November 7, 2006, 4:19 AM CT

Green Plants Share Bacterial Toxin

A toxin that can make bacterial infections turn deadly is also found in higher plants, researchers at UC Davis, the Marine Biology Laboratory at Woods Hole, Mass. and the University of Nebraska have found. Lipid A, the core of endotoxin, is located in the chloroplasts, structures that carry out photosynthesis within plant cells.

The lipid A in plant cells is evidently not toxic. The human intestine contains billions of Gram-negative bacteria, but lipid A does not become a problem unless bacteria invade the bloodstream.

"We've no idea what it's doing, but it must be something important because it's been retained for a billion years of evolution of plant chloroplasts," said Peter Armstrong, professor of molecular and cellular biology at UC Davis and senior author on the paper.

Endotoxin is better known to bacteriologists and physicians as part of the outer coat of Gram-negative bacteria such as E. coli. The lipid A core of bacterial endotoxin activates the immune system and can cause septic shock, a major cause of death from infection. It is distinct from the toxin found in E. coli strain 0157, responsible for the recent outbreak of food poisoning tied to spinach.

Bacteria were thought to be the only source of lipid A. However, R.L. Pardy, professor at the University of Nebraska-Lincoln, recently found a similar molecule in Chlorella, a single-celled relative of more advanced plants. Armstrong's lab at UC Davis developed methods to visualize lipid A in cells, using a protein from the immune system of the horseshoe crab, and the researchers began collaborating.........

Posted by: Erica      Permalink         Source

November 2, 2006, 8:53 PM CT

Where Seeds Store Iron

Biologists have learned where and how some plant seeds store iron, a valuable discovery for scientists working to improve the iron content of plants. Their research helps address the worldwide problem of iron deficiency and malnutrition in humans.

The team found that iron is stored in the developing vascular system of the seed of Arabidopsis, a model plant used in research. In particular, iron is stored in the vacuole, a plant cell's central storage site. The researchers also learned this localization depends on a protein called VIT1, known to transport iron into the vacuole.

"Iron deficiency is the most common human nutritional disorder in the world today, afflicting more than 3 billion people worldwide," said Mary Lou Guerinot, a biologist at Dartmouth College in N.H. and the principal investigator on the study. "Most of these people rely on plants for their dietary iron, but plants are not high in iron, and the limited availability of iron in the soil can limit plant growth. Our study suggests that iron storage in the vacuole is a promising, and, before now, largely unexplored target for increasing the iron content of seeds. Such nutrient-rich seeds would benefit both human health and agricultural productivity."

The findings were published online in the Nov. 2, 2006, ScienceExpress, the advance publication site for the journal Science.........

Posted by: Erica      Permalink         Source

November 1, 2006, 5:26 PM CT

Why There Are More Species In The Tropics?

Why are there more species in the tropics than in the temperate regions of the globe? Many of the world's species live in the tropics (perhaps more than half), but the reason has been debated for more than 100 years.

Many researchers have hypothesized that climatic factors somehow cause species to originate more quickly in tropical regions. In a paper appearing in the recent issue of The American Naturalist, John Wiens and a group of researchers from Stony Brook University have shown that, contrary to expectations, species seem to evolve at similar rates in tropical and temperate regions. What causes the difference in species numbers between tropical and temperate regions is not something special about the tropics that leads to more rapid speciation, but rather that the temperate areas were colonized more recently, leaving less time for species to originate and accumulate in these regions.

The researchers studied the causes of high tropical species richness in treefrogs in the Americas. Combining analyses of evolutionary trees based on DNA sequences with GIS-based methods for analyzing the effects of climate on species distributions, the researchers found no relationship between how quickly species originate within a group and whether that group is tropical or temperate.........

Posted by: Janet      Permalink         Source

November 1, 2006, 4:19 PM CT

Old Leaves Need To Die In Time

In a study from the recent issue of The American Naturalist, researchers Alex Boonman and co-workers from the Netherlands show that it is beneficial for plants growing in a dense stand to shed their oldest, lower leaves once these become shaded. By using transgenic tobacco plants that do not shed their lower leaves, they were able to show that shaded old leaves become a burden to a plant because they no longer photosynthesize but still require energy to be maintained.

