Table Of Contents Page, PNAS Volume 122, Number 44
This Week in PNAS
Core Concepts
QnAs
Retrospective
For five decades, Jim A. Estes studied sea otters in the Aleutian archipelago of Alaska,
discovering how otters structured entire communities. By consuming sea urchins, otters
released kelp from herbivory, kelp beds flourished, and kelps sheltered a ...
Commentaries
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Perspective
China’s emergence as one of the world’s top producers of high-quality science raises
critical questions about its trajectory toward achieving scientific leadership. Traditional
methods for evaluating the power of national scientific ecosystems, however, ...
Letters
Physical Sciences
Applied Physical Sciences
The soft corals (Cnidaria, Octocorallia), a diverse group of colonial marine invertebrates,
can reversibly tune their body stiffness in response to external stimuli. This capability
is attributed to their dynamic skeletal systems, which consist of ...
The movement patterns of animals while searching for food have been studied extensively
in recent decades. However, although human search behavior has existed since the beginning
of civilization, not much is known about human search patterns, particularly ...
Particle-like chiral magnetic skyrmions can flow in nanotracks and behave like chiral
fluids. Using interacting flows to perform logical operations is an important topic
in microfluidics and nanofluidics. Here, we report a basic nanofluidic logic ...
Quantifying heat transport in turbulent convection remains a challenge. The two competing
models of heat transport predict that the nondimensional heat flux, known as the Nusselt
number (Nu), is proportional to (classical scaling) and (ultimate-regime ...
Biophysics and Computational Biology
Malaria parasites infect red blood cells where they digest host hemoglobin and release
free heme inside a lysosome-like organelle called the food vacuole. To detoxify excess
heme, parasites form hemozoin crystals that rapidly tumble inside this ...
Complex systems such as the conscious brain and financial markets often operate near
criticality, a regime that supports flexible and efficient function. When perturbed,
however, rapid deviations from, and prolonged recovery to, criticality can severely
...
Anomer-retaining glycoside hydrolases (GHs) generally catalyze a double displacement
reaction via a covalent intermediate. However, neutron crystallography of glycoside
ligand-bound states has not been performed. In this study, we investigated β-...
Surface interactions play a crucial role in shaping the motility patterns and ecological
adaptations of swimming bacteria. Previous studies have primarily focused on peritrichous
bacteria like Escherichia coli, whose multiple flagella form a bundle during ...
Accurate structure prediction of biomolecular complexes is crucial for understanding
biological processes and enabling drug discovery. While AlphaFold3 represents a significant
advancement, enhancing its accuracy for specific binding sites remains a ...
HIV pre-exposure prophylaxis (PrEP) is transforming global HIV prevention, but its
implementation coincides with observations of rising bacterial sexually transmitted
infection (STI) rates among men who have sex with men, raising questions about whether
...
Memory consolidation refers to a process of engram reorganization and stabilization
that is thought to occur primarily during sleep through a combination of neural replay,
homeostatic plasticity, synaptic maturation, and pruning. From a computational ...
Chemistry
Antimicrobial peptides (AMPs) are highly potent and broad-spectrum antibiotics, found
as components of the innate immune system in almost all forms of life. Despite being
commonly accepted that the mechanism of action of AMPs is associated with the ...
Enzyme-based self-labeling tags enable the covalent attachment of synthetic molecules
to proteins inside living cells. A frontier of this field is designing cell-permeable
multifunctional ligands that contain fluorophores in combination with affinity tags
...
A significant question in next generation vaccine development is: How long are coformulated
products stable on the shelf? The recent review by the US Food and Drug Administration
of a single, prefilled syringe of the SHINGRIX™ vaccine has highlighted the ...
Recent studies have suggested that the commensal microbiome positively affects cancer
prognosis and treatment outcomes. However, only a few strategies for regulating the
microbiome composition have been reported. In this study, we identified gold(I) ...
