Table Of Contents Page, PNAS Volume 113, Number 43
This Week in PNAS
Letters (Online Only)
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A field experiment shows that subtle linguistic cues might not affect voter behavior
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Science and Culture
Core Concepts
Commentaries
PNAS Plus Significance Statements
Physical Sciences
Applied Mathematics
T cells must respond differently to antigens of varying affinity presented at different
doses. Previous attempts to map peptide MHC (pMHC) affinity onto T-cell responses
have produced inconsistent patterns of responses, preventing formulations of ...
Applied Physical Sciences
In nature, several seabirds (e.g., gannets and boobies) dive into water at up to 24
m/s as a hunting mechanism; furthermore, gannets and boobies have a slender neck,
which is potentially the weakest part of the body under compression during high-speed
...
Findings of laser-assisted atom probe tomography experiments on boron carbide elucidate
an approach for characterizing the atomic structure and interatomic bonding of molecules
associated with extraordinary structural stability. The discovery of ...
Electrolyte-gated organic transistors offer low bias operation facilitated by direct
contact of the transistor channel with an electrolyte. Their operation mode is generally
defined by the dimensionality of charge transport, where a field-effect ...
Astronomy
We analyze data from the Quarter 1–17 Data Release 24 (Q1–Q17 DR24) planet candidate
catalog from NASA’s Kepler mission, specifically comparing systems with single transiting planets to systems
with multiple transiting planets, and identify a population ...
Chemistry
Here, using ultrafast electron crystallography (UEC), we report the observation of
rippling dynamics in suspended monolayer graphene, the prototypical and most-studied
2D material. The high scattering cross-section for electron/matter interaction, the
...
A recently proposed chemomechanical group transfer theory of rotary biomolecular motors
is applied to treat single-molecule controlled rotation experiments. In these experiments,
single-molecule fluorescence is used to measure the binding and release rate ...
Mechanism of O2 activation and substrate hydroxylation in noncoupled binuclear copper monooxygenases
Peptidylglycine α-hydroxylating monooxygenase (PHM) and dopamine β-monooxygenase (DβM)
are copper-dependent enzymes that are vital for neurotransmitter regulation and hormone
biosynthesis. These enzymes feature a unique active site consisting of two ...
The molecular-level details of crystallization remain unclear for many systems. Previous
work has speculated on the phenomenological similarities between molecular crystallization
and protein folding. Here we demonstrate that molecular crystallization can ...
Little is known about the influence of nanoconfinement on calcium carbonate mineralization.
Here, colloidal probe atomic force microscopy is used to confine the calcite–solution
interface with a silica microsphere and to measure Derjaguin–Landau–Verwey–...
G-protein–coupled receptors (GPCRs) recognize ligands of widely different efficacies,
from inverse to partial and full agonists, which transduce cellular signals at differentiated
levels. However, the mechanism of such graded activation remains unclear. ...
Earth, Atmospheric, and Planetary Sciences
The magnitude of aerosol radiative forcing caused by anthropogenic emissions depends
on the baseline state of the atmosphere under pristine preindustrial conditions. Measurements
show that particle formation in atmospheric conditions can occur solely from ...
The Paleocene–Eocene Thermal Maximum (PETM) (∼56 Ma) was a ∼170,000-y (∼170-kyr) period
of global warming associated with rapid and massive injections of 13C-depleted carbon into the ocean–atmosphere system, reflected in sedimentary components
as a ...
Earth sustains its magnetic field by a dynamo process driven by convection in the
liquid outer core. Geodynamo simulations have been successful in reproducing many
observed properties of the geomagnetic field. However, although theoretical considerations
...
Coastal flood hazard varies in response to changes in storm surge climatology and
the sea level. Here we combine probabilistic projections of the sea level and storm
surge climatology to estimate the temporal evolution of flood hazard. We find that
New ...
Engineering
The search for high-affinity aptamers for targets such as proteins, small molecules,
or cancer cells remains a formidable endeavor. Systematic Evolution of Ligands by
EXponential Enrichment (SELEX) offers an iterative process to discover these aptamers
...
