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Aggiornato: 13 settimane 1 giorno fa

Waters of high Asia

Gio, 19/08/2021 - 18:44

How translation stops

Gio, 19/08/2021 - 18:44

High-entropy herringbone alloy

Gio, 19/08/2021 - 18:44

Poultry passport to pandemic

Gio, 19/08/2021 - 18:44

Fueling outbreaks

Gio, 19/08/2021 - 18:44

Hydra recovers from the "Blip"

Gio, 19/08/2021 - 18:44

Collapse of fluke populations

Gio, 19/08/2021 - 18:44

Fluid support

Gio, 19/08/2021 - 18:44

Epigenetic control of metastasis

Gio, 19/08/2021 - 18:44

Contrapuntal gene risk

Gio, 19/08/2021 - 18:44

When an internship adds value

Gio, 19/08/2021 - 18:44

Accurate prediction of protein structures and interactions using a three-track neural network

Gio, 19/08/2021 - 18:44

DeepMind presented notably accurate predictions at the recent 14th Critical Assessment of Structure Prediction (CASP14) conference. We explored network architectures that incorporate related ideas and obtained the best performance with a three-track network in which information at the one-dimensional (1D) sequence level, the 2D distance map level, and the 3D coordinate level is successively transformed and integrated. The three-track network produces structure predictions with accuracies approaching those of DeepMind in CASP14, enables the rapid solution of challenging x-ray crystallography and cryo–electron microscopy structure modeling problems, and provides insights into the functions of proteins of currently unknown structure. The network also enables rapid generation of accurate protein-protein complex models from sequence information alone, short-circuiting traditional approaches that require modeling of individual subunits followed by docking. We make the method available to the scientific community to speed biological research.

Mechanisms that ensure speed and fidelity in eukaryotic translation termination

Gio, 19/08/2021 - 18:44

Translation termination, which liberates a nascent polypeptide from the ribosome specifically at stop codons, must occur accurately and rapidly. We established single-molecule fluorescence assays to track the dynamics of ribosomes and two requisite release factors (eRF1 and eRF3) throughout termination using an in vitro–reconstituted yeast translation system. We found that the two eukaryotic release factors bound together to recognize stop codons rapidly and elicit termination through a tightly regulated, multistep process that resembles transfer RNA selection during translation elongation. Because the release factors are conserved from yeast to humans, the molecular events that underlie yeast translation termination are likely broadly fundamental to eukaryotic protein synthesis.

Mammalian retrovirus-like protein PEG10 packages its own mRNA and can be pseudotyped for mRNA delivery

Gio, 19/08/2021 - 18:44

Eukaryotic genomes contain domesticated genes from integrating viruses and mobile genetic elements. Among these are homologs of the capsid protein (known as Gag) of long terminal repeat (LTR) retrotransposons and retroviruses. We identified several mammalian Gag homologs that form virus-like particles and one LTR retrotransposon homolog, PEG10, that preferentially binds and facilitates vesicular secretion of its own messenger RNA (mRNA). We showed that the mRNA cargo of PEG10 can be reprogrammed by flanking genes of interest with Peg10’s untranslated regions. Taking advantage of this reprogrammability, we developed selective endogenous encapsidation for cellular delivery (SEND) by engineering both mouse and human PEG10 to package, secrete, and deliver specific RNAs. Together, these results demonstrate that SEND is a modular platform suited for development as an efficient therapeutic delivery modality.

Spatiotemporal invasion dynamics of SARS-CoV-2 lineage B.1.1.7 emergence

Gio, 19/08/2021 - 18:44

Understanding the causes and consequences of the emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern is crucial to pandemic control yet difficult to achieve because they arise in the context of variable human behavior and immunity. We investigated the spatial invasion dynamics of lineage B.1.1.7 by jointly analyzing UK human mobility, virus genomes, and community-based polymerase chain reaction data. We identified a multistage spatial invasion process in which early B.1.1.7 growth rates were associated with mobility and asymmetric lineage export from a dominant source location, enhancing the effects of B.1.1.7’s increased intrinsic transmissibility. We further explored how B.1.1.7 spread was shaped by nonpharmaceutical interventions and spatial variation in previous attack rates. Our findings show that careful accounting of the behavioral and epidemiological context within which variants of concern emerge is necessary to interpret correctly their observed relative growth rates.

Large-sample evidence on the impact of unconventional oil and gas development on surface waters

Gio, 19/08/2021 - 18:44

The impact of unconventional oil and gas development on water quality is a major environmental concern. We built a large geocoded database that combines surface water measurements with horizontally drilled wells stimulated by hydraulic fracturing (HF) for several shales to examine whether temporal and spatial well variation is associated with anomalous salt concentrations in United States watersheds. We analyzed four ions that could indicate water impact from unconventional development. We found very small concentration increases associated with new HF wells for barium, chloride, and strontium but not bromide. All ions showed larger, but still small-in-magnitude, increases 91 to 180 days after well spudding. Our estimates were most pronounced for wells with larger amounts of produced water, wells located over high-salinity formations, and wells closer and likely upstream from water monitors.

Stabilizing perovskite-substrate interfaces for high-performance perovskite modules

Gio, 19/08/2021 - 18:44

The interfaces of perovskite solar cells (PSCs) are important in determining their efficiency and stability, but the morphology and stability of imbedded perovskite-substrate interfaces have received less attention than have top interfaces. We found that dimethyl sulfoxide (DMSO), which is a liquid additive broadly applied to enhance perovskite film morphology, was trapped during film formation and led to voids at perovskite-substrate interfaces that accelerated the film degradation under illumination. Partial replacement of DMSO with solid-state carbohydrazide reduces interfacial voids. A maximum stabilized power conversion efficiency (PCE) of 23.6% was realized for blade-coated p-type/intrinsic/n-type (p-i-n) structure PSCs with no efficiency loss after 550-hour operational stability tests at 60°C. The perovskite mini-modules showed certified PCEs of 19.3 and 19.2%, with aperture areas of 18.1 and 50.0 square centimeters, respectively.