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SCIENCE sciencemag.org 25 MARCH 2016 • VOL 351 ISSUE 6280 1411
CR
ED
ITS
: (T
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) JA
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.; H
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MAGNETOHYDRODYNAMICS
Simulating turbulent solar magnetic fields
An accurate simulation of solar
magnetic fields must reproduce
both the large-scale dynamo and
small-scale turbulence. Simply
increasing the computational
resolution does not always
help, because it can prevent
the 11-year solar cycle from
emerging. Hotta et al. show
how both large- and small-scale
phenomena can be reproduced
in some of the highest-resolution
simulations yet available. This
will improve our understanding of
both the solar magnetic field and
other turbulent magnetohydrody-
namic systems. — KTS
Science, this issue p. 1427
RESEARCHEdited by Stella Hurtley
I N SC IENCE J O U R NA L S
C-H BOND ACTIVATION
Methane borylation in a cyclohexane sea Although methane combusts
readily at high temperatures,
it is generally the hardest
hydrocarbon to transform
under gentler conditions, owing
to its particularly strong C-H
bonds. Cook et al. now show
that soluble rhodium, iridium,
and ruthenium catalysts can
slice through these C-H bonds
to add boron substituents to
methane at 150°C. Smith et al.
report the iridium-catalyzed
reaction using phosphine
ligands to enhance activity.
Both studies were performed in
cyclohexane solvent, revealing
a remarkable selective prefer-
ence for the methane reaction
over functionalization of the
cyclic hydrocarbon. — JSY
Science, this issue pp. 1421 and 1424
SOLAR CELLS
Perovskite solar cells recycle photonsInorganic-organic perovskite
solar cells are very efficient in
part because the charge carriers
exhibit very long path lengths.
Pazos-Outón et al. show that
photon recycling, as seen previ-
ously in highly efficient gallium
arsenide solar cells, contributes
to this effect (see the Perspective
by Yabionovitch). In most solar
cells, the recombination of
photogenerated charge carriers
(electrons and holes) wastes all of
the energy. In these lead tri-iodide
cells, recombination emits a
photon that can be reabsorbed
and create more charge carriers.
— PDS
Science, this issue p. 1430;
see also p. 1401
STRUCTURAL BIOLOGY
A human spliceosomal subcomplex The spliceosome is an RNA and
protein molecular machine that
cuts out introns from messenger
RNAs. Agafonov et al. used cryo–
electron microscopy to determine
the structure of the largest
intermediate subcomplex on the
assembly pathway for the human
spliceosome (see the Perspective
by Cate). The structure shows
substantial differences from the
equivalent yeast complex. It also
reveals how the subcomplex must
dock onto the rest of the spliceo-
some and hints at the structural
changes the complex must go
through to form the mature spli-
ceosome. — GR
Science, this issue p. 1416;
see also p. 1390
ECONOMICS
Another social science looks at itselfExperimental economists have
joined the reproducibility discus-
sion by replicating selected
published experiments from two
top-tier journals in economics.
Camerer et al. found that two-
thirds of the 18 studies examined
yielded replicable estimates of
effect size and direction. This
proportion is somewhat lower
than unaffiliated experts were
willing to bet in an associated
prediction market, but roughly in
line with expectations from sam-
ple sizes and P values. — GJC
Science, this issue p. 1433
MEMORY FORMATION
Coding what is known and what is newDo neural activity patterns during
sleep reflect the replay of a novel
experience or an invariant preex-
isting dynamic? Grosmark and
Buzsáki observed that both famil-
iar and novel aspects of learned
information are replayed during
synchronous bursts of activity
in the hippocampus. Familiarity
was encoded by fast-firing less-
modifiable neurons that showed
rate and sequence correlations
that persisted into postlearning
sleep. The novel features of an
MAG
SimsolAn a
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namic sys
An example of one of the solar magnetic field simulations
HIV: Toward broadly neutralizing antibodies for all Jardine et al., p. 1458
Published by AAAS
sciencemag.org SCIENCE1412 25 MARCH 2016 • VOL 351 ISSUE 6280
experience were represented by a different set of slowly firing and highly plastic cells. — PRS
Science, this issue p. 1440
CLOUD FORMATION
Organic contributions to cloud theoryCurrent theories about the formation of cloud droplets from aerosol particles containing organic components assume that the organic molecules are distributed throughout the droplet. Ruehl et al. show that this assumption is not always correct (see the Perspective by Noziere). During droplet nucleation, droplet diameters were 50% larger than predicted by the standard model. This suggests that the organic particles reside in a surface layer rather than in the bulk of the droplet. Models that neglect organic surface activity will thus underestimate how well organic-rich particles seed clouds. — HJS
Science, this issue p. 1447;
