Table Of Contents Page, PNAS Volume 121, Number 7
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Brief Report
“Complex multicellularity,” conventionally defined as large organisms with many specialized
cell types, has evolved five times independently in eukaryotes, but never within prokaryotes.
A number of hypotheses have been proposed to explain this phenomenon, ...
Physical Sciences
Applied Physical Sciences
Self-assembly of complex and functional materials remains a grand challenge in soft
material science. Efficient assembly depends on a delicate balance between thermodynamic
and kinetic effects, requiring fine-tuning affinities and concentrations of ...
Biophysics and Computational Biology
Self-replication of amyloid fibrils via secondary nucleation is an intriguing physicochemical
phenomenon in which existing fibrils catalyze the formation of their own copies. The
molecular events behind this fibril surface-mediated process remain largely ...
The loss of elastic stability (buckling) can lead to catastrophic failure in the context
of traditional engineering structures. Conversely, in nature, buckling often serves
a desirable function, such as in the prey-trapping mechanism of the Venus fly trap
...
DNA structure can regulate genome function. Four-stranded DNA G-quadruplex (G4) structures
have been implicated in transcriptional regulation; however, previous studies have
not directly addressed the role of an individual G4 within its endogenous ...
Chemistry
The kinetic resolution of racemic amino acids mediated by dipeptides and pyridoxal
provides a prebiotically plausible route to enantioenriched proteinogenic amino acids.
The enzymatic transamination cycles that are key to modern biochemical formation of
...
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Capturing rare yet pivotal events poses a significant challenge for molecular simulations.
Path sampling provides a unique approach to tackle this issue without altering the
potential energy landscape or dynamics, enabling recovery of both thermodynamic ...
The growth rates of crystals are largely dictated by the chemical reaction between
solute and kinks, in which a solute molecule severs its bonds with the solvent and
establishes new bonds with the kink. Details on this sequence of bond breaking and
...
Transition metals and related compounds are known to exhibit high catalytic activities
in various electrochemical reactions thanks to their intriguing electronic structures.
What is lesser known is their unique role in storing and transferring electrons ...
Solar-driven photocatalytic CO2 reduction is an energy-efficient and sustainable strategy to mitigate CO2 levels in the atmosphere. However, efficient and selective conversion of CO2 into multi-carbon products, like C2H4, remains a great challenge due to ...
Macrophages are integral components of the innate immune system, playing a dual role
in host defense during infection and pathophysiological states. Macrophages contribute
to immune responses and aid in combatting various infections, yet their production
...
Earth, Atmospheric, and Planetary Sciences
Limiting global warming to 2 °C requires urgent action on land-based mitigation. This
study evaluates the biogeochemical and biogeophysical implications of two alternative
land-based mitigation scenarios that aim to achieve the same radiative forcing. One
...
Most of the nitrogen (N) accessible for life is trapped in dinitrogen (N2), the most stable atmospheric molecule. In order to be metabolized by living organisms,
N2 has to be converted into biologically assimilable forms, so-called fixed N. Nowadays,
...
Engineering
Stinger-like structures in living organisms evolved convergently across taxa for both
defensive and offensive purposes, with the main goal being penetration and damage.
Our observations over a broad range of taxa and sizes, from microscopic radiolarians
...
Integrating reactive radicals into membranes that resemble biological membranes has
always been a pursuit for simultaneous organics degradation and water filtration.
In this research, we discovered that a radical polymer (RP) that can directly trigger
the ...
Environmental Sciences
Emerging contaminants (EC) distributed on surfaces in the environment can be oxidized
by gas phase species (top–down) or by oxidants generated by the underlying substrate
(bottom–up). One class of EC is the neonicotinoid (NN) pesticides that are widely
...
Clay minerals are implicated in the retention of biomolecules within organic matter
in many soil environments. Spectroscopic studies have proposed several mechanisms
for biomolecule adsorption on clays. Here, we employ molecular dynamics simulations
to ...
Global warming increases available sensible and latent heat energy, increasing the
thermodynamic potential wind intensity of tropical cyclones (TCs). Supported by theory,
observations, and modeling, this causes a shift in mean TC intensity, which tends
to ...
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Physics
Charge transport in solids at low temperature reveals a material’s mesoscopic properties
and structure. Under a magnetic field, Shubnikov–de Haas (SdH) oscillations inform
complex quantum transport phenomena that are not limited by the ground state ...
