June 4, 2002
For more information on these science news and feature
story tips, contact the public information officer
listed at (703) 292-8070.
Editor: Josh Chamot
Contents of this News Tip:
Lakes Show Troubling Changes
Researchers believe atmospheric nitrogen from auto
emissions and agriculture on the heavily populated
Front Range of the Colorado Rockies is causing increased
algal growth in high alpine lakes.
Scientist Diane McKnight of the University of Colorado
at Boulder found that, since about 1940, nitrogen
enrichment and climatic changes have resulted in more
algae, shifts in the dominant algal species, and the
accumulation of organic sediment in a lake known as
Green Lake 4.
"Over the past 20 years, nitrogen deposition has increased
in the Green Lakes Valley watershed and the lake ice
cover has become progressively thinner," said McKnight,
whose research is supported by the National Science
The five lakes in Green Lakes Valley - including Green
Lake 4, at 11,500 feet above sea level - account for
about 40 percent of Boulder's water supply. "The City
of Boulder owns the watershed and makes a substantial
effort to protect the water quality of the lakes,
including a ban on hikers," McKnight said. "But there
are no means for the city to protect the watershed
from atmospheric . . . influences on water quality."
Similar trends have been observed in alpine lakes in
Rocky Mountain National Park about 20 miles to the
north, McKnight said. The Green Lakes study is part
of NSF's Long-Term Ecological Research (LTER) program,
a network of more than 20 sites in North America and
Antarctica where researchers document ecological and
climate changes over decades and centuries.
Results of the Green Lake 4 study indicate that more
algal growth in the lake can occur at lower nitrogen
levels than those that could cause acidification,
McKnight said. They also suggest tougher standards
than those proposed may be needed to protect water
quality in alpine lakes on the Front Range, many of
which are sources of water for Front Range communities
in Colorado. [Cheryl Dybas]
Top of Page
Method Could Shorten Time to Develop New Drugs
Researchers have devised a new way to simulate the
interactions between drugs and the molecules they
target. The new computer model treats the target molecules
as flexible structures that stretch and bend, rather
than as rigid objects, potentially improving the accuracy
and speed of pharmaceutical tests.
"The race is on between sophisticated lab procedures
and their computational analogs," said team leader
J. Andrew McCammon of the University of California,
San Diego (UCSD). "Our method both verifies and competes
with costly lab methods that rely on thousands of
Drugs are typically small molecules (called ligands)
that bind tightly to a targeted protein (a receptor)
and disrupt the protein's activity. Modern drug designers
look for the binding sites, and until now used rigid
crystal models for the search. In nature, target proteins
are dynamic, flexing molecules.
For their study, funded in part by NSF, McCammon's
group used computers at NSF's San Diego Supercomputer
Center (SDSC) and an SDSC "satellite site" at UCSD.
The UCSD approach is called the 'relaxed-complex' scheme
because the computational scheme allows the receptor
protein to relax into any possible conformation. The
team then tests various scenarios of ligand and receptor,
determining which potential drug binds best to the
target protein. "This allows us to use a building-block
approach to constructing the best ligands," said Jung-Hsin
Lin, a researcher in McCammon's group.
The method could be applied to every conceivable type
of drug for which there are three-dimensional structures
or predicted structures for the target to which the
drug would bind. While it is computationally intensive,
McCammon pointed out that by avoiding a brute-force
approach in the lab (involving protein synthesis and
purification, synthesis of the many ligands, and a
large number of trials), drug designers may be able
to save both time and money by using the new method.
Top of Page
to Monitor Tsunamis, Earthquakes
New observatories equipped with various instruments,
including seismometers, are being built deep below
the seabed under the auspices of the Ocean Drilling
Program (ODP), which is funded principally by NSF,
with substantial contributions from international
partners. The project will allow scientists to continuously
monitor and record information and develop a long-term
understanding of geological hazards such as tsunamis
and major earthquakes.
These observatories, funded in part by NSF, fill an
important void in scientific monitoring, say researchers.
On land, the Global Seismic Network (GSN) provides
adequate earthquake monitoring capabilities for most
continental regions and islands, but large areas of
the ocean floor have remained unmonitored until now.
The U.S. Global Seismic Network and its international
affiliate, the Federation of Digital Seismic Networks,
operate nearly 200 seismic stations, said scientist
John Orcutt of the Scripps Institution of Oceanography.
"Even though nearly every island has a modern seismic
observatory, enormous gaps in the coverage exist,
limiting scientific and operational coverage for seismic
studies of sources and the deep interior of the Earth,"
An ODP expedition on the research ship JOIDES Resolution
(Leg 203) next month will drill a hole in the seafloor
of the Pacific Ocean that will serve as the location
of a future observatory.
The observatory's instrumentation will connect to the
Internet through a satellite communications telemetry
link. The site is more than 1200 miles from any other
seismic observatory and will provide important information
on earthquakes affecting Central and South America.
"This station and other future installations at sea
will greatly enhance the coverage for these particularly
threatening earthquakes," Orcutt said. [Cheryl
Top of Page
of Undersea Earthquakes Tied to Ocean Tides
Scientists studying an active seafloor volcano in the
Pacific Ocean have determined that there is a correlation
between hundreds of micro-earthquakes and ocean tides.
In research funded by NSF, geophysicist Maya Tolstoy
of the Lamont-Doherty Earth Observatory at Columbia
University found that earthquakes coming from the
Axial Volcano on the Juan de Fuca Ridge (located off
the coasts of Washington and Oregon) are occurring
during tidal flows when the weight of the water is
at a minimum.
Tolstoy and colleagues also found a tidal correlation
with signals for harmonic tremors, which researchers
believe result from super-heated water moving in cracks
in Earth's crust. The results suggest that seafloor
crust is essentially breathing with the ebb and flow
of ocean tides, allowing more movement of water through
the crust and the release of seismic energy on a regular
"Scientists have long postulated that earthquakes and
tidal movements are somehow connected," said Tolstoy,
"but the link has been difficult to identify. It's
only within the last decade that the technology has
been available to make the long-term seismic recordings
of the seafloor necessary to finding this correlation.
We now have an interesting and important view into
how Axial Volcano's deformation, and perhaps the deformation
of other undersea volcanoes, actually works." [Cheryl
Top of Page