Strained, multicyclic hydrocarbons are increasingly important structural motifs for
drug discovery. In particular, substituted bicyclo[1.1.1]pentanes (BCPs) have risen
to prominence as bioisosteres for the ubiquitous benzene ring. Despite their favorable
...
Computer Sciences
People acquire concepts through rich physical and social experiences and use them
to understand and navigate the world. In contrast, large language models (LLMs), trained
solely through next-token prediction on text, exhibit strikingly human-like ...
Earth, Atmospheric, and Planetary Sciences
The impact history of the Moon provides the opportunity to better understand mass
transfer in the Solar System. While Earth’s meteorite collection serves as a key reference
for material flux in the Earth–Moon system, it suffers from profound biases ...
Precise and accurate geochronology is essential for reconstructing Earth’s history
and coeval life evolution. The Early Triassic was a critical time interval following
the greatest Phanerozoic mass extinction, recording remarkable biotic changes and
a ...
Antarctic ice cores provide a unique archive of Earth’s atmosphere and its largest
extant ice sheet. The oldest continuous ice core extends back 800 ky, though discontinuous
ice cores from the Allan Hills blue ice area (BIA) have been shown to preserve ...
Jupiter’s poles feature striking polygons of cyclones that drift westward over time,
a motion governed by -drift (vortex motion caused by the latitudinal variation of the Coriolis force).
This study investigates how -drift and the resulting westward ...
The Permian–Triassic (P-Tr) transition (~252 Ma) witnessed Earth’s most severe biocrisis,
which has long been linked to Siberian Traps volcanism and associated environmental
upheaval. Major perturbation of the global carbon (C) and sulfur (S) cycles is ...
Anthropogenic ammonia (NH3) emissions have significantly increased in recent decades due to enhanced agricultural
activities, contributing to global air pollution. While the effects of NH3 on surface air quality are well documented, its influence on ...
Light pollution has been traditionally modeled using clear or completely overcast
conditions. Usually, atmospheric conditions are more complex and involve variable
cloudiness. To predict light pollution in a realistic atmosphere, we developed a model
for ...
Triple oxygen isotope values of xylem water were measured along the length of smooth
horsetail stems (Equisetum laevigatum). Extreme isotope enrichment is observed moving from base to stem tip. δ18O values range from −8.3‰ at the base to 82.6‰ at the tip. ...
Engineering
Self-organization underpins the emergence of complex structure in living systems but
remains a major challenge for engineering synthetic multicellular materials. Here,
we present intrinsically disordered protein display platform (iDP2), a generalizable ...
Enhancing mechanical strength and water resistance in cellulose fiber-based materials
is crucial for their adoption as sustainable alternatives to petroleum plastics. However,
achieving these improvements through a simple, economical, and ecofriendly ...
Conductive folding metamaterials (CFMs) represent a class of cross-physical-domain
new-type metamaterials. However, the inherently nonfoldable nature of intrinsic conductive
materials and the incompatibility between conductivity and extreme foldability ...
Physics
Over the past two decades, the number of close social connections increased substantially,
at least by a factor of two. At the same time, societal opinions have become increasingly
polarized in many Western countries. To explore whether these trends could ...
Social Sciences
Psychological and Cognitive Sciences
Current models frame the allocation of cognitive control as a process of expected
utility maximization. The benefits of a candidate control signal are weighed against
its costs (e.g., opportunity costs). Recent theorizing has found that, despite ...
While practicing a new motor skill, resting for a few seconds can improve performance
immediately after the rest. This improvement, referred to as “micro-offline gains”
(MOGs), has been interpreted as rapid offline learning and is thought to be supported
...
Automatic processing allows humans to perform tasks with minimal effort following
learning. Although theories of automaticity propose that learning should result in
faster processing, studies have universally found that learning reduces the amplitude
of ...
Social Sciences
Over the past two decades, the number of close social connections increased substantially,
at least by a factor of two. At the same time, societal opinions have become increasingly
polarized in many Western countries. To explore whether these trends could ...
