| Chestnut Trees Return to the Eastern U.S. The imposing 100-foot American chestnut tree that once dominated forests in the eastern U.S. may soon return, fortified by a new resistance to an Asian fungus. That blight essentially wiped out the tree during the past century, altering entire forest ecosystems. Scientists are releasing a sixth-generation hybrid this year for planting in several locations, confident that it will show the resistance of its hardy Chinese cousin.The hybridization began decades ago, when breeders crossed the American and Chinese chestnuts to obtain the resistance genes. But because the American variety grows up to 50 feet taller and lacks lower branches, the researchers have had to backcross repeatedly to recapture those traits. The sixth generation should now have about 94 percent American character and “should have high resistance to the blight,” says Sara Fitzsimmons, a research technologist at Pennsylvania State University’s School of Forest Resources who works on the project. She won’t rest assured, however, until the trees grow on national forest­land for 10 years or so. Meanwhile scientists will continue to breed seedlings optimized for the sharply different local conditions from Maine to Georgia. [More] rss.sciam.com |
Are urban tapeworms on the rise? Anthony Franz says an undercooked salmon salad gave him a 9-foot-tapeworm, and in August he sued the Chicago restaurant that served it to him. [More] rss.sciam.com |
Fed Seeks Greater Protection for Sharks The National Oceanic and Atmospheric Administration expressed support today for Senate legislation intended to strengthen shark conservation but expressed concern about a provision that it says would encroach on other countries' sovereignty.Stephanie Hunt of NOAA's legislative affairs office said the agency supports provisions requiring that sharks brought to U.S. ports have their fins intact. That policy is already in effect along the Atlantic Coast, but Pacific ports use a biomass ratio system that critics say is full of loopholes. [More] rss.sciam.com |
100 Years Ago: Punch Cards and the Census SEPTEMBER 1959 RADIATION -- “What should the citizen conclude about ionizing radiation? Ionizing radiation has always been with us and will be for all foreseeable time. Our genetic system is probably well adjusted by natural selection to normal background radiation. Added radiation will increase the frequency of mutations; most of these will be harmful. Exposure to radiation in large amounts will increase malignant disease; small amounts may possibly do the same. In view of these potentially harmful effects every reasonable effort should be made to reduce the levels of ionizing radiation to which man is exposed to the lowest levels that can reasonably be attained. As to fallout from nuclear-weapons tests, the citizen will conclude that it contributes in a small way to world-wide levels of radiation. For this reason alone the tests should be discontinued. --George W. Beadle” [More] rss.sciam.com |
Study estimates hot air released by the U.S. health care system What does the U.S. health care system have in common with cattle farms and power plants ? It is responsible for a fair chunk of the nation's greenhouse gas emissions. The system, especially via hospitals and the pharmaceutical industry, contributes 8 percent of those climate-warming gases, according to a study published in the November 10 issue of the Journal of the American Medical Association . [More] rss.sciam.com |