Chromatin instability and mitochondrial decline are conserved processes that contribute to cellular aging. Although both processes have been explored individually in the context of their distinct signaling pathways, the mechanism that determines which process dominates during aging of individual cells is unknown. We show that interactions between the chromatin silencing and mitochondrial pathways lead to an epigenetic landscape of yeast replicative aging with multiple equilibrium states that represent...
Thu Jul 16, 2020 20:39
The hypothesis that water has a second critical point at deeply supercooled conditions was formulated to provide a thermodynamically consistent interpretation of numerous experimental observations. A large body of work has been devoted to verifying or falsifying this hypothesis, but no unambiguous experimental proof has yet been found. Here, we use histogram reweighting and large-system scattering calculations to investigate computationally two molecular models of water, TIP4P/2005 and TIP4P/Ice,...
Thu Jul 16, 2020 20:39
Knowledge of rotational energy transfer (RET) involving carbon monoxide (CO) molecules is crucial for the interpretation of astrophysical data. As of now, our nearly perfect understanding of atom-molecule scattering shows that RET usually occurs by only a simple "bump" between partners. To advance molecular dynamics to the next step in complexity, we studied molecule-molecule scattering in great detail for collision between two CO molecules. Using advanced imaging methods and quasi-classical and...
Thu Jul 16, 2020 20:39
The tumor microenvironment plays a critical regulatory role in cancer progression, especially in central nervous system metastases. Cancer cells within the cerebrospinal fluid (CSF)–filled leptomeninges face substantial microenvironmental challenges, including inflammation and sparse micronutrients. To investigate the mechanism by which cancer cells in these leptomeningeal metastases (LM) overcome these constraints, we subjected CSF from five patients with LM to single-cell RNA sequencing. We found...
Thu Jul 16, 2020 20:39
New York City (NYC) has emerged as one of the epicenters of the current severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. To identify the early transmission events underlying the rapid spread of the virus in the NYC metropolitan area, we sequenced the virus that causes coronavirus disease 2019 (COVID-19) in patients seeking care at the Mount Sinai Health System. Phylogenetic analysis of 84 distinct SARS-CoV-2 genomes indicates multiple, independent, but isolated introductions...
Thu Jul 16, 2020 20:39
Preliminary evidence suggests that climate may modulate the transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Yet it remains unclear whether seasonal and geographic variations in climate can substantially alter the pandemic trajectory, given that high susceptibility is a core driver. Here, we use a climate-dependent epidemic model to simulate the SARS-CoV-2 pandemic by probing different scenarios based on known coronavirus biology. We find that although variations in weather...
Thu Jul 16, 2020 20:39
CRISPR-Cas systems are found widely in prokaryotes, where they provide adaptive immunity against virus infection and plasmid transformation. We describe a minimal functional CRISPR-Cas system, comprising a single ~70-kilodalton protein, Cas, and a CRISPR array, encoded exclusively in the genomes of huge bacteriophages. Cas uses a single active site for both CRISPR RNA (crRNA) processing and crRNA-guided DNA cutting to target foreign nucleic acids. This hypercompact system is active in vitro and in...
Thu Jul 16, 2020 20:39
Optical frequency combs were introduced around 20 years ago as a laser technology that could synthesize and count the ultrafast rate of the oscillating cycles of light. Functioning in a manner analogous to a clockwork of gears, the frequency comb phase-coherently upconverts a radio frequency signal by a factor of to provide a vast array of evenly spaced optical frequencies, which is the comb for which the device is named. It also divides an optical frequency down to a radio frequency, or translates...
Thu Jul 16, 2020 20:39
Synapses connect neurons together to form the circuits of the brain, and their molecular composition controls innate and learned behavior. We analyzed the molecular and morphological diversity of 5 billion excitatory synapses at single-synapse resolution across the mouse brain from birth to old age. A continuum of changes alters synapse composition in all brain regions across the life span. Expansion in synapse diversity produces differentiation of brain regions until early adulthood, and compositional...
Thu Jul 16, 2020 20:39
Human genetic history in East Asia is poorly understood. To clarify population relationships, we obtained genome-wide data from 26 ancient individuals from northern and southern East Asia spanning 9500 to 300 years ago. Genetic differentiation in this region was higher in the past than the present, which reflects a major episode of admixture involving northern East Asian ancestry spreading across southern East Asia after the Neolithic, thereby transforming the genetic ancestry of southern China....
Thu Jul 16, 2020 20:39
High-performance piezoelectric materials are critical components for electromechanical sensors and actuators. For more than 60 years, the main strategy for obtaining large piezoelectric response has been to construct multiphase boundaries, where nanoscale domains with local structural and polar heterogeneity are formed, by tuning complex chemical compositions. We used a different strategy to emulate such local heterogeneity by forming nanopillar regions in perovskite oxide thin films. We obtained...
Thu Jul 16, 2020 20:39
Isomerization-based strategies to enable the stereodivergent construction of complex polyenes from geometrically defined alkene linchpins remain conspicuously underdeveloped. Mitigating the thermodynamic constraints inherent to isomerization is further frustrated by the considerations of atom efficiency in idealized low–molecular weight precursors. In this work, we report a general ambiphilic C3 scaffold that can be isomerized and bidirectionally extended. Predicated on highly efficient triplet energy...
Thu Jul 16, 2020 20:39
The fractionation of crude-oil mixtures through distillation is a large-scale, energy-intensive process. Membrane materials can avoid phase changes in such mixtures and thereby reduce the energy intensity of these thermal separations. With this application in mind, we created spirocyclic polymers with N-aryl bonds that demonstrated noninterconnected microporosity in the absence of ladder linkages. The resulting glassy polymer membranes demonstrated nonthermal membrane fractionation of light crude...
Thu Jul 16, 2020 20:39
Restricted V(D)J recombination during fetal development was postulated to limit antibody repertoire breadth and prevent autoimmunity. However, newborn serum contains abundant autoantibodies, suggesting that B cell tolerance during gestation is not yet fully established. To investigate this apparent paradox, we evaluated the reactivities of more than 450 antibodies cloned from single B cells from human fetal liver, bone marrow, and spleen. We found that incomplete B cell tolerance in early human fetal...
Thu Jul 16, 2020 20:39
The emergence of the betacoronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease 2019 (COVID-19), represents a considerable threat to global human health. Vaccine development is focused on the principal target of the humoral immune response, the spike (S) glycoprotein, which mediates cell entry and membrane fusion. The SARS-CoV-2 S gene encodes 22 N-linked glycan sequons per protomer, which likely play a role in protein folding and immune...
Thu Jul 16, 2020 20:39
Targeting the cross-talk between tumor-initiating cells (TICs) and the niche microenvironment is an attractive avenue for cancer therapy. We show here, using a mouse model of squamous cell carcinoma, that TICs play a crucial role in creating a niche microenvironment that is required for tumor progression and drug resistance. Antioxidant activity in TICs, mediated by the transcription factor NRF2, facilitates the release of a nuclear cytokine, interleukin-33 (IL-33). This cytokine promotes differentiation...
Thu Jul 16, 2020 20:39
Although reef-building corals are declining worldwide, responses to bleaching vary within and across species and are partly heritable. Toward predicting bleaching response from genomic data, we generated a chromosome-scale genome assembly for the coral Acropora millepora. We obtained whole-genome sequences for 237 phenotyped samples collected at 12 reefs along the Great Barrier Reef, among which we inferred little population structure. Scanning the genome for evidence of local adaptation, we detected...
Thu Jul 16, 2020 20:39
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