Catálogo de publicaciones - revistas

<jats:title>Microglia take control</jats:title> <jats:p> Changes in the activity of microglia, the primary immune cells of the central nervous system, are linked with major human diseases, including stroke, epilepsy, psychiatric disorders, and neurodegeneration. Cserép <jats:italic>et al.</jats:italic> identified a specialized morphofunctional communication site between microglial processes and neuronal cell bodies in the mouse and the human brain (see the Perspective by Nimmerjahn). These junctions are formed at specific areas of the neuronal somatic membranes and possess a distinctive nanoarchitecture and specialized molecular composition linked to mitochondrial signaling. The junctions appear to provide a major site for microglia-neuron communication and may help to mediate the neuroprotective effects of microglia after acute brain injury. </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="6477" page="528" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aax6752">528</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6477" page="510" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aba4472">510</jats:related-article> </jats:p>

<jats:title>Growing coaxial nanotubes</jats:title> <jats:p> Heterostructures of highly crystalline two-dimensional materials such as graphene, hexagonal boron nitride (hBN), and molybdenum disulfide (MoS <jats:sub>2</jats:sub> ) are now routinely assembled from films or grown as layers. Xiang <jats:italic>et al.</jats:italic> report the growth of one-dimensional analogs of these heterostructures on single-walled carbon nanotubes (SWCNTs) through a chemical vapor deposition (see the Perspective by Gogotsi and Yakobson). Single-crystalline monolayers or multilayers of hBN or MoS <jats:sub>2</jats:sub> were grown that maintained the electrical conductivity of the SWCNT. A monolayer of MoS <jats:sub>2</jats:sub> was grown on a trilayer of hBN that encapsulated a SWCNT. </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="6477" page="537" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aaz2570">537</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6477" page="506" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aba6133">506</jats:related-article> </jats:p>

<jats:title>Charging up cobalt for hydroformylation</jats:title> <jats:p> Hydroformylation reactions are applied at massive scale in the chemical industry to transform olefins into aldehydes. The original catalysts were neutral cobalt complexes. Hood <jats:italic>et al.</jats:italic> now report that positively charged cobalt complexes, stabilized by chelating phosphine ligands, show higher activities at lower pressures than their neutral counterparts, approaching the activities of precious rhodium catalysts. These charged catalysts are particularly adept at accelerating the reactions of internal olefins while avoiding decomposition. Spectroscopic studies implicate the involvement of 19-electron intermediates in the catalytic cycle. </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="6477" page="542" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aaw7742">542</jats:related-article> </jats:p>

<jats:title>A learning mechanism in the striatum</jats:title> <jats:p> An intriguing characteristic of the striatum is the random spatial distribution and high degree of intermingling between expression of dopamine receptor types 1 (D1) and 2 (D2) within striatal projection neurons (SPNs). The resulting highly entropic mosaic extends through a homogeneous space and is mostly devoid of histological boundaries. The rules established locally by D1- and D2-expressing SPNs (D1-SPNs and D2-SPNs) are thus likely critical in defining how functional territories develop throughout the striatum. Matamales <jats:italic>et al.</jats:italic> found that activated D2-SPNs access and modify developing behavioral programs encoded by regionally defined ensembles of transcriptionally active D1-SPNs. This process is slow because it depends on the molecular integration of additive neuro-modulatory signals. However, with time, it creates the regