Ants garden in Amazon to improve their survival
BIODIVERSITY
Amid the lush diversity of plants growing in the Amazonian jungle, there are large areas that consist almost entirely of a single tree species, Duroia hirsuta. Local Indian legend says these tree stands are cultivated by a forest imp, earning them the name, devil's gardens. But researchers from Stanford and the University of Colorado at Denver recently found that colonies of ants nesting in this particular tree are so protective of their host that they kill off any nearby plants. The researchers planted cedar trees inside devil's gardens in the Peruvian rainforest, allowing ants on some of the saplings but not others, and watched as ants chewed holes in their leaves and squirted acid onto them from their abdomens, killing many saplings within a day or two. By doing so, they help their host tree spread, providing future nests for colonies that can include millions of ants. The dutiful ants even treated the human researchers the same way they would a foreign plant: ''They latch onto your arm with their mandibles, and then they spray acid on you," said Megan Frederickson, a biology doctoral student at Stanford, and the study's lead researcher. Fortunately, the tiny ants, only about three millimeters long, pose no danger to people.
BOTTOM LINE: The findings contribute to the scientific understanding of how biodiversity evolves in the rainforest, in particular how two or more species may evolve together, using each other as resources.
CAUTIONS: The experiments did not reveal how the ants distinguish between their host tree and other species. The researchers' tried to fool the ants by grafting the hollow stems of a host tree onto cedar saplings, but the ants killed the new trees anyway.
WHAT'S NEXT: Frederickson plans to research whether ants use some kind of chemical cue to recognize the tree in which they nest, and whether they are capable of killing off large, established trees as well as saplings.
WHERE TO FIND IT: Nature, Sept. 22, 2005
CHRIS BERDIK
INFLUENZA
Vaccines, drugs may be less effective than thought
Many doctors' first line of defense against the flu may not offer much defense at all, according to two studies released last week. A research team at the Centers for Disease Control and Prevention and a separate group at the Cochrane Vaccines Field program in Rome say their studies of influenza vaccines and drugs point to a startling ineffectiveness against influenza viruses. The news comes as countries around the world are stockpiling vaccines and antiviral drugs to prepare for what scientists fear is an emerging pandemic. In one study, CDC scientists found that resistance to adamantanes, an inexpensive family of drugs widely used to treat flu, has increased by 12 percent since the mid-1990s. Of the resistant viruses the team identified, 61 percent of those isolated in the last two years were from Asia, where many predict the next pandemic will begin, most likely from avian flu. A second study found that flu vaccines offer only limited protection to elderly residents of long-term care facilities and even less to senior citizens who live in communities.
BOTTOM LINE: If the goal is to prevent influenza, ''Current vaccines will not do it," said Tom Jefferson, a scientist at Cochrane Vaccines Field and lead author of one of the studies. ''We need public health measures coupled perhaps with better vaccines." The new research also is alarming news for poor nations that can't afford the newer, more effective flu medicines that wealthier nations are stockpiling.
CAUTIONS: The researchers don't have good data on why resistance to flu drugs is increasing. And in the Italian report, many of the studies included in the scientists' review of flu vaccine effectiveness were weak, Jefferson said. ''We used what was available."
WHAT'S NEXT: The CDC is investigating other possible cases of drug resistance among other influenza antiviral medications, such as Tamiflu and Relenza.
WHERE TO FIND IT: The Lancet, Sept. 21 online edition
KELLI WHITLOCK BURTON
GUM DISEASE
Wisdom teeth may be trouble, even if they don't cause pain
Wisdom teeth may be more of a problem than previously realized, according to experts speaking at a news conference in Boston last week. A handful of studies, called the ''Third Molar Clinical Trials," were initiated in the late 1990s in response to concerns that wisdom teeth were getting pulled too often. The results, published in a series of articles over the past few years, show that 25 percent or more of young adults with all four wisdom teeth develop gum disease involving at least one of those wisdom teeth -- a rate considerably higher than expected, the researchers said. Additionally, the studies reinforced mounting evidence that gum disease is linked to medical problems, such as cardiovascular and kidney diseases. And one of the studies found that pregnant women with periodontal disease involving their wisdom teeth are more likely to deliver low birth-weight babies.
BOTTOM LINE: People need to have their wisdom teeth evaluated regularly by a dentist for signs of gum disease.
CAUTIONS: These studies were partly funded by the American Association of Oral and Maxillofacial Surgeons, an organization of dentists who perform wisdom teeth extractions.
WHAT'S NEXT: The researchers did not answer the all-important question: Whether someone whose wisdom teeth are healthy should get them pulled anyway. To answer this, scientists will have to compare the results of gum disease in patients who have their wisdom teeth removed and those who don't.
WHERE TO FIND IT: Many of the studies have been published in the Journal of Oral and Maxillofacial Surgery over the past four years.
MICHAEL E. HOCHMAN
SMOKING
Just a few cigarettes a day boost disease risks
Despite years of anti-tobacco campaigns, one in four Americans still smokes. As compared with the 1950's, many more Americans today consider themselves ''light-smokers." But can you smoke just one or two cigarettes a day without harming your health? Scientists from Norway have found that smoking just 1-4 cigarettes a day significantly increases ones' risk of dying from cancer and cardiovascular diseases. Researchers tracked the health of some 43,000 men and women starting from the mid-1970's. Women who were light-smokers were five times more likely to die from lung cancer and almost three times more likely to die from heart disease. Men who smoked just a few cigarettes a day faced smaller increases in risks. Smokers faced the steepest rise in health consequences with the first few cigarettes they use per day.
BOTTOM LINE: This study dispels the myth that smoking just one or two cigarettes a day does little harm. ''There is no safe cigarette," said Dr. Tobias Kurth, a physician at Brigham and Women's Hospital who studies tobacco use.
CAUTIONS: Researchers studied the relationship between smoking and death from diseases, but they did not analyze how smoking impacts a person's risks for developing the diseases in the first place. The consequences might have been worse if the researchers had counted diseases diagnosed, instead of just deaths. Many smokers today practice ''sporadic smoking." They don't normally smoke but will light up during a weekend party. This study doesn't show whether smoking once in a while carries the same risks as chronic smoking.
WHAT'S NEXT: ''Educators need to get this message out," said Kurth, particularly to young women.
WHERE TO FIND IT: Tobacco Control: September 2005.
ALISON Z. YANG 
