Coexistence of three liquid phases in individual atmospheric aerosol particles [Earth, Atmospheric, and Planetary Sciences]
Individual atmospheric particles can contain mixtures of primary organic aerosol (POA), secondary organic aerosol (SOA), and secondary inorganic aerosol (SIA). To predict the role of such complex multicomponent particles in air quality and climate, information on the number and types of phases present in the particles is needed. However, the... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 15, 2021 Category: Science Authors: Yuanzhou Huang, Fabian Mahrt, Shaun Xu, Manabu Shiraiwa, Andreas Zuend, Allan K. Bertram Tags: Earth, Atmospheric, and Planetary Sciences Physical Sciences Source Type: research

Collagen IV differentially regulates planarian stem cell potency and lineage progression [Developmental Biology]
The extracellular matrix (ECM) provides a precise physical and molecular environment for cell maintenance, self-renewal, and differentiation in the stem cell niche. However, the nature and organization of the ECM niche is not well understood. The adult freshwater planarian Schmidtea mediterranea maintains a large population of multipotent stem cells (neoblasts),... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 15, 2021 Category: Science Authors: Andy Chan, Sophia Ma, Bret J. Pearson, Danny Chan Tags: Developmental Biology Biological Sciences Source Type: research

A complement factor H homolog, heparan sulfation, and syndecan maintain inversin compartment boundaries in C. elegans cilia [Cell Biology]
Age-related macular degeneration (AMD) is a leading cause of blindness among the elderly. Canonical disease models suggest that defective interactions between complement factor H (CFH) and cell surface heparan sulfate (HS) result in increased alternative complement pathway activity, cytolytic damage, and tissue inflammation in the retina. Although these factors are... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 15, 2021 Category: Science Authors: Natalie Acker, Harold Smith, Claire Devine, Sharon L. Oltjen, Sofia Tsiropoulou, Zeljka Smit-McBride, Karen Lange, Oliver E. Blacque, Joanne A. Matsubara, Andrew Gordus, Andy Golden, Bruce E. Vogel Tags: Cell Biology Biological Sciences Source Type: research

Predicting social tipping and norm change in controlled experiments [Social Sciences]
The ability to predict when societies will replace one social norm for another can have significant implications for welfare, especially when norms are detrimental. A popular theory poses that the pressure to conform to social norms creates tipping thresholds which, once passed, propel societies toward an alternative state. Predicting when... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 15, 2021 Category: Science Authors: James Andreoni, Nikos Nikiforakis, Simon Siegenthaler Tags: Social Sciences Source Type: research

Interferon regulatory factor 4 controls effector functions of CD8+ memory T cells [Immunology and Inflammation]
The transcription factor IRF4 is required for CD8+ T cell activation, proliferation, and differentiation to effector cells and thus is essential for robust CD8+ T cell responses. The function of IRF4 in memory CD8+ T cells yet needs to be explored. To investigate the role of IRF4 for maintaining differentiation... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 15, 2021 Category: Science Authors: Aenne Harberts, Constantin Schmidt, Joanna Schmid, Daniel Reimers, Friedrich Koch–Nolte, Hans–Willi Mittrucker, Friederike Raczkowski Tags: Immunology and Inflammation Biological Sciences Source Type: research

E2A-regulated epigenetic landscape promotes memory CD8 T cell differentiation [Immunology and Inflammation]
During an acute viral infection, CD8 T cells encounter a myriad of antigenic and inflammatory signals of variable strength, which sets off individual T cells on their own differentiation trajectories. However, the developmental path for each of these cells will ultimately lead to one of only two potential outcomes after... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 15, 2021 Category: Science Authors: David M. Schauder, Jian Shen, Yao Chen, Moujtaba Y. Kasmani, Matthew R. Kudek, Robert Burns, Weiguo Cui Tags: Immunology and Inflammation Biological Sciences Source Type: research

