Table Of Contents Page, PNAS Volume 119, Number 2
This Week in PNAS
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Commentaries
Letters
Physical Sciences
Applied Mathematics
We consider epidemiological modeling for the design of COVID-19 interventions in university
populations, which have seen significant outbreaks during the pandemic. A central
challenge is sensitivity of predictions to input parameters coupled with ...
Applied Physical Sciences
Various physical tweezers for manipulating liquid droplets based on optical, electrical,
magnetic, acoustic, or other external fields have emerged and revolutionized research
and application in medical, biological, and environmental fields. Despite ...
Earth, Atmospheric, and Planetary Sciences
Prochlorococcus is both the smallest and numerically most abundant photosynthesizing organism on
the planet. While thriving in the warm oligotrophic gyres, Prochlorococcus concentrations drop rapidly in higher-latitude regions. Transect data from the ...
The Earth's inner core started forming when molten iron cooled below the melting point.
However, the nucleation mechanism, which is a necessary step of crystallization, has
not been well understood. Recent studies have found that it requires an ...
Engineering
Stem cells are of great interest in tissue regeneration due to their ability to modulate
the local microenvironment by secreting bioactive factors (collectively, secretome).
However, secretome delivery through conditioned media still requires time-...
Precise information on localized variations in blood circulation holds the key for
noninvasive diagnostics and therapeutic assessment of various forms of cancer. While
thermal imaging by itself may provide significant insights on the combined implications
...
Environmental Sciences
Bottom trawling is widespread globally and impacts seabed habitats. However, risks
from trawling remain unquantified at large scales in most regions. We address these
issues by synthesizing evidence on the impacts of different trawl-gear types, seabed
...
Deforestation affects local and regional hydroclimate through changes in heating and
moistening of the atmosphere. In the tropics, deforestation leads to warming, but
its impact on rainfall is more complex, as it depends on spatial scale and synoptic
...
Sustainability Science
Deforestation affects local and regional hydroclimate through changes in heating and
moistening of the atmosphere. In the tropics, deforestation leads to warming, but
its impact on rainfall is more complex, as it depends on spatial scale and synoptic
...
Social Sciences
Economic Sciences
Pooled testing increases efficiency by grouping individual samples and testing the
combined sample, such that many individuals can be cleared with one negative test.
This short paper demonstrates that pooled testing is particularly advantageous in
the ...
Environmental Sciences
Late-life ambient air pollution is a risk factor for brain aging, but it remains unknown
if improved air quality (AQ) lowers dementia risk. We studied a geographically diverse
cohort of older women dementia free at baseline in 2008 to 2012 (n = 2,239, ...
Psychological and Cognitive Sciences
Human learning is supported by multiple neural mechanisms that maturate at different
rates and interact in mostly cooperative but also sometimes competitive ways. We tested
the hypothesis that mature cognitive mechanisms constrain implicit statistical ...
Social Sciences
The US scientific workforce is primarily composed of White men. Studies have demonstrated
the systemic barriers preventing women and other minoritized populations from gaining
entry to science; few, however, have taken an intersectional perspective and ...
View related content:
Sustainability Science
Fisheries managers have increasingly adopted rights-based management (i.e., “catch
shares” or “individual transferable quotas” [ITQs]) to address economic and biological
management challenges under prior governance regimes. Despite their ability to ...
Biological Sciences
Applied Biological Sciences
Stem cells are of great interest in tissue regeneration due to their ability to modulate
the local microenvironment by secreting bioactive factors (collectively, secretome).
However, secretome delivery through conditioned media still requires time-...
Biophysics and Computational Biology
NMR-assisted crystallography—the integrated application of solid-state NMR, X-ray
crystallography, and first-principles computational chemistry—holds significant promise
for mechanistic enzymology: by providing atomic-resolution characterization of stable
...
Microtubules (MTs) are polymers of αβ-tubulin heterodimers that stochastically switch
between growth and shrinkage phases. This dynamic instability is critically important
for MT function. It is believed that GTP hydrolysis within the MT lattice is ...
Cell Biology
Low-density lipoprotein (LDL) delivers cholesterol to mammalian cells through receptor-mediated
endocytosis. The LDL cholesterol is liberated in lysosomes and transported to the
plasma membrane (PM) and from there to the endoplasmic reticulum (ER). Excess ...
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Developmental Biology
Fate and behavior of neural progenitor cells are tightly regulated during mammalian
brain development. Metabolic pathways, such as glycolysis and oxidative phosphorylation,
that are required for supplying energy and providing molecular building blocks to
...
Ecology
Prochlorococcus is both the smallest and numerically most abundant photosynthesizing organism on
the planet. While thriving in the warm oligotrophic gyres, Prochlorococcus concentrations drop rapidly in higher-latitude regions. Transect data from the ...
Networks are vital tools for understanding and modeling interactions in complex systems
in science and engineering, and direct and indirect interactions are pervasive in
all types of networks. However, quantitatively disentangling direct and indirect ...
