April 11, 2007, 9:19 PM CT

Nongreen Plants On Other Planets

NASA researchers believe they have found a way to predict the color of plants on planets in other solar systems.

Green, yellow or even red-dominant plants may live on extra-solar planets, as per researchers whose two scientific papers appear in the recent issue of the journal, Astrobiology. The researchers studied light absorbed and reflected by organisms on Earth, and determined that if astronomers were to look at the light given off by planets circling distant stars, they might predict that some planets have mostly non-green plants.

"We can identify the strongest candidate wavelengths of light for the dominant color of photosynthesis on another planet," said Nancy Kiang, lead author of the study and a biometeorologist at NASA's Goddard Institute for Space Studies, New York. Kiang worked with a team of researchers from the Virtual Planetary Laboratory (VPL) at the California Institute of Technology, Pasadena, Calif. VPL was formed as part of the NASA Astrobiology Institute (NAI), based at the NASA Ames Research Center in California's Silicon Valley.

"This work broadens our understanding of how life may be detected on Earth-like planets around other stars, while simultaneously improving our understanding of life on Earth," said Carl Pilcher, director of the NAI at NASA Ames. "This approach -- studying Earth life to guide our search for life on other worlds -- is the essence of astrobiology"......... Posted by: Erica      Read more         Source

April 10, 2007, 5:56 PM CT

Coral Reef Tells The History Of Soil Erosion

Coral reefs, like tree rings, are natural archives of climate change. But oceanic corals also provide a faithful account of how people make use of land through history, says Robert B. Dunbar of Stanford University.

As per a research findings reported in the Feb. 22 issue of Geophysical Research Letters, Dunbar and colleagues used coral samples from the Indian Ocean to create a 300-year record of soil erosion in Kenya, the longest land-use archive ever obtained in corals. A chemical analysis of the corals revealed that Kenya has been losing valuable topsoil since the early 1900s, when British settlers began farming the region.

"We observed that soil erosion in Kenya increased dramatically after World War I, coinciding with British colonialism and a series of large-scale agricultural experiments that provoked a dramatic change in human use of the landscape," said Dunbar, a professor of geological and environmental sciences. "Today, the Kenyan landscape continues to lose topsoil to the Indian Ocean, primarily because of human pressure".

Erosion is a serious threat, he noted, because the loss of fertile soil often is accompanied by a decrease in food production. As per one recent study, soil erosion is a global problem that has caused widespread damage to agriculture and animal husbandry, placing about 2.6 billion people who are at risk of famine. "This is especially worrisome in East and sub-Saharan Africa, where per capita food production has declined for the last half-century," Dunbar said......... Posted by: Janet      Read more         Source

April 2, 2007, 9:54 PM CT

Picky-eater Flies Losing Smell Genes

A UC Davis researcher is hot on the scent of some lost fruit fly genes. As per population biology graduate student Carolyn McBride, the specialist fruit fly Drosophila sechellia is losing genes for smell and taste receptors 10 times faster than its generalist relative Drosophila simulans. The findings could help scientists understand how some insect pests adapt to feeding on a particular plant.

Genes are lost when mutations destroy their function. "Drosophila sechellia may be losing genes that helped its ancestors detect and assess plants it no longer uses," said McBride, whose research was recently reported in the journal Proceedings of the National Academy of Sciences.

A native of the Seychelles islands in the Indian Ocean, D. sechellia split from its sister species D. simulans half a million years ago -- just a blink of evolutionary time. While D. simulans feeds on a variety of plants, D. sechellia specializes in eating the Indian mulberry, which repels other fruit flies. D. sechellia has evolved resistance to the toxins of its host fruit, and a strong chemical attraction to its scent.

For her genetic analysis, McBride drew on the recently sequenced genomes of D. sechellia and D. simulans, which are available to the public.

"This is the first time that biologists have been able to compare whole genome sequences from closely related insects that differ dramatically in their ecology," she said. McBride also compared the genes of these two flies to another close relative, the classic lab fruit fly Drosophila melanogaster......... Posted by: Janet      Read more         Source

April 1, 2007, 9:07 PM CT

Right angles are all wrong for tree frog adhesion

Tree frogs have the unique ability to stick to smooth surfaces even when they are tilted well beyond the vertical - some small tree frogs can even adhere when completely upside down. On the other hand when walking or jumping they can detach their toe pads easily. Scientists from the University of Glasgow will present insights into how this fascinating ability is controlled at the Society for Experimental Biologys Annual Meeting in Glasgow, UK.

