Catálogo de publicaciones - revistas

<jats:title>Origins of collective contraction</jats:title> <jats:p> In contrast to plants and fungi, animals can deform their bodies by the collective activity of contractile cells. Collective contractility underlies processes such as gastrulation and muscle-based motility. Brunet <jats:italic>et al.</jats:italic> report that a close relative of animals, a choanoflagellate they name <jats:italic>Choanoeca flexa</jats:italic> , forms cup-shaped colonies that undergo collective contractility, leading to a rapid change in colony morphology (see the Perspective by Tomancak). <jats:italic>C. flexa</jats:italic> colonies are each composed of a monolayer of polarized cells. In response to sudden darkness, a light-sensing protein triggers coordinated, polarized contraction of <jats:italic>C. flexa</jats:italic> cells, which results in colony inversion. The cellular mechanisms underlying this process are conserved between <jats:italic>C. flexa</jats:italic> and animals, indicating that their last common ancestor was also capable of polarized cell contraction. </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="6463" page="326" related-article-type="in-this-issue" vol="366" xlink:href="10.1126/science.aay2346">326</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6463" page="300" related-article-type="in-this-issue" vol="366" xlink:href="10.1126/science.aaz1289">300</jats:related-article> </jats:p>

<jats:title>Inspecting S states in photosynthesis</jats:title> <jats:p> Oxygenic photosynthesis uses a Mn <jats:sub>4</jats:sub> CaO <jats:sub>5</jats:sub> cluster in the oxygen-evolving complex to extract electrons from water and produce dioxygen. Visualizing each of the chemical states in this process, S <jats:sub>0</jats:sub> to S <jats:sub>4</jats:sub> , and assigning chemical identities and mechanisms on the basis of structures has been a challenge addressed recently by work at x-ray free-electron lasers. Suga <jats:italic>et al.</jats:italic> used serial crystallography at cryogenic temperatures to trap and determine the structures of several stable states during photosystem II water oxidation (see the Perspective by Britt and Marchiori). Changes around the water cluster already happen in the S <jats:sub>2</jats:sub> state and set the stage for water insertion that occurs during transition to the S <jats:sub>3</jats:sub> state. A short 1.9-angstrom distance between the two oxygen atoms in the S <jats:sub>3</jats:sub> state is consistent with theoretical studies supporting an oxyl/oxo mechanism for oxygen-oxygen coupling. </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="6463" page="334" related-article-type="in-this-issue" vol="366" xlink:href="10.1126/science.aax6998">334</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6463" page="305" related-article-type="in-this-issue" vol="366" xlink:href="10.1126/science.aaz4522">305</jats:related-article> </jats:p>

<jats:title>Spatial structure of species change</jats:title> <jats:p> Biodiversity is undergoing rapid change driven by climate change and other human influences. Blowes <jats:italic>et al.</jats:italic> analyze the global patterns in temporal change in biodiversity using a large quantity of time-series data from different regions (see the Perspective by Eriksson and Hillebrand). Their findings reveal clear spatial patterns in richness and composition change, where marine taxa exhibit the highest rates of change. The marine tropics, in particular, emerge as hotspots of species richness losses. Given that human activities are affecting biodiversity in magnitudes and directions that differ across the planet, these findings will provide a much needed biogeographic understanding of biodiversity change that can help inform conservation prioritization. </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="6463" page="339" related-article-type="in-this-issue" vol="366" xlink:href="10.1126/science.aaw1620">339</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6463" page="308" related-article-type="in-this-issue" vol="366" xlink:href="10.1126/science.aaz4520">308</jats:related-article> </jats:p>

<jats:title>Many ruptures across many scales</jats:title> <jats:p> The period of seismic quiescence in Southern California was rudely interrupted by the Ridgecrest earthquake sequence in July 2019. Ross <jats:italic>et al.</jats:italic> mapped the slip sequences during the magnitude 6.4 and 7.1 earthquakes that shook the region. They found that ruptures of a few larger, but many smaller, faults occurred during both earthquakes. The Ridgecrest sequence calls for rethinking seismic hazard, as multifault ruptures are not usually considered when assessing seismic risk. </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="6463" page="346" related-article-type="in-this-issue" vol="366" xlink:href="10.1126/science.aaz0109">346</jats:related-article> </jats:p>

<jats:title>A statistical model to find disease genes</jats:title> <jats:p> Genetic variation is high among individuals, which makes it difficult to identify any one specific pathogenetic variant in patients with idiopathic disease, especially those that are in noncoding regions of the genome. Examining tissue-specific and population-level RNA sequencing data, Mohammadi <jats:italic>et al.</jats:italic> developed a statistical test, analysis of expression variation (ANEVA), that can quantify how one individual's gene expression fits in the context of the variation within the general population. By applying ANEVA to a dosage outlier test, the authors identified pathogenic gene transcripts in patients with Mendelian muscle dystrophy. </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="6463" page="351" related-article-type="in-this-issue" vol="366" xlink:href="10.1126/science.aay0256">351</jats:related-article> </jats:p>

