Summaries of newsworthy papers:
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Planetary science: How lunar rocks got magnetized
Infectious disease: Controlling malarial infection in blood cells
Stem cells: How to build a pituitary gland
Evolution: Primates leaped from solitary to social living
Human evolution: The great body trade-off
Comment: Lemaître translation mystery solved
Astrophysics: Pulsars and supernovae go two-by-two
Cancer: Precancerous cells put under surveillance
Biology: Circadian clock controls stem cells
Photophysics: Controlling blinking quantum dots
And finally… The world’s tiniest four-wheel-drive electric ‘car’
Geographical listing of authors
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[1] & [2] Planetary science: How lunar rocks got magnetized (pp 212-218; N&V)
Two explanations for the ancient magnetic field generated by the Moon
are presented in this week’s Nature. Previous research has attributed
this magnetic field to an early lunar dynamo; however, models suggesting
thermal or compositional convection as a driving force have been unable
to reproduce the seemingly long duration of the dynamo.
Christina Dwyer and colleagues propose that mechanical stirring of the
Moon’s liquid core, arising from differential motion between the solid
silicate mantle and the liquid core beneath, could have generated a
dynamo. Such differential motion comes from Earth-driven precession of
the lunar spin axis, when the Moon was closer to the Earth. They show
that this mechanism provides sufficient power to keep the dynamo
operating long enough to cover the period of magnetism recorded in lunar
rocks and naturally shuts off when the Moon has receded far enough from
the Earth.
Michael Le Bars and co-authors suggest that large impacts on the Moon
may have changed its rotation rate. Subsequent tidal distortion at the
core–mantle boundary could then have caused differential movements of
the core, thereby powering a transient lunar dynamo.
Both sets of findings implicate mechanical forces and although these
mechanisms differ, they may also account for aspects of magnetic fields
on other bodies, such as large asteroids.
CONTACT
Christina Dwyer (University of California, Santa Cruz, CA, USA)Author
paper [1] Tel: +1 831 459 1784; E-mail:[email protected]
Michael Le Bars (CNRS and Université Aix-Marseille, France)Author paper
[2] Tel: +33 4 13 55 20 73; E-mail:[email protected]
Dominique Jault (ETH Zurich, Switzerland) N&V author
E-mail: [email protected]
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[3] Infectious disease: Controlling malarial infection in blood cells (AOP)
DOI: 10.1038nature10606
An interaction that is crucial for facilitating invasion of red blood
cells by malarial parasites is identified in Nature this week. This
host–parasite receptor–ligand interaction does not seem to be
strain-specific and may, therefore, provide new possibilities for
anti-malarial therapies.
Infection of red blood cells (erythrocytes) by the malaria
parasite Plasmodium falciparum requires a series of signalling events
between erythrocyte receptors and corresponding molecules on the
parasites. Of the few known receptor–ligand interactions, none are
universal to all parasite strains. Gavin Wright and colleagues identify
specific interaction between the parasite ligand PfRH5 and erythrocyte
receptor basigin (BSG) that is essential for invasion. They show that
invasion can be inhibited by using anti-BSG antibodies, and this effect
was observed across all laboratory-adapted and field strains tested.
PfRh5 has been shown to be essential for blood stage growth inP.
falciparum. The discovery of cross-strain dependency on PfRh5
interaction with BSG in red blood cell infection may provide a focus for
the development of invasion-blocking drugs and vaccines.
CONTACT
Gavin Wright (Wellcome Trust Sanger Institute, Hinxton, UK)
Tel: +44 1223 496852; E-mail:[email protected]
For more information about the briefing, please contact the Sanger
Institute Media Office:
Tel: +44 1223 492368; E-mail: [email protected]
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[4] Stem cells: How to build a pituitary gland (AOP)
DOI: 10.1038nature10637
A system to produce a functioning pituitary gland from mouse embryonic
stem cells is described in Nature this week. The generation of
functional hormone-producing cells may open the possibility of
therapeutic interventions for pituitary defects.
