Catálogo de publicaciones - revistas

<jats:title>Cellular response to nutrient status</jats:title> <jats:p> An intricate regulatory mechanism is taking shape around control of the mechanistic target of rapamycin complex 1 (mTORC1) protein kinase complex. Physiological responses of cells to nutrient abundance is regulated by signaling through mTORC1, which interacts with a complex of other proteins at the lysosome that includes small guanosine triphosphatases (GTPases), GTPase-activating proteins, and others. Lawrence <jats:italic>et al.</jats:italic> present a cryo–electron microscopy structure and biochemical experiments that reveal that the small GTPases act in unanticipated ways in the complex. The tumor suppressor folliculin (FLCN), along with FLCN-interacting protein 2, interacts with its partner GTPase RagC in both active and inactive states, suggesting that a particularly elaborate and stringent regulatory mechanism is at work. </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="6468" page="971" related-article-type="in-this-issue" vol="366" xlink:href="10.1126/science.aax0364">971</jats:related-article> </jats:p>

<jats:title>Terrestrial record of recovery</jats:title> <jats:p> The extinction that occurred at the end of the Cretaceous period is best known as the end of the nonavian dinosaurs. In theory, this paved the way for the expansion of mammals as well as other taxa, including plants. However, there are very few direct records of loss and recovery of biotic diversity across this event. Lyson <jats:italic>et al.</jats:italic> describe a new record from the Cretaceous-Paleogene in Colorado that includes unusually complete vertebrate and plant fossils that describe this event in detail, including the recovery and expansion of mammalian body size and increasing plant and animal biotic diversity within the first million years. </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="6468" page="977" related-article-type="in-this-issue" vol="366" xlink:href="10.1126/science.aay2268">977</jats:related-article> </jats:p>

<jats:title>Stacking control</jats:title> <jats:p> Recent searches for two-dimensional magnets have turned up a number of related van der Waals materials, such as chromium triiodide (CrI <jats:sub>3</jats:sub> ) and chromium tribromide (CrBr <jats:sub>3</jats:sub> ). Although their properties are expected to be similar, in bilayer form, the former is antiferromagnetic, whereas the latter appears to be a ferromagnet. Chen <jats:italic>et al.</jats:italic> used spin-polarized scanning tunneling microscopy to determine that the nature of the magnetic state in bilayer CrBr <jats:sub>3</jats:sub> depends on the type of stacking of its monolayers. An antiferromagnetic state formed when the two monolayers were oriented in the same direction, whereas the opposite orientation led to ferromagnetism. </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="6468" page="983" related-article-type="in-this-issue" vol="366" xlink:href="10.1126/science.aav1937">983</jats:related-article> </jats:p>

<jats:title>Looking for a strange metal</jats:title> <jats:p> In many materials, charge carriers are well described as noninteracting quasiparticles. However, in materials with strong correlations, this approximation can break down, leading to anomalous transport properties at high temperatures. Huang <jats:italic>et al.</jats:italic> used quantum Monte Carlo calculations to look for this so-called strange metal phase in the simplest two-dimensional model of interacting electrons, the Hubbard model. They found that the calculated resistivity had a linear temperature dependence when hole doping was introduced, as expected in the strange metal phase. This observation provides confidence that simplified models can be used to describe and understand the behavior of real materials, such as cuprate high-temperature superconductors. </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="6468" page="987" related-article-type="in-this-issue" vol="366" xlink:href="10.1126/science.aau7063">987</jats:related-article> </jats:p>

<jats:title>A tag team approach to forming C–N bonds</jats:title> <jats:p> Many pharmaceutical compounds contain carbon-nitrogen (C–N) bonds in just one of two mirror-image orientations. Forging these bonds with electron-rich nitrogen reactants is challenging because the nitrogen groups can coordinate with, and thus interfere with, the catalyst. Li <jats:italic>et al.</jats:italic> report a cooperative approach to overcoming this obstacle (see the Perspective by Ovian and Jacobsen). They used a copper catalyst to activate the carbon reactant and then a hydrogen-bonding thiourea catalyst to set the product geometry with high selectivity. The reaction is compatible with a broad range of diazo ester and amine coupling partners. </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="6468" page="990" related-article-type="in-this-issue" vol="366" xlink:href="10.1126/science.aaw9939">990</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6468" page="948" related-article-type="in-this-issue" vol="366" xlink:href="10.1126/science.aaz6166">948</jats:related-article> </jats:p>

