Catálogo de publicaciones - revistas

<jats:title>Knowing the Enemy</jats:title> <jats:p> Infection of host cells by HIV-1 is mediated by an envelope glycoprotein (Env) trimeric spike on the surface of the virus. Proteins comprising the Env trimer must be cleaved for infectivity, and thus viral fusion involves three Env conformations. The flexibility of the Env trimer has made it a challenge to determine a high-resolution structure, although such a structure is key both for understanding trimer function and for guiding vaccine design. <jats:bold> Lyumkis <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6165" page="1484" related-article-type="in-this-issue" vol="342" xlink:href="10.1126/science.1245627">1484</jats:related-article> ) and <jats:bold> Julien <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6165" page="1477" related-article-type="in-this-issue" vol="342" xlink:href="10.1126/science.1245625">1477</jats:related-article> ) studied soluble cleaved trimers stabilized by specific mutations but that have kept a near-native antigenicity profile. Lyumkis <jats:italic>et al.</jats:italic> present a high-resolution structure of the trimer in complex with a broadly neutralizing antibody, and Julien <jats:italic>et al.</jats:italic> present a crystal structure of the trimer in complex with another broadly neutralizing antibody. </jats:p>

<jats:title>Knowing the Enemy</jats:title> <jats:p> Infection of host cells by HIV-1 is mediated by an envelope glycoprotein (Env) trimeric spike on the surface of the virus. Proteins comprising the Env trimer must be cleaved for infectivity, and thus viral fusion involves three Env conformations. The flexibility of the Env trimer has made it a challenge to determine a high-resolution structure, although such a structure is key both for understanding trimer function and for guiding vaccine design. <jats:bold> Lyumkis <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6165" page="1484" related-article-type="in-this-issue" vol="342" xlink:href="10.1126/science.1245627">1484</jats:related-article> ) and <jats:bold> Julien <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6165" page="1477" related-article-type="in-this-issue" vol="342" xlink:href="10.1126/science.1245625">1477</jats:related-article> ) studied soluble cleaved trimers stabilized by specific mutations but that have kept a near-native antigenicity profile. Lyumkis <jats:italic>et al.</jats:italic> present a high-resolution structure of the trimer in complex with a broadly neutralizing antibody, and Julien <jats:italic>et al.</jats:italic> present a crystal structure of the trimer in complex with another broadly neutralizing antibody. </jats:p>

<jats:title>Spin Berry's Phase</jats:title> <jats:p> When a quantum mechanical system performs an adiabatic cyclic path in the space of the parameters that affect its state (such as, for example, the magnetic field) its wave function may acquire an additional phase rather than go back to its original value. This quantity, called the Berry's phase, is associated with the topological properties of the parameter space and has been observed in materials such as graphene and bismuth. <jats:bold> Murakawa <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6165" page="1490" related-article-type="in-this-issue" vol="342" xlink:href="10.1126/science.1242247">1490</jats:related-article> ) observe a Berry's phase equal to π in the material BiTeI in which the phenomenon is predicted to be a consequence of a very strong coupling of spin and orbital degrees of freedom realized through the so-called Rashba effect. </jats:p>

<jats:title>Artificial Complexity</jats:title> <jats:p> Quantum optics probes the interactions between light and matter. Building up from a simple, single-atom system, the exchange of virtual photons between systems of several (or many) atoms is expected to give rise to many exotic effects. Because controlling the separation of the atoms on the atomic scale is experimentally challenging, artificial atom systems may provide a more tractable route for systematic study, as described by <jats:bold> van Loo <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6165" page="1494" related-article-type="in-this-issue" vol="342" xlink:href="10.1126/science.1244324">1494</jats:related-article> , published online 14 November). Using a system of two separate superconducting qubits in a microwave transmission line, they show how the interaction between the two qubits can be controlled and mediated by electromagnetic modes. The results illustrate a feasible route to probing the complexity of many-body effects that may otherwise be difficult to realize. </jats:p>

<jats:title>Relaxing in a Water Jet</jats:title> <jats:p> High-energy irradiation of liquid water and its solutes can transiently liberate electrons, which act as potent chemical reductants, but they are challenging to characterize precisely. Seeking to bridge the gap between liquid and gas, <jats:bold> Elkins <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6165" page="1496" related-article-type="in-this-issue" vol="342" xlink:href="10.1126/science.1246291">1496</jats:related-article> ) report results from photoelectron spectroscopy of hydrated electron dynamics in a liquid jet. The results reveal a very rapid transition from the electronic excited state to the ground state, prior to full relaxation of the solvent shell. </jats:p>