Regulation of longevity by depolarization-induced activation of PLC-{beta}-IP3R signaling in neurons [Neuroscience]
Mitochondrial ATP production is a well-known regulator of neuronal excitability. The reciprocal influence of plasma-membrane potential on ATP production, however, remains poorly understood. Here, we describe a mechanism by which depolarized neurons elevate the somatic ATP/ADP ratio in Drosophila glutamatergic neurons. We show that depolarization increased phospholipase-Cβ (PLC-β) activity by... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 15, 2021 Category: Science Authors: Ching-On Wong, Nicholas E. Karagas, Jewon Jung, Qiaochu Wang, Morgan A. Rousseau, Yufang Chao, Ryan Insolera, Pushpanjali Soppina, Catherine A. Collins, Yong Zhou, John F. Hancock, Michael X. Zhu, Kartik Venkatachalam Tags: Neuroscience Biological Sciences Source Type: research

A guideline to limit indoor airborne transmission of COVID-19 [Engineering]
The current revival of the American economy is being predicated on social distancing, specifically the Six-Foot Rule, a guideline that offers little protection from pathogen-bearing aerosol droplets sufficiently small to be continuously mixed through an indoor space. The importance of airborne transmission of COVID-19 is now widely recognized. While tools... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 15, 2021 Category: Science Authors: Martin Z. Bazant, John W. M. Bush Tags: Engineering Physical Sciences Source Type: research

Shedding light on 19th century spectra by analyzing Lippmann photography [Applied Mathematics]
From uncovering the structure of the atom to the nature of the universe, spectral measurements have helped some of science’s greatest discoveries. While pointwise spectral measurements date back to Newton, it is commonly thought that hyperspectral images originated in the 1970s. However, the first hyperspectral images are over a century... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 15, 2021 Category: Science Authors: Gilles Baechler, Arnaud Latty, Michalina Pacholska, Martin Vetterli, Adam Scholefield Tags: Applied Mathematics Physical Sciences Source Type: research

Killed whole-genome reduced-bacteria surface-expressed coronavirus fusion peptide vaccines protect against disease in a porcine model [Microbiology]
We report here a synthetic biology-based vaccine platform that employs an expression vector with an inducible... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 15, 2021 Category: Science Authors: Denicar Lina Nascimento Fabris Maeda, Debin Tian, Hanna Yu, Nakul Dar, Vignesh Rajasekaran, Sarah Meng, Hassan M. Mahsoub, Harini Sooryanarain, Bo Wang, C. Lynn Heffron, Anna Hassebroek, Tanya LeRoith, Xiang-Jin Meng, Steven L. Zeichner Tags: Microbiology, Coronavirus (COVID-19) Biological Sciences Source Type: research

Host barriers to SARS-CoV-2 demonstrated by ferrets in a high-exposure domestic setting [Microbiology]
Ferrets (Mustela putorius furo) are mustelids of special relevance to laboratory studies of respiratory viruses and have been shown to be susceptible to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and onward transmission. Here, we report the results of a natural experiment where 29 ferrets in one home had... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 15, 2021 Category: Science Authors: Kaitlin Sawatzki, Nichola J. Hill, Wendy B. Puryear, Alexa D. Foss, Jonathon J. Stone, Jonathan A. Runstadler Tags: Microbiology, Coronavirus (COVID-19) Biological Sciences Source Type: research

Inner Workings: Making headway with the mysteries of life’s origins [Earth, Atmospheric, and Planetary Sciences]
In 1863, Charles Darwin opined in a letter to a friend that contemplating the origin of life was “mere rubbish thinking” and that “one might as well think of [the] origin of matter.” Many researchers today would agree with Darwin. And yet, whereas cosmologists know how particles, elements, and many... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 14, 2021 Category: Science Authors: Adam Mann Tags: Inner Workings, Biochemistry, Earth, Atmospheric, and Planetary Sciences, Front Matter Source Type: research

Highly efficient photosynthesis of hydrogen peroxide in ambient conditions [Engineering]
Photosynthesis of hydrogen peroxide (H2O2) in ambient conditions remains neither cost effective nor environmentally friendly enough because of the rapid charge recombination. Here, a photocatalytic rate of as high as 114 μmol⋅g−1⋅h−1 for the production of H2O2 in pure water and open air is achieved by using a Z-scheme heterojunction,... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 14, 2021 Category: Science Authors: Yu-Xin Ye, Jinhui Pan, Fangyan Xie, Li Gong, Siming Huang, Zhuofeng Ke, Fang Zhu, Jianqiao Xu, Gangfeng Ouyang Tags: Engineering Physical Sciences Source Type: research

