body and viral defends infections. itself against both cancer Making Silicon cancer “I hope will people now put working [the gene on other for] RNase types of L Naturally on the list of genes they look at,” says Sil- verman.

In the new study, the men with prostate cancer had inherited mutations in one of

Chemists glim se organic substance in P ankton - P

SCIENCE NEWS This Week

Cancer Clue RNA-destroying enzyme may thwart prostate-tumor growth - The sue and shape ofa walnut, the prostate gland is the source of the fluid that carries a man’s sperm. It’s also a source of great concern to many men: In 2001, physicians in the United States diagnosed nearly 200,000 cases of prostate cancer and more than 30,000 men died of the disease.

By studying families that include several men with prostate cancer, scientists have now identified a tumor-suppressing gene on chromosome 1. It’s unclear whether mutations in this eagerly sought gene will ultimately explain many cases of prostate cancer, but investigators are optimistic that their work has revealed a novel facet of tumor-cell biology. Also, they say, the find- ing could suggest new ways of diagnosing or treating prostate cancer.

Although newly associated with prostate cancer, the gene has been studied since the 1970s. It encodes an enzyme known as RNase L, which degrades RNA, a chemical relative of DNA. Linking defects in this gene to prostate cancer is “the first example where RNA turnover is implicated in tumor suppression,” says Robert H. Silverman of the Cleveland Clinic Foundation.

Silverman has investigated RNase L for most of his career. Last year, he got an unex- pected phone call from a group of geneticists who had been tracking down a hereditary prostate cancer gene on chromosome 1 since 1996. The geneticists, led by John Carpten of the National Human Genome Research Institute in Bethesda, Md., told Silverman that they had found inherited mutations in $ the gene for RNAse L in two families

8 plagued by prostate caner. The researchers, including Silverman, now reveal their find- & ings in the February Nature Genetics.

Z The most widely recognized duty of $ RNase L is to suppress infections by z. degrading viral and cellular RNA, but 2 there have been hints that the enzyme lim- $ its tumor growth. RNase L helps damaged i cells commit suicide, which is one way the

their two copies ofthe enzyme’s gene. Then, a spontaneous mutation in a prostate cell must have deactivated the other copy, per- mitting the cell to avoid suicide and divide without limits.

Ofeight families the geneticists suspected

For the first time, signs of a compound composed of both carbon and silicon have been found within a living organism. Besides its biological novelty, the find could open new routes for making silicon-based materials, according to researchers who

of having a prostate cancer-causing gene on chromosome 1, only two have so far revealed mutations in the gene for RNase L, Carpten and his colleagues report. They continue to look for disabling muta- tions in the gene in the other families.

The gene for RNAse L is only the second gene to be identified for heredi- tary prostate cancer, which makes up about 10 percent of cases. The first has so far accounted for only a few prostate can- cer-prone families and is not commonly

report discoveringthe substance in diatoms, a type of plankton.

The diatoms’ ability to pull silicon-con- taining chemicals from water and use them to build microscopic shells of pure silica

has long tantalized researchers. Some scientists have sus- pected that to pull off this feat of ceramic engineering, diatoms must make a carbon- silicon compound during the process.

In an upcoming issue of the British journal Dalton 7h.m~- actions, Christopher T.G. Knight of the Uni-

mutated in men who versity of Illinois at develop prostate can- BUSY DIATOMS New research suggests Urbana-Champaign cer without a family that diatoms can produce a carbon-sllicon and his colleagues at history of the disease compound previously unknown in blology. LakeheadUnivemityin (SN: lO/~OO,o,p. 230). Thunder Bay, Ontario,

While the gene for RNase L may simi- report what they say is the first solid indica- h l y explain just a small fraction of prostate tion of a so-called organosilicon compound cancer cases, its protein could offer insight in an organism. into more-general causes of the cancer and To capture a glimpse of the short-lived perhaps an avenue to treat it. Researchers compound, which survivesfor no morethan have also struggled to distinguish unthreat- a few hours, the researchers first deprived ening prostate tumors that grow slowly Navicula pelliculosa diatoms of silicon. from those that quickly kill a man. Mea- Without the element, the diatoms can’t suring the activity of RNase L in tumors make their shells. might provide another clue for such crucial Next, the researchers fed the diatoms an diagnoses. isotope of silicon that a nuclear magnetic

The new study is “simultaneously excit- resonance (NMR) instrument can detect. ing and disappointing,” says cancer geneti- Then, they placed the live diatoms within cist Timothy Rebbeck ofthe University of the instrument to determine what com- Pennsylvania School of Medicine in pounds the diatoms produced while mak- Philadelphia. “It’s a very interesting find- ing their shells. ing, but we need to find out a lot more About 6 hours aRer receivingthe silicon, about this gene before we understand its the diatoms produced asilicon-carbon com- role in hereditary prostate cancer or prostate cancer in general.”

To that end, Carpten and his col- leagues plan to join geneticists at Howard University in Washington, D.C., to study the gene in about 60 African- American families with a strong history of prostate cancer. African-American men, for reasons largely unknown, are much more likely than men in most other ethnic groups to develop prostate cancer and die from it. -J. TRAVIS

pound that the researchers detected as a characteristic peak in the NMR spectrum. The scientists identified the small but telling signal because it matched one produced by synthetic organosilicon compounds they had made previously.

In laboratories, researchers need extreme conditions such as high temper- atures and pressures to extract silicon compounds from water and transform those into solid silica. Understanding how diatoms do it could lead to less expensive

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NEWS This Week

routes for making silicon-based materi- als, says Knight.

Silicon is an important nutrient for many plants, so the new research might also even- tually help researchers combat silicon depletion in crops, a problem in some parts of the world, says Knight. Silicon can also stimulate bone growth, so the work could lead to new treatments for osteoporosis, he adds.

