In the News
This roundup summarizes
some notable recent items
about scientific research,
selected from news reports
compiled in Sigma Xi’s free
electronic newsletters Science in the News Daily and
Science in the News Weekly.
Online: http://sitn.sigmaxi.
org­ and http://www.americanscientist.org/sitnweekly
Swarms of Giant
Trilobites
Trilobites roamed the ocean
floor for some 300 million
years. The largest known
examples of these extinct
arthropods recently turned
up in a Portuguese quarry.
Previously, specimens larger
than 30 centimeters were
rare. But the new cache of
thousands of fossils includes
individuals that top 80 centimeters in length. What’s
more, many of the animals
were clustered in groups of
a few to more than a thousand, some of them in the
act of shedding their exoskeletons. The authors say
the clusters prove that trilobites, like today’s horseshoe
crabs, gathered in social
groups to molt and mate.
Gutiérrez-Marco, J. C., et al. Giant trilobites and trilobite clusters
from the Ordovician of Portugal.
Geology 37:443–446 (May)
Little Boxes Made of…
DNA origami forces a long circular strand of DNA into a specific shape by mixing it with
many shorter “staple” strands.
The staple strands entwine
with complementary sections
of the long strand and pull it
into shape. Researchers have
used the method to create
nanoscale smiley faces, a map
of North America—and now,
three-dimensional DNA boxes
just 30 nanometers across. The
3-D advance used a computer
program to predict the sequences of 220 staple strands
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that would assemble the one
long strand into a box. The
nanocubes even open up
when exposed to a specific
DNA “key,” hinting at future
applications in drug delivery. Andersen, E. S., et al. Self­ ssembly of a nanoscale DNA
a
box with a controllable lid. Nature 459:73-76 (May 7)
Sleepy Genes
People with narcolepsy suffer
from uncontrollable daytime
drowsiness and sudden bouts
of sleep. The condition arises
from lack of hypocretin, a
wakefulness-promoting hormone produced by just a few
brain cells. Narcoleptics share
a variant of the gene for an
immune system protein, human leukocyte antigen (HLA).
Researchers have therefore
suspected that an autoimmune disorder kills the
hypocretin-producing brain
cells, but further evidence
has been hard to find. Now a
genetic study of nearly 4,000
narcoleptics and healthy
controls identifies another
­narcolepsy-associated variation in an immune-system
gene. This one codes for Tcell receptor alpha, a protein
that interacts with HLA. Still,
not everyone with the mutations has narcolepsy, so the
next step is to find what triggers the autoimmune assault.
Hallmayer, J., et al. Narcolepsy is
strongly associated with the T-cell
receptor alpha locus. Nature Genetics (published online May 3)
Better Bee News
The U.S. and Europe have
watched in despair as their
honeybee (Apis mellifera)
populations decline. Some
researchers have predicted
a grim global crisis in which
crops won’t bear fruit for
want of pollinators. But a
new analysis of a global database of managed honeybees
shows that, despite local losses, global bee numbers have
risen 45 percent since 1961.
Furthermore, the authors
note that it’s luxury crops
such as cherries, mangoes
and nuts—not staples such as
rice and wheat—that require
bees. Global demand for luxury crops has escalated out of
proportion to total food production, and out of proportion to the bees—leading to
a perceived pollinator crisis.
Aizen, M. A., and L. D. Harder.
The global stock of domesticated honey bees is growing slower than agricultural demand
for pollination. Current Biology
(published online May 7)
Effici-ant Decisions
Forget comparison shopping.
When rock ants (Temnothorax
albipennis) have to find a new
home, workers start scouting
for a dry dark crevice under a
rock. But there’s no need for
individual ants to compare
different crannies and choose
the best. So say researchers
who attached tiny radio transmitters to hundreds of the
two-millimeter-long workers.
The transmitters revealed that
most scouts visited only one
potential nest site. Ants that
found a good-enough nest
on the first try stayed there,
whereas 40 percent of ants
that found a substandard (too
bright) nest quickly left it to
keep searching. The result: A
quorum accumulated at the
good-enough nest, and the
colony moved in. Robinson, E. J. H., et al. Do ants
make direct comparisons? Proceedings of the Royal Society B:
Biological Sciences (published
online April 22)
Hunting the Indus
Language
When it disappeared some
4,000 years ago, the Indus
culture left behind sculp-
tures, carts and the earliest
evidence of urbanization
on the Indian subcontinent.
Whether it also left written
records is a matter of debate.
Many Indus artifacts are inscribed with pictographs, but
it is unclear whether these
represented the culture’s spoken language. A new statistical analysis suggests that they
did. Researchers analyzed the
pattern in which the symbols
appeared and found that
it was neither random nor
completely rigid. Rather, the
sequence was most like that
of words or characters used
to represent known spoken
languages. Without another
Rosetta Stone, however, the
meaning of the symbols remains a mystery.
Rao, R. P. N., et al. Entropic
evidence for linguistic structure
in the Indus script. Science (published online April 23)
Stop Scratching!
Scratching satisfies an itch.
But how it does so is a neurological puzzle. Now researchers have tracked down neurons that are active during
itching and also calmed by
scratching. Spinal cord cells
called spinothalamic tract
(STT) neurons receive itch signals from neurons in the skin,
and transmit those signals to
the brain. To see if scratching could calm the same STT
cells, neuroscientists injected
the legs of sedated monkeys
(Macaca fasciularis) with
histamine. The STT neurons
went crazy—and scratching
the legs slowed the firing in a
subset of the cells. Researchers hope to target comparable neurons in humans to
stop itching in diseases such
as shingles or psoriasis.
Davidson, S., et al. Relief of itch
by scratching: State-dependent
inhibition of primate spinothalamic tract neurons. Nature Neuroscience 12:544–546 (May)
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