Cryo-EM structure of Mycobacterium smegmatis DyP-loaded encapsulin [Biochemistry]
Encapsulins containing dye-decolorizing peroxidase (DyP)-type peroxidases are ubiquitous among prokaryotes, protecting cells against oxidative stress. However, little is known about how they interact and function. Here, we have isolated a native cargo-packaging encapsulin from Mycobacterium smegmatis and determined its complete high-resolution structure by cryogenic electron microscopy (cryo-EM). This encapsulin comprises... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 14, 2021 Category: Science Authors: Yanting Tang, An Mu, Yuying Zhang, Shan Zhou, Weiwei Wang, Yuezheng Lai, Xiaoting Zhou, Fengjiang Liu, Xiuna Yang, Hongri Gong, Quan Wang, Zihe Rao Tags: Biochemistry Biological Sciences Source Type: research

Discriminating symbiosis and immunity signals by receptor competition in rice [Plant Biology]
Plants encounter various microbes in nature and must respond appropriately to symbiotic or pathogenic ones. In rice, the receptor-like kinase OsCERK1 is involved in recognizing both symbiotic and immune signals. However, how these opposing signals are discerned via OsCERK1 remains unknown. Here, we found that receptor competition enables the discrimination... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 14, 2021 Category: Science Authors: Chi Zhang, Jiangman He, Huiling Dai, Gang Wang, Xiaowei Zhang, Chao Wang, Jincai Shi, Xi Chen, Dapeng Wang, Ertao Wang Tags: Plant Biology Biological Sciences Source Type: research

Orphan nuclear receptor ERR-{gamma} regulates hepatic FGF23 production in acute kidney inȷury [Medical Sciences]
Fibroblast growth factor 23 (FGF23), a hormone generally derived from bone, is important in phosphate and vitamin D homeostasis. In acute kidney injury (AKI) patients, high-circulating FGF23 levels are associated with disease progression and mortality. However, the organ and cell type of FGF23 production in AKI and the molecular mechanism... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 14, 2021 Category: Science Authors: Kamalakannan Radhakrishnan, Yong–Hoon Kim, Yoon Seok Jung, Don–Kyu Kim, Soon–Young Na, Daeȷin Lim, Dong Hun Kim, Jina Kim, Hyung–Seok Kim, Hyon E. Choy, Sung Jin Cho, In–Kyu Lee, Şamil Ayvaz, Stefanie Nittka, Da Tags: Medical Sciences Biological Sciences Source Type: research

Impaired TRPV4-eNOS signaling in trabecular meshwork elevates intraocular pressure in glaucoma [Physiology]
Primary Open Angle Glaucoma (POAG) is the most common form of glaucoma that leads to irreversible vision loss. Dysfunction of trabecular meshwork (TM) tissue, a major regulator of aqueous humor (AH) outflow resistance, is associated with intraocular pressure (IOP) elevation in POAG. However, the underlying pathological mechanisms of TM dysfunction... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 14, 2021 Category: Science Authors: Pinkal D. Patel, Yen-Lin Chen, Ramesh B. Kasetti, Prabhavathi Maddineni, William Mayhew, J. Cameron Millar, Dorette Z. Ellis, Swapnil K. Sonkusare, Gulab S. Zode Tags: Physiology Biological Sciences Source Type: research

Biomechanical trade-offs in the pelvic floor constrain the evolution of the human birth canal [Anthropology]
Compared with most other primates, humans are characterized by a tight fit between the maternal birth canal and the fetal head, leading to a relatively high risk of neonatal and maternal mortality and morbidities. Obstetric selection is thought to favor a spacious birth canal, whereas the source for opposing selection... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 14, 2021 Category: Science Authors: Ekaterina Stansfield, Krishna Kumar, Philipp Mitteroecker, Nicole D. S. Grunstra Tags: Anthropology Biological Sciences Source Type: research