When a many-body system is driven away from equilibrium, order can spontaneously emerge
in places where disorder might be expected. Here we report an unexpected order in
the flow of a concentrated emulsion in a tapered microfluidic channel. The velocity
...
Solid-state shock-wave propagation is strongly nonequilibrium in nature and hence
rate dependent. Using high-power pulsed-laser-driven shock compression, unprecedented
high strain rates can be achieved; here we report the directional amorphization in
...
Extracellular matrix stiffness influences biological functions of some tumors. However,
it remains unclear how cancer subtypes with different oncogenic mutations respond
to matrix stiffness. In addition, the relevance of matrix stiffness to in vivo tumor
...
Physics
The monomer surface mobility is the single most important parameter that decides the
nucleation density and morphology of islands during thin-film growth. During template-assisted
surface growth in particular, low surface mobilities can prevent monomers ...
In vivo, the human genome folds into a characteristic ensemble of 3D structures. The
mechanism driving the folding process remains unknown. We report a theoretical model
for chromatin (Minimal Chromatin Model) that explains the folding of interphase ...
View related content:
Three-dimensional chromosome structures from energy landscape
Social Sciences
Anthropology
The origin of human violence and warfare is controversial, and some scholars contend
that intergroup conflict was rare until the emergence of sedentary foraging and complex
sociopolitical organization, whereas others assert that violence was common and of
...
Economic Sciences
Strong social capital is increasingly recognized as an organizational advantage. Better
knowledge sharing and reduced transaction costs increase work efficiency. To mimic
the formation of the associated communication network, we propose the Expert Game,
...
Social Sciences
In the current paper, we report a large-scale randomized field experiment, conducted
among Jewish Israelis during widespread violence. The study examines the effectiveness
of a “real world,” multichanneled paradoxical thinking intervention, with messages
...
Laboratory experiments have shown that parents who believe their child’s abilities
are fixed engage with their child in unconstructive, performance-oriented ways. We
show that children of parents with such “fixed mindsets” have lower reading skills,
even ...
Intergroup violence is common among humans worldwide. To assess how within-group social
dynamics contribute to risky, between-group conflict, we conducted a 3-y longitudinal
study of the formation of raiding parties among the Nyangatom, a group of East ...
Biological Sciences
Anthropology
The origin of human violence and warfare is controversial, and some scholars contend
that intergroup conflict was rare until the emergence of sedentary foraging and complex
sociopolitical organization, whereas others assert that violence was common and of
...
Applied Biological Sciences
In nature, several seabirds (e.g., gannets and boobies) dive into water at up to 24
m/s as a hunting mechanism; furthermore, gannets and boobies have a slender neck,
which is potentially the weakest part of the body under compression during high-speed
...
Extracellular matrix stiffness influences biological functions of some tumors. However,
it remains unclear how cancer subtypes with different oncogenic mutations respond
to matrix stiffness. In addition, the relevance of matrix stiffness to in vivo tumor
...
Biochemistry
Initiation is a highly regulated, rate-limiting step in transcription. We used a series
of approaches to examine the kinetics of RNA polymerase (RNAP) transcription initiation
in greater detail. Quenched kinetics assays, in combination with gel-based ...
The transcription factor T-bet (Tbox protein expressed in T cells) is one of the master
regulators of both the innate and adaptive immune responses. It plays a central role
in T-cell lineage commitment, where it controls the TH1 response, and in gene ...
Terpenes are structurally diverse natural products involved in many ecological interactions.
The pivotal enzymes for terpene biosynthesis, terpene synthases (TPSs), had been described
only in plants and fungi in the eukaryotic domain. In this report, we ...
All of the heme-degrading enzymes that have been characterized to date require molecular
oxygen as a cosubstrate. Escherichia coli O157:H7 has been shown to express heme uptake and transport proteins, as well as
use heme as an iron source. This enteric ...
The midpoint potential (Em) of , the one-electron acceptor quinone of Photosystem II (PSII), provides the thermodynamic
reference for calibrating PSII bioenergetics. Uncertainty exists in the literature,
with two values differing by ∼80 mV. Here, we have ...
