nature v457 n7227 Jan 15,20009 RESEARCH HIGHLIGHTS

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CHEMICAL BIOLOGY
Fluorescent timers
Nature Chem. Biol. doi:10.1038/nchembio.138 (2009)
New fluorescent ‘timers’ that gradually
change colour from blue to red could allow
researchers to track the age and dynamic
behaviour of proteins in living cells.
Previous work suggested that some red
fluorescent proteins start out fluorescing
blue, but then change to red as the protein
is chemically modified over time. Vladislav
Verkhusha and his colleagues at the Albert
Einstein College of Medicine in New York
mutated a red fluorescent protein called
mCherry, then screened for mutants that had
altered maturation rates from blue to red.
The researchers developed three
fluorescent proteins, each with a specific
maturation rate. The proteins were used
to track newly synthesized proteins in
mammalian cells grown in culture.

MICROSCOPY
Inside information
Phys. Rev. Lett. 102, 018101 (2009)
Sliced chromosome is on the menu,
thanks to a tour-de-force
of X-ray microscopy.
Yoshinori Nishino of
the RIKEN SPring-8
Center in Hyogo, Japan,
and his co-workers
have recorded threedimensional
sectional
images of a human
chromosome (pictured
right) using coherent X-ray
diffraction microscopy.
Chromosomes are toothem, and fluorescent light microscopy can
reveal only selected features. By contrast,
the X-ray diffraction method offers a full
three-dimensional view of electron density
in a single chromosome about 2 micrometres
across, showing the internal structure with a
resolution of about 120 nanometres.
ANIMAL BEHAVIOUR
Caught red hydrocarboned
Curr. Biol. 19, 78–81 (2009)
Ants, like other social creatures, strive to
minimize antisocial behaviour by punishing
cheaters. For example, fertile worker
Aphaenogaster cockerelli ants that could
undermine the unity of a colony with a
single reproducing queen are attacked by
nestmates. Although it has remained unclear
how would-be cheats are identified, evidence
suggested that variations in the hydrocarbons
in ants’ cuticles might be involved. Jürgen
Liebig of Arizona State University in Tempe
and his colleagues show that
when A. cockerelli workers in
colonies headed up by a queen
are manually coated with
pentacosane, a hydrocarbon
linked with fertility, they are
attacked by their nestmates.
Because ant eggs
carry distinctive related
hydrocarbons that prevent
them from being identified
and destroyed, cheaters
probably cannot suppress
their chemical profiles. Thus,
hydrocarbons could provide
an inherently reliable method to
catch cheats.MOLECULAR BIOLOGY
A bilingual genetic code
Science 323, 259–261 (2009)
A ciliate called Euplotes crassus seems to have
violated the rules of genetics.
Messenger RNA is used as a template
to assemble proteins by means of threeletter
sequences called codons. Each codon
corresponds to either a single amino acid or
a ‘stop’ signal. However, Vadim Gladyshev of
the University of Nebraska in Lincoln and his
colleagues found that in E. crassus, the codon
UGA could encode two amino acids: cysteine
or selenocysteine.
The codon could be read in both ways
within the same gene, depending on its
location within the mRNA strand and the
presence and exposure of a specific sequence
near the end of the mRNA molecule. The
results suggest that the genetic code can be
evolutionarily expanded.
ECOLOGICAL ACOUSTICS
Love buzz
Science doi:10.1126/science.1166541 (2009)
The buzz of flying female mosquitoes
acts as a mating signal to attract males.
When Ronald Hoy and his team at Cornell
University in Ithaca, New York, listened
closer, they found that when both sexes of
Aedes aegypti get together, they change their
buzz pitch to match, producing a courtship
duet. But rather than duo at their usual wing
beat frequencies — of around 400 hertz
for females and 600 hertz in males — the
mosquitoes take their acoustics up a notch to
a shared harmonic frequency of 1,200 hertz.
Male mosquitoes were previously thought