Environmental Sciences
Late-life ambient air pollution is a risk factor for brain aging, but it remains unknown
if improved air quality (AQ) lowers dementia risk. We studied a geographically diverse
cohort of older women dementia free at baseline in 2008 to 2012 (n = 2,239, ...
Pacific Ocean tuna is among the most-consumed seafood products but contains relatively
high levels of the neurotoxin methylmercury. Limited observations suggest tuna mercury
levels vary in space and time, yet the drivers are not well understood. Here, we ...
Immunology and Inflammation
Lethal toxin (LeTx)-mediated killing of myeloid cells is essential for Bacillus anthracis, the causative agent of anthrax, to establish systemic infection and induce lethal
anthrax. The “LeTx-sensitive” NLRP1b inflammasome of BALB/c and 129S macrophages ...
Medical Sciences
Lipoprotein-associated phospholipase A2 (Lp-PLA2) associates with low- and high-density lipoproteins in human plasma and specifically
hydrolyzes circulating oxidized phospholipids involved in oxidative stress. The association
of this enzyme with the ...
Microbiology
Hemachromatosis (iron-overload) increases host susceptibility to siderophilic bacterial
infections that cause serious complications, but the underlying mechanisms remain
elusive. The present study demonstrates that oral infection with hyperyersiniabactin
(...
Saccharibacteria are a group of widespread and genetically diverse ultrasmall bacteria
with highly reduced genomes that belong to the Candidate Phyla Radiation. Comparative
genomic analyses suggest convergent evolution of key functions enabling the ...
Myeloid lineage cells such as macrophages and dendritic cells (DCs), targeted by HIV-1,
are important vehicles for virus dissemination through the body as well as viral reservoirs.
Compared to activated lymphocytes, myeloid cells are collectively more ...
Bacterial behavior and virulence during human infection is difficult to study and
largely unknown, as our vast knowledge of infection microbiology is primarily derived
from studies using in vitro and animal models. Here, we characterize the physiology
of ...
The reductive acetyl-coenzyme A (acetyl-CoA) pathway, whereby carbon dioxide is sequentially
reduced to acetyl-CoA via coenzyme-bound C1 intermediates, is the only autotrophic
pathway that can at the same time be the means for energy conservation. A ...
Neuroscience
Invariant stimulus recognition is a challenging pattern-recognition problem that must
be dealt with by all sensory systems. Since neural responses evoked by a stimulus
are perturbed in a multitude of ways, how can this computational capability be achieved?...
Little is known about how dopamine (DA) neuron firing rates behave in cognitively
demanding decision-making tasks. Here, we investigated midbrain DA activity in monkeys
performing a discrimination task in which the animal had to use working memory (WM)
to ...
Plant Biology
Carpels in maize undergo programmed cell death in half of the flowers initiated in
ears and in all flowers in tassels. The HD-ZIP I transcription factor gene GRASSY TILLERS1 (GT1) is one of only a few genes known to regulate this process. To identify ...
The target of rapamycin (TOR) kinase is a master regulator that integrates nutrient
signals to promote cell growth in all eukaryotes. It is well established that amino
acids and glucose are major regulators of TOR signaling in yeast and metazoan, but
...
Population Biology
We consider epidemiological modeling for the design of COVID-19 interventions in university
populations, which have seen significant outbreaks during the pandemic. A central
challenge is sensitivity of predictions to input parameters coupled with ...
Psychological and Cognitive Sciences
Human learning is supported by multiple neural mechanisms that maturate at different
rates and interact in mostly cooperative but also sometimes competitive ways. We tested
the hypothesis that mature cognitive mechanisms constrain implicit statistical ...
Sustainability Science
Pacific Ocean tuna is among the most-consumed seafood products but contains relatively
high levels of the neurotoxin methylmercury. Limited observations suggest tuna mercury
levels vary in space and time, yet the drivers are not well understood. Here, we ...
Bottom trawling is widespread globally and impacts seabed habitats. However, risks
from trawling remain unquantified at large scales in most regions. We address these
issues by synthesizing evidence on the impacts of different trawl-gear types, seabed
...
Natural disasters impose huge uncertainty and loss to human lives and economic activities.
Landslides are one disaster that has become more prevalent because of anthropogenic
disturbances, such as land-cover changes, land degradation, and expansion of ...
Cover image: Pictured is an organoid derived from human embryonic stem cells that mimics the structure of a developing human brain. Daniel Gonzalez-Bohorquez et al. report that removing the gene encoding the enzyme fatty acid synthase, which converts glucose into fatty acids, in mouse embryos diminishes brain size. Inhibiting fatty acid synthase in human stem cell�derived forebrain organoids also uncovered a role for the enzyme in regulating the activity of human brain progenitors. The findings suggest that fatty acid synthase�dependent lipid metabolism plays a crucial role in human brain development. See the article by Gonzalez-Bohorquez et al., e2112040119. Image credit: Daniel Gonzalez-Bohorquez.
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