We theoretically propose a multidimensional high-harmonic echo spectroscopy technique
which utilizes strong optical fields to resolve coherent electron dynamics spanning
an energy range of multiple electronvolts. Using our recently developed semi-...
Sustainability Science
Limiting global warming to 2 °C requires urgent action on land-based mitigation. This
study evaluates the biogeochemical and biogeophysical implications of two alternative
land-based mitigation scenarios that aim to achieve the same radiative forcing. One
...
Social Sciences
Anthropology
Global polls have shown that people in high-income countries generally report being
more satisfied with their lives than people in low-income countries. The persistence
of this correlation, and its similarity to correlations between income and life ...
Demography
Schelling’s 1971 work on the dynamics of segregation showed that even a small degree
of homophily, the desire to live among like neighbors, can lead to a starkly segregated
population. One of the driving factors for this result is that the notion of ...
Economic Sciences
As the world moves away from fossil fuels, there is growing recognition of the need
for a just transition of those working in carbon-intensive industries and for policy
to support this transition. While recent policies such as the U.S. Inflation Reduction
...
Social Sciences
We test whether the classification of households into poverty categories is meaningfully
influenced by the poverty measurement approach that is employed. These classification
techniques are widely used by governments, non-profit organizations, and ...
Sustainability Science
As the world moves away from fossil fuels, there is growing recognition of the need
for a just transition of those working in carbon-intensive industries and for policy
to support this transition. While recent policies such as the U.S. Inflation Reduction
...
We test whether the classification of households into poverty categories is meaningfully
influenced by the poverty measurement approach that is employed. These classification
techniques are widely used by governments, non-profit organizations, and ...
Ensuring healthy and sustainable food systems in increasing social, economic, and
ecological change is a key global priority to protect human and environmental health.
Seafood is an essential component of these food systems and a critical source of ...
Biological Sciences
Applied Biological Sciences
Macrophages are integral components of the innate immune system, playing a dual role
in host defense during infection and pathophysiological states. Macrophages contribute
to immune responses and aid in combatting various infections, yet their production
...
Biochemistry
The kinetic resolution of racemic amino acids mediated by dipeptides and pyridoxal
provides a prebiotically plausible route to enantioenriched proteinogenic amino acids.
The enzymatic transamination cycles that are key to modern biochemical formation of
...
View related content:
DNA structure can regulate genome function. Four-stranded DNA G-quadruplex (G4) structures
have been implicated in transcriptional regulation; however, previous studies have
not directly addressed the role of an individual G4 within its endogenous ...
To facilitate analysis and sharing of mass spectrometry (MS)-based proteomics data,
we created online tools called CURTAIN (https://curtain.proteo.info) and CURTAIN-PTM (https://curtainptm.proteo.info) with an accompanying series of video tutorials (https:...
The maintenance of cholesterol homeostasis is crucial for normal function at both
the cellular and organismal levels. Two integral membrane proteins, 3-hydroxy-3-methylglutaryl
coenzyme A reductase (HMGCR) and Scap, are key targets of a complex feedback ...
Monoterpene indole alkaloids (MIAs) are a large and diverse class of plant natural
products, and their biosynthetic construction has been a subject of intensive study
for many years. The enzymatic basis for the production of aspidosperma and iboga ...
Biophysics and Computational Biology
Self-replication of amyloid fibrils via secondary nucleation is an intriguing physicochemical
phenomenon in which existing fibrils catalyze the formation of their own copies. The
molecular events behind this fibril surface-mediated process remain largely ...
Capturing rare yet pivotal events poses a significant challenge for molecular simulations.
Path sampling provides a unique approach to tackle this issue without altering the
potential energy landscape or dynamics, enabling recovery of both thermodynamic ...
The misfolding and aggregation of α-synuclein is linked to a family of neurodegenerative
disorders known as synucleinopathies, the most prominent of which is Parkinson’s disease
(PD). Understanding the aggregation process of α-synuclein from a mechanistic ...
The protein crescentin is required for the crescent shape of the freshwater bacterium
Caulobacter crescentus (vibrioides). Crescentin forms a filamentous structure on the inner, concave side of the curved
cells. It shares features with eukaryotic ...
Ligand-induced conformational changes are critical to the function of many membrane
proteins and arise from numerous intramolecular interactions. In the photocycle of
the model membrane protein bacteriorhodopsin (bR), absorption of a photon by retinal
...