The first broad-spectrum antibiotic chloramphenicol and one of the newest clinically
important antibacterials, linezolid, inhibit protein synthesis by targeting the peptidyl
transferase center of the bacterial ribosome. Because antibiotic binding should ...
Protein biogenesis is tightly linked to protein quality control (PQC). The role of
PQC machinery in recognizing faulty polypeptides is becoming increasingly understood.
Molecular chaperones and cytosolic and vacuolar degradation systems collaborate to
...
Biophysics and Computational Biology
Single-molecule experiments have been used with great success to explore the mechanochemical
cycles of processive motor proteins such as kinesin-1, but it has proven difficult
to apply these approaches to nonprocessive motors. Therefore, the ...
A recently proposed chemomechanical group transfer theory of rotary biomolecular motors
is applied to treat single-molecule controlled rotation experiments. In these experiments,
single-molecule fluorescence is used to measure the binding and release rate ...
The search for high-affinity aptamers for targets such as proteins, small molecules,
or cancer cells remains a formidable endeavor. Systematic Evolution of Ligands by
EXponential Enrichment (SELEX) offers an iterative process to discover these aptamers
...
G-protein–coupled receptors (GPCRs) recognize ligands of widely different efficacies,
from inverse to partial and full agonists, which transduce cellular signals at differentiated
levels. However, the mechanism of such graded activation remains unclear. ...
In vivo, the human genome folds into a characteristic ensemble of 3D structures. The
mechanism driving the folding process remains unknown. We report a theoretical model
for chromatin (Minimal Chromatin Model) that explains the folding of interphase ...
View related content:
Three-dimensional chromosome structures from energy landscape
Ribosomes of trypanosomatids, a family of protozoan parasites causing debilitating
human diseases, possess multiply fragmented rRNAs that together are analogous to 28S
rRNA, unusually large rRNA expansion segments, and r-protein variations compared with
...
Specific protein−protein interactions are crucial in the cell, both to ensure the
formation and stability of multiprotein complexes and to enable signal transduction
in various pathways. Functional interactions between proteins result in coevolution
...
Understanding protein−protein interactions is central to our understanding of almost
all complex biological processes. Computational tools exploiting rapidly growing genomic
databases to characterize protein−protein interactions are urgently needed. Such ...
View related content:
Cell Biology
During mitosis, the mammalian Golgi vesiculates and, upon partitioning, reassembles
in each daughter cell; however, it is not clear whether the disassembly process per
se is important for partitioning or is merely an outcome of mitotic entry. Here, we
...
Forkhead box protein A1 (FOXA1) is a pioneer factor of estrogen receptor α (ER)–chromatin
binding and function, yet its aberration in endocrine-resistant (Endo-R) breast cancer
is unknown. Here, we report preclinical evidence for a role of FOXA1 in Endo-R ...
Capping Protein (CP) plays a central role in the creation of the Arp2/3-generated
branched actin networks comprising lamellipodia and pseudopodia by virtue of its ability
to cap the actin filament barbed end, which promotes Arp2/3-dependent filament ...
Intestinal stem cells (ISCs) are maintained by a niche mechanism, in which multiple
ISCs undergo differential fates where a single ISC clone ultimately occupies the niche.
Importantly, mutations continually accumulate within ISCs creating a potential ...
The recent developments in cryo-EM have revolutionized our access to previously refractory
structures. In particular, such studies of mammalian mitoribosomes have confirmed
the absence of any 5S rRNA species and revealed the unexpected presence of a ...
Developmental Biology
Epigenetic memory, in particular DNA methylation, is established during development
in differentiating cells and must be erased to create naïve (induced) pluripotent
stem cells. The ten-eleven translocation (TET) enzymes can catalyze the oxidation
of 5-...
Environmental Sciences
Protist–alga symbiosis is widespread in the ocean, but its characteristics and function
in situ remain largely unexplored. Here we report the symbiosis of the ciliate Mesodinium rubrum with cryptophyte cells during a red-tide bloom in Long Island Sound. ...