In recent years, social media has become increasingly fragmented, as platforms evolve
and new alternatives emerge. Yet most research studies a single platform—typically
X/Twitter, or occasionally Facebook—leaving little known about the broader social
...
Biological Sciences
Agricultural Sciences
Soybean serves as a critical source of plant-based protein for both livestock and
human nutrition, making seed protein content a key agronomic trait. However, modern
soybean cultivars exhibit reduced seed protein content compared to their wild relatives,
...
Biochemistry
Anomer-retaining glycoside hydrolases (GHs) generally catalyze a double displacement
reaction via a covalent intermediate. However, neutron crystallography of glycoside
ligand-bound states has not been performed. In this study, we investigated β-...
Tau aggregation into amyloid fibrils is linked to the development of neurodegenerative
diseases, including Alzheimer’s disease (AD). The molecular processes driving aggregation
in disease are still being uncovered, highlighting the need for innovative ...
Altered β-amyloid (Aβ) homeostasis is a critical event triggering the shift from healthy
aging to Alzheimer disease (AD) through the overproduction and impaired clearance
of Aβ peptides. The Aβ-degrading enzymes (ADEs) are a collective group of proteases
...
Male moths rely on antennal olfactory sensilla to detect female-emitted sex pheromones
during mate localization, a process critically mediated by pheromone-binding proteins
(PBPs) that facilitate ligand transport to dendritic membrane-bound pheromone ...
Rheumatoid arthritis is a chronic inflammatory disease driven by abnormal protein
modifications. These include citrullination of arginine residues by the calcium-activated
enzyme peptidylarginine deiminase 4 (PAD4). However, calcium in body fluids may not
...
l-Fucose, a 6-deoxy-monosaccharide, is often incorporated into O-antigens in Rhizobia
where it serves as an important marker for host recognition. Here, we biochemically
and structurally characterize WrtF, an O-antigen polysaccharide l-fucosyltransferase ...
Biophysics and Computational Biology
Antimicrobial peptides (AMPs) are highly potent and broad-spectrum antibiotics, found
as components of the innate immune system in almost all forms of life. Despite being
commonly accepted that the mechanism of action of AMPs is associated with the ...
Surface interactions play a crucial role in shaping the motility patterns and ecological
adaptations of swimming bacteria. Previous studies have primarily focused on peritrichous
bacteria like Escherichia coli, whose multiple flagella form a bundle during ...
Accurate structure prediction of biomolecular complexes is crucial for understanding
biological processes and enabling drug discovery. While AlphaFold3 represents a significant
advancement, enhancing its accuracy for specific binding sites remains a ...
Cell Biology
Enzyme-based self-labeling tags enable the covalent attachment of synthetic molecules
to proteins inside living cells. A frontier of this field is designing cell-permeable
multifunctional ligands that contain fluorophores in combination with affinity tags
...
The asymmetric resting distribution of the three major phospholipid classes on the
mammalian plasma membrane, with phosphatidylserine and phosphatidylethanolamine mostly
on the inner leaflet and phosphatidylcholine mostly on the outer leaflet, is ...
Developmental Biology
Recent work suggests that asymmetric segregation of preexisting and newly synthesized
canonical histone 3.1 (H3.1), but not variant histone 3.3A (H3.3A), plays an important
role in the asymmetric outcome of Drosophila germline stem cell (GSC) and ...
Ecdysone-induced protein 93 (E93) is an adult specifier that governs insect pupal-adult
conversion. It affects the reproductive transition in adult Aedes aegypti mosquitoes, the significant vectors of numerous devastating human diseases. Here,
we show ...
Environmental Sciences
Cigarette butts are widely discarded in urban green spaces, yet their microbial health
risks remain poorly understood. In a nationwide survey across China, we investigated
the presence, sources, health risks, and drivers of antibiotic resistance genes (...