Moreover, the nutrients in these leaves can be more usefully employed by the plant when re-allocated to new leaves at the top of the canopy, where more light is available and higher photosynthetic rates can be attained. Previously, theoretical modeling has been extensively used to investigate how plants should distribute their leaf area and nutrients to maximize their photosynthesis and fitness. However, a direct experimental test was lacking till now.

"Keeping up with the neighbors is important for plants in leaf canopies" Alex Boonman states, "because failure to project enough leaf area at the top of the canopy means that some other plant will do it, with shading and therefore diminished photosynthesis as the consequence." The transgenics, which were originally developed by Susheng Gan and Richard Amasino at the University of Wisconsin, indeed produced less leaf area in the upper canopy layer than normal plants and performed less well in competition exeriments.........

Posted by: Erica      Permalink         Source

October 31, 2006, 4:56 AM CT

Grasslands To Go Native

Montana rancher and inventor Lee Arbuckle may soon change the nation's market for native grass seed, a tricky-to-harvest crop worth hundreds of millions and vital to restoring wildlands.

With the help of the Montana Manufacturing Extension Center at Montana State University, Arbuckle and his wife Maggie have spent the last five years researching and developing a native grass seed harvester. The Arbuckle Native Seedster will be manufactured in Billings, with the first one on the market in 2007.

"We're going to change the economics of the native grass seed industry," Arbuckle said. "The Seedster isn't a combine or a stripper, but a new-fangled plucker. This harvester isn't a better mousetrap; it's the first one".

Native grass seed is a growing market. Federal, state and local governments purchase large amounts of native seed, as do ranchers and landscapers. Such seed produces grasses that are prized for their drought and wildfire resistance, ability to stabilize eroding soil, desirability as forage and reseeding capacity. Much of the seed market is for the restoration of lands disturbed by mining, road construction and fires.

The Plant Materials Program of the U.S. Department of Agriculture estimated that in 2001 more than 19 million pounds of PMP released varieties of native seed species sold for $94 million, representing only a fraction of the market.........

Posted by: Erica      Permalink         Source

October 26, 2006, 4:56 AM CT

Pollinators Help One-third Of Crop Production

Pollinators such as bees, birds and bats affect 35 percent of the world's crop production, increasing the output of 87 of the leading food crops worldwide, finds a new study published recently (Wednesday, Oct. 25), in the Proceedings of the Royal Society B: Biological Sciences and co-authored by a conservation biologist at the University of California, Berkeley.

The study is the first global estimate of crop production that is reliant upon animal pollination. It comes one week after a National Research Council (NRC) report detailed the troubling decline in populations of key North American pollinators, which help spread the pollen needed for fertilization of such crops as fruits, vegetables, nuts,.

Of particular concern in the NRC report was the decline of the honey bee, a species introduced from Europe and a critical pollinator for California's almond industry. The report pointed out that it takes about 1.4 million colonies of honey bees to pollinate 550,000 acres of this state's almond trees.

In an effort to better understand how dependent crop production is upon pollinators worldwide, an international research team led by Alexandra-Maria Klein, an agroecologist from the University of Goettingen in Gera number of, conducted an extensive review of scientific studies from 200 countries and for 115 of the leading global crops.........

Posted by: Erica      Permalink         Source

October 22, 2006, 8:19 PM CT

Newton's Apple Tree Bears Fruit

Ed Vetter (S.B. 1942) gave MIT an apple tree that is a direct descendant of the tree under which Isaac Newton sat when he is said to have conceived the theory of gravity.

"I couldn't think of a better place than MIT to put a tree that illustrates a law of physics," says Vetter, whose tree stands in MIT's President's Garden, a sunny spot off the Infinite Corridor.

This fall, the beloved tree bore bright, healthy fruit--a sure sign of flourishing and a link between past and present days.