to be deaf to frequencies above 800 hertz.The researchers then examined the ‘ears’ of
A. aegypti, and confirmed that both sexes
can hear up to 2,000 hertz. They call for more
research on the mating behaviours of the
mosquitoes, which carry yellow fever and
dengue virus.
CHEMICAL SYNTHESIS
Take that, flu
Angew. Chem. Int. Edn doi:10.1002/anie.200804883
(2009)
With the constant threat of a flu pandemic,
the quest for cheaper, more efficient routes
by which to make the flu treatment Tamiflu
is keeping chemists busy. Yujiro Hayashi and
his team at the Tokyo University of Science
report the highest-yielding route so far using
inexpensive reagents and just nine reactions,
all in three one-pot processes.
The first pot uses diphenylprolinol silyl
ether, an organocatalyst — a class of catalysts
that don’t involve expensive and toxic metals.
The organocatalyst helps the first two starting
materials to react, and they go on to react
with a third. The product goes into pot two
to undergo a domino reaction — a cascade of
reactions whereby each group of a molecule
with many functional groups reacts in turn.
In pot three, the final three reactions produce
Tamiflu, or (–)-oseltamivir, in 57% yield.
The authors say that their scheme is ideal
for large-scale production.
CELL BIOLOGY
Lost nuclei
J. Cell Biol. doi:10.1083/jcb.200811035 (2009)
Certain mutations in the gene LMNA cause
a rare form of muscular dystrophy, possibly
through improper positioning of cell nuclei.
The disease, called autosomal dominant
Emery-Dreifuss muscular dystrophy
(AD-EDMD), and others like it are puzzling
because the mutant proteins — in this case
lamins A and C — are expressed throughout
the body, not just in affected tissues.
Tom Misteli of the US National Cancer
Institute in Bethesda, Maryland, and
his colleagues looked at muscle fibres
from mouse models of the disease and
compared them with those of normal
mice. Muscle fibres contain hundreds of
nuclei, but a handful are recruited to the
point where muscle and neuron meet, the
neuromuscular junction. In the diseased
mice, proteins found in muscle that
mediate that recruitment don’t associate
properly with lamin A. The nuclei get
misplaced, neuromuscular junctions become
malformed and gene expression in the cells
is disrupted.
EVOLUTIONARY BIOLOGY
Headstrong
PLoS ONE doi:10.1371/journal.pone.0003980 (2008)
Large body size confers obvious advantages
in cricket fights, but Chinese gamblers have
also looked to the head when placing their
bets going back some eight centuries. New
research bolsters the practice, providing the
first evidence that males have developed
larger heads — and mouth parts — as
weaponry in aggressive turf battles.
Kevin Judge and Vanessa Bonanno at
the University of Toronto Mississauga in
Canada pitted fall field crickets (Gryllus
pennsylvanicus) of similar body size against
each other; those with bigger heads and
mouth parts won 75% of battles that escalated
to ‘grappling’. The bigger the difference in
head size, the more likely the head-strong
cricket was to win.
But the team found no evidence of
signalling that would influence disputes
settled before grappling took place,
suggesting that evolutionary selection takes
place in the heat of the battle.
CHEMISTRY
An aromatic hybrid
Angew. Chem. Int. Edn doi:10.1002/anie.200805554
(2008)
After years of trying, chemists have finally
made a molecule somewhere between
benzene (C6H6), and its inorganic boron/
nitrogen equivalent borazine (B3N3H6).
In the molecule, 1,2-dihydro-1,2-azaborine,
one of benzene’s carbon atoms is replaced
with a nitrogen, and another with a boron
atom. Scientists have been trying to make this
compound since the 1960s, with no luck.
David Dixon at the University of Alabama in
Tuscaloosa, Lev Zakharov at the University of
Oregon in Eugene and their colleagues have
now succeeded. The compound, which they
made by stabilizing the reactive intermediates
with a chromium-based protecting unit, is
stable, and like benzene is aromatic, although
not as strongly.

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