Development of the pituitary gland is a complex process involving the
juxtaposition of two tissue types. Yoshiki Sasai and colleagues present
a method for organogenesis using mouse embryonic stem cells to produce
pituitary tissues. Embryonic stem cells are stimulated in a
three-dimensional culture that mimics the tissue interactions to produce
all five hormone-producing cell types of the pituitary gland. Of these,
corticotrophs were shown to successfully secrete the appropriate hormone
in response to its natural releasing factor (a hormone secreted by the
hypothalamus).
Transplantation of these tissues into mice with pituitary defects
resulted in rescue of the levels of the affected hormone.
CONTACT
Yoshiki Sasai (RIKEN Center for Developmental Biology, Kobe, Japan)
Tel: +81 78 306 1841; E-mail:[email protected]
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[5] Evolution: Primates leaped from solitary to social living (pp 219-222; N&V)
Models suggest that primates went from being solitary foragers to living
in large groups in one step, rather than group sizes increasing
gradually. The study on primate social evolution, published
in Nature this week, suggests that the shift from nocturnal to diurnal
living is linked to the origin of sociality. Such findings may help us
to understand the evolution of our closest relatives and the emergence
of early human social behaviour.
Phylogenetic comparative methods use information on the evolutionary
relationships of species (phylogenetic trees) to make inferences about
the evolution of traits, many of which can’t be recorded in fossils.
Susanne Shultz and colleagues use these methods to test competing
theories for the evolution of social behaviour in primates. They deduce
that large groups evolved directly from solitary foraging, followed
later by grouping structures such as pair-living and single-male harems.
The switch to social living evolved at the same time as a change from
nocturnal to diurnal activity. Thus, group living may have been an
adaptation to protect against the increased predation risk associated
with diurnal living, the authors suggest.
CONTACT
Susanne Shultz (University of Oxford, UK)
Tel: +44 1865 274 625; E-mail:[email protected]
Joan Silk (University of California, Los Angeles, CA, USA) N&V author
Tel: +1 310 825 2655; E-mail: [email protected]
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[6] Human evolution: The great body trade-off (AOP)
DOI: 10.1038nature10629
The expensive-tissue hypothesis in humans, which suggests that the size
of the brain is at the expense of the size of the digestive tract, is
challenged in this week’s Nature.
The human brain is about three times larger than that of our closest
living relative, the chimpanzee, and therefore requires more energy.
However, relative whole-body energy consumption rates of the two when at
rest are about equal. The expensive-tissue hypothesis has been put
forward as an explanation of this, and although animals such as fish
seem to support this, the theory has not been confirmed in humans, or
other mammals and birds.
Ana Navarrete and colleagues studied the size of various visceral
organs, such as the heart, lungs and stomach, along with the brain in a
sample of 100 mammal species. They found that, when controlling for
fat-free body mass, brain size in these animals did not negatively
correlate with the mass of the digestive tract or any other expensive
organ. This seems to refute the idea that expensive tissues compete for
energy. The authors suggest instead that energy trade-offs with less
expensive but abundant tissues, such as fat, may explain part of brain
size variation.
Brain development and fat storage have been put forward as strategies to
buffer against starvation and, in support of this, mammals in general
show an inverse relationship between brain mass and fatty tissue mass.
Humans, however, demonstrate large brains and are also relatively fatty.
The team suggest that this dual protection may have resulted from
improved diet quality, the move from quadrupedal to more efficient
bipedal locomotion, and an overall increase in net energy intake.
CONTACT
Ana Navarrete (University of Zurich, Switzerland)
Tel: +41 44 635 54 24; E-mail:[email protected]
Comment: Lemaître translation mystery solved (pp 171-173)
In this week’s Nature, Mario Livio solves the mystery of why
paragraphs disappeared during the 1931 translation of Georges Lemaître’s
landmark 1927 paper showing that the Universe is expanding. Some
observers have suggested that American astronomer Edwin Hubble or a
biased editor might have removed these sections to ensure that Hubble
retained credit for being the ‘first’, in 1929, to measure that
expansion rate.