Microbiome reduction and endosymbiont gain from a switch in sea urchin life history [Evolution]
Animal gastrointestinal tracts harbor a microbiome that is integral to host function, yet species from diverse phyla have evolved a reduced digestive system or lost it completely. Whether such changes are associated with alterations in the diversity and/or abundance of the microbiome remains an untested hypothesis in evolutionary symbiosis. Here,... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 14, 2021 Category: Science Authors: Tyler J. Carrier, Brittany A. Leigh, Dione J. Deaker, Hannah R. Devens, Gregory A. Wray, Seth R. Bordenstein, Maria Byrne, Adam M. Reitzel Tags: Evolution Biological Sciences Source Type: research

Optical vector field rotation and switching with near-unity transmission by fully developed chiral photonic crystals [Applied Physical Sciences]
State-of-the-art nanostructured chiral photonic crystals (CPCs), metamaterials, and metasurfaces have shown giant optical rotatory power but are generally passive and beset with large optical losses and with inadequate performance due to limited size/interaction length and narrow operation bandwidth. In this work, we demonstrate by detailed theoretical modeling and experiments that... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 14, 2021 Category: Science Authors: Chun-Wei Chen, Iam Choon Khoo Tags: Applied Physical Sciences Source Type: research

Learning effective physical laws for generating cosmological hydrodynamics with Lagrangian deep learning [Astronomy]
The goal of generative models is to learn the intricate relations between the data to create new simulated data, but current approaches fail in very high dimensions. When the true data-generating process is based on physical processes, these impose symmetries and constraints, and the generative model can be created by... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 14, 2021 Category: Science Authors: Biwei Dai, Uroš Selȷak Tags: Astronomy Physical Sciences Source Type: research

Two sources of uncertainty independently modulate temporal expectancy [Neuroscience]
The environment is shaped by two sources of temporal uncertainty: the discrete probability of whether an event will occur and—if it does—the continuous probability of when it will happen. These two types of uncertainty are fundamental to every form of anticipatory behavior including learning, decision-making, and motor planning. It remains... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 14, 2021 Category: Science Authors: Matthias Grabenhorst, Laurence T. Maloney, David Poeppel, Georgios Michalareas Tags: Neuroscience Biological Sciences Source Type: research

Mycobacterial fatty acid catabolism is repressed by FdmR to sustain lipogenesis and virulence [Microbiology]
Host-derived fatty acids are an important carbon source for pathogenic mycobacteria during infection. How mycobacterial cells regulate the catabolism of fatty acids to serve the pathogenicity, however, remains unknown. Here, we identified a TetR-family transcriptional factor, FdmR, as the key regulator of fatty acid catabolism in the pathogen Mycobacterium marinum... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 14, 2021 Category: Science Authors: Wenyue Dong, Xiaoqun Nie, Hong Zhu, Qingyun Liu, Kunxiong Shi, Linlin You, Yu Zhang, Hongyan Fan, Bo Yan, Chen Niu, Liang-Dong Lyu, Guo-Ping Zhao, Chen Yang Tags: Microbiology Biological Sciences Source Type: research

The impact of identity by descent on fitness and disease in dogs [Evolution]
Domestic dogs have experienced population bottlenecks, recent inbreeding, and strong artificial selection. These processes have simplified the genetic architecture of complex traits, allowed deleterious variation to persist, and increased both identity-by-descent (IBD) segments and runs of homozygosity (ROH). As such, dogs provide an excellent model for examining how these evolutionary... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 14, 2021 Category: Science Authors: Jazlyn A. Mooney, Abigail Yohannes, Kirk E. Lohmueller Tags: Evolution Biological Sciences Source Type: research

Cholestenone functions as an antibiotic against Helicobacter pylori by inhibiting biosynthesis of the cell wall component CGL [Microbiology]
Helicobacter pylori, a pathogen responsible for gastric cancer, contains a unique glycolipid, cholesteryl-α-D-glucopyranoside (CGL), in its cell wall. Moreover, O-glycans having α1,4-linked N-acetylglucosamine residues (αGlcNAc) are secreted from gland mucous cells of gastric mucosa. Previously, we demonstrated that CGL is critical for H. pylori survival and that αGlcNAc serves as... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 14, 2021 Category: Science Authors: Junichi Kobayashi, Masatomo Kawakubo, Chifumi Fujii, Nobuhiko Arisaka, Masaki Miyashita, Yoshiko Sato, Hitomi Komura, Hisanori Matoba, Jun Nakayama Tags: Microbiology Biological Sciences Source Type: research