Evolution
Plastids, the photosynthetic organelles, originated >1 billion y ago via the endosymbiosis
of a cyanobacterium. The resulting proliferation of primary producers fundamentally
changed global ecology. Endosymbiotic gene transfer (EGT) from the intracellular ...
Genetics
Senescence, i.e., functional decline with age, is a major determinant of health span
in a rapidly aging population, but the genetic basis of interindividual variation
in senescence remains largely unknown. Visual decline and age-related eye disorders
are ...
DNA:RNA hybrids can lead to DNA damage and genome instability. This damage can be
prevented by degradation of the RNA in the hybrid by two evolutionarily conserved
enzymes, RNase H1 and H2. Indeed, RNase H-deficient cells have increased chromosomal
...
In plants, gametogenesis occurs late in development, and somatic mutations can therefore
be transmitted to the next generation. Longer periods of growth are believed to result
in an increase in the number of cell divisions before gametogenesis, with a ...
Immunology and Inflammation
T cells must respond differently to antigens of varying affinity presented at different
doses. Previous attempts to map peptide MHC (pMHC) affinity onto T-cell responses
have produced inconsistent patterns of responses, preventing formulations of ...
Natural infections expose the immune system to escalating antigen and inflammation
over days to weeks, whereas nonlive vaccines are single bolus events. We explored
whether the immune system responds optimally to antigen kinetics most similar to ...
The T-cell antigen receptor (TCR) is an assembly of eight type I single-pass membrane
proteins that occupies a central position in adaptive immunity. Many TCR-triggering
models invoke an alteration in receptor complex structure as the initiating event,
...
Aberrant immune activation mediated by T effector cell populations is pivotal in the
onset of autoimmunity in type 1 diabetes (T1D). T follicular helper (TFH) cells are
essential in the induction of high-affinity antibodies, and their precursor memory
...
Macrophages are central in coordinating immune responses, tissue repair, and regeneration,
with different subtypes being associated with inflammation-initiating and proresolving
actions. We recently identified a family of macrophage-derived proresolving ...
Medical Sciences
Activating mutations in FMS-like tyrosine kinase 3 (FLT3) are common in acute myeloid
leukemia (AML) and drive leukemic cell growth and survival. Although FLT3 inhibitors
have shown considerable promise for the treatment of AML, they ultimately fail to
...
Carcinosarcomas (CSs) of the uterus and ovary are highly aggressive neoplasms containing
both carcinomatous and sarcomatous elements. We analyzed the mutational landscape
of 68 uterine and ovarian CSs by whole-exome sequencing. We also performed ...
The identification of tumor subpopulations that adversely affect patient outcomes
is essential for a more targeted investigation into how tumors develop detrimental
phenotypes, as well as for personalized therapy. Mass spectrometry imaging has ...
The prognosis of cholangiocarcinoma (CC) is dismal. Notch has been identified as a
potential driver; forced exogenous overexpression of Notch1 in hepatocytes results
in the formation of biliary tumors. In human disease, however, it is unknown which
...
Microbiology
Many Leishmania (Viannia) parasites harbor the double-stranded RNA virus Leishmania RNA virus 1 (LRV1), which has been associated with increased disease severity in animal models
and humans and with drug treatment failures in humans. Remarkably, LRV1 ...
View related content:
The herpes simplex virus (HSV) infected cell culture polypeptide 27 (ICP27) protein
is essential for virus infection of cells. Recent studies suggested that ICP27 inhibits
splicing in a gene-specific manner via an unknown mechanism. Here, RNA-sequencing
...
Middle East respiratory syndrome coronavirus (MERS-CoV) infects humans from zoonotic
sources and causes severe pulmonary disease. Virions require spike (S) glycoproteins
for binding to cell receptors and for catalyzing virus–cell membrane fusion. Fusion
...
Integrative and conjugative elements (ICEs) are ubiquitous mobile genetic elements
present as “genomic islands” within bacterial chromosomes. Symbiosis islands are ICEs
that convert nonsymbiotic mesorhizobia into symbionts of legumes. Here we report the
...
