SCIENCE
NEWS
This Week
“This is a beautiful result,” comments
photonics specialist Masaya Notomi of
NTT Basic Research Laboratories in
Atsugi, Japan.
“It shows the first practical steps toward
being able to store optical bits of data,” says
electrical engineer Keren Bergman of
Columbia University. The IBM loops can
store up to 10 bits of high-speed data so far,
but they’ll need to store 10 to 100 times as
much to be useful, she adds.
More than a year ago, another IBM
team led by Vlasov reported retarding
light in silicon by a different means—
passing it through ultrathin slabs of the semiconductor punctuated by arrays of holes
(SN: 11/5/05, p. 292). Such a structure,
known as a photonic crystal, remains a
potentially useful component for manipulating light on chips, Vlasov says.
Indeed, Notomi, Takasumi Tanabe, and
their colleagues at NTT report, also in the
January Nature Photonics, that they’ve
developed a new photonic crystal that
retards light more than 170 times as much
as the 2005 IBM crystal did.
That’s “a great achievement,” Vlasov says.
Scientists are continuing to pursue both
the photonic-crystal and silicon-loop
approaches to find the most advantageous
combination of light retardation, information capacity, and ease of integration
with chip production. —P. WEISS
Paleotrickery
A lengthy lineage for
leaf-mimicking insects
For at least 47 million years, some insects
have escaped predators by looking like
foliage and moving like swaying leaves, a
new fossil find suggests.
Many creatures elude predators by blending into their surroundings. But the 3,000
or so species in an insect group called the
phasmids take camouflage to an extreme,
says Sonja Wedmann of the Institute for
Paleontology in Bonn, Germany.
Most modern-day phasmids have bodies and legs that look like sticks and twigs,
but at least 37 known species are shaped
like the tree leaves that they eat or frequent
during daylight hours, she notes. To complete the deception, phasmids occasionally
move back and forth to mimic the motion
of a leaf or twig in the breeze.
Paleontologists have found precious few
FAKING IT Researchers recently discovered
a 47-million-year-old fossil of an insect
(Eophyllium messelensis) that, like its modern-day relative (inset), has a leaflike shape and
measures about 6 centimeters long.
phasmid fossils, and they had never previously unearthed one of a leaf insect. Wedmann and her colleagues describe their discovery of such a fossil in a report posted
online Dec. 29, 2006 for an upcoming
Proceedings of the National Academy of Sciences.
The 6-centimeter-long, almost-complete
leaf insect was preserved in fine-grained sediments. They were laid down in a broad, shallow lake that formed about 47 million years
ago inside a volcanic crater in what is now
Germany. Portions of the creature’s antennae
and legs are missing, but its abdomen is the
size and shape of some fossil leaves retrieved
from the same strata, says Wedmann. The
genitalia of the fossil insect are almost identical to those of modern leaf insects, a sign
that subsequent species changed little in the
millions of years that followed.
“This creature has all the features you’d
expect of a primitive leaf insect,” says Conrad C. Labandeira, a paleontologist at the
Smithsonian Institution’s National Museum
of Natural History in Washington, D.C.
Unlike some modern leaf mimics, the
newly discovered Eophyllium messelensis
didn’t have flattened projections on its front
legs that made them look like small bits of
leaves. The legs, like those of most living
phasmids, were slightly curved where they
joined the body. When the modern insects
aren’t on the move, they often extend their
front legs forward, hold them together, and
tuck their heads down into a position that
helps them blend into their environment.
Many scientists suspect that ancient ani-
mals behaved quite differently than their
modern-day relatives do, says Michael S.
Engel, an entomologist at the University of
Kansas in Lawrence. However, “fossils such
as Eophyllium provide direct evidence to
the contrary,” he notes.
Other fossils unearthed from the same
rocks include remains of fish, birds, bats,
and small primates called lorises. The shape
and variety of fossil leaves collected suggest
that the lake was surrounded by a rich tropical ecosystem—the same type of environment in which leaf insects are found today,
says Wedmann. —S. PERKINS
Better Blood
New tool removes agent
of brain disease
Scientists have developed a device that fil-
ters from blood the mutant proteins that
cause the human form of mad cow disease.
This new tool could boost the safety of
donated blood.
Infectious proteins called prions cause
mad cow disease, scrapie in sheep, and variant Creutzfeldt-Jakob disease (vCJD) in
people. Since the early 1980s, doctors have
diagnosed more than 200 cases of the fatal
human disease worldwide, most of which
seem to have resulted from eating beef
tainted with prions. However, there’s evidence that at least three people contracted
the disease from blood transfusions that
carried prions.
Scientists are working to reduce the risk
of obtaining prions from beef. Researchers
in the United States and Japan reported
online Dec. 31, 2006 in Nature Biotechnology that they have engineered cattle that
are free of the proteins that mutate to cause
mad cow disease.
However, Robert Rohwer of the Veterans Affairs Medical Center in Baltimore,
who studies vCJD and other prion-related
diseases, notes that if these cattle enter the
food supply, disease risk won’t drop right
away. Prions can linger in a person’s blood
from beef that they ate years ago.
“This is a disease with a very long incubation period during which people infected
with vCJD appear completely normal,”
Rohwer says.
To develop a way to extract prions from
blood, Rohwer and his colleagues searched
a library of millions of chemicals for ones
that stick tightly to prions. The team coated
tiny beads with each chemical and incubated the beads with prions isolated from
people, hamsters, and other animals. After
excluding those chemicals that were too
expensive or too toxic or that stuck too
readily to other blood components, the
researchers narrowed their focus to a compound that they call L13.
PNAS