see also p. 1396
TUMOR IMMUNOLOGY
The cellular ancestry of tumor antigens One contributing factor in antitumor immunity is the reper-toire of neoantigens created by genetic mutations within tumor cells. Like the corresponding mutations, these neoantigens show intratumoral heteroge-neity. Some are present in all tumor cells (clonal), and others are present in only a fraction
of cells (subclonal). In a study of lung cancer and melanoma, McGranahan et al. found that a high burden of clonal tumor neoantigens correlated with improved patient survival, an increased presence of tumor-infiltrating lymphocytes, and a durable response to immuno-therapy. — PAK
Science, this issue p. 1463
CANCER
The spread of bad neighborhoods Our genomes have complex three-dimensional (3D) arrange-ments that partition and regulate gene expression. Cancer cells frequently have their genomes grossly rearranged, disturbing this intricate 3D organization. Hnisz et al. show that the disrup-tion of these 3D neighborhoods can bring oncogenes under the control of regulatory elements normally kept separate from them (see the Perspective by Wala and Beroukim). These novel juxtapositions can result in the inappropriate activation of onco-genes. — GR
Science, this issue p. 1454;
see also p. 1398
FOREST ECOSYSTEMS
Forest recovery in China is not so clear cut Frequently in developing nations, forests shrink as trees are cut and agriculture expands. This trend does not tend to reverse until significant economic devel-opment and urbanization occur. Viña et al. used remote sensing and analytical models to show that heavily deforested regions in China experienced regrowth between 2000 and 2010 in spite of China’s status as a developing
nation. The key to this success was China’s strong conser-
vation policies. Despite this, densely forested regions still shrank, and forest growth may have come
at the expense of forests shrinking elsewhere. — SN
Sci. Adv.2 10.1126.sciadv.00965
(2016).
STRUCTURAL BIOLOGY
A domain swap makes motor ringsCells are packed with protein complexes. Cells must appropri-ately assemble these complexes while ensuring that component proteins do not aggregate pre-maturely. Baker et al. show that the FliG protein, part of the bac-terial flagellar motor complex, can polymerize to forms rings by “domain swapping.” Domains within a single FliG can interact with each other or “swap” with neighboring FliG proteins to form the same interaction—a molecular form of linking arms. The flexibility of the peptides that tether these domains ensures that FliG remains a monomer in the cytoplasm. FliG binding to a scaffolding ring promotes motor assembly by increasing the local concen-tration of FliG and promoting domain swapping. — GR
Nat. Struct. Mol. Biol. 197, 23 (2016).
GENETICS
When Mom or Dad’s inheritance countsRetinoblastoma (Rb), a largely inherited form of pediatric eye cancer, arises when patients carry two utant copies of the RB1 tumor suppressor gene. However, not all individuals car-rying two mutant copies of RB1
go on to develop cancer. Eloy et
al. investigated why, focusing on one specific mutation of RB1,and found differences depend-ing on whether the mutant gene was maternally or paternally inherited. Maternal inheritance led to higher Rb protein expres-sion, and because the particular mutation allowed for some residual protein function, this probably protected some indi-viduals from developing cancer. Thus, in some cases, parent-of-origin effects can explain why genetic carriers may not always go on to develop disease. — LMZ
PLOS Genet. 12, e1005888 (2016).
1412
alythat heavily defoin China experiencbetween 2000 anof China’s status
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Sci. Adv.2 10
RESEARCH | IN SCIENCE JOURNALS
Tumors contain cells expressing
a variety of novel antigens
Edited by Kristen Mueller
and Jesse SmithIN OTHER JOURNALS
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Published by AAAS
sciencemag.org SCIENCE1413-B 25 MARCH 2016 • VOL 351 ISSUE 6280
RESEARCH
SYNTHETIC BIOLOGY
Designing and building a minimal genome A goal in biology is to understand
the molecular and biological
function of every gene in a cell.
One way to approach this is to
build a minimal genome that
includes only the genes essential
for life. In 2010, a 1079-kb
genome based on the genome
of Mycoplasma mycoides
(JCV-syn1.0) was chemically
synthesized and supported cell
growth when transplanted into
cytoplasm. Hutchison III et al.
used a design, build, and test
cycle to reduce this genome to
531 kb (473 genes). The result-
ing JCV-syn3.0 retains genes
involved in key processes such
as transcription and translation,
but also contains 149 genes of
unknown function. — VV
Science, this issue p. 1414
TRANSPORTER FUNCTION
A proton pump in action
P-type adenosine triphos-
phatases (ATPases) use the
energy from ATP hydrolysis to
pump cations across biological
membranes. The electrochemi-
cal gradients that are generated
control many essential cellular
processes. Veshaguri et al. incor-
porated a plant proton pump
into vesicles and monitored
the dynamics of single pumps.
