RESEARCH HIGHLIGHTS
Selections from the
scientific literature
PL ANETARY SCIENCE
The dunes of Saturn’s largest
moon, Titan, may be held
together by static electricity.
Grains of sand acquire
electrostatic charge as they
rub against each other, but on
Earth this effect is generally
negligible because gravity
and a high density of heavy
silicate particles minimize
interactions between the
particles. Joshua Méndez
Harper at the Georgia Institute
of Technology in Atlanta
and his colleagues recreated
conditions on Titan, which
has one-seventh the gravity of
Earth and hydrocarbon-based
sand. In their lab experiments,
the researchers showed that
these lighter grains generated
electrostatic forces strong
enough to clump some of the
grains together.
This could explain why sand
dunes at Titan’s equator seem
to grow into the wind.
Nature Geosci. http://dx.doi.
org/10.1038/ngeo2921 (2017)
M O LECUL AR B IO LO GY
Drug stalls protein
translation
The discovery of a compound
that interrupts the production
of a specific protein could
open up a fresh path to drug
discovery.
Cells rely on complex
molecular machines called
ribosomes to translate the
genetic code and make
proteins. Robert Dullea at
Pfizer Worldwide Research
and Development in
Cambridge, Massachusetts,
Jamie Cate at the University
of California, Berkeley, and
their colleagues studied
a compound that causes
ribosomes to stall while
producing the protein PCSK9,
CHRISTOPHE COURTEAU/NPL
Titan’s electrified
dunes
A NI M A L B E H AV I OU R
Playful call makes parrots merry
Hearing laughter can make people laugh,
and it seems that kea parrots react similarly,
displaying play behaviour after hearing a
particular call from fellow birds. This makes
them the first non-mammals known to
experience ‘contagious’ merriment.
Raoul Schwing, now at the University of
Vienna, and his colleagues studied kea parrots
(Nestor notabilis; pictured) in the wild in
New Zealand. They played a warbling sound
that is made by the birds and associated with
which slows the removal
of cholesterol from the
blood. They found that the
compound temporarily stops
ribosomes from synthesizing
PCSK9 when they encounter a
specific protein sequence, and
affects the production of only
a few other proteins.
Feeding the compound
to rats reduced their
cholesterol levels. Such
ribosome-stalling compounds
could be used to inhibit
proteins that are difficult to
target with other kinds of
drugs, the authors say.
PLoS Biol. 15, e2001882 (2017)
Curr. Biol. 27, R1–R2 (2017)
E VOLU T I ON
Diet drives
primate brain size
Primates’ large brains may be
due to the animals’ diet rather
than their social behaviour,
challenging a popular theory.
Alex DeCasien and her
colleagues at New York
University compiled existing
data on primate brain and
body size, and sorted the
species into four dietary
categories: omnivores, leafeaters, fruit-eaters and those
that eat both leaves and fruit.
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playful behaviour, for five minutes at a time.
The researchers found that the animals played
more often and for longer periods of time when
they heard the warble than when they heard
non-play kea calls, the tweets of a local robin or
an artificial tone. Play stopped shortly after the
sound ceased.
The authors conclude that the call is not
a courtship invitation but stimulates playful
emotion.
The primates that ate fruit
had significantly larger brains
than those that ate just leaves;
and the more fruit they ate,
the larger was the ratio of
their brain size to their body
size. The authors think this
could be due to a combination
of factors — one being the
high nutritional content of
fruit, another being cognitive
adaptations that help the
primates to forage for fruit.
Such adaptations could allow
them, for example, to extract
fruit from protective skins.
The team also found no
correlation between brain
JULIAN THOMSON
RESEARCH HIGHLIGHTS THIS WEEK
size and the level of social
complexity. This contradicts
a widely accepted theory that
states that large brains evolved
to help primates manage large
social networks.
Nature Ecol. Evol. http://dx.doi.
org/10.1038/s41559-017-0112
(2017)
AGEING
Senescent cells
cleared out
A newly developed molecule
causes ageing cells to commit
suicide, restoring some signs of
health and stamina in old mice.
Damaged cells that stop
dividing, called senescent
cells, accumulate with age, and
are thought to contribute to
inflammation, tissue damage
and age-related diseases. To
find ways to clear these cells,
Peter de Keizer at the Erasmus
University Medical Center in
Rotterdam, the Netherlands,
and his colleagues designed a
peptide that impairs binding
between the proteins FOXO4
and p53 — an interaction that
normally inhibits the ‘selfdestruct’ signal in senescent
cells. Infusions of the peptide
reversed decline in kidney
function in aged mice, and
eliminated weight loss and
liver damage caused in mice
by chemotherapy drugs. In
mice with a premature-ageing
condition, treatment with the
peptide caused regrowth of fur
that had been lost, and doubled
how far the animals could run.