Parental bias in expression and interaction of genes in the equine placenta [Genetics]
Most autosomal genes in the placenta show a biallelic expression pattern. However, some genes exhibit allele-specific transcription depending on the parental origin of the chromosomes on which the copy of the gene resides. Parentally expressed genes are involved in the reciprocal interaction between maternal and paternal genes, coordinating the allocation... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 14, 2021 Category: Science Authors: Pouya Dini, Theodore Kalbfleisch, Jose M. Uribe–Salazar, Mariano Carossino, Hossam El–Sheikh Ali, Shavahn C. Loux, Aleȷandro Esteller–Vico, Jamie K. Norris, Lakshay Anand, Kirsten E. Scoggin, Carlos M. Rodriguez Lopez, James Breen Tags: Genetics Biological Sciences Source Type: research

Setting molecular traps in yeast for identification of anticancer drug targets [Genetics]
Almost 25 y have passed since Lee Hartwell et al. (1) proposed that systematic efforts to map genetic interactions in model systems promised to accelerate identification of new anticancer drug targets that exploit the unique molecular context of tumor cells. Synthetic lethal interactions, in which mutation of a gene causes... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 14, 2021 Category: Science Authors: Grant W. Brown, Brenda Andrews Tags: Genetics, Commentaries Commentary Source Type: research

An ABC transporter of the ABCC subfamily localized at the plasma membrane confers glyphosate resistance [Agricultural Sciences]
Synthetic herbicides have been used widely for more than 70 y and have substantially contributed to the efficiency of agriculture. Glyphosate [N-(phosphonomethyl)glycine] was marketed in 1974 under the trade name Roundup and has become the most used herbicide worldwide. It is a postemergence, nonselective herbicide of low toxicity to animals... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 14, 2021 Category: Science Authors: Nikolaus Amrhein, Enrico Martinoia Tags: Agricultural Sciences, Commentaries Commentary Source Type: research

Reply to Best and Ashby: The concept of evolutionarily stable strategies (ESS) helps link ecology and evolution [Biological Sciences]
To demonstrate the existence of an evolutionarily stable strategy (ESS) in fluctuating ecological systems (such as predator−prey system with limit cycles) is important. Deriving the analytic conditions for such an ESS can be of great help when studying real biological systems. A main aim of our study (1) was just... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 14, 2021 Category: Science Authors: Katrin Grunert, Helge Holden, Espen R. Jakobsen, Nils Chr. Stenseth Tags: Applied Mathematics, Letters, Population Biology, Letters and Replies Source Type: research

Evolutionarily stable strategies are well studied in periodically fluctuating populations [Biological Sciences]
Grunert et al. (1) examine evolutionarily stable strategies (ESSs) of a predator−prey system where the population dynamics either tend to an equilibrium or fluctuate periodically. The authors claim to have “extended the ESS concept to be applicable for periodically fluctuating ecological systems.” However, the ESS concept is already well-established in... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 14, 2021 Category: Science Authors: Alex Best, Ben Ashby Tags: Applied Mathematics, Letters, Population Biology, Letters and Replies Source Type: research

A scientific theory of gist communication and misinformation resistance, with implications for health, education, and policy [Colloquium Paper]
A framework is presented for understanding how misinformation shapes decision-making, which has cognitive representations of gist at its core. I discuss how the framework goes beyond prior work, and how it can be implemented so that valid scientific messages are more likely to be effective, remembered, and shared through social... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 13, 2021 Category: Science Authors: Valerie F. Reyna Tags: Psychological and Cognitive Sciences, Colloquia, Arthur M. Sackler Colloquium Advancing the Science and Practice of Science Communication: Misinforma Arthur M. Sackler Colloquium on Advancing the Science and Practice of Science Communication: Misinforma Source Type: research

