July 8, 2002
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Editor: Josh Chamot
Contents of this News Tip:
New Evidence
Found for "Oxidative Stress" Theory of Aging
Researchers have uncovered strong evidence for the
long-held theory that the very oxygen we require to
live is a contributor to aging, and antioxidant molecules
can offset these effects.
The support for the "oxidative stress" model of aging
comes from experiments that boosted fruit fly life
spans in direct proportion to antioxidant production
from manipulated genes. Researchers from the University
of Southern California (USC) and University of California
at Irvine reported their findings in the June 19 issue
of the journal Genetics. The study was funded
in part by NSF.
Many researchers believe that antioxidant substances
such as vitamins C and E protect cells from the damaging
effects of oxidation by neutralizing free-radicals
- charged molecules that cells produce when they burn
oxygen fuel. To test this theory directly, the researchers
created fruit flies that had an extra copy of either
of two antioxidant-producing genes known as superoxide
dismutases, or SODs.
In control fruit flies, the researchers left the extra
SOD genes inactive. Unsurprisingly, these flies lived
a normal life span. In the experimental flies, the
researchers activated the extra copy, causing the
flies' cells to produce far more antioxidant enzymes
than normal. These flies enjoyed a longevity boost
of up to 40 percent, says lead researcher John Tower,
a biologist at USC. And the magnitude of the boost
was exactly proportional to the amount of extra SOD
production, suggesting that the antioxidants were
directly responsible, Tower says.
"It demonstrates that antioxidant activity is a rate-limiting
factor for fly lifespan," he says. "There was no negative
effect on metabolism from the SOD over-expression.
So we're extending life span without some kind of
trade-off or deficit in the creatures' metabolism,"
says Tower.
But now at least, says Tower, it's known that the beneficial
effects of antioxidants occur when the genes are made
to supply the substance. Drugs or gene therapy might
some day be used to stimulate human cells to over-express
SOD or similar genes, though it won't happen soon,
he says. [Cheryl Dybas]
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A Fish-Eye
View of Management Through an Evolutionary Lens
Fishing, whether for business or pleasure, is regulated
by agencies that impose size and catch limits on commonly
exploited species. But the practice of selectively
harvesting only the largest fish may be causing the
average size of fish to decrease. David Conover, scientist
at the Marine Sciences Research Center at Stony Brook
University, reveals this finding in his paper "Sustaining
Fisheries Yield over Evolutionary Time Scales," which
appeared in the July 5 issue of Science.
Conover posits that fishery management plans ignore
the possibility of evolutionary changes in harvestable
fish populations. The researchers have observed such
evolutionary trends in experimental fish populations.
In a study jointly funded by NSF, NOAA, and the New
York Sea Grant Program, Conover and his colleagues
observed the Atlantic silverside (Menidia menidia),
a small, common, marine fish. The researchers found
that by removing large individuals, the average size
in the population declined dramatically in just four
generations. Conversely, when the smaller individuals
were selected out, the average size increased.
Conover believes that fish harvesting has impacts beyond
the immediate ecological response to changes in fish
abundance. "Our study illustrates how well-intentioned
management plans that appear to maximize yield on
ecological time scales may have the opposite effect
after accounting for evolutionary dynamics," reports
Conover. Fishing may have evolutionary impacts that
lead to genetic changes in the population that affect
the growth rates of fish, and ultimately the productivity
of harvested populations, he adds.
"More work is needed to determine whether or not evolutionary
changes are occurring in wild populations," says Conover.
But if so, the author suggests reevaluating our reliance
on minimum size restriction as a basic management
tool establishing no-take reserves or marine protected
areas that may, if properly designed, maintain the
natural genetic variation of marine life. [Cheryl
Dybas]
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NSF Accountability
Reporting Lauded Twice
The Association of Government Accountants (AGA) will
honor NSF again this year for the third consecutive
year with its Certificate of Excellence in Accountability
Reporting (CEAR), the AGA announced July 8. AGA established
the certificate program in 1997 -- in conjunction
with the Chief Financial Officers Council and the
Office of Management and Budget -- to improve federal
financial accountability. The award recognizes federal
agencies for financial soundness and for excellent
preparation, issuance and timeliness of their accountability
reports. NSF is one of eight federal agencies so honored.
In an effort to meet accountability and performance
reporting requirements while also communicating to
the public in an engaging and meaningful way, NSF
this year also developed a user-friendly brochure
of management and performance highlights to complement
the formal and statutory accountability report. This
brochure was recognized by the League of American
Communications Professionals (LACP) in its 2001 Annual
Report Competition. LACP ranked it 4th overall in
a competition of more than 600 entries. [Mary
Hanson]
For NSF's Managment and Performance Highlights brochure,
see: http://www.nsf.gov/pubsys/ods/getpub.cfm?nsf02099
For NSFs FY01 Accountability Report, see: http://www.nsf.gov/pubsys/ods/getpub.cfm?nsf02097
For more on AGA, see: http://AGACGFM.ORG/cear/index.htm
For more on LACP, see: http://www.lacp.com/2001ars/competition.htm
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