Catálogo de publicaciones - revistas

<jats:title>Turning down tolerance</jats:title> <jats:p> Persister cells, which are found in abundance in biofilms, adopt a quiescent state and survive antimicrobial treatments, seeding disease recurrence and incubating new resistance mutations. Building on work implicating the reactive small-molecule hydrogen sulfide in bacterial defense against antibiotics, Shatalin <jats:italic>et al.</jats:italic> conducted a structure-based screen for inhibitors of a bacterial hydrogen sulfide–producing enzyme and found a group of inhibitors that act through an allosteric mechanism (see the Perspective by Mah). These inhibitors potentiated bactericidal antibiotics in vitro and in mouse infection models. They also suppressed persister bacteria and disrupted biofilm formation. This strategy of taking out persister cells may be promising for treating recalcitrant infections and holding the line against drug-resistant bacteria. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , abd8377, this issue p. <jats:related-article issue="6547" page="1169" related-article-type="in-this-issue" vol="372">1169</jats:related-article> ; see also abj3062, p. <jats:related-article issue="6547" page="1153" related-article-type="in-this-issue" vol="372">1153</jats:related-article> </jats:p>

<jats:title>Cell size set by cell cycle regulation</jats:title> <jats:p> In the <jats:italic>Arabidopsis</jats:italic> meristem, cell sizes are regularized despite asymmetric cell divisions. D'Ario <jats:italic>et al.</jats:italic> describe a balanced regulatory system that controls the duration of the growth phase of the cell cycle preceding DNA synthesis. KIP-related protein 4 (KRP4) inhibits progression to DNA synthesis. Because the amount of KRP4, which binds to mitotic chromosomes, is titrated to the amount of chromosomal DNA, daughter cells begin with similar amounts of KRP4 despite possible asymmetric cell divisions. Deviations are adjusted as excess KRP4 is degraded and the cell size is normalized. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , abb4348, this issue p. <jats:related-article issue="6547" page="1176" related-article-type="in-this-issue" vol="372">1176</jats:related-article> </jats:p>

<jats:title>Imaging polariton dynamics</jats:title> <jats:p> Two-dimensional (2D) materials can confine light to volumes much shorter than the wavelength, and, together, the long propagation lengths make them attractive materials for developing nanophotonic platforms. Characterizing the spatiotemporal control of 2D polariton wave packets has been hindered for the same reasons that make their potential applications exciting: They have extremely small wavelengths and are strongly confined inside the material. Kurman <jats:italic>et al.</jats:italic> developed a new pump-probe technique based on electron emission that provides access to the spatiotemporal dynamics of 2D polaritons. The nanometric spatial resolution and femtosecond temporal resolution will be useful for probing the excitation dynamics of these materials. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , abg9015, this issue p. <jats:related-article issue="6547" page="1181" related-article-type="in-this-issue" vol="372">1181</jats:related-article> </jats:p>

<jats:title>Shuttling protons in ammonia synthesis</jats:title> <jats:p> An electrochemical route to ammonia could substantially lower the greenhouse gas emissions associated with the current thermal Haber-Bosch process. One relatively promising option under study involves reductive formation of lithium nitride, which can be protonated to ammonia. However, the ethanol used to date as a local proton source in these studies may degrade under the reaction conditions. Suryanto <jats:italic>et al.</jats:italic> report the use of a tetraalkyl phosphonium salt in place of ethanol (see the Perspective by Westhead <jats:italic>et al.</jats:italic> ). This cation can stably undergo deprotonation–reprotonation cycles and, as an added benefit, it enhances the ionic conductivity of the medium. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , abg2371, this issue p. <jats:related-article issue="6547" page="1187" related-article-type="in-this-issue" vol="372">1187</jats:related-article> ; see also abi8329, p. <jats:related-article issue="6547" page="1149" related-article-type="in-this-issue" vol="372">1149</jats:related-article> </jats:p>

<jats:title>Prethermal time crystal</jats:title> <jats:p> Characterizing and understanding different phases of matter in equilibrium is usually associated with the process of thermalization, where the system equilibrates. Recent efforts probing nonequilibrium systems have revealed that periodic driving of the system can suppress the natural tendency for equilibration yet still form new, nonequilibrium phases. Kyprianidis <jats:italic>et al.</jats:italic> used a quantum simulator composed of 25 trapped ion qubits and spins to observe such a nonequilibrium phase of matter: the disorder-free prethermal discrete time crystal. The flexibility and tunability of their quantum simulator provide a powerful platform with which to study the exotic phases of matter. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , abg8102, this issue p. <jats:related-article issue="6547" page="1192" related-article-type="in-this-issue" vol="372">1192</jats:related-article> </jats:p>

<jats:title>Bonding to a quantum corral</jats:title> <jats:p> Chemical bonds generally form between electronic states of atoms; in principle, other electronic states could also form bonds. Stilp <jats:italic>et al.</jats:italic> found that the electronic states created within quantum corrals, large rings of iron atoms on a copper surface, can form chemical bonds with metal atoms on an atomic force microscope tip. The corral states form from many electrons but have a large spatial extent compared with an atomic orbital. The covalent bond to a 48-atom corral state had an energy of just 5 millielectron volts. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , abe2600, this issue p. <jats:related-article issue="6547" page="1196" related-article-type="in-this-issue" vol="372">1196</jats:related-article> </jats:p>

<jats:title>Spiral features in the early Universe</jats:title> <jats:p>The early assembly of galaxies is thought to have produced disturbed and asymmetric objects. Morphological features seen in nearby galaxies, such as stellar disks, bulges, and spiral arms, require time to form and would be disturbed by the frequent galaxy mergers that occurred at early times. Tsukui and Iguchi identified a distant galaxy containing a disk of gas with a spiral morphology. The galaxy also has a compact central mass concentration due to a combination of a supermassive black hole and a possible stellar bulge. These features must have formed within 1.4 billion years after the Big Bang.</jats:p> <jats:p> <jats:italic>Science</jats:italic> , abe9680, this issue p. <jats:related-article issue="6547" page="1201" related-article-type="in-this-issue" vol="372">1201</jats:related-article> </jats:p>

<jats:title>Gliogenesis in the adult mouse brain</jats:title> <jats:p> Neural stem cells in the adult mouse brain can generate both neurons and glia. Exactly where each stem cell is positioned can determine what type of neurons it generates. Delgado <jats:italic>et al.</jats:italic> show that neural stem cells are also choosy about what sorts of glia they make and when (see the Perspective by Baldwin and Silver). Injury or selective deletion of platelet-derived growth factor receptor β (PDGFRβ) from the stem cells kicked them into overdrive and revealed their selectivity with respect to gliogenesis. An unusual type of glial progenitor cell, intraventricular oligodendrocyte progenitors, are found nestled between the cilia of ependymal cells derived from tight clusters of PDGFRβ-expressing stem cells. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , abg8467, this issue p. <jats:related-article issue="6547" page="1205" related-article-type="in-this-issue" vol="372">1205</jats:related-article> ; see also abj1139, p. <jats:related-article issue="6547" page="1151" related-article-type="in-this-issue" vol="372">1151</jats:related-article> </jats:p>