Neuroscience
Oscillatory neural dynamics play an important role in the coordination of large-scale
brain networks. High-level cognitive processes depend on dynamics evolving over hundreds
of milliseconds, so measuring neural activity in this frequency range is ...
Pain is a critical component hindering recovery and regaining of function after surgery,
particularly in the elderly. Understanding the role of pain signaling after surgery
may lead to novel interventions for common complications such as delirium and ...
In humans, drinking replenishes fluid loss and satiates the sensation of thirst that
accompanies dehydration. Typically, the volume of water drunk in response to thirst
matches the deficit. Exactly how this accurate metering is achieved is unknown; recent
...
In the central nervous system, NMDA receptors mediate excitatory neurotransmissions
and play important roles in synaptic plasticity. The regulation of NMDA receptor trafficking
is critical for neural functions in the brain. Here, we directly visualized ...
Changes in the functional connectivity (FC) of large-scale brain networks are a prominent
feature of brain aging, but defining their relationship to variability along the continuum
of normal and pathological cognitive outcomes has proved challenging. Here ...
Current therapies for Alzheimer’s disease (AD) are symptomatic and do not target the
underlying Aβ pathology and other important hallmarks including neuronal loss. PPARγ-coactivator-1α
(PGC-1α) is a cofactor for transcription factors including the ...
Melanocortin-4 receptor (Mc4r)–expressing neurons in the autonomic nervous system,
particularly in the paraventricular nucleus of the hypothalamus (PVH), play an essential
role in blood pressure (BP) control. Mc4r-deficient (Mc4rKO) mice are severely ...
Despite the recognized role of tumor necrosis factor (TNF) in inflammation and neuronal
degeneration, anti-TNF therapeutics failed to treat neurodegenerative diseases. Animal
disease models had revealed the antithetic effects of the two TNF receptors (...
Pharmacology
Pentameric ligand-gated ion channels or Cys-loop receptors are responsible for fast
inhibitory or excitatory synaptic transmission. The antipsychotic compound chlorpromazine
is a widely used tool to probe the ion channel pore of the nicotinic ...
Active G protein-coupled receptor (GPCR) conformations not only are promoted by agonists
but also occur in their absence, leading to constitutive activity. Association of
GPCRs with intracellular protein partners might be one of the mechanisms underlying
...
Plant Biology
Hybrid vigor or heterosis refers to the superior performance of F1 hybrid plants over their parents. Heterosis is particularly important in the production
systems of major crops. Recent studies have suggested that epigenetic regulation such
as DNA ...
Transcriptional regulation of gene expression is a major mechanism used by plants
to confer phenotypic plasticity, and yet compared with other eukaryotes or bacteria,
little is known about the design principles. We generated an extensive catalog of
...
Photosynthetic organisms support cell metabolism by harvesting sunlight to fuel the
photosynthetic electron transport. The flow of excitation energy and electrons in
the photosynthetic apparatus needs to be continuously modulated to respond to dynamics
of ...
The vast abundance of terpene natural products in nature is due to enzymes known as
terpene synthases (TPSs) that convert acyclic prenyl diphosphate precursors into a
multitude of cyclic and acyclic carbon skeletons. Yet the evolution of TPSs is not
well ...
Psychological and Cognitive Sciences
The visual images in the eyes contain much more information than the brain can process.
An important selection mechanism is feature-based attention (FBA). FBA is best described
by attention filters that specify precisely the extent to which items ...
Corrections (Online Only)
Cover image: Pictured is a high-speed image of a northern gannet diving into water. Brian Chang et al. studied how seabirds, especially gannets, can plunge-dive into water at high speeds without sustaining neck injuries. The authors analyzed morphological features from a gannet specimen and data from controlled experimental dives, and found that hydrodynamic drag on the heads of diving seabirds might induce buckling in the birds' necks, and that strong neck muscles allow the birds to survive the compression forces. See the article by Chang et al. on pages 12006–12011. Image courtesy of Brian Chang and Sunghwan Jung.
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