In addition to providing physical support and taking in nutrients, plant roots secrete a wide variety of compounds that affect other nearby roots, as well as insects and microbes. But because it goes on unseen, bactericidal root activity has not been extensively investigated—until now. Using the model plant Arabidopsis thaliana, a relative of garden-variety cabbage, Jorge Vivanco and co-workers at Colorado State University, together with Frederick Ausubel at Harvard Medical School, demonstrated that "root exudates" contain antimicrobial agents that ward off the continual attacks by soil pathogens.

The work is published in the March 10 issue of the journal Nature.

The telltale paw prints with huge 10 centimetre-long nails spoke volumes. But now definitive corroborating DNA evidence seals the case of the most northerly sighting of a grizzly bear. The discovery fuels mounting evidence that Canada's High Arctic is no longer the sole preserve of the polar bear -- Nanuk is having to make room for its southern cousin.

The evidence of the barren ground grizzly bear (Ursus arctos) was discovered on Melville Island, an uninhabited part of the western Arctic archipelago 1,500 kilometres due north of Yellowknife, and 1,000 kilometres north of the Arctic Circle.

Harbor Branch scientists have received new funding for a research program they hope will make large-scale culturing of spiny lobster economically feasible. The project is based on the serendipitous discovery that lobster larvae are settling on open water fish cages in Puerto Rico by the thousands. The research, along with the some of the lobster's more fascinating habits such as their tendency to crawl in huge single-file lines when crossing open areas between island coasts and reefs, will be the focus of the next Harbor Branch Ocean Science Lecture Series event, on March 9.

By a vote of 84 in favor, 34 against and 37 abstaining, with 36 absent, the UN today approved a declaration calling on all UN Member States to ban all forms of human cloning, including cloning for medical treatment, as incompatible with human dignity and the protection of human life.

While in general agreement, some delegates said they opposed banning therapeutic cloning. The Declaration, negotiated by a Working Group last month, also banned "genetic engineering techniques that may be contrary to human dignity" and called for a prevention of the exploitation of women and adequate protection for human life in the application of life sciences. The Declaration has been welcomed by many as a clear expression of the ethical norms that should guide scientific research.

UCLA biochemists have determined the three-dimensional structure of a major domain of telomerase, the enzyme that helps maintain telomeres – small pieces of DNA on the ends of chromosomes that act as protective caps -- allowing DNA ends to be copied completely when cells are replicated.

This is the first major piece of telomerase for which the structure is known. Telomerase plays a key role in most cancers, and this work ultimately may lead to targets for drug intervention, the scientists said. The discovery is the cover story in the March 4 issue of the journal Molecular Cell.

A team from the chemistry and biology departments of New York University, in collaboration with Memorial Sloan Kettering Cancer Center (MSKCC), has uncovered a conformational switch--a change in shape in a carcinogen-damaged DNA site--in tumor suppressor genes altered by a known cancer-causing chemical found in cigarette smoke. This finding may open new horizons for understanding the initiation of chemically induced cancers.

The findings appear as the cover story in the latest issue of the Journal of Molecular Biology. This team was headed by Dinshaw Patel at MSKCC, Nicholas Geacintov, chair of NYU's chemistry department, and Suse Broyde, a professor in NYU's biology department.

A major step in the development of the vertebrate embryo - the establishment of a back that morphs into a brain, spinal cord and muscles - turns out to be so important that the body uses at least three signals to make sure it happens properly.

The discovery, reported this month in the journal Developmental Cell by researchers at the University of California, Berkeley, finally explains an 80-year-old observation that revolutionized the way biologists think about embryonic and fetal development and set the stage for the stem cell debate.

By injecting a therapeutic gene directly into the brain, researchers have treated a naturally occurring genetic disease in cats. This is the first genetic disease affecting the central nervous system to be successfully treated in an animal larger than mice and rats. If this approach can be successfully applied to humans, say the researchers, it might one day treat an entire class of diseases called lysosomal storage disorders which cause severe, sometimes fatal, disabilities in about one in 5,000 births. The members of the research team from the University of Pennsylvania School of Veterinary Medicine, the Children's Hospital of Philadelphia and the U.S. Naval Academy published their findings in this month's issue of the Annals of Neurology

Researchers have long suspected that fertilizer runoff from big farms can trigger sudden explosions of marine algae capable of disrupting ocean ecosystems and even producing "dead zones" in the sea. Now a new study by Stanford University scientists presents the first direct evidence linking large-scale coastal farming to massive algal blooms in the sea.

Writing in the March 10 issue of the journal Nature, the authors conclude that some highly productive regions of the ocean are much more vulnerable to agricultural runoff than was previously assumed.

The body attempts to protect itself from HIV infection via the innate immune system. Defensins are proteins found in cells, which have been shown to have anti-HIV activity. However, the mechanism by which the defensins control HIV infection has not been known. Appearing online on February 17 in advance of publication in the March 1 print edition of the Journal of Clinical Investigation, Theresa Chang and colleagues from Mount Sinai School of Medicine analyze how alpha-defensin-1, in particular, inhibits HIV infection in CD4+ T cells. CD4 + T cells are white blood cells that have molecules called CD4 on their exterior. They help orchestrate the body's response to viruses and therefore play important roles in the immune system.