The toe pads of tree frogs are coated with a thin mucus which adhere to surfaces by wet adhesion, like wet tissue paper sticking to glass. The process by which they detach their toe pads is called peeling and is akin to us removing a sticking plaster from ourselves, explains Dr Jon Barnes, head of the research group, We were keen to understand why a tree frog on an overhanging surface didnt simply peel off rather than adhere.

To investigate this, researchers measured adhesive and frictional forces simultaneously on individual toe pads of Whites tree frogs (Family Hylidae), while varying the surface angle. It was observed that the change from adhesion to peeling is a gradual process, with adhesive forces weakening at angles above 90. Thus frogs maintain a grip by keeping the angle of their toes with respect to a surface at a low value, and detach when this angle increases beyond 90. By examining the behaviour of the frogs scientists were able to correlate this observation with how the animals positioned their legs - they spread their legs out sideways to minimise the angle between their feet and the surface......... Posted by: Kelly      Read more         Source

March 27, 2007, 7:01 PM CT

New science of metagenomics

The emerging field of metagenomics, where the DNA of entire communities of microbes is studied simultaneously, presents the greatest opportunity -- perhaps since the invention of the microscope -- to revolutionize understanding of the microbial world, says a new report from the National Research Council. The report calls for a new Global Metagenomics Initiative to drive advances in the field in the same way that the Human Genome Project advanced the mapping of our genetic code.

Microorganisms are essential to life on Earth, transforming key elements into energy, maintaining the chemical balance in the atmosphere, providing plants and animals with nutrients, and performing other functions necessary for survival. There are billions of non-malignant microbes in the human body, for example, that help to digest food, break down toxins, and fight off disease-causing microbes. Microbes are used commercially for a number of purposes, including making antibiotics, remediating oil spills, enhancing crop production, and producing biofuels.

Historically, microbiology focused on the study of individual species of organisms that could be grown in a laboratory and examined under a microscope, but most of the life-supporting activities of microbes are carried out by complex communities of microorganisms, and a number of cannot be grown in laboratory culture. Metagenomics will transform modern microbiology by giving researchers the tools to study entire communities of microbes -- the vast majority of which are likely to be previously unknown species that cannot be cultured -- and how they interact to perform such functions as balancing the atmosphere's composition, fighting disease, and supporting plant growth, the new report says......... Posted by: Janet      Read more         Source

March 25, 2007, 9:31 PM CT

Metabolic Strategy Of Stressed Cell

Investigators at St. Jude Children's Research Hospital have mapped out a number of of the dynamic genetic and biochemical changes that make up a cell's response to a shortage of a molecule called Coenzyme A (CoA), a key player in metabolism. The results provide the most detailed look ever obtained of the complex metabolic changes in a cell triggered by a potentially fatal stress.

Metabolism is the sum of all biochemical reactions involved in maintaining the health of the cell, including breaking down and synthesizing various molecules to produce energy and build substances the cell needs to operate normally. CoA plays key roles in the cell's metabolism by participating in biochemical reactions in specific areas throughout the cell.

The St. Jude study is a significant contribution to the growing field of metabolomicsthe study of the molecules involved in metabolism. Coupled with genetic studies of the cell, metabolomics is giving researchers a more detailed picture of how the body maintains its health in both normal environments and during times of stress, such as starvation or disease.

A report on this work appears in the recent issue of "Chemistry and Biology."

The scientists studied the response to decreased CoA in a mouse model by blocking CoA production with hopantenate (HoPan). HoPan is a chemical that interferes with pantothenate kinase (PanK), the enzyme that triggers the first step of CoA production. Following the shutdown of CoA production, the cells quickly recycled CoA from other jobs so it could concentrate all its efforts on a single task: extracting life-supporting energy from nutrients in the mitochondria. Mitochondria are the powerhouses of the cell, so-called because these bags of enzymes host a series of complex biochemical pathways that produce the energy-rich molecule ATPthe cell's "currency" with which it "buys" chemical reactions that consume energy......... Posted by: Janet      Read more         Source

March 25, 2007, 9:12 PM CT

Man's earliest direct ancestors

Modern man"s earliest known close ancestor was significantly more apelike than previously believed, a New York University College of Dentistry professor has found.

A computer-generated reconstruction by Dr. Timothy Bromage, a paleoanthropologist and Adjunct Professor of Biomaterials and of Basic Science and Craniofacial Biology, shows a 1.9 million-year-old skull belonging to Homo rudolfensis, the earliest member of the human genus, with a surprisingly small brain and distinctly protruding jaw, features commonly associated with more apelike members of the hominid family living as much as three million years ago.