By trawling the archives of the Royal Astronomical Society in London,
Livio located a lost letter from Lemaître to the editor ofMonthly
Notices of the Royal Astronomical Society. In it, the Belgian
mathematician and priest describes how he has translated his earlier
paper himself from French to English at their request. In the course of
the translation, he also deliberately omitted several paragraphs and
footnotes that he deemed to have been superseded by new research.
The letter thus ends the controversy that has blown up in recent months
about whether Lemaître’s translated paper was censored by a third party.
Livio’s discovery frees Hubble from these accusations, and shows that
Lemaître was unconcerned with getting the credit for the discovery, now
known as Hubble’s law.
CONTACT
Mario Livio (Space Telescope Science Institute, Baltimore, MD, USA)
Tel: +1 410 338 4439; E-mail:[email protected]
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[7] Astrophysics: Pulsars and supernovae go two-by-two (AOP)
DOI: 10.1038nature10529
The discovery of two distinct subpopulations of X-ray pulsars reported
in Nature this week may reveal how their neutron stars formed. The two
subpopulations are most probably associated with the two different types
of supernova explosions that, until now, have been hard to tell apart.
Two types of supernovae are thought to produce the vast majority of
neutron stars in the Universe: iron-core-collapse supernovae and
electron-capture supernovae. Christian Knigge and colleagues present
findings that support the existence of two kinds of X-ray pulsar
components in the population of BeX-ray binaries — which are well-known
strong sources of X-rays. These two components have different
characteristic spin and orbital periods, and orbital eccentricities,
which the authors suggest most probably correspond to the two types of
neutron-star-forming supernovae.
CONTACT
Christian Knigge (University of Southampton, UK)
Tel: +44 23 8059 3955; E-mail:[email protected]
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[8] Cancer: Precancerous cells put under surveillance (AOP)
DOI: 10.1038nature10599
An important component of intrinsic anti-cancer processes is described
in this week’s Nature. The work shows how the cellular senescence
program and the immune system interact to hinder liver cancer
development in a mouse model of the disease.
Oncogene-induced senescence — a process that prevents cells from
proliferating upon abnormal activation of oncogenes — is an important
tumour-suppressing mechanism. Lars Zender and colleagues now demonstrate
that oncogene-expressing senescent liver cells in mice are detected and
cleared through a tumour antigen-directed immune response. Preventing
this process of ‘senescence surveillance’ promotes the development of
liver cancer. Furthermore, the authors find senescent liver cells
accumulate in the livers of immune-suppressed patients, demonstrating
that senescence surveillance may also operate in humans.
This study establishes the importance of senescence surveillance in the
senescence anti-tumour pathway, by mounting antigen-specific immune
responses against peptides expressed in premalignant senescent cells,
the authors note. They are hopeful that strategies building on these
findings may hold promise for future cancer therapies.
CONTACT
Lars Zender (Helmholtz Centre for Infection Research, Braunschweig, Germany)
Tel: +49 531 6181 3130; E-mail:[email protected]
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[9] Biology: Circadian clock controls stem cells (AOP)
DOI: 10.1038nature10649
The circadian clock has a role in controlling the behaviour of stem
cells in the skin, according to a mouse model reported in this week’s
Nature. Disruption of this molecular clock affects various
regulatory processes performed by epidermal stem cells and
predisposition to the development of tumours.
Epidermal stem cells maintain homeostasis of the skin and are
responsible for tissue renewal. These cells alternate between active or
dormant states that respond differently to stimulation — states that
Salvador Benitah and co-workers demonstrate can coexist in mouse hair
follicle stem cells. The authors show that the circadian clock regulates
the activation state and the heterogeneity of these cells by regulating
their ability to respond to environmental cues.
The clock establishes a population of ‘ready-to-go’ cellsthat can
rapidly proliferate in response to activation stimuli. Simultaneously,
the clock can prevent other stem cells from becoming responsive. Benitah
and colleagues infer that disruption of this clock-controlled mechanism
could have long-term consequences on tissue homeostasis, ageing and
carcinogenesis.
CONTACT
Salvador Aznar Benitah (Center for Genomic Regulation and UPF,
Barcelona, Spain)
Tel: +34 933 160 212; E-mail:[email protected]
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[10] Photophysics: Controlling blinking quantum
dots (pp 203-207)
An important advance in the understanding of the random intermittent
emission of light in quantum dots is presented in this week’s Nature.