<jats:title>Peering inside extrasolar rocky bodies</jats:title> <jats:p> The oxygen fugacity of a rock, f <jats:sub> O <jats:sub>2</jats:sub> </jats:sub> , is a measure of how oxidizing or reducing its surroundings were when the rock formed. Different minerals form at different f <jats:sub> O <jats:sub>2</jats:sub> </jats:sub> and have different physical properties, so the internal structure of an exoplanet depends on this value. Doyle <jats:italic>et al.</jats:italic> exploited the signature left behind when rocky bodies impact a white dwarf—the remnant of a dead star. By examining the rock-forming elements left on the surface of each white dwarf, they determine f <jats:sub> O <jats:sub>2</jats:sub> </jats:sub> in the impacting body. Six systems all had similar f <jats:sub> O <jats:sub>2</jats:sub> </jats:sub> to bodies in the Solar System, consistent with the idea that rocky exoplanets often have internal properties similar to those of Earth and Mars. </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="6463" page="356" related-article-type="in-this-issue" vol="366" xlink:href="10.1126/science.aax3901">356</jats:related-article> </jats:p>

<jats:title>Large-scale, continuous 3D printing</jats:title> <jats:p> Many three-dimensional (3D) printing methods build up structures layer by layer, which causes a lamination layer between each discrete step. Continuous printing can be done from a fluid bed if a so-called dead layer is used to buffer between the solidified structure and pool of resin. However, printing speeds are limited by the heat buildup from the exothermic polymerization process, thus limiting the ultimate size of the printed object. Walker <jats:italic>et al.</jats:italic> use a pumped, nonreactive fluorinated oil to act as the dead layer that removes heat during polymerization. This approach allows for both speedup and scale-up of the printing process. </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="6463" page="360" related-article-type="in-this-issue" vol="366" xlink:href="10.1126/science.aax1562">360</jats:related-article> </jats:p>

<jats:title>Charging through the looking glass</jats:title> <jats:p> Asymmetric catalysis is a commonly applied technique to prepare just one of two mirror-image products in a chemical reaction. But what if you already have the compound you want, stuck in a mixture of left- and right-handed enantiomers? Shin <jats:italic>et al.</jats:italic> now show that light-induced electron transfer can trigger a favorable succession of proton and hydrogen-atom transfer steps, both of which are susceptible to biasing by catalysts, to preferentially convert a mixture of cyclic urea enantiomers into just one (see the Perspective by Wendlandt). </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="6463" page="364" related-article-type="in-this-issue" vol="366" xlink:href="10.1126/science.aay2204">364</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6463" page="304" related-article-type="in-this-issue" vol="366" xlink:href="10.1126/science.aay6919">304</jats:related-article> </jats:p>

<jats:title>Generating large-scale cluster states</jats:title> <jats:p> The development of a practical quantum computer requires universality, scalability, and fault tolerance. Although much progress is being made in circuit platforms in which arrays of qubits are addressed and manipulated individually, scale-up of such systems is experimentally challenging. Asavanant <jats:italic>et al.</jats:italic> and Larsen <jats:italic>et al.</jats:italic> explore an alternative route: measurement-based quantum computation, which is a platform based on the generation of large-scale cluster states. As these are optically prepared and easier to handle (one simply performs local measurements on each individual component of the cluster state), such a platform is readily scalable and fault tolerant. The topology of the cluster state ensures that the approach meets the requirements for quantum computation. </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="6463" page="373" related-article-type="in-this-issue" vol="366" xlink:href="10.1126/science.aay2645">373</jats:related-article> , p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6463" page="369" related-article-type="in-this-issue" vol="366" xlink:href="10.1126/science.aay4354">369</jats:related-article> </jats:p>

<jats:title>Generating large-scale cluster states</jats:title> <jats:p> The development of a practical quantum computer requires universality, scalability, and fault tolerance. Although much progress is being made in circuit platforms in which arrays of qubits are addressed and manipulated individually, scale-up of such systems is experimentally challenging. Asavanant <jats:italic>et al.</jats:italic> and Larsen <jats:italic>et al.</jats:italic> explore an alternative route: measurement-based quantum computation, which is a platform based on the generation of large-scale cluster states. As these are optically prepared and easier to handle (one simply performs local measurements on each individual component of the cluster state), such a platform is readily scalable and fault tolerant. The topology of the cluster state ensures that the approach meets the requirements for quantum computation. </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="6463" page="373" related-article-type="in-this-issue" vol="366" xlink:href="10.1126/science.aay2645">373</jats:related-article> , p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6463" page="369" related-article-type="in-this-issue" vol="366" xlink:href="10.1126/science.aay4354">369</jats:related-article> </jats:p>