Dr. Bromage"s findings call into question the extent to which H. rudolfensis differed from earlier, more apelike hominid species. Specifically, he is the first scientist to produce a reconstruction of the skull that questions renowned paleontologist and archeologist Richard Leakey"s depiction of modern man"s earliest direct ancestor as having a vertical facial profile and a relatively large brain an interpretation widely accepted until now.

Dr. Bromage"s reconstruction also suggests that humans developed a larger brain and more vertical face with a less pronounced jaw and smaller teeth at least 300,000 years later than commonly believed, perhaps as recently as 1.6 million to one million years ago, when two later species, H. ergaster and H. erectus, lived. Dr. Bromage presented his findings today at the annual scientific session of the International Association for Dental Research in New Orleans......... Posted by: Janet      Read more         Source

March 25, 2007, 8:24 PM CT

Watch Out When They Get Near Wine

Ladybugs may look pretty but they also have a dark side. In some places, the polka-dotted insects have become a nuisance by invading homes and crops, including some vineyards. To make matters worse, the bugs produce a foul-smelling liquid that, besides irritating homeowners, can be inadvertently processed along with grapes and taint the aroma and flavor of wine.

Now, chemists at Iowa State University in Ames, Iowa, say they have identified several compounds that are responsible for the ladybugs noxious odor, a finding that could lead to new strategies to detect and eliminate the offensive compounds. Their study, which could lead to better tasting wine, was presented today at the 233rd national meeting of the American Chemical Society.

A growing number of winemakers say that their wines have an abnormal aroma and flavor, known as ladybug taint, that resembles the bugs characteristic odor. Winemakers report that there are more ladybugs in vineyards and on the grapes during harvest. Experts think that the bugs accidentally become mixed into the juice during processing and fermentation, resulting in inferior wine.

Led by Jacek Koziel, Ph.D., an agricultural engineer at the university, the Iowa scientists used a highly-sensitive multidimensional gas chromatograph and a panel of human sniffers to characterize and identify the odors emitted by a group of live ladybugs as a number of as 300 in all. All of the ladybugs were a single species of multicolored Asian ladybird beetle (Harmonia axyridis)......... Posted by: Kelly      Read more         Source

March 25, 2007, 6:58 PM CT

Excess nutrients or water limit biodiversity

Too much of a good thing (nutrients or water) actually decreases the diversity of species in an ecosystem while it increases the productivity of a few species, as per a grassland experiment conducted by University of Minnesota researchers.

The reduction in species diversity occurs because increasing the amounts of limiting resources, such as nitrogen and water, makes an ecosystem more homogeneous and consequently reduces the number of opportunities for competing species to coexist. Put another way, it reduces the number of niches, allowing a few species to dominate.

The study, conducted by David Tilman, Regents Professor of Ecology, and Stanley Harpole will be published March 25 in the online version of the journal Nature. Harpole, who is now a postdoctoral associate at the University of California, Irvine, was a graduate student at the University of Minnesota when the research was carried out.

"In essence, the data in the article strongly supports a new explanation for why the world contains so a number of species," said Tilman. "It shows that plant diversity is directly correlation to the number of limiting factors (such as soil moisture, nitrogen, phosphorous, potassium and water)."

It also helps explain why grasslands, lakes and rivers that are polluted with nitrogen and phosphorous (commonly from agriculture) have fewer species. The reduction of species where the Mississippi River empties into the Gulf of Mexico is one of the best known examples of this phenomenon......... Posted by: Erica      Read more         Source

March 22, 2007, 10:29 PM CT

Decline In Alaska's Sea Lion Population

A new study out of Alaska points out the impacts of climate change on marine ecosystems, and the need for increased research and stronger science based management to address future concerns.

Studies by a team of scientists at the North Pacific Universities Marine Mammal Research Consortium http://www.marinemammal.org/ revealed that a sudden ocean climate change 30 years ago changed todays Alaska marine ecosystems, and may be a leading factor in the decline of Alaskas endangered western stock of Steller sea lions.

Theories why the Steller sea lion population declined by more than 80 percent during the 1980s include pollution, commercial fishing, and subsistence harvesting. The new study points instead to a climate regime shifta natural event in the oceans climatic cyclein the late 1970s that may be responsible for current regional population of about 40,000, compared with 235,000 in the 1970s.

The publication, entitled Bottom-up forcing and the decline of Steller sea lions in Alaska: assessing the ocean climate hypothesis observed that climate change affected water temperatures and ocean currents determining the abundance of available fish for the sea lions to eat. Changes in prey led to a decline in the sea lion population. Using interdisciplinary research methods was key in determining the root cause of the sea lion decline......... Posted by: Kelly      Read more         Source