Pumping was stochastically
interrupted by long-lived inactive
or leaky states. The work reveals
how these proton pumps are
regulated by a protein domain
and by pH gradients. — VV
Science, this issue p. 1469
PHYSIOLOGICAL ECOLOGY
Variability for a day or a season Species that experience larger
seasonal climatic fluctuations
are likely to be more physiologi-
cally flexible and thus likely to
occur across a wider elevational
range. Daily changes in tempera-
ture are also common but have
rarely been considered. Chan et
al. used a global data set of ver-
tebrates to look at how these two
different sets of variation affect a
species’ elevational distribution
(see the Perspective by Perez et
al.). Unexpectedly, larger daily
fluctuations were associated
with smaller elevational distri-
butions. Thus, specialists are
favored where daily fluctuations
are dominant, whereas general-
ists are favored where seasonal
fluctuations are the main climate
influence. — SNV
Science, this issue p. 1437;
see also p. 1392
PROTEIN EVOLUTION
Variation and transcription factor binding Little is known about the phe-
notypic and functional effects
of genetic variants that result
in amino acid changes within
functional proteins. Barrera et
al. investigated whether amino
acid variants changed the DNA
binding specificity or affinity of
transcription factors. Predictive
analyses identified changes in
the proteins, and protein-binding
microarrays verified changes
that affected transcription
factor function, including those
associated with disease. Thus,
within-human protein sequence
variation can affect transcrip-
tional regulatory networks,
which, depending on the genetic
variant, may confer robust-
ness and buffer against amino
acid changes and could explain
phenotypic variation among
individuals. — LMZ
Science, this issue p. 1450
DFT METHODS
A comparison of DFT methods Density functional theory (DFT)
is now routinely used for simu-
lating material properties. Many
software packages are available,
which makes it challenging
to know which are the best to
use for a specific calculation.
Lejaeghere et al. compared the
calculated values for the equa-
tion of states for 71 elemental
crystals from 15 different widely
used DFT codes employing
40 different potentials (see
the Perspective by Skylaris).
Although there were variations
in the calculated values, most
recent codes and methods
converged toward a single value,
with errors comparable to those
of experiment. — MSL
Science, this issue p. 1415;
see also p. 1394
HIV-1 VACCINES
Baby steps toward bNAbs
Some HIV-infected individu-
als develop heavily mutated,
broadly neutralizing antibod-
ies (bNAbs) that target HIV.
Scientists aim to design
vaccines that would elicit such
antibodies. Jardine et al. report
an important step toward this
goal: They engineered an immu-
nogen that could engage B cells
from HIV-uninfected individu-
als that express the germline
versions of the immunoglobulin
genes harbored by a particular
class of bNAbs. The frequencies
of these B cells, their affinities
for the immunogen, and struc-
tural analysis suggest that the
immunogen is a promising can-
didate. Further shaping of the B
cell response with subsequent
immunogens may eventually
elicit bNAbs in people. — KLM
Science, this issue p. 1458
NEURODEVELOPMENT
Tracking neuronal transcriptional programs Early in brain development,
cortical neurons are born near
the ventricles, then migrate to
their functional destinations.
Telley et al. used a fluorescent
labeling technique to see what
transcripts characterize these
earliest stages of neural develop-
ment. Waves of transcriptional
programs are initiated, then
passed by as the neuron
progresses from proliferative
to migratory and finally to con-
nectivity phases. — PJH
Science, this issue p. 1443
CARDIOVASCULAR BIOLOGY
A GRK2 peptide prevents heart failureDuring cardiac hypertrophy,
sustained high blood pressure
causes the heart walls to thicken
to deal with the increased load.
If left unchecked, cardiac hyper-
trophy leads to heart failure. A
particular part of the kinase and
scaffolding protein GRK2 inhibits
a G protein that promotes car-
diac hypertrophy. Schumacher
et al. generated mice that
overexpressed a peptide of this
inhibitory region of GRK2 in the
heart. Under conditions that
cause heart failure, these mice
developed less cardiac hypertro-
phy and retained greater cardiac
function. — WW
Sci. Signal. 9, ra30 (2016).
AUTOIMMUNITY
A glucose balancing act
In autoimmune diseases, T
cells engage their hyperdrive,
both proliferating and secret-
ing inflammatory cytokines at
greater rates than normal. Little
is known about the metabolic
changes that fuel this process.
Yang et al. report that a defect in
reactive oxygen species (ROS)
could boost proinflammatory
T cells in rheumatoid arthritis.
A defect in glycolytic flux led to
increased ROS consumption,
which bypassed a cell cycle
checkpoint and contributed to
hyperproliferation and proin-
flammatory cell differentiation.
What’s more, restoring intracel-
lular ROS reduced proliferation
and suppressed inflammation.
— ACC
Sci. Transl. Med. 8, 331ra38 (2016).
Edited by Stella HurtleyALSO IN SCIENCE JOURNALS
Published by AAAS