Catálogo de publicaciones - revistas

<jats:title>Activated by interaction</jats:title> <jats:p> Cytokines trigger immune responses when they bind to their cognate receptors. Class I cytokine receptors rely on the associated Janus kinase 2 (JAK2) to initiate signal transduction. There has been debate over whether activation involves ligand-induced dimerization of these receptors or ligand-induced conformational change of preformed dimers. Wilmes <jats:italic>et al.</jats:italic> imaged cytokine receptors in the plasma membranes of live human cells by single-molecule fluorescence microscopy and observed ligand-induced dimerization. They found that the JAK2 pseudokinase domains contribute to dimerization and that hyperactive JAK2 mutants promote dimerization, consistent with the model that dimerization triggers activation. </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="6478" page="643" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aaw3242">643</jats:related-article> </jats:p>

<jats:title>Liver disease defect identified</jats:title> <jats:p> The energy sensor adenosine monophosphate–activated protein kinase (AMPK) is implicated in liver damage in nonalcoholic steatohepatitis (NASH), a leading cause of liver-associated death in humans. Zhao <jats:italic>et al.</jats:italic> used mouse models of NASH and samples from human NASH patients to show that AMPK, the activity of which is lost in NASH, phosphorylates the enzyme procaspase-6. In normal liver cells, this modification limits the activation of caspase-6 and the consequent caspase activation cascade that leads to apoptosis. AMPK and caspase-6 may thus provide therapeutic targets for the treatment of NASH. </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="6478" page="652" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aay0542">652</jats:related-article> </jats:p>

<jats:title> Graceful choreography for CO <jats:sub>2</jats:sub> and H <jats:sub>2</jats:sub> O </jats:title> <jats:p> One challenge for efficient electrochemical reduction of carbon dioxide (CO <jats:sub>2</jats:sub> ) is that the gas is hydrophobic, but many of its desirable reactions require water (H <jats:sub>2</jats:sub> O). García de Arquer <jats:italic>et al.</jats:italic> addressed this problem by combining a copper electrocatalyst with an ionomer assembly that intersperses sulfonate-lined paths for the H <jats:sub>2</jats:sub> O with fluorocarbon channels for the CO <jats:sub>2</jats:sub> . The electrode architecture enables production of two-carbon products such as ethylene and ethanol at current densities just over an ampere per square centimeter. </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="6478" page="661" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aay4217">661</jats:related-article> </jats:p>

<jats:title>Water-selective zeolite membranes</jats:title> <jats:p> The yield of many gas-phase industrial reactions is limited by the formation of water as a by-product. Li <jats:italic>et al.</jats:italic> harnessed the water-sieving properties of NaA zeolite crystals by forming them into continuous defect-free membranes within tube reactors (see the Perspective by Carreon). These membranes can let water pass but reject gases such as hydrogen, carbon monoxide, and carbon dioxide (CO <jats:sub>2</jats:sub> ). When these membranes were used in CO <jats:sub>2</jats:sub> hydrogenation to form methanol with water as a by-product, substantial increases were observed in both the CO <jats:sub>2</jats:sub> conversion and methanol yield. </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="6478" page="667" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aaz6053">667</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6478" page="624" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aba4997">624</jats:related-article> </jats:p>

<jats:title>Major-league magnetostriction</jats:title> <jats:p> Magnetoelectric materials polarize in response to either electric or magnetic fields, making them attractive for data-storage applications. Long <jats:italic>et al.</jats:italic> discovered a ytterbium-based molecular magnetoelectric material with high magnetoelectric coupling (see the Perspective by Zhou and Han). An applied magnetic field strains the material, which changes its electrical properties. The required field is much lower than other magnetoelectric materials, and this work highlights the potential for using molecular materials in devices. </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="6478" page="671" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aaz2795">671</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6478" page="627" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aba6642">627</jats:related-article> </jats:p>

<jats:title>Synthesis of Taxol's complicated cousin</jats:title> <jats:p> Propellane molecules contain three rings that all share a common edge, thereby collectively resembling a propeller. Canataxpropellane, a yew-derived natural product related to the cancer drug Taxol, is unusual in that it has two different propellane motifs in its backbone. Schneider <jats:italic>et al.</jats:italic> report a chemical synthesis of this intricate compound in under 30 steps. Key features of the route include a Diels-Alder reaction rendered asymmetric by introduction of a chiral silyl auxiliary, followed by a photochemical cycloaddition to establish the cyclobutane core. </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="6478" page="676" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aay9173">676</jats:related-article> </jats:p>

<jats:title>Heat seeking is cool</jats:title> <jats:p> Mosquitoes seek hosts using several cues, one of which is body heat. Greppi <jats:italic>et al.</jats:italic> hypothesized that cooling-activated receptors could be used for locating mammalian hosts if they were rewired downstream for repulsion responses (see the Perspective by Lazzari). A gene family conserved in insects and known to be responsible for sensing changes in temperature in fruit flies was the starting point. Genome-wide analyses and labeled CRISPR-Cas9 mutants allowed visualization of the receptor in neurons of <jats:italic>Anopheles gambiae</jats:italic> mosquitoes' antennae and assessment of adult female mosquitoes with a disrupted copy of the receptor. This ancestral insect temperature regulatory system has been repurposed for host-finding by malaria mosquitoes. </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="6478" page="681" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aay9847">681</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6478" page="628" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aba4484">628</jats:related-article> </jats:p>

<jats:title>Increasing temperatures and declines</jats:title> <jats:p> One aspect of climate change is an increasing number of days with extreme heat. Soroye <jats:italic>et al.</jats:italic> analyzed a large dataset of bumble bee occurrences across North America and Europe and found that an increasing frequency of unusually hot days is increasing local extinction rates, reducing colonization and site occupancy, and decreasing species richness within a region, independent of land-use change or condition (see the Perspective by Bridle and van Rensburg). As average temperatures continue to rise, bumble bees may be faced with an untenable increase in frequency of extreme temperatures. </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="6478" page="685" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aax8591">685</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6478" page="626" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aba6432">626</jats:related-article> </jats:p>

<jats:title>Microglia modulate memories</jats:title> <jats:p> Synaptic reorganization and circuit rewiring leads to loss or weakening of connections between neurons and may result in the erasure of previously formed memories. Microglia eliminate excessive synapses in the developing brain and regulate the dynamics of synaptic connections between neurons throughout life. However, it is still unclear whether forgetting is related to microglia activity and how microglia regulate memory erasure in the adult brain. Wang <jats:italic>et al.</jats:italic> discovered that microglia eliminated synaptic components in the adult hippocampus and that depleting microglia or inhibiting phagocytosis of microglia prevented forgetting. Synapse elimination by microglia may thus lead to degradation of memory engrams and forgetting of previously learned contextual fear memory. </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="6478" page="688" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aaz2288">688</jats:related-article> </jats:p>

<jats:title>Not too sticky</jats:title> <jats:p> There is increasing evidence for a role of liquid-liquid phase separation (LLPS) in many cellular processes. Many proteins that undergo LLPS include prionlike domains (PLDs), which are enriched in polar amino acids and often interspersed with aromatic residues. Combining experimental data with simulations, Martin <jats:italic>et al.</jats:italic> quantified concentrations of PLDs in coexisting dilute and dense phases as a function of temperature and show that the phase behavior is determined by the number of aromatic residues and their patterning, with uniform patterning of aromatic residues promoting LLPS and inhibiting aggregation. They developed a sticker-and-spacers model that can predict the phase behavior of PLDs on the basis of their sequence. </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="6478" page="694" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aaw8653">694</jats:related-article> </jats:p>