<jats:title> Magnesium for <jats:italic>Salmonella</jats:italic> growth </jats:title> <jats:p> In mammals, macrophages are a first line of defense against pathogenic bacteria like <jats:italic>Salmonella.</jats:italic> These immune cells possess a metal-ion transporter called SLC11A1 or NRAMP1, which is known to be involved in infection resistance. Cunrath and Bumann studied mice that only differ in one allele of the <jats:italic>SLC11A1</jats:italic> gene, which leaves mice either susceptible or resistant to infection. Proteomic analyses showed that bacteria isolated from mice with functional <jats:italic>SLC11A1</jats:italic> alleles experienced metal starvation, particularly of magnesium. The resulting impairment of bacterial growth seems to be the primary mode of action of SLC11A1 against invading pathogens. </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="6468" page="995" related-article-type="in-this-issue" vol="366" xlink:href="10.1126/science.aax7898">995</jats:related-article> </jats:p>

<jats:title>Making well-behaved algorithms</jats:title> <jats:p> Machine learning algorithms are being used in an ever-increasing number of applications, and many of these applications affect quality of life. Yet such algorithms often exhibit undesirable behavior, from various types of bias to causing financial loss or delaying medical diagnoses. In standard machine learning approaches, the burden of avoiding this harmful behavior is placed on the user of the algorithm, who most often is not a computer scientist. Thomas <jats:italic>et al.</jats:italic> introduce a general framework for algorithm design in which this burden is shifted from the user to the designer of the algorithm. The researchers illustrate the benefits of their approach using examples in gender fairness and diabetes management. </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="6468" page="999" related-article-type="in-this-issue" vol="366" xlink:href="10.1126/science.aag3311">999</jats:related-article> </jats:p>

<jats:title>Where do horns come from?</jats:title> <jats:p> One of the most pronounced examples of a sexually selected trait is the prothoracic horns of scarab beetles, which, in the most extreme cases, can be nearly half as long as the length of the beetle. It is fairly easy to understand how selection might have shaped these horns, but understanding how development shaped them from a hornless ancestor is a much more complex proposition. Hu <jats:italic>et al.</jats:italic> show that these horns are generated from wing homologs and argue that many other insect traits may have followed similar transcriptional paths (see the Perspective by Nijhout). </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="6468" page="1004" related-article-type="in-this-issue" vol="366" xlink:href="10.1126/science.aaw2980">1004</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6468" page="946" related-article-type="in-this-issue" vol="366" xlink:href="10.1126/science.aaz9010">946</jats:related-article> </jats:p>

<jats:title>A brain circuit to control alcohol intake</jats:title> <jats:p> Most people are exposed to alcohol at some point in their lives, but only a small fraction will develop a compulsive drinking disorder. Siciliano <jats:italic>et al.</jats:italic> first established a behavioral measure to assess how predisposition interacts with experience to produce compulsive drinking in a subset of mice (see the Perspective by Nixon and Mangieri). In search of the underlying neurobiological mechanism, they discovered that a discrete circuit between the medial prefrontal cortex and brainstem is central for the development of compulsive drinking. This circuit serves as both a biomarker for the development of compulsive drinking and a driver of its expression. It can bidirectionally control compulsive behavior by mitigating or mimicking punishment signals. </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="6468" page="1008" related-article-type="in-this-issue" vol="366" xlink:href="10.1126/science.aay1186">1008</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6468" page="947" related-article-type="in-this-issue" vol="366" xlink:href="10.1126/science.aaz7357">947</jats:related-article> </jats:p>