Cryptococcus neoformans is a fungal pathogen responsible for cryptococcosis and cryptococcal meningitis.
The C. neoformans’ capsular polysaccharide and its shed exopolysaccharide function both as key virulence
factors and to protect the fungal cell from ...
The pharynx of the nematode Caenorhabditis elegans is a neuromuscular organ that exhibits typical pumping motions, which result in the
intake of food particles from the environment. In-depth inspection reveals slightly
different dynamics at the various ...
Cell Biology
Metabolic reprogramming is critical during clear cell renal cell carcinoma (ccRCC)
tumorigenesis, manifested by accumulation of lipid droplets (LDs), organelles that
have emerged as new hallmarks of cancer. Yet, regulation of their biogenesis is still
...
Phase separation (PS) drives the formation of biomolecular condensates that are emerging
biological structures involved in diverse cellular processes. Recent studies have
unveiled PS-induced formation of several transcriptional factor (TF) condensates ...
Zinc is an essential nutrient—it is stored during periods of excess to promote detoxification
and released during periods of deficiency to sustain function. Lysosome-related organelles
(LROs) are an evolutionarily conserved site of zinc storage, but ...
Studies in shift workers and model organisms link circadian disruption to breast cancer.
However, molecular circadian rhythms in noncancerous and cancerous human breast tissues
and their clinical relevance are largely unknown. We reconstructed rhythms ...
Cell cycle plasticity underlies fractional resistance to palbociclib in ER+/HER2− breast tumor cells
The CDK4/6 inhibitor palbociclib blocks cell cycle progression in Estrogen receptor–positive,
human epidermal growth factor 2 receptor–negative (ER+/HER2−) breast tumor cells.
Despite the drug’s success in improving patient outcomes, a small percentage of ...
Tobacco and alcohol are risk factors for human papillomavirus–negative head and neck
squamous cell carcinoma (HPV− HNSCC), which arises from the mucosal epithelium of the upper aerodigestive tract.
Notably, despite the mutagenic potential of smoking, HPV− ...
Cyclin-dependent kinase 9 (CDK9) plays a critical role in transcription initiation
and is essential for maintaining gene silencing at heterochromatic loci. Inhibition
of CDK9 increases sensitivity to immunotherapy, but the underlying mechanism remains
...
Circadian RNA expression is essential to ultimately regulate a plethora of downstream
rhythmic biochemical, physiological, and behavioral processes. Both transcriptional
and posttranscriptional mechanisms are considered important to drive rhythmic RNA
...
Ecology
Understanding the assembly of multispecies microbial communities represents a significant
challenge in ecology and has wide applications in agriculture, wastewater treatment,
and human healthcare domains. Traditionally, studies on the microbial community ...
Environmental Sciences
Tree mortality due to global change—including range expansion of invasive pests and
pathogens—is a paramount threat to forest ecosystems. Oak forests are among the most
prevalent and valuable ecosystems both ecologically and economically in the United
...
Genetics
Chronic kidney disease (CKD) is characterized by a gradual loss of kidney function
and affects ~13.4% of the global population. Progressive tubulointerstitial fibrosis,
driven in part by proximal tubule (PT) damage, is a hallmark of late stages of CKD
and ...
Cryptorchidism is the most common form of disorder of sex development in male dogs,
but its hereditary predisposition is poorly elucidated. The gonadal transcriptome
of nine unilaterally cryptorchid dogs and seven control dogs was analyzed using RNA-seq.
...
Immunology and Inflammation
Intrathecal synthesis of central nervous system (CNS)-reactive autoantibodies is observed
across patients with autoimmune encephalitis (AE), who show multiple residual neurobehavioral
deficits and relapses despite immunotherapies. We leveraged two common ...
Epigenetic regulation plays a crucial role in the pathogenesis of autoimmune diseases
such as inflammatory arthritis. DNA hypomethylating agents, such as decitabine (DAC),
have been shown to dampen inflammation and restore immune homeostasis. In the ...
Cancer therapy, including immunotherapy, is inherently limited by chronic inflammation-induced
tumorigenesis and toxicity within the tumor microenvironment. Thus, stimulating the
resolution of inflammation may enhance immunotherapy and improve the ...
