growth at the molecular level," said Steve Kay, Dean of the Division of Biological Sciences at UC San Diego and one of the leaders of the research team. "The more we understand about these genetic mechanisms and how they switch on and off plant growth, the better we will be at designing tailor-made crops to increase our production of food and fuel for the world's rapidly growing population"......... Posted by: Erica      Read more         Source

September 18, 2008, 9:18 PM CT

Coating copies microscopic biological surfaces

Someday, your car might have the metallic finish of some insects or the deep black of a butterfly's wing, and the reflectors might be patterned on the nanostructure of a fly's eyes, as per Penn State scientists who have developed a method to rapidly and inexpensively copy biological surface structures.

"Only a small fraction of mutations in evolutionary processes are successful," said Akhlesh Lakhtakia, the Charles Godfrey Binder (Endowed) Professor of Engineering Science and Mechanics. "But evolution has gone on for at least a billion years. A huge range of biological surface architectures have been created and are available".

Lakhtakia and colleagues, Carlo G. Pantano, distinguished professor of materials science and engineering, and director of Penn State's Materials Research Institute, and Raúl J. Martín-Palma, visiting professor, Penn State, and professor department of applied physics, Universidad Autonomia de Madrid, used the conformal evaporated film by rotation (CEFR) technique to produce coatings that capture the micro- and nanostructure of biological surfaces in a thin coating of glass. The results appear in recent issues of Applied Physics Letters and Nanotechnology.

In the CEFR technique, the scientists thermally evaporate the material that forms the coating in a vacuum chamber. The object receiving the coating is fixed to a holder and rotated about once every two seconds. The scientists have coated butterfly wings and a fly, creating replicas of these templates with identical surface characteristics. The scientists are using chalcogenide glasses composed of varying combinations of germanium, antimony and selenium......... Posted by: Kelly      Read more         Source

September 18, 2008, 9:09 PM CT

Walnut Trees Emit Aspirin-Like Chemical to Deal With Stress

Walnut trees respond to stress by producing significant amounts of a chemical form of aspirin, researchers have discovered.

The finding, by researchers at the National Center for Atmospheric Research (NCAR) in Boulder, Colo., opens up new avenues of research into the behavior of plants and their impacts on air quality, and also has the potential to give farmers an early warning signal about crops that are failing.

"Unlike humans, who are advised to take aspirin as a fever suppressant, plants have the ability to produce their own mix of aspirin-like chemicals, triggering the formation of proteins that boost their biochemical defenses and reduce injury," says NCAR scientist Thomas Karl, who led the study. "Our measurements show that significant amounts of the chemical can be detected in the atmosphere as plants respond to drought, unseasonable temperatures, or other stresses".

For years, researchers have known that plants in a laboratory may produce methyl salicylate, which is a chemical form of acetylsalicylic acid, or aspirin. But scientists had never before detected methyl salicylate in an ecosystem or verified that plants emit the chemical in significant quantities into the atmosphere.

The team of researchers reported its findings last week in the journal Biogeoscience. The research was funded by the National Science Foundation (NSF), NCAR's sponsor......... Posted by: Erica      Read more         Source

September 18, 2008, 9:01 PM CT

'Redesigned hammer' that forged evolution of pregnancy in mammals

New Haven, Conn. Yale scientists have shown that the origin and evolution of the placenta and uterus in mammals is linked to evolutionary changes in a single regulatory protein, as per a report in Proceedings of the National Academy of Sciences

"A number of past studies have shown that genes are regulated and altered by changes within their own structures. This is the first work suggesting that the evolution of transcription factors separate regulatory proteins may play an active role in the origin and evolution of structural innovations like the placenta and uterus," said senior author Gunter Wagner, the Alison Richard Professor of Ecology & Evolutionary Biology at Yale.

Pregnancy is a biologically unusual situation where one organism lives and develops inside another that is genetically different. Ordinarily, the immune system identifies and destroys the dissimilar tissue as if it were a parasite. But in some early mammals, changes 'turned down' the immune system, allowing the developing embryo to grow and thrive unchallenged by the maternal immune response.

With the evolution of the uterus and placenta, it became possible for mammals to protect their growing young and to ensure they were not exposed to an unpredictable environment, like their egg-laying relatives. This study identified one of the genetic switches that tempered the immune system and allowed formation of the placenta and internal development of young......... Posted by: Kelly      Read more         Source

September 14, 2008, 10:19 PM CT

How corals adapt to day and night

Researchers have uncovered a gene in corals that responds to day/night cycles, which provides some tantalizing clues into how symbiotic corals work together with their plankton partners.

