Catálogo de publicaciones - revistas

<jats:title>Secrets of a fast base editor</jats:title> <jats:p> CRISPR-Cas9 base editors comprise RNA-guided Cas proteins fused to an enzyme that can deaminate a DNA nucleoside. No natural enzyme deaminates adenine in DNA, and so a breakthrough came when a natural transfer RNA deaminase was fused to Cas9 and evolved to give an adenine base editor (ABE) that works on DNA. Further evolution provided the enzyme ABE8e, which catalyzes deamination more than 1000 times faster than early ABEs. Lapinaite <jats:italic>et al.</jats:italic> now present a 3.2-angstrom resolution structure of ABE8e bound to DNA in which the target adenine is replaced with an analog designed to trap the catalytic conformation. The structure, together with kinetic data comparing ABE8e to earlier ABEs, explains how ABE8e edits DNA bases and could inform future base-editor design. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6503" page="566" related-article-type="in-this-issue" vol="369" xlink:href="10.1126/science.abb1390">566</jats:related-article> </jats:p>

<jats:title>Graphene nanoribbons made on oxides</jats:title> <jats:p> Atomically precise nanographenes and nanoribbons have been synthesized on metal surfaces that catalyze cyclode-hydrogenation of precursors. However, for use in devices, these structures usually must be transferred to insulating or semiconducting surfaces. Kolmer <jats:italic>et al.</jats:italic> synthesized precise graphene nanoribbons on the surface of rutile titanium dioxide (TiO <jats:sub>2</jats:sub> ) that assisted the cyclode-hydrofluorination of specifically designed precursor molecules through a series of thermally triggered transformations. Scanning tunneling microscopy and spectroscopy confirmed the formation of well-defined zigzag ends of the nanoribbons as well as their weak interaction with the substrate. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6503" page="571" related-article-type="in-this-issue" vol="369" xlink:href="10.1126/science.abb8880">571</jats:related-article> </jats:p>

<jats:title>Cleaner skies</jats:title> <jats:p> Particulate air pollution in the contiguous United States has decreased considerably over recent decades, but where exactly has that progress been made? Colmer <jats:italic>et al.</jats:italic> analyzed 36 years of data and found that the spatial distribution of fine particulate matter concentrations has remained largely unchanged over that interval (see the Perspective by Ma). Although, fine particulate pollution levels have dropped overall, those areas that were most and least polluted in 1981 remain so today. We may have made important strides in pollution control, but we have been less successful in addressing disparities of exposure between communities. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6503" page="575" related-article-type="in-this-issue" vol="369" xlink:href="10.1126/science.aaz9353">575</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6503" page="503" related-article-type="in-this-issue" vol="369" xlink:href="10.1126/science.abb0943">503</jats:related-article> </jats:p>

<jats:title>Origins of an alpine flora</jats:title> <jats:p> The evolution of high mountain floras is strongly influenced by tectonic and climatic history. Ding <jats:italic>et al.</jats:italic> document the timing, tempo, and mode by which the world's most species-rich alpine flora, that of the Tibet-Himalaya-Hengduan region, was assembled. Alpine assemblages in the region are older than previously thought, with lineages tracing their alpine ancestry to the early Oligocene—older than any other modern alpine system. Alpine species diversified faster during periods of orogeny and intensification of the Asian monsoon, and the Hengduan Mountains—the most species-rich area in this region—played a key biogeographic role as the location of the earliest pulse of alpine diversification in the Oligocene. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6503" page="578" related-article-type="in-this-issue" vol="369" xlink:href="10.1126/science.abb4484">578</jats:related-article> </jats:p>

<jats:title>Epidemic in Northern California</jats:title> <jats:p> Genome sequencing of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreaks is valuable for tracing the sources and perhaps for drawing lessons about preventing future outbreaks. Genomic analysis by Deng <jats:italic>et al.</jats:italic> revealed that Northern California experienced a complex series of introductions of the virus, deriving not only from state-to-state transmission but also from international travel by air and ship. The study highlights the importance of being able to rapidly test and trace contacts of positive cases to enable swift control. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6503" page="582" related-article-type="in-this-issue" vol="369" xlink:href="10.1126/science.abb9263">582</jats:related-article> </jats:p>

<jats:title>Predicting large solar flares</jats:title> <jats:p> The sudden release of magnetic energy on the Sun drives powerful solar flares, which are difficult to predict. Kusano <jats:italic>et al.</jats:italic> derived physics-based thresholds for the onset of large solar flares and show how they can be predicted from routine solar observations (see the Perspective by Veronig). They tested their method using observations of the Sun from 2008 to 2019. In most cases, the method correctly identifies which regions will produce large flares within the next 20 hours, although there are some false positives and false negatives. The method also provides the exact location where each flare will begin and limits on how powerful it will be. Accurate predictions of solar flares could improve forecasts of space weather conditions around Earth. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6503" page="587" related-article-type="in-this-issue" vol="369" xlink:href="10.1126/science.aaz2511">587</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6503" page="504" related-article-type="in-this-issue" vol="369" xlink:href="10.1126/science.abb6150">504</jats:related-article> </jats:p>

<jats:p>A weekly roundup of information on newly offered instrumentation, apparatus, and laboratory materials of potential interest to researchers.</jats:p>