Evolution
While microbial symbioses are fundamental to the nutrition of many animal groups,
current paradigms focus on symbiont functions at the host individual level. It remains
unclear whether microbial symbioses can sustain colony-level fitness in social insects,...
Genetics
Gastric adenocarcinoma and proximal polyposis of the stomach (GAPPS) is an autosomal
dominant syndrome characterized by polyposis localized in the gastric body and fundus
with a strong tendency for adenocarcinoma. The genetic mutations that accumulate ...
The chytrid fungus Batrachochytrium dendrobatidis (Bd) infects amphibians and causes chytridiomycosis, a disease linked to global amphibian
decline. Despite its ecological importance, Bd has lacked robust tools for genetic manipulation, limiting molecular ...
Breast cancer is the leading cause of death in women under 50. The majority of breast
cancers are estrogen receptor α-positive (ER+) and are commonly treated with hormonal
therapies such as tamoxifen that inhibit ER activity. The TP53 tumor suppressor ...
Immunology and Inflammation
In animal models, exposure to heightened maternal inflammation in utero is associated
with altered offspring hippocampal development, including reduced dendritic arborization
and density. However, the effects of prenatal maternal inflammation (PNMI) on ...
Inflammasome initiates inflammation via the maturation of interleukin-1 beta (IL-1β).
Periodontitis is a prevalent, male-biased disease characterized by inflammation-driven
bone loss, yet the mechanism(s) of this sex bias is unknown. This study explored ...
Medical Sciences
HIV pre-exposure prophylaxis (PrEP) is transforming global HIV prevention, but its
implementation coincides with observations of rising bacterial sexually transmitted
infection (STI) rates among men who have sex with men, raising questions about whether
...
Exosomes are signaling messengers facilitating intercellular communication by delivering
molecular cargo. Here, we observed increased levels of exosomal periostin (POSTN)
in the blood plasma of patients with proliferative diabetic retinopathy (PDR). ...
Receptor tyrosine kinase pathway rewiring represents a fundamental mechanism underlying
acquired resistance to EGFR tyrosine kinase inhibitors in EGFR-mutant non-small-cell
lung cancer (NSCLC). While posttranslational modifications facilitate aberrant ...
Macrophages are recruited to sites of infection contributing to the killing of bacteria,
but also to malignant tumors, where they promote angiogenesis and suppress antitumor
immune responses. The metabolic microenvironment in tumors is frequently depleted
...
Microbiology
Malaria parasites infect red blood cells where they digest host hemoglobin and release
free heme inside a lysosome-like organelle called the food vacuole. To detoxify excess
heme, parasites form hemozoin crystals that rapidly tumble inside this ...
Self-organization underpins the emergence of complex structure in living systems but
remains a major challenge for engineering synthetic multicellular materials. Here,
we present intrinsically disordered protein display platform (iDP2), a generalizable ...
Bacteria acquire new genes by horizontal gene transfer, typically mediated by mobile
genetic elements (MGEs). While plasmids, bacteriophages, and certain integrative and
conjugative elements are well characterized, the broader diversity of MGEs remains
...
Orthoflaviviruses are a genus of arthropod-transmitted RNA viruses that infect humans
and other vertebrate animals on a global scale, resulting in extensive morbidity and
mortality. Among the orthoflaviviruses, tick-borne encephalitis viruses (TBEV) are
...
Neuroscience
Memory consolidation refers to a process of engram reorganization and stabilization
that is thought to occur primarily during sleep through a combination of neural replay,
homeostatic plasticity, synaptic maturation, and pruning. From a computational ...
Serial order memory, a key type of episodic representation, requires the encoding
of map–like context information (interitem relationships) to facilitate recall. In
rodent models, both spatial and nonspatial order memory depend heavily on the hippocampus.
...
