Phase plates can in principle overcome the poor image contrast in electron cryo-microscopy (cryo-EM) and the resulting limits on the structural reconstruction of small proteins. However, previous designs have been unstab...Phase plates can in principle overcome the poor image contrast in electron cryo-microscopy (cryo-EM) and the resulting limits on the structural reconstruction of small proteins. However, previous designs have been unstable and compromised the high-resolution signal. They have thus been unable to surpass results achieved by standard cryo-EM. Here, we show that the laser phase plate (LPP), installed in a custom, modern Titan Krios microscope, enhances the resolution in single-particle reconstruction of small proteins by improving specimen-motion correction, recovery of information from the early frames, as well as particle visualization, 3D classification, and alignment. These advances use standard defocus ranges and reconstruction procedures, but open the door to LPP-tailored protocols offering further improvements by leveraging the LPP demonstrated here.
Decades of improvement in surface ozone exposure in the United States risk being reversed by wildfires.Decades of improvement in surface ozone exposure in the United States risk being reversed by wildfires.
Tyukavina A, Poulson AJ, Pickering J
… +19 more, Adusei B, Hansen MC, Potapov P, Baggett A, Dominguez CO, Mikus A, Oktaviandra A, Turubanova S, Komarova A, Parker D, Pickens AH, Zalles V, Byrne W, Painter S, Thomas L, Ireland A, He Y, Harris N, Song XP
Quantifying the drivers of tree cover loss globally provides a synoptic understanding of pressures on the world's forests. Existing information about tree cover loss drivers relies on maps of coarse spatial and thematic...Quantifying the drivers of tree cover loss globally provides a synoptic understanding of pressures on the world's forests. Existing information about tree cover loss drivers relies on maps of coarse spatial and thematic resolution. In this study, we quantified the global extent of tree cover loss in 2018 at the scale of individual disturbances and provided a comprehensive accounting of land use outcomes using a global probability sample of 600 5 × 5-kilometer blocks mapped with high-resolution (3- to 10-meter) satellite data. Out of 277 thousand square kilometers of estimated global tree cover loss, nearly a third (29.0%) was due to long-term conversion of tree cover to other land uses, including conversion of natural tree cover to pasture (15.0%), cropland (6.4%), and nontimber tree plantations (3.8%).
Most predictions of whether populations will adapt to warming range edges ignore species interactions. We experimentally tested whether range-edge populations can adapt to warming within a competitive, model plant commun...Most predictions of whether populations will adapt to warming range edges ignore species interactions. We experimentally tested whether range-edge populations can adapt to warming within a competitive, model plant community ( spp. and duckweeds). Notably, we found that adaptation to warming range edges was possible only when populations evolved with interspecific competitors. Moreover, competitors enabled the evolution of both high-temperature tolerance and increased thermal performance breadth at the range edge, but not at the cooler range core. Our results reveal that competitors accelerate thermal adaptation when there is a shared evolutionary response to both competition and warming. Overall, we highlight the urgency of including community context in predicting future range shifts, showing that antagonistic interactions do not necessarily hinder adaptation to climate deterioration.
Physicists find that minimal assumptions about nature inevitably lead to stringlike theories.Physicists find that minimal assumptions about nature inevitably lead to stringlike theories.
Amid a flood of AI advances, astrophysicists are questioning the soul of their field.Amid a flood of AI advances, astrophysicists are questioning the soul of their field.
Recent memories are consolidated during sleep by spontaneous reactivation. However, whether and how memory reactivation affects sleep dynamics remain unclear. By tracking and modulating memory activity during sleep in mi...Recent memories are consolidated during sleep by spontaneous reactivation. However, whether and how memory reactivation affects sleep dynamics remain unclear. By tracking and modulating memory activity during sleep in mice, we revealed that negative memory reactivation promoted arousal, whereas positive memory supported sleep stability. This regulation was mediated by the reactivation of experience-specific hippocampus-amygdala engram circuits during sleep. In chronic stress models, negative memory reactivation promoted sleep disturbance, and targeted suppression of memory reactivation restored normal sleep. Our findings establish a memory-dependent sleep regulation in which memory reactivation engages downstream circuits responsive to specific memory content.
The construction of stereogenic C(sp)-C(sp) bonds through cross-coupling remains a formidable challenge owing to competing β-hydride elimination and homocoupling as well as the poor inherent stereocontrol of radical path...The construction of stereogenic C(sp)-C(sp) bonds through cross-coupling remains a formidable challenge owing to competing β-hydride elimination and homocoupling as well as the poor inherent stereocontrol of radical pathways. In this work, we report a scalable stereoretentive radical-radical cross-coupling of two distinct, transient alkyl radicals, derived from enantioenriched sulfonylhydrazides and achiral primary and secondary alkyl halides, achieved without chiral ligands, directing groups, or exogenous redox agents. This substrate-controlled approach leverages a nickel-catalyzed, redox-neutral manifold, which enables precise kinetic matching of diazene-mediated radical generation and halogen atom transfer. The reaction produced enantiospecificities of 80 to 96% and synthetically useful yields (up to 90%) across diverse piperidine and pyrrolidine scaffolds while tolerating ethers, free amines, aryl halides, heterocycles, olefins, and other sensitive motifs. Mechanistic studies support caged radical rebound at nickel to preserve chirality, followed by nickel(I)-nickel(III)-mediated radical capture and reductive elimination.
New policy leaves universities in charge of probing misconduct allegations against faculty.New policy leaves universities in charge of probing misconduct allegations against faculty.
Sweeping proposed rule would also restrict foreign collaborations and cut funding for open-access fees.Sweeping proposed rule would also restrict foreign collaborations and cut funding for open-access fees.
Allen Institute initiative aims to capture earliest cellular damage underlying disease and identify new drug targets.Allen Institute initiative aims to capture earliest cellular damage underlying disease and identify new drug targets.
What do randomized controlled trials really tell us about the effects of ultraprocessed foods?What do randomized controlled trials really tell us about the effects of ultraprocessed foods?
Vignieri S, Sonawala U, Seale M
… +12 more, Huang J, Smith KT, Lopez B, Yeston JS, VanHook AM, Leder K, Uzogara E, Nusinovich Y, Maroso M, Smith J, Szuromi P, Hallberg D