In This Issue [This Week in PNAS]
ANTHROPOLOGY Detail of a mummified blue-fronted Amazon parrot recovered from Pica 8 cemetery in the Atacama Desert. Parrot rearing in the pre-Columbian Atacama Desert The feathers of tropical birds were signs of wealth and status in pre-Columbian Andean societies. However, understanding of the import networks that brought the feathers to... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 13, 2021 Category: Science Tags: In This Issue This Week in PNAS Source Type: research

An ultra-high-affinity small organic ligand of fibroblast activation protein for tumor-targeting applications [Medical Sciences]
We describe the development of OncoFAP, an ultra-high-affinity ligand of fibroblast activation protein (FAP) for targeting applications with pan-tumoral potential. OncoFAP binds to human FAP with affinity in the subnanomolar concentration range and cross-reacts with the murine isoform of the protein. We generated various fluorescent and radiolabeled derivatives of OncoFAP... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 13, 2021 Category: Science Authors: Jacopo Millul, Gabriele Bassi, Jacqueline Mock, Abdullah Elsayed, Christian Pellegrino, Aureliano Zana, Sheila Dakhel Plaza, Lisa Nadal, Andreas Gloger, Eleonore Schmidt, Ilaria Biancofiore, Etienne J. Donckele, Florent Samain, Dario Neri, Samuele Cazzama Tags: Medical Sciences Biological Sciences Source Type: research

A model for a partnership of lipid transfer proteins and scramblases in membrane expansion and organelle biogenesis [Cell Biology]
The autophagy protein ATG2, proposed to transfer bulk lipid from the endoplasmic reticulum (ER) during autophagosome biogenesis, interacts with ER residents TMEM41B and VMP1 and with ATG9, in Golgi-derived vesicles that initiate autophagosome formation. In vitro assays reveal TMEM41B, VMP1, and ATG9 as scramblases. We propose a model wherein membrane... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 13, 2021 Category: Science Authors: Alireza Ghanbarpour, Diana P. Valverde, Thomas J. Melia, Karin M. Reinisch Tags: Cell Biology, Brief Reports Biological Sciences Source Type: research

The role of annealing in determining the yielding behavior of glasses under cyclic shear deformation [Physics]
Yielding behavior in amorphous solids has been investigated in computer simulations using uniform and cyclic shear deformation. Recent results characterize yielding as a discontinuous transition, with the degree of annealing of glasses being a significant parameter. Under uniform shear, discontinuous changes in stresses at yielding occur in the high annealing... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 13, 2021 Category: Science Authors: Himangsu Bhaumik, Giuseppe Foffi, Srikanth Sastry Tags: Physics Physical Sciences Source Type: research

Cardenolides, toxicity, and the costs of sequestration in the coevolutionary interaction between monarchs and milkweeds [Ecology]
For highly specialized insect herbivores, plant chemical defenses are often co-opted as cues for oviposition and sequestration. In such interactions, can plants evolve novel defenses, pushing herbivores to trade off benefits of specialization with costs of coping with toxins? We tested how variation in milkweed toxins (cardenolides) impacted monarch butterfly... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 13, 2021 Category: Science Authors: Anurag A. Agrawal, Katalin Boroczky, Meena Haribal, Amy P. Hastings, Ronald A. White, Ren–Wang Jiang, Christophe Duplais Tags: Ecology Biological Sciences Source Type: research

Reduced phase stability and faster formation/dissociation kinetics in confined methane hydrate [Applied Physical Sciences]
The mechanisms involved in the formation/dissociation of methane hydrate confined at the nanometer scale are unraveled using advanced molecular modeling techniques combined with a mesoscale thermodynamic approach. Using atom-scale simulations probing coexistence upon confinement and free energy calculations, phase stability of confined methane hydrate is shown to be restricted to... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 13, 2021 Category: Science Authors: Dongliang Jin, Benoit Coasne Tags: Applied Physical Sciences Source Type: research

Stress-dependent activation of myosin in the heart requires thin filament activation and thick filament mechanosensing [Physiology]
Myosin-based regulation in the heart muscle modulates the number of myosin motors available for interaction with calcium-regulated thin filaments, but the signaling pathways mediating the stronger contraction triggered by stretch between heartbeats or by phosphorylation of the myosin regulatory light chain (RLC) remain unclear. Here, we used RLC probes in... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 13, 2021 Category: Science Authors: So-Jin Park-Holohan, Elisabetta Brunello, Thomas Kampourakis, Martin Rees, Malcolm Irving, Luca Fusi Tags: Physiology Biological Sciences Source Type: research