Corals are fascinating animals that form the largest biological constructions in the world, sprawling coral reefs that cover less than 0.2 % of the seafloor yet provide habitats for more than 30% of marine life. In shallow waters that don't have abundant food, corals have developed a close relationship with small photosynthetic critters called dinoflagellates. The dinoflagellates use sunlight to produce energy for the coral, which in turn use that energy to construct mineralized skeletons for protection. The mineral production, known as coral calcification, is closely tied with the day/night cycle, though the molecular mechanism behind this synchronization is mysterious.

Aurelie Moya and colleagues have now characterized the first coral gene that responds to the light cycle; this gene, called STPCA, makes an enzyme that converts carbon dioxide to bicarbonate (baking soda) and is twice as active at night compared to daytime. The researchers found that the enzyme concentrates in the watery layer right under the calcified skeleton, which combined with studies showing that STPCA inhibitors lower calcification rates, confirms a direct role for STPCA in this process......... Posted by: Janet      Read more         Source

September 10, 2008, 8:41 PM CT

A molecular clue to evolution

A Florida State University researcher who uses high-powered computers to map the workings of proteins has uncovered a mechanism that gives researchers a better understanding of how evolution occurs at the molecular level.

Such an understanding eventually could lead to the development of new and more effective antiparasitic drugs.

Wei Yang is an assistant professor in FSU's Department of Chemistry and Biochemistry and a faculty member in the university's Institute of molecular biophysics. Working with colleagues from FSU, Duke University and Brandeis University, he recently produced remarkable computer models of an enzyme that carries the unwieldy name of inosine monophosphate dehrydrogenase, or IMPDH for short. IMPDH is responsible for initiating certain metabolic processes in DNA and RNA, enabling the biological system to reproduce quickly.

"In creating these simulations of IMPDH, we observed something that hadn't been seen before," Yang said. "Previously, enzymes were believed to have a single 'pathway' through which they deliver catalytic agents to biological cells in order to bring about metabolic changes. But with IMPDH, we determined that there was a second pathway that also was used to cause these chemical transformations. The second pathway didn't operate as efficiently as the first one, but it was active nevertheless"......... Posted by: Janet      Read more         Source

September 10, 2008, 8:04 PM CT

Okapi survived poaching onslaught

A set of stripy legs in a camera trap photo snapped in an African forest indicates something to cheer about, say scientists from the Wildlife Conservation Society. The legs belong to an okapia rare forest giraffewhich apparently has survived in the Democratic Republic of Congo's Virunga National Park, despite over a decade of civil war and increased poaching.

"This is the first time this species has been captured on film in this park. Known to occur in the park from the early 1900s it had not been seen here for over 50 years. Two years ago sightings of dung and other tracks were made in the park by a team of pygmy trackers who knew Okapi sign. It is very encouraging to see that this animal has survived," said WCS researcher, Deo Kujirakwinja, who organized the recent camera trap survey. "A number of animals have suffered in this park as a result of the ten years of insecurity in the region, so it's encouraging to see that the okapi has survived".

Measuring up to 8 feet in length and standing up to 6 feet at the shoulder, the okapi has striped legs that give the animal a superficial resemblance to a zebra. It is, in fact, a close relative of the much larger giraffe. The animal's current range occurs in the Ituri Forest in northern DR Congo. They are classified as Near Threatened by the World Conservation Union (IUCN) and are at risk primarily from habitat destruction......... Posted by: Kelly      Read more         Source

September 10, 2008, 6:58 PM CT

Small males are more often meals

Female spiders are voracious predators and consume a wide range of prey, which sometimes includes their mates. Many hypotheses have been proposed for why females eat males before or after mating. Scientists Shawn Wilder and Ann Rypstra from Miami University in Ohio found, as per a research findings reported in the recent issue of the American Naturalist, that the answer may be simpler than previously thought. Males are more likely to be eaten if they are much smaller than females, which likely affects how easy they are to catch. In one species of spider, Hogna helluo, large males were never consumed while small males were consumed 80% of the time. This result was also confirmed when Wilder and Rypstra examined published data from a wide range of spider species. Males are more likely to be eaten in species where males are small relative to females.

Much research on sexual cannibalism has focused on a few extreme cases involving sexual selection and sperm competition. However, by looking at data on a wide range of spiders, Wilder and Rypstra discovered that the size of the male relative to the female (often referred to as sexual size dimorphism) determines how often sexual cannibalism occurs in a species. "We were surprised to find that such a simple characteristic such as how small males are relative to females has such a large effect on the frequency of sexual cannibalism," states Shawn Wilder. In a number of cases, sexual cannibalism may not be a complex balancing act of costs and benefits for males and females but rather a case of a hungry female eating a male when he is small enough to catch. In an interesting twist, evolution does not appear to be driving this relationship. For example, females would not become larger to consume more males because each male would then be a smaller meal to the larger female and males would not become smaller to be eaten more often because they would not get to mate as often. Rather, sexual cannibalism may be a byproduct of the evolution of large females and small males in a predatory species......... Posted by: Kelly      Read more         Source