The peptide seemed to have
little effect on normal cells,
probably because FOXO4
is scarce in non-senescent
cells. The researchers are now
preparing to test the safety of
their molecule in humans.
ESA/ROSETTA/NAVCAM
Cell 169, 132–147 (2017)
CANCER
How fat boosts
breast cancer
A molecule made by fat
cells in human breast tissue
increases the growth of certain
breast-cancer cells. The
finding suggests a potential
reason why larger breast size
seems to correlate with a
higher risk of cancer.
Fat cells are thought to
interact with cancer cells
in the breast. To learn how,
Wen-Hwa Lee at China
Medical University in Taiwan
and his colleagues grew human
breast-cancer cells along
with fat cells isolated from
human breast tumours that
had been surgically removed.
The team found that the fat
cells promoted the growth
of cancer cells that made a
protein called MCT2. The
researchers pinpointed a small
molecule, β-hydroxybutyrate,
that is secreted by the fat cells
and is transported into tumour
cells by MCT2. This molecule
upregulated several cancer
genes, boosting the growth of
human breast-tumour cells
that express MCT2.
Nature Commun. 8, 14706 (2017)
ASTR O N O M Y
Landslides cause
comet eruptions
The collapse of cliffs on
comets can create plumes of
gas and dust, which contribute
to comets’ characteristic tails.
Such outbursts are frequent,
but their cause has been
unclear. Maurizio Pajola at
the NASA Ames Research
Center in Moffett Field,
California, and his colleagues
analysed images taken by
high-resolution cameras
on the European Space
Agency’s Rosetta spacecraft
as it orbited the comet 67P/
Churyumov–Gerasimenko.
By comparing images taken
before and after an outburst
on 10 July 2015 (pictured),
the team traced the origin of
the event to the collapse of an
already fractured cliff, and a
subsequent landslide.
In a separate study,
Mohamed Ramy El-Maarry
at the University of Colorado,
Boulder, and his colleagues
used Rosetta’s instruments
to map 67P’s surface over
an 18-month period. They
concluded that most such
surface changes are caused
by increased exposure to
sunlight — which evaporates
ice and weakens land
structures — when the comet’s
orbit takes it close to the Sun
every 6.5 years. Given that
these landscape shifts are
relatively cosmetic, the authors
suggest that the landforms on
comet 67P have not changed
significantly since at least
1959, when it entered its
current orbit.
Nature Astron. 1, 0092 (2017);
Science http://doi.org/b4r6
(2017)
S E I S M OLOGY
Quake shows rare
complexity
A large earthquake that
rocked New Zealand’s South
Island in 2016 was one of the
most complex ever recorded,
involving the rupture of at
least 12 major faults.
A team led by Ian Hamling
of GNS Science in Lower
Hutt, New Zealand, used field
mapping, satellite observations
and other measurements to
analyse the magnitude-7.8
quake (pictured), which struck
on 14 November. They studied
the network of geological
faults that ruptured along
more than 170 kilometres
during the quake. They
found that many more faults
broke, and at greater depths,
than the country’s national
seismic-hazard model
suggested was possible.
Officials in other parts of
the world may want to reassess
their local earthquake risk, the
authors suggest.
Science http://doi.org/b4r7
(2017)
V I R OLOGY
What makes bird
flu jump species?
A single-letter change in the
RNA sequence of an avian
influenza virus called H7N9
could explain its continuing
ability to infect humans as well
as birds.
H7N9 has caused illness in
more than 1,000 people since
early 2013, and proved fatal in
about 40% of cases. Honglin
Chen at the University of
Hong Kong and his colleagues
compared the genome
sequence of the 2013 H7N9
strain, which infects people,
with all other available flu
sequences. They found a
single-letter substitution in
the RNA for one of the viral
proteins in the 2013 strain.
This mutation boosts the
virus’s ability to infect human
and mouse cells, without
disrupting its ability to
replicate in bird cells.
This single-letter change
came from another avian flu
virus, H9N2, and emerged
in 2000. Surveillance
programmes that monitor for
this sequence in avian viruses
may identify those that could
potentially jump into humans.
Nature Commun. 8, 14751 (2017)
NATURE.COM
For the latest research published by
Nature visit:
www.nature.com/latestresearch
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