A translational riboswitch coordinates nascent transcription-translation coupling [Biophysics and Computational Biology]
Bacterial messenger RNA (mRNA) synthesis by RNA polymerase (RNAP) and first-round translation by the ribosome are often coupled to regulate gene expression, yet how coupling is established and maintained is ill understood. Here, we develop biochemical and single-molecule fluorescence approaches to probe the dynamics of RNAP–ribosome interactions on an mRNA... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 13, 2021 Category: Science Authors: Surajit Chatterjee, Adrien Chauvier, Shiba S. Dandpat, Irina Artsimovitch, Nils G. Walter Tags: Biophysics and Computational Biology Biological Sciences Source Type: research

Hippocampal astrocytic neogenin regulating glutamate uptake, a critical pathway for preventing epileptic response [Neuroscience]
Epilepsy, a common neurological disorder, is featured with recurrent seizures. Its underlying pathological mechanisms remain elusive. Here, we provide evidence for loss of neogenin (NEO1), a coreceptor for multiple ligands, including netrins and bone morphological proteins, in the development of epilepsy. NEO1 is reduced in hippocampi from patients with epilepsy... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 13, 2021 Category: Science Authors: Dong Sun, Zhi-Bing Tan, Xiang-Dong Sun, Zhi-Peng Liu, Wen-Bing Chen, Leena Milibari, Xiao Ren, Ling-Ling Yao, Daehoon Lee, Chen Shen, Jin-Xiu Pan, Zhi-Hui Huang, Lin Mei, Wen-Cheng Xiong Tags: Neuroscience Biological Sciences Source Type: research

Repeated mutation of a developmental enhancer contributed to human thermoregulatory evolution [Evolution]
Humans sweat to cool their bodies and have by far the highest eccrine sweat gland density among primates. Humans’ high eccrine gland density has long been recognized as a hallmark human evolutionary adaptation, but its genetic basis has been unknown. In humans, expression of the Engrailed 1 (EN1) transcription factor... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 13, 2021 Category: Science Authors: Daniel Aldea, Yuji Atsuta, Blerina Kokalari, Stephen F. Schaffner, Rexxi D. Prasasya, Adam Aharoni, Heather L. Dingwall, Bailey Warder, Yana G. Kamberov Tags: Evolution Biological Sciences Source Type: research

Central human B cell tolerance manifests with a distinctive cell phenotype and is enforced via CXCR4 signaling in hu-mice [Immunology and Inflammation]
Central B cell tolerance, the process restricting the development of many newly generated autoreactive B cells, has been intensely investigated in mouse cells while studies in humans have been hampered by the inability to phenotypically distinguish autoreactive and nonautoreactive immature B cell clones and the difficulty in accessing fresh human... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 13, 2021 Category: Science Authors: Thiago Alves da Costa, Jacob N. Peterson, Julie Lang, Jeremy Shulman, Xiayuan Liang, Brian M. Freed, Susan A. Boackle, Pilar Lauzurica, Raul M. Torres, Roberta Pelanda Tags: Immunology and Inflammation Biological Sciences Source Type: research

De novo biosynthesis of a nonnatural cobalt porphyrin cofactor in E. coli and incorporation into hemoproteins [Biochemistry]
We report here that a common laboratory... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 13, 2021 Category: Science Authors: Lydia J. Perkins, Brian R. Weaver, Andrew R. Buller, Judith N. Burstyn Tags: Biochemistry, Chemistry Physical Sciences Source Type: research

Brd4-bound enhancers drive cell-intrinsic sex differences in glioblastoma [Genetics]
Sex can be an important determinant of cancer phenotype, and exploring sex-biased tumor biology holds promise for identifying novel therapeutic targets and new approaches to cancer treatment. In an established isogenic murine model of glioblastoma (GBM), we discovered correlated transcriptome-wide sex differences in gene expression, H3K27ac marks, large Brd4-bound enhancer... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 13, 2021 Category: Science Authors: Najla Kfoury, Zongtai Qi, Briana C. Prager, Michael N. Wilkinson, Lauren Broestl, Kristopher C. Berrett, Arnav Moudgil, Sumithra Sankararaman, Xuhua Chen, Jason Gertz, Jeremy N. Rich, Robi D. Mitra, Joshua B. Rubin Tags: Genetics Biological Sciences Source Type: research

