Bad news for oak forests of the Northwest; sudden oak death was detected in Oregon last month. Though it's unclear how it arrived, it's feared that this killer spread from the central California coast, where it has destroyed thousands of oak trees since 1994. A recent discovery of the infectious agent, the fungus Phytophthora ramorum, in rhododendrons has provided the first clue in what up until now has been the mysterious appearance of this deadly pathogen. Although Phytophthora's European relatives have a healthy genetic diversity, the California strain is remarkably nondiverse, says forest pathologist Matteo Garbelotto, University of California, Berkeley. The researchers' molecular studies revealed a single, highly successful genotype in isolates taken from Santa Cruz to Napa Valley, supporting the notion that the pathogen was introduced into the California ecosystem, possibly via the rhododendron. At the annual meeting of the American Phytopathological Society, in Salt Lake City on Aug. 28, Garbelotto's colleague David Rizzo, at University of California, Davis, reported on experiments testing the susceptibility of different oak strains nationwide. He found differences in susceptibility, with tan oak being the most vulnerable. This correlates with field observations: in some areas, tan oaks have shown nearly 100 percent mortality, according to the researchers. Rizzo and Garbelotto also believe that the infection, while highly contagious, is not spread from tree to tree. They think it needs a platform, which may be where the rhododendron and other leafy plants fit into the picture. "We understand that in order to have a final outcome with a lot of dying oaks, we need a whole plant community that's providing spatial links and habitat for spores," said Garbelotto.
Half Full, Half Empty?
More than half of the 64 human embryonic stem cell lines (ESCs) approved for federal funding by the Bush administration "are in the earliest stages of development" and may not be immediately ready for research (See also "Half a Loaf is not Good Enough" and "Stem Cells: Steady Momentum Toward Funding"). But Tommy Thompson, secretary of the Department of Health and Human Services, told a US Senate panel Sept. 5 in Washington that the cells' usefulness will ultimately be determined through actual research. The National Institutes of Health's Human Embryonic Stem Cell Registry will be ready before the end of September. Research applications will be accepted beginning Oct. 1, but grants will not be awarded until eight to nine months later, Thompson said. Additional cell lines will be available by the time federal funding is available early next year, he added. Sen. Edward Kennedy (D-Mass.), chairman of the Senate Committee on Health, Education, Labor, and Pensions, convened the hearing to examine the adequacy of the administration's limited funding of ESC research. It was the first of three hearings this month in the Senate, where a majority of members support broader research. "Many of the lines cited are not really viable or robust or usable," complained Sen. Arlen Specter (R-Pa.), who is cosponsoring legislation to expand federal ESC research. President George W. Bush has promised to veto any such legislation. Thompson countered that the 24 or 25 fully developed cell lines are "adequate" for research to begin. He announced a major roadblock had been lifted because the government had reached an agreement with the WiCell Research Institute Inc. to license five ESC lines derived by James Thomson at the University of Wisconsin. That agreement, Thompson said, "is a very important step in beginning the basic research that needs to be done before we can approach treatments and cures.
Radio Waves Could Keep Zebra Mussels at Bay
Radio waves might alleviate the zebra mussel problem in the Great Lakes. Since arriving by ballast in an ocean-going vessel in the 1980s, these miniature mussels have spread from the Lakes to the mouth of the Mississippi River, risking endangerment of some native species and clogging intake pipes of lakeside plants, making them unusable (See also, "Battling the Bioinvaders"). At the American Chemical Society's annual meeting, held in Chicago in August, Matthew Ryan, a chemist at Purdue University, Calumet, reported that extremely low frequency (ELF) waves can selectively kill zebra mussels while leaving native species untouched. He also reported finding high levels of calcium in the water of the treated animals, which, Ryan believes, shows that ELF kills by interfering with ion balance. Zebra mussels might be particularly sensitive to ELF because of their small size and the prodigious rate at which they filter-feed. They have to work hard to maintain ion balance against a large concentration gradient, according to Ryan. "Tweaking that equilibrium and disturbing the balance would put thermochemistry in our favor," he says. In Ryan's experiments, more than 1,000 zebra mussels, housed in tanks, were exposed to ELF generated from an oscillating magnetic dipole resonator; Purdue has filed a patent on this instrument, he says. By the 40th day, the mussels were all dead, while in control tanks only 10 percent died. The data are "iron-clad," says Ryan. "We know that it kills them, it follows stress. They clam up--rather mussel up, [and] we see them lose nutrients in the water."