Hippocampal degeneration is a feature of both normal aging and Alzheimer’s disease
(AD). Prior to macroscopic degeneration, microstructural changes occur such as demyelination,
iron deposition, or subtle atrophy, which can be characterized in vivo using ...
Circadian clocks form complex networks to orchestrate the behavior and physiology
of animals. Elucidating the organization of these clock networks is critical to understanding
how circadian clocks achieve robust timing. Clock neurons have been best ...
Soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins
drive synaptic transmission in a temporally and spatially precise manner. Recent studies
have identified several disease-causing SNARE variants that give rise to ...
Animals in the wild must balance multiple, potentially mutually exclusive goals simultaneously
in order to survive. Yet laboratory tests of decision-making often investigate how
animals optimize their behavior to achieve a single, well-defined goal, which ...
Chronic pain affects 20 to 30% of the population and imposes a significant socioeconomic
burden as it is often accompanied by substantial emotional comorbidities such as anxiety
and depression. Yet, the mechanisms underlying the interactions between the ...
How are systems supporting high-level cognition organized in the human brain? We hypothesize
that cognitive processes involved in understanding people and places are implemented
by distinct neural systems with parallel anatomical organization. We test ...
Maladaptive responses to uncertainty, including excessive risk seeking or avoidance,
are linked to a range of mental disorders. One expression of these is a provariance
bias (PVB), i.e., risk-seeking manifests as a preference for choosing options with
...
Cognitive biases, which come from the shortcuts our brains use to make decisions,
often lead people to misjudge sizes, amounts, or other magnitudes. However, it is
still unclear how these biases evolved. Nonhuman animals like primates and corvids
share ...
The Superior Colliculus (SC) is a multimodal integration midbrain structure receiving
input from various sensory systems (visual, auditory, and somatosensory) and using
this information to guide rapid, reflexive responses. Research using invasive animal
...
Physiology
Pregnancy requires a supportive uterine environment facilitated by steroid hormone–regulated
differentiation of endometrial stromal fibroblasts into decidual cells and tight control
of inflammation. Serum response factor (SRF) is a widely expressed ...
Plant Biology
Triple oxygen isotope values of xylem water were measured along the length of smooth
horsetail stems (Equisetum laevigatum). Extreme isotope enrichment is observed moving from base to stem tip. δ18O values range from −8.3‰ at the base to 82.6‰ at the tip. ...
Psychological and Cognitive Sciences
Current models frame the allocation of cognitive control as a process of expected
utility maximization. The benefits of a candidate control signal are weighed against
its costs (e.g., opportunity costs). Recent theorizing has found that, despite ...
People acquire concepts through rich physical and social experiences and use them
to understand and navigate the world. In contrast, large language models (LLMs), trained
solely through next-token prediction on text, exhibit strikingly human-like ...
While practicing a new motor skill, resting for a few seconds can improve performance
immediately after the rest. This improvement, referred to as “micro-offline gains”
(MOGs), has been interpreted as rapid offline learning and is thought to be supported
...
Automatic processing allows humans to perform tasks with minimal effort following
learning. Although theories of automaticity propose that learning should result in
faster processing, studies have universally found that learning reduces the amplitude
of ...
Systems Biology
Complex systems such as the conscious brain and financial markets often operate near
criticality, a regime that supports flexible and efficient function. When perturbed,
however, rapid deviations from, and prolonged recovery to, criticality can severely
...
Corrections
Cover image: Pictured are small skeletal elements called sclerites from a red gorgonian (Leptogorgia chilensis). Chenhao Hu et al. explored the role of sclerites in the ability of soft corals, such as L. chilensis, to dynamically alternate between flexible and rigid states. The authors found that the complex, branching geometries of L. chilensis sclerites form a robust granular jamming system, locking into a stable configuration at a critical density. The results could inform the design of granular particles with tunable jamming properties for applications ranging from soft robotics to mechanical dampeners. See the article by Hu et al. e2504541122. Image credit: James C. Weaver and Ling Li.
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