The findings shed light on the origin of photoluminescent blinking
behaviour and uncover a new mechanism for this action. Moreover, the
work demonstrates that the blinking mechanism can be controlled or
completely suppressed by applying a suitable electrical potential.
Nanocrystal quantum dots randomly emit light even under constant
irradiation, switching between an ON and OFF state ― a property that can
hamper experiments trying to track single particles. This blinking
behaviour had been explained by a mechanism in which the presence of
additional charges in the nanocrystal core leads to the OFF state.
Victor Klimov and colleagues uncover a second mechanism in which an
excited electron becomes trapped for a certain period of time at the
surface of the nanocrystal before being released to the emitting core.
They show that an appropriate voltage potential can fill in the electron
traps, thereby completely suppressing blinking. Blinking can also be
controlled varying the thickness of the shell layer.
CONTACT
Victor Klimov (Los Alamos National Laboratory, NM, USA)
Tel: +1 505 665 8284; E-mail:[email protected]
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[11] And finally... The world’s tiniest
four-wheel-drive electric ‘car’ (pp 208-211; N&V)
A nanometre-scale four-wheeled molecule that can move in a controlled
way is described in Nature this week. The car-like molecule is
fuelled by electrons and may pave the way for applications requiring
artificial transporters operating at the nanoscale.
Controlled movement of molecules along surfaces is an appealing property
for the development of molecular mechanical systems. However, this
requires molecules that respond to an energy input by changing the
interaction with the surface, thereby generating motion. Ben Feringa and
colleagues overcome this challenge by designing a molecule with four
rotary units attached to a central axis. Firing electrons at the
molecule induces conformational changes of the rotors, thereby
propelling the motor along a copper surface.
Tweaking the shape of the individual rotary units can alter the system
so that the molecule follows random or linear trajectories or remains
stationary. The authors are hopeful that their system will drive the
advancement of molecular mechanical systems with directionally
controlled motion.
CONTACT
Benjamin Feringa (University of Groningen, Netherlands)
Tel: +31 503 634 235 or tel: +31 612 158 742; E-mail:[email protected]
Paul Weiss (University of California, Los Angeles, CA, USA) N&V author
Tel: +1 814 865 3693; E-mail: [email protected]
GEOGRAPHICAL LISTING OF AUTHORS:
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The following list of places refers to the whereabouts of authors on
the papers numbered in this release. For example, London: 4 - this means
that on paper number four, there will be at least one author affiliated
to an institute or company in London. The listing may be for an author's
main affiliation, or for a place where they are working temporarily.
Please see the PDF of the paper for full details.
BELGIUM
Brussels: 2
FRANCE
Marseille: 2
Paris: 2
GERMANY
Aachen: 8
Braunschweig: 8
Hannover: 8
Heidelberg: 8
Munich: 8
Reutlingen: 8
JAPAN
Kobe: 4
Nagoya: 4
Tokyo: 3
Tsukuba: 4
NETHERLANDS
Enschede: 11
Groningen: 11
NEW ZEALAND
Auckland: 5
SENEGAL
Dakar: 3
SPAIN
Barcelona: 9
SWITZERLAND
Dübendorf: 11
Fribourg: 9
Zurich: 6, 8, 11
UNITED KINGDOM
Hinxton: 3
London: 8
Oxford: 3, 5, 7
Southampton: 7
UNITED STATES OF AMERICA
California
Pasadena: 1
Santa Cruz: 1
Massachusetts
Boston: 3
New Mexico
Los Alamos: 10
Ohio
Columbus: 9
PRESS CONTACTS…
From North America and Canada
Neda Afsarmanesh, Nature New York
Tel: +1 212 726 9231; E-mail: [email protected]
From Japan, Korea, China, Singapore and Taiwan
Mika Nakano, Nature Tokyo
Tel: +81 3 3267 8751; E-mail: [email protected]
From the UK
Rebecca Walton, Nature, London
Tel: +44 20 7843 4502; E-mail: [email protected]
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