<jats:title>Access via Vibration</jats:title> <jats:p> Molecular beam studies over the past decade have elucidated many subtle quantum mechanical factors governing the influence of vibrational excitation on the outcome of elementary chemical reactions. However, these studies have generally had to focus on reagents that can be easily made to vibrate by direct absorption in the infrared (IR). <jats:bold>Wang et al.</jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6165" page="1499" related-article-type="in-this-issue" vol="342" xlink:href="10.1126/science.1246546">1499</jats:related-article> ) show that a variation on stimulated Raman pumping can efficiently excite the IR-inactive stretch vibration in the diatomic molecule, hydrogen deuteride (HD). As a result, they can probe the influence of that vibration on the outcome of the HD + F reaction. Through a combined spectroscopic and theoretical investigation, they uncover Feshbach resonances along the reaction coordinate that are only accessible through vibrational preexcitation. </jats:p>

<jats:title>Salt to Squeeze</jats:title> <jats:p> Simple table salt, NaCl, is the only known stable phase of Na and Cl at ambient conditions. Previous attempts to understand its structure and chemical properties under pressure and at high temperatures revealed phase and bonding transitions, while keeping the balance of one Na to one Cl. Using crystal structure prediction algorithms, <jats:bold> Zhang <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6165" page="1502" related-article-type="in-this-issue" vol="342" xlink:href="10.1126/science.1244989">1502</jats:related-article> ; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6165" page="1459" related-article-type="in-this-issue" vol="342" xlink:href="10.1126/science.1247699">Ibáñez Insa</jats:related-article> </jats:bold> ) show that other compounds—including Na <jats:sub>3</jats:sub> Cl, Na <jats:sub>2</jats:sub> Cl, Na <jats:sub>3</jats:sub> Cl <jats:sub>2</jats:sub> , NaCl <jats:sub>3</jats:sub> , and NaCl <jats:sub>7</jats:sub> are as stable as NaCl across a range of pressures. </jats:p>

<jats:title>Power in Numbers</jats:title> <jats:p> Avian brood parasites target particular bird species to raise their offspring, sometimes at great cost to the foster family. <jats:bold> Feeney <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6165" page="1506" related-article-type="in-this-issue" vol="342" xlink:href="10.1126/science.1240039">1506</jats:related-article> ; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6165" page="1452" related-article-type="in-this-issue" vol="342" xlink:href="10.1126/science.1247758">Spottiswoode</jats:related-article> </jats:bold> ) analyzed the global distribution of brood parasitism and found a correlation with the occurrence of cooperative breeders across multiple taxa. For example, Australian fairy wrens breed both singly and in cooperative groups, but the group breeders are better able to resist parasites than lone pairs, indicating that the prevalence of cooperative breeding may be a response to brood parasites. </jats:p>

<jats:title>Not All Mice Are Equal</jats:title> <jats:p> Different laboratories often use different strains of inbred animals, but one cannot make behavioral comparisons and assume that their reaction to interventions will necessarily be similar. <jats:bold> Kumar <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6165" page="1508" related-article-type="in-this-issue" vol="342" xlink:href="10.1126/science.1245503">1508</jats:related-article> ) have detected differences in cocaine response between the widely used C57BL/6N and C57BL/6J mouse strains and used quantitative trait locus analysis to identify a mutation in an inducible gene, <jats:italic>Cyfip</jats:italic> , that interacts with the Fragile X protein (FMRP) to regulate sensitivity and sensitization to cocaine through regulation of neuronal connectivity. </jats:p>

<jats:title>An Enzyme Drill</jats:title> <jats:p> Cellulase enzymes degrade the cell walls of plants by breaking down cellulose into its constituent sugar fragments and thus have attracted interest for biofuels production. Using transmission electron microscopy <jats:bold> Brunecky <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6165" page="1513" related-article-type="in-this-issue" vol="342" xlink:href="10.1126/science.1244273">1513</jats:related-article> ; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6165" page="1454" related-article-type="in-this-issue" vol="342" xlink:href="10.1126/science.1247697">Berlin</jats:related-article> </jats:bold> ) discovered that an especially active cellulase, CelA, from <jats:italic>Caldicellulosiruptor bescii</jats:italic> bacteria does not move along the surface of the substrate, but drills into the cellulose to form cavities. </jats:p>