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about 7 percent longer. “Clearly, there’s some kind of cross talk

between the reproductive organs and thesoma [body] of the animal,” says LeonardGuarente of the Massachusetts Institute ofTechnology, who investigates the geneticfactors of longevity.

The ovary-transplant process kills manymouse egg cells. So, it’s not clear whetherthe differences seen in the experiment resultdirectly from the transplanted ovaries orindirectly from the reduction in eggs. Inprevious research, the nematodeCaenorhabditis elegans lived 60 percentlonger than normal if its germ cells—eggsor sperm—were destroyed, Cynthia Kenyonof the University of California, San Fran-cisco reported in the Jan. 18, 2002 Science.

Kenyon cautions that the germ-cell con-nection to longevity she found in nematodesmay not apply to mice. “When we under-stand both systems better,” she says, “we canfind out whether it’s a coincidence or whetherthere’s some evolutionarily conserved mech-anism operating in the two animals.”

In time, Carey speculates, the researchcould lead to life-prolonging interventionsthat exploit whatever signal helps keep themice youthful.

“Reproduction is the cardinal function inlife,” Carey says. “It denies logic to believethat it isn’t central to aging.” —S. MCDONAGH

Not So Green?Using hydrogen as fuel may hurt environment

Fossil fuels are often reviled because theyproduce planet-warming carbon dioxide.However, replacing them with hydrogengas—considered to be a clean-burningsource of energy—may generate a differentset of environmental problems, includinglarge and long-lasting ozone holes, accord-ing to a new analysis.

The potential problems with hydrogendon’t stem from the oxidation of the gasitself, which produces only water vapor.Instead, drawbacks may arise from thealmost inevitable leaks of hydrogen gas fromfacilities that produce it, containers thatstore it, and fuel cells that use it to generateelectricity, says John M. Eiler, a geochemistat the California Institute of Technology inPasadena, who has analyzed seepage ratesfrom current hydrogen facilities.

Around 15 percent of the hydrogen gasproduced to meet future fuel needs couldleak into the atmosphere, Eiler and his col-leagues estimate in the June 13 Science.That loss could boost the atmospheric con-centration of hydrogen at Earth’s surfacefrom its natural level of 0.5 parts per mil-lion to around 2.3 ppm, they say.

According to the researchers’ scenario,

some of the gas leaked at ground level even-tually will make its way into upper layers ofthe atmosphere and react with oxygen tocreate water. An infusion of hydrogen gaswould moisturize the upper atmosphere,which is typically dry because it’s so cold.The result would be cooler and cloudierupper layers, the researchers say.

That change wouldn’t be good for theupper atmosphere’s ozone layer becausemany of the chemical reactions that destroyozone take place on ice crystals, says Eiler.If all technologies that derive their energyfrom fossil fuels were instead powered byhydrogen fuel cells, the ozone hole overAntarctica could get 4 percent larger, loseup to 7 percent more ozone than it cur-rently does, and last about 1 week longereach spring. Effects on the Northern Hemi-sphere’s ozone hole, which currently isn’tas extensive as the one over Antarctica,might be stronger, the researchers hold.

A rise in atmospheric concentrations ofhydrogen gas could have several othereffects, says Eiler. An increase in high-alti-tude clouds might boost the proportion ofincoming radiation reflected back intospace. Also, soil microbes that use hydro-gen gas as a nutrient might become moreprolific, with unknown ecological results.

The atmospheric consequences describedby Eiler’s team “certainly are plausible,” saysPaul C. Novelli, an atmospheric scientistwith the National Oceanic and AtmosphericAdministration in Boulder, Colo. Whetherthose outcomes materialize may welldepend on the hydrogen-munching soilmicroorganisms that are a major consumerof atmospheric hydrogen, Novelli notes.

Eiler agrees. He and his colleagues’ recentresearch suggests that as much as 90 per-cent of the hydrogen gas emitted from today’ssources, which include vehicles and forestfires, ends up locked in soil. —S. PERKINS

Fixed FocusAdjustable lenses fromliquid droplets

Grinding glass is one way to make a lens.Using plastic goop, a little salt, and elec-tricity is now another way. That’s whatresearchers at Lucent Technologies’ BellLabs in Murray Hill, N.J., have done to cre-ate lenses the size of sesame seeds.

The lenses are even adjustable. The saltadded to the goop, a liquid-polymer pre-cursor, makes it electrically conductive, sothe lenses’ shapes can be adjusted by apply-ing voltages. Once the droplet assumes thedesired form, a few minutes under an ultra-violet lamp polymerizes the liquid into ahard lens.

These lenses may cut the price of theassemblies of laser chips and light-manip-

Using innovative optics to take thetwinkle out of starlight, a telescope inHawaii has recorded the sharpest-

ever infrared images of the globular clusterM-13, a crowded grouping of Milky Waystars. The resolution is comparable to dis-cerning the separation between car head-lights on the Golden Gate Bridge whilestanding 3,850 kilometers away in Hawaii.Researchers presented the images lastweek at a meeting of the Canadian Astro-nomical Society in Waterloo, Ontario.

Like other so-called adaptive-opticssystems, the device installed on the Gem-ini North Telescope atop Hawaii’s MaunaKea reduces blurriness by using a flexiblemirror whose computer-controlled shapechanges 1,000 times per second to com-pensate for Earth’s turbulent atmosphere.Compared with other systems, the Gem-ini device corrects for turbulence higherin the atmosphere, where most of itoccurs, and thus sharpens images over aslightly wider region of sky, notes projectscientist Glen Herriot of the NationalResearch Council of Canada in Victoria,British Columbia.

Gemini imaged the center of M-13 atseveral infrared wavelengths, which willenable astronomers to determine thetype, mass, and age of individual stars,says Tim Davidge of the NationalResearch Council. —R. COWEN

Sharpening a HeavenlyImageClear view of globularcluster’s crowded core

CORE IMAGE Center of the globularcluster M-13, some 23,000 light-years away.This image was taken at one of the threenear-infrared wavelengths recorded by theGemini North Telescope.

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