NEWS OF THE WEEK BUSINESS
FLUORIDE SHORTFALL Fertilizer plant closure puts nationwide crimp on fluoridation
T
HE ONGOING SHUTDOWN OF
a phosphate fertilizer plant in Florida has led to a sharp drop in supplies of a key water fluoridation chemical and to spot fluoride shortages in towns and cities across the U.S. The Fort Meade, Fla., facility, operated by U.S. Agri-Chemicals, makes hydrofluosilicic acid (H2SiF6, HFS) as a by-product of the conversion of phosphate ore intofinishedfertilizer. With the plant winding down operations, some 15% of U.S. HFS capacity is coming off the market. The Centers for Disease Control & Prevention has warned of
Discovery helps explain how the crucial gibberellin plant hormones work
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OCTOBER
BIOCHEMISTRY
GIBBERELLIN RECEPTOR FOUND
UNBOUND Binding of a gibberellin (GA) to GID1 releases transcription factors (GA-TRXN) from a repressor, shown here as fragments after being chewed by the protein-degrading machinery (SCF).
C&EN
says.-MICHAEL MCCOY
The researchers suggest that, when bound to agibberellin, GID1 interacts with another protein that represses the expression of gibberellin-dependent transcription factors. The interaction leads to destruction of the repressor protein by the plant's protein-degrading machinery and release of the transcription factors. Liberated, the transcription factors activate certain genes required for plant TARGET OF THE PLANT HORsity. His is one of two teams that i mones known as gibberel- recently discovered a receptor for development. The proposed mechanism paralauxin, another key plant hormone 1 lins has been identified. Gibberellins induce many well- (C&EN, May 30, page 11). "Gib- lels that advanced for auxin, notes characterized responses in plants, berellins have been known for botany professor Peter McCourt including stem elongation, but decades and have a central role in of the University of Toronto. In both cases, small how they do so is not known. plant growth and organic molecules Now, Japanese researchers led by development," he initiate a proteinNagoya University's Makoto Mat- adds. protein interacsuoka have discovered a receptor GID1 is a soltion that eventufor these compounds, called GID1, uble protein in ally destroys one and propose a mechanism for gib- the nuclei of rice of the proteins. berellin signaling. plant cells. That "We now know GID1 can bind to all biologi- it is a gibberellin Gibberellic acid the core biochemcally ac active gibberellins, includ- receptor is based cany istry of these ing gibberellic acid. Its on several lines of discovery is "extremely evidence (Nature 2005,437,693). small molecules," McCourt says. important" and "very The work is "so complete—it has all "What's next is tofigureout how exciting," says Mark Es- the data to demonstrate that this that core biochemistry regulates telle of Indiana Univer- protein is a receptor," Estelle says. development.'-MAUREEN ROUHI PLANT
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an emerging shortage that "will be experienced throughout the water industry." The pinch has been most severe in New England where, for example, the town of Shrewsbury, Mass., ran out of HFS in mid-September. Compounding the supply situation, demand for HFS is spiking in California as a result of the intended start of fluoridation in some communities. Unable to procure adequate supplies, the San Francisco Public Utilities Commission has delayed until late fall plans to treat the remaining 20% of its customer base. HFS suppliers are scrambling
to meet demand in the face of the supply shortfall. "Customers depending on product from U.S. Agri-Chemicals are having to find alternative sources of supply," says Mark Looney, vice president of sales and marketing at Solvay Fluorides. Fortunately, Looney adds, water consumption is entering a seasonal slow period, and he sees supply dislocations ending soon. Shrewsbury, in fact, found new supplies late last month. Long-term reliefwill depend on increased outputfromMosaic and PCS Phosphates, fertilizer makers that are the country's largest HFS makers. A Mosaic representative says the company is doing all it can to adjust its HFS supply capability. David Messerlie, CEO of fluorides marketer LCI, is confident that fertilizer companies will be able to squeeze out more HFS. "Things are working themselves out," he
3,
2005
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