Catálogo de publicaciones - revistas

<jats:p>Extreme wildfires are becoming more common and increasingly affecting Earth’s climate. Wildfires in boreal forests have attracted much less attention than those in tropical forests, although boreal forests are one of the most extensive biomes on Earth and are experiencing the fastest warming. We used a satellite-based atmospheric inversion system to monitor fire emissions in boreal forests. Wildfires are rapidly expanding into boreal forests with emerging warmer and drier fire seasons. Boreal fires, typically accounting for 10% of global fire carbon dioxide emissions, contributed 23% (0.48 billion metric tons of carbon) in 2021, by far the highest fraction since 2000. 2021 was an abnormal year because North American and Eurasian boreal forests synchronously experienced their greatest water deficit. Increasing numbers of extreme boreal fires and stronger climate–fire feedbacks challenge climate mitigation efforts.</jats:p>

<jats:p>Our capability to reconstruct past landscapes and the processes that shape them underpins our understanding of paleo-Earth. We take advantage of a global-scale landscape evolution model assimilating paleoelevation and paleoclimate reconstructions over the past 100 million years. This model provides continuous quantifications of metrics critical to the understanding of the Earth system, from global physiography to sediment flux and stratigraphic architectures. We reappraise the role played by surface processes in controlling sediment delivery to the oceans and find stable sedimentation rates throughout the Cenozoic with distinct phases of sediment transfer from terrestrial to marine basins. Our simulation provides a tool for identifying inconsistencies in previous interpretations of the geological record as preserved in sedimentary strata, and in available paleoelevation and paleoclimatic reconstructions.</jats:p>

<jats:p>Laning is a paradigmatic example of spontaneous organization in active two-component flows that has been observed in diverse contexts, including pedestrian traffic, driven colloids, complex plasmas, and molecular transport. We introduce a kinetic theory that elucidates the physical origins of laning and quantifies the propensity for lane nucleation in a given physical system. Our theory is valid in the low-density regime, and it makes different predictions about situations in which lanes may form that are not parallel with the direction of flow. We report on experiments with human crowds that verify two notable consequences of this phenomenon: tilting lanes under broken chiral symmetry and lane nucleation along elliptic, parabolic, and hyperbolic curves in the presence of sources or sinks.</jats:p>

<jats:p>Echolocating toothed whales (odontocetes) capture fast-moving prey in dark marine environments, which critically depends on their ability to generate powerful, ultrasonic clicks. How their supposedly air-driven sound source can produce biosonar clicks at depths of &gt;1000 meters, while also producing rich vocal repertoires to mediate complex social communication, remains unknown. We show that odontocetes possess a sound production system based on air driven through nasal passages that is functionally analogous to laryngeal and syringeal sound production. Tissue vibration in different registers produces distinct echolocation and communication signals across all major odontocete clades, and thus provides a physiological basis for classifying their vocal repertoires. The vocal fry register is used by species from porpoises to sperm whales for generating powerful, highly air-efficient echolocation clicks.</jats:p>

<jats:p>Plant pathogens cause recurrent epidemics, threatening crop yield and global food security. Efforts to retool the plant immune system have been limited to modifying natural components and can be nullified by the emergence of new pathogen strains. Made-to-order synthetic plant immune receptors provide an opportunity to tailor resistance to pathogen genotypes present in the field. In this work, we show that plant nucleotide-binding, leucine-rich repeat immune receptors (NLRs) can be used as scaffolds for nanobody (single-domain antibody fragment) fusions that bind fluorescent proteins (FPs). These fusions trigger immune responses in the presence of the corresponding FP and confer resistance against plant viruses expressing FPs. Because nanobodies can be raised against most molecules, immune receptor–nanobody fusions have the potential to generate resistance against plant pathogens and pests delivering effectors inside host cells.</jats:p>

<jats:p>In addition to the conserved RNA polymerases (Pols) I-III in eukaryotes, two atypical polymerases, Pols IV and V, specifically produce non-coding RNA in the RNA-directed DNA methylation (RdDM) pathway in plants. Here, we report on the structures of cauliflower Pol V in the free and elongation conformations. A conserved tyrosine residue of NRPE2 stacks with a dsDNA branch of the transcription bubble to potentially attenuate elongation by inducing transcription stalling. The non-template DNA strand is captured by NRPE2 to enhance backtracking, thereby increasing 3′-5′ cleavage which likely underpins Pol V’s high fidelity. The structures also illuminate the mechanism of Pol V transcription stalling and enhanced backtracking which may be important for Pol V’s retention on chromatin to serve its function in tethering downstream factors for RdDM.</jats:p>

<jats:p> Brains contain networks of interconnected neurons and so knowing the network architecture is essential for understanding brain function. We therefore mapped the synaptic-resolution connectome of an entire insect brain ( <jats:italic>Drosophila</jats:italic> larva) with rich behavior, including learning, value computation, and action selection, comprising 3016 neurons and 548,000 synapses. We characterized neuron types, hubs, feedforward and feedback pathways, as well as cross-hemisphere and brain-nerve cord interactions. We found pervasive multisensory and interhemispheric integration, highly recurrent architecture, abundant feedback from descending neurons, and multiple novel circuit motifs. The brain’s most recurrent circuits comprised the input and output neurons of the learning center. Some structural features, including multilayer shortcuts and nested recurrent loops, resembled state-of-the-art deep learning architectures. The identified brain architecture provides a basis for future experimental and theoretical studies of neural circuits. </jats:p>

<jats:p> Autoimmune diseases such as ankylosing spondylitis (AS) can be driven by emerging neoantigens that disrupt immune tolerance. Here, we developed a workflow to profile posttranslational modifications involved in neoantigen formation. Using mass spectrometry, we identified a panel of cysteine residues differentially modified by carboxyethylation that required 3-hydroxypropionic acid to generate neoantigens in patients with AS. The lysosomal degradation of integrin αIIb [ITGA2B (CD41)] carboxyethylated at Cys96 (ITGA2B-ceC96) generated carboxyethylated peptides that were presented by HLA-DRB1*04 to stimulate CD4 <jats:sup>+</jats:sup> T cell responses and induce autoantibody production. Immunization of HLA-DR4 transgenic mice with the ITGA2B-ceC96 peptide promoted colitis and vertebral bone erosion. Thus, metabolite-induced cysteine carboxyethylation can give rise to pathogenic neoantigens that lead to autoreactive CD4 <jats:sup>+</jats:sup> T cell responses and autoantibody production in autoimmune diseases. </jats:p>

<jats:p>America’s science, technology, and innovation ecosystem is a powerful engine for progress, but it was conceived in the last century for last century’s goals. Today, the nation’s aspirations have never been bigger: robust health and ample opportunity for everyone, tackling the climate crisis and using it to reimagine infrastructure and humanity’s relationship with nature, global security and stability, a competitive economy that creates good-paying jobs, and a strong, thriving democracy. The purpose of science and technology is to open the doors that make these aspirations possible. As President Biden said, “We can channel the full talents of all our people into a greater measure of hope and opportunity for our nation and for the world.”</jats:p>