Medical Sciences
Lipid synthesis is regulated by the actions of Scap, a polytopic membrane protein
that binds cholesterol in membranes of the endoplasmic reticulum (ER). When ER cholesterol
levels are low, Scap activates SREBPs, transcription factors that upregulate genes
...
It is known that pre-mRNAs in eukaryotic cells can be processed to circular RNAs by
a backsplicing mechanism. Circular RNAs have great stability and can sequester proteins
or small RNAs to exert functions on cellular pathways. Because viruses often ...
The Ebola virus causes hemorrhagic fever in humans and poses a significant threat
to global public health. Although two viral vector vaccines have been approved to
prevent Ebola virus disease, they are distributed in the limited ring vaccination
setting ...
Microbiology
Bats are associated with the circulation of most mammalian filoviruses (FiVs), with
pathogenic ones frequently causing deadly hemorrhagic fevers in Africa. Divergent
FiVs have been uncovered in Chinese bats, raising concerns about their threat to public
...
Neuroscience
Neural dynamics can reflect intrinsic dynamics or dynamic inputs, such as sensory
inputs or inputs from other brain regions. To avoid misinterpreting temporally structured
inputs as intrinsic dynamics, dynamical models of neural activity should account ...
Puromycin is covalently added to the nascent chain of proteins by the peptidyl transferase
activity of the ribosome and the dissociation of the puromycylated peptide typically
follows this event. It was postulated that blocking the translocation of the ...
Synaptic plasticity [long-term potentiation/depression (LTP/D)], is a cellular mechanism
underlying learning. Two distinct types of early LTP/D (E-LTP/D), acting on very different
time scales, have been observed experimentally—spike timing dependent ...
Pharmacology
Cancer invasion and metastasis are known to be potentiated by the expression of aquaporins
(AQPs). Likewise, the expression levels of AQPs have been shown to be prognostic for
survival in patients and have a role in tumor growth, edema, angiogenesis, and ...
A key step in drug discovery, common to many disease areas, is preclinical demonstration
of efficacy in a mouse model of disease. However, this demonstration and its translation
to the clinic can be impeded by mouse-specific pathways of drug metabolism. ...
Plant Biology
Marine photosynthetic dinoflagellates are a group of successful phytoplankton that
can form red tides in the ocean and also symbiosis with corals. These features are
closely related to the photosynthetic properties of dinoflagellates. We report here
three ...
Mature forests and their extremely old trees are rare and threatened ancient vestiges
in remote European high-mountain regions. Here, we analyze the role that extremely
long-living trees have in mature forests biodiversity in relation to their singular
...
Protein S-acyl transferases (PATs) catalyze S-acylation, a reversible post-translational modification critical for membrane association,
trafficking, and stability of substrate proteins. Many plant proteins are potentially
S-acylated but few have ...
Plants tightly control growth of their lateral organs, which led to the concept of
apical dominance. However, outgrowth of the dormant lateral primordia is sensitive
to the plant’s nutritional status, resulting in an immense plasticity in plant ...
The interplay between the circadian clock and abiotic stress responses mediated by ABF3 and CCA1/LHY
Climate change is a global concern for all life on our planet, including humans and
plants. Plants’ growth and development are significantly affected by abiotic stresses,
including adverse temperature, inadequate or excess water availability, nutrient ...
Sustainability Science
Ensuring healthy and sustainable food systems in increasing social, economic, and
ecological change is a key global priority to protect human and environmental health.
Seafood is an essential component of these food systems and a critical source of ...
Systems Biology
The energy metabolism of the brain is poorly understood partly due to the complex
morphology of neurons and fluctuations in ATP demand over time. To investigate this,
we used metabolic models that estimate enzyme usage per pathway, enzyme utilization
over ...
Correction
Cover image: Pictured are coral polyps (Stylophora pistillata), which live in symbiosis with dinoflagellates. Xiaoyi Li et al. used cryo-EM to determine the structures of photosystem I-chlorophyll a/c-peridinin protein complexes from two species of marine dinoflagellates, which harvest light and generate electrons during photosynthesis. The authors found that PsaA/B subunits in a red tidal and a coral symbiotic dinoflagellate species were smaller than those found in other eukaryotes. Additionally, other subunits of the complex were larger than expected. According to the authors, the findings reveal how the dinoflagellate photosystem I likely originated from red algae. See the article by Li et al. e2315476121. Image credit: Wenda Wang.
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