OF
NOTE
ASTRONOMY
Dance of the dead
The neutron star XTE J1739-285 is the
burned-out remains of what was once a
brilliant celestial body. Now, astronomers
have evidence that it’s the fastest-spinning
stellar corpse known.
X-ray observations indicate that the neutron star spins 1,122 times a second, about
30 percent faster than the previous record
holder, report Phil Kaaret of the University
of Iowa in Iowa City and his colleagues in the
March 10 Astrophysical Journal Letters.
NASA’s Rossi X-ray Timing Explorer
discovered the neutron star in 1999 when
it emitted bursts of X rays. After several
years of quiescence, it began sending out
new bursts in 2005. Studies of other neutron stars had shown that variations in
the brightness of X-ray bursts indicate
the stars’ rotation rates.
Late last year, the Rossi telescope found
oscillations indicating that XTE J1739-285
was spinning faster than any neutron star
previously observed. Since then, the star
has again quieted, and scientists are waiting to observe more bursts to confirm the
high spin rate, Kaaret and his team say.
The maximum rotation of a neutron star
would reveal its composition, notes Kaaret.
For instance, an interior composed solely of
electrons and protons squeezed together
into neutrons can’t be compressed as much
as more-exotic particles can and so can’t
rotate as rapidly. Additional studies of the
spin rates of neutron stars might let
astronomers rule out some estimates of the
objects’ compositions. —R. C.
ENVIRONMENT
I. MCALLISTER/RAINCOAST CONSERVATION SOCIET Y
Hibernation
concentrates
chemicals
Some pollutants build up in grizzly bears
even as they doze through the winter, tests
of the animals’ hair and fat indicate.
Hibernating bears don’t drink, eat, or
excrete waste, so food- and waterborne contaminants neither enter nor leave their bodies. Nevertheless, chemical concentrations
in the animals’ fat may change as they use
up that energy source.
The body converts some compounds into
water-soluble metabolites that get excreted
in urine. In a slumbering grizzly, such
metabolites might accumulate.
Researchers led by Peter S. Ross, a Sidney, British Columbia–based mammal toxicologist with the government agency
Fisheries and Oceans Canada, tested
11 grizzlies in the fall of 2003 and 14 others the following spring. In the March 15
Environmental Science &
Technology, Ross, Jennie
Christensen, and their colleagues report that many
pollutants increased in concentration in body fat, while
some decreased.
For example, the overall
concentration of polychlo-
rinated biphenyls (PCBs)
more than doubled. Poly-chlorinated diphenyl ether
concentrations increased by
58 percent. However, concentrations of certain PCBs and other contaminants declined, suggesting that they
had been metabolized.
Some of the pollutants whose concentrations increased in shrinking fat stores—but
none that decreased—are typically metabolized by an enzyme that may be suppressed
during hibernation, the researchers found.
Ross’ team notes that the bears’ diets created two distinct contamination patterns
in the fall—one in fish-eating bears and
another in bears living far from water. The
distinctive patterns blurred during hibernation, as metabolic processes erased the
differences in pollutants within the bodies
of bears in the two groups. —B. H.
in Blacksburg wondered how much chloroform arises when a person washes dishes
or showers with a triclosan-containing
product. The researchers tested several antibacterial liquid soaps in purified water and
tap-water samples from Atlanta and
Danville, Va., by adding a quarter of a gram
of soap per liter of water and measuring the
reaction products after 1 minute.
The scientists plugged
their results into a formula
to predict a person’s chloroform exposure. Use of triclosan-containing products
could boost the chloroform
reaching a person’s skin or
airways by 15 to 40 percent
over the chemical’s allowable concentration in tap
water, the researchers
report online and in an
upcoming Environmental
Science & Technology.
To determine people’s actual exposures
to chloroform during dishwashing or showering will require further studies, notes
Vikesland. But with the potential for additional chloroform exposure from antibacterial soaps of questionable benefit, “people
should think about what they are using and
whether they actually need it,” he says. —A. C.
BEARS’ BURDEN Grizzlies
concentrate some pollutants
in their fat even while they
fast during hibernation.
BIOMEDICINE
Emerging bug
pilfers DNA
CHEMISTRY
Scrubbing troubles
Triclosan, an antibacterial agent found in
many soaps, may increase a person’s exposure to a potentially toxic chemical, new
research suggests.
Although there is little evidence of any
benefit from using antibacterial soaps
instead of regular soaps in the home, people in the United States employ around
1,500 kilograms of triclosan each day in
kitchen and personal-care products.
Previous research has shown that triclosan reacts with chlorine, the most common disinfectant for drinking water. The
resulting by-products include chloroform,
suspected to cause cancer. Chloroform also
forms when chlorine reacts with organic
material in water.
Environmental chemist Peter J.
Vikesland and his coworkers at the Virginia
Polytechnic Institute and State University
A bacterium that’s spreading in U.S. hospitals and on the battlefields of the Middle
East has filched some of its most dangerous
genes from other bacteria, say researchers
who sequenced the bug’s genome.
In 2004, the Centers for Disease Control
and Prevention reported that 240 U.S. soldiers in the Middle East had suffered
antibiotic-resistant bloodborne infections
due to Acinetobacter baumannii. Stateside
hospitals have also reported a rise in stubborn infections from the bug. According
to previous research, it kills up to 75 percent of the people it infects.
Michael Snyder and his colleagues at Yale
University sequenced the genome of the
more virulent of the two known strains of
A. baumannii. Using a new technology
called high-density pyrosequencing, the
team decoded the genome in a few weeks.
The genome includes 28 stretches of
DNA that match sequences found in other
organisms. Fully 17 percent of A. baumannii’s genome appears to have been
imported, says Snyder, who compares the
bug’s genome to a pair of old, patched jeans.