The MIT apple tree was grown from a cutting of a tree in England's Royal Botanical Gardens that was grown from a cutting of Newton's apple tree. Vetter was given the plant as a gift from the National Bureau of Standards when he left office as undersecretary of the U.S. Commerce Department in 1977. He presented the young plant to MIT that same year.

"I'll be honest with you, whenever I'm at MIT I always stop to see how the tree is doing," he says. "I've watched it grow from eight inches to 12 feet. It makes me feel good to know that it has flourished and that people enjoy it".

It is a fact, he says, that over the years the tree has become the apple of his eye.........

Posted by: Erica      Permalink         Source

October 16, 2006, 9:22 PM CT

Dietitian Offers Substitutes For Spinach's Nutrients

While the U.S. Food and Drug Administration has lifted the ban on fresh spinach and the produce is back on a number of grocery store shelves and restaurant plates, some consumers may not be so eager to return to eating the leafy greens that left at least three people dead and 199 others sickened across 26 states after an E coli O157:H7 outbreak.

A dietitian at Washington University in St. Louis offers advice on finding new sources of the nutrients offered by spinach for those who are avoiding the leaf vegetable because they are still concerned about its safety.

"If you're wary of fresh spinach, there are other foods out there to take its place," says Connie Diekman, R.D., director of University Nutrition at Washington University in St. Louis. "It's important to remember that if spinach was a staple of your diet and you're just not ready to eat it again, be sure to replace those nutrients you're missing with something equally nutritious. A variety of foods can meet the nutrient needs of spinach and that variety can spice your menus and meet your needs too!".

Since the FDA issued its warning on Sept. 14 of an E coli O157:H7 outbreak citing fresh bagged spinach as the main suspect, a number of spinach lovers have had to improvise, and Diekman admits it's hard to beat the nutrients in spinach.........

Posted by: Erica      Permalink         Source

October 16, 2006, 9:09 PM CT

Apricot And Cashew Nut Leftovers

I was surfing this morning and this article got my attention.

Apricot and cashew nut by-products can be used as renewable feedstocks to make nanomaterials, say researchers in the US.

George John and Praveen Kumar Vemula from the City College of the City University of New York, US, have used plant-derived resources to make a variety of soft nanomaterials, which are useful for a wide variety of applications.

John started with amygdalin, a by-product from the apricot industry and used an enzyme catalysis route to make amphiphiles - molecules with both hydrophilic and hydrophobic parts - that have very effective gelation properties, even before purification. John used the hydrogel formed from these amphiphiles as a successful drug delivery vehicle for curcumin, a well-known drug with anti-inflammatory and anti-cancer properties. 'Enzyme catalysis was used as a tool to make and break the hydrogels, which triggered controlled drug delivery,' said John.........

Posted by: Erica      Permalink         Source

October 12, 2006, 9:04 PM CT

Health of Florida's Coral Reef

NASA satellite data was used to help monitor the health of Florida's coral reef as part of a field research effort completed this August and September.

The project was the first comprehensive assessment of the resiliency of reefs along the National Oceanic and Atmospheric Administration's (NOAA) Florida Keys National Marine Sanctuary. The sanctuary is administered by NOAA in partnership with the Florida Department of Environmental Protection. The Sanctuary stretches from the Dry Tortugas to the southern boundary of Biscayne National Park. The area north of there has reefs and is part of the Florida Reef Resilience Program, but lies outside the sanctuary. Researchers are trying to determine why some reefs are resilient to environmental changes and impacts. The work may also identify ways to care for reefs worldwide.

At nearly 175 sites, scuba divers recorded the number and species of coral and the extent of bleaching -- corals turn white when tiny algae that live inside them die. Bleaching is a symptom of coral stress, which can be caused by high water temperatures, other environmental stresses, or disease. The project was part of the Florida Reef Resiliency Program, funded by the state of Florida and The Nature Conservancy. It involved volunteers and scientists from several agencies, organizations and universities, including the University of South Florida.........

Posted by: Kelly      Permalink         Source