“The potential.. . is profound,” comments Daniel Morse ofthe University of California, Santa Barbara. However, Knight and his coworkers haven’t yet determined the com- pounds exact structure, Morse notes. More- over, the NMR signal indicating an organosilicon compound is weak, he says.

Despite these caveats, Morse adds, the work “is suggestive” that organosilicon com- pounds are made by organisms.

Although Knight concedes that the NMR signal for the new compound isn’t strong, “we have no doubt about it,” he says. One reason for his confidence is that the char- acteristic signal always appeared 6 hours after the researchers gave silicon to staxved diatoms. Further, Knight notes, his team has reproduced the experiment on multi- ple NMR instruments and with several diatom colonies. -J. GORMAN

Forbidden Tests Panel seeks ban on human clones

A national advisory panel has asked &ngress to forbid cloning aimed at creat- ing achild but urged the lawmakers to per- mit other medical experiments with cloned human cells.

Specifcally, the Jan. 18 recommendation calls for a “legally enforceable ban” on placement in a woman’s uterus of a human blastocyst derived from the procedure known as nuclear transplantation. A blas- tocyst is a multicellular stage of develop- ment that occurs after an egg is fertilized and before it’s considered an embryo. In nuclear transplantation in animals, researchers place DNA from an existing animal inside an egg they’ve stripped of its own DNA. The egg is then tricked into dividing, as iffertilized.

The panel is sponsored by the National Academies in Washington, D.C., four non- profit scientific-advisory groups. It recom- mends that nucleartransplantation remain

available to scientists studying embryonic stem cells. Since stem cells have the poten- tial to develop into avariety of tissues, such cells have shown medical promise as replacements for dying tissue. Scientists would use cloning for such purposes by put- tingthe nucleus from aperson’s cells into a human egg and deriving stem cells from the blastocyst. This procedure is called ther-

maneuvers with a mother ship to refuel or transfer data.

John W. Suh of Xerox Palo Alto (Calif.) Research Center and his colleagues may have come up with a solution. They’ve demonstrated that artificial whiskers, or cilia, which could be mounted on a mother satellite, are strong and precise enough to move a companion vehicle with

apeutic cloning. The new recommendation falls in line

with the United Kingdom’s December 2001 ban on human reproductive cloning but not therapeutic cloning. On Jan. 18, a British Court of Appeals upheld a distinction between the two. Robert May, president of the Royal Societyin London, hailed the unanimous three- judge affirmation as an “admirably sensible” move that will “permit legiti- mate uses of

great finesse. Suh says the group’s mays of microscopic

cilia have positioned a satellite-like object to within a few micrometers of a target spot. That’s good news for satellite makers, given that “space cilia are lightweight and rela- tively low cost,” says team member Karl F.

Bohringer of the University of Washington in Seattle. The scientists reported their work in the most recent (December 2001) issue of Smart Materials andstructures.

Originally inspired by cloning technology wee navigational hairs on in research while various microorganisms, outlawing any Bohringer, Suh, Gregory T. attempts to carry A. Kovacs of Stanford Uni- out human repro- versity, and their students ductive cloning.” have been developing cilia

Accordingto U.S. since the early 1990s (SN: law, experiments on 7/26/97,p. 62). Unlike bio- human reproductive cloning remain legal, logical cilia, the team’s artificial ones are but federal funds can’t be used. made bv coating silicon wafers with a laver

WHISK(ER)ED AWAY BY flapping, these microcilia may maneuver pocket- size spacecraft as they dock.

Any attempt to clone a human being would be dangerous for the woman and child and likely to fail, says Irving L. Weiss- man of Stanford University, who chaired the panel that wrote the report. He adds that only a small percentage of attempts at animal cloning results in the birth ofhdthy animals (SN: 10/20/01, p. 250).

The scientific panel recommends that a federal ban on reproductive cloning remain in place for 5 years. At that point, the pro- hibition should be reviewed only ifnew sci- entific evidence indicates such cloning is

of tun&ten sanudwiched between pairs of silicon-nitride and plastic films. After por- tions of those five layers are etched away, shovel-shaped paddles remain. They are about as long as day-old whiskers and have built-in, tungsten-based electric heaters, which are used to drive the structures.

Unequal thermal expansion plus con- traction of the plastics when heated flexes particular paddles up and down at a rate of up to 60 times per second. Each upward stroke slightly shifts a cilium’s tip horizon- d y . Consequently, rapid and coordinated

safe and a “broad national dialogue on soci- etal, religious, and ethical issues suggests that a reconsideration of the ban is war- ranted:’ the panel says. -N. SEPPA

flapping of a cilia array can transport an overlying object along.

In simulated microgravity, a set of four cilia chips with just over 1,000 cilia moved an aluminum block about as hefty as a rac-

Little Levers for Satellites

quetball-and a million times & massive as any of the little cilia themselves.

The cilia “are very nice, because you can move something like on a conveyor belt and place it at some ParticUlarpoint; comments Volker Saile of the Institute for Microstruc- Cilia may precisely dock

tiny spacecraft

In an era of satellite design now in its infancy, large and costly spacecraft are giv- ing way to fleets of cheaper, miniaturized satellites. Some may be as small as a deck of cards. One challenge of this approach is designing means to subtly position the spacecraft. during their frequent docking

ture Technology-a joint venture of the Karlsruhe (Germany) University and the Karlsruhe Research Center, a German national laboratory.

One catch, Bohringer notes, is that the heating elements make the cilia power- hungry. Redesigning them to use electro- static forces might boost the whiskers’ appeal to power-conscious satellite makers, I he adds. -P. WElSS v)

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