Emergence of hierarchy in networked endorsement dynamics [Applied Mathematics]
Many social and biological systems are characterized by enduring hierarchies, including those organized around prestige in academia, dominance in animal groups, and desirability in online dating. Despite their ubiquity, the general mechanisms that explain the creation and endurance of such hierarchies are not well understood. We introduce a generative model... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 13, 2021 Category: Science Authors: Mari Kawakatsu, Philip S. Chodrow, Nicole Eikmeier, Daniel B. Larremore Tags: Applied Mathematics Physical Sciences Source Type: research

Reply to Evaristo et al.: Strong evidence for the need of correcting extraction bias in an early study of ecohydrological separation [Biological Sciences]
In their reexamination of an earlier study (1) in which water isotope data from globally distributed sites were compiled, Evaristo et al. (2) show that, after accounting for extraction artifacts, precipitation offsets of xylem water (dxylem_c) are still statistically distinct from those of stream (dstream)/groundwater (dgw) in a majority of... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 13, 2021 Category: Science Authors: Xin Song, Yongle Chen, Brent R. Helliker, Xianhui Tang, Fang Li, Youping Zhou Tags: Earth, Atmospheric, and Planetary Sciences, Environmental Sciences, Letters, Letters and Replies Source Type: research

Implication of stem water cryogenic extraction experiment for an earlier study is not supported with robust context-specific statistical assessment [Biological Sciences]
Chen et al. (1) conclude that “the extraction error-corrected result tends to nullify support for ecohydrological separation as a globally widespread phenomenon” based on an extrapolation of results from a carefully designed experiment under controlled conditions. The extrapolation was performed using global precipitation offset data (2) compiled from field-based studies... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 13, 2021 Category: Science Authors: Jaivime Evaristo, Yusuf Jameel, Kwok P. Chun Tags: Earth, Atmospheric, and Planetary Sciences, Environmental Sciences, Letters, Letters and Replies Source Type: research

Harnessing psilocybin: antidepressant-like behavioral and synaptic actions of psilocybin are independent of 5-HT2R activation in mice [Neuroscience]
Depression is a widespread and devastating mental illness and the search for rapid-acting antidepressants remains critical. There is now exciting evidence that the psychedelic compound psilocybin produces not only powerful alterations of consciousness, but also rapid and persistent antidepressant effects. How psilocybin exerts its therapeutic actions is not known, but... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 13, 2021 Category: Science Authors: Natalie Hesselgrave, Timothy A. Troppoli, Andreas B. Wulff, Anthony B. Cole, Scott M. Thompson Tags: Neuroscience Biological Sciences Source Type: research

CD317 puts the brakes on dendritic cell trafficking to the CNS [Immunology and Inflammation]
Myelin-reactive immune cell attack in multiple sclerosis (MS) causes inflammatory demyelinating lesions in the central nervous system (CNS), resulting in an array of neurological complications, which may result in permanent disability (1). The first episode of neurological symptoms is termed “clinically isolated syndrome” (CIS). Arresting disease pathogenesis during CIS is... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 13, 2021 Category: Science Authors: Sarah E. Barnes, May H. Han Tags: Immunology and Inflammation, Commentaries Commentary Source Type: research

Understanding why we do what we do during a global pandemic [Environmental Sciences]
We are, at this writing, slowly beginning to see the light at the end of the COVID-19 tunnel. Eighteen percent of the population has now been vaccinated, and the national third wave of COVID-19 cases is on the wane. Both of these forces are conspiring to give us hope that... (Source: Proceedings of the National Academy of Sciences)
Source: Proceedings of the National Academy of Sciences - April 13, 2021 Category: Science Authors: Sandro Galea Tags: Environmental Sciences, Commentaries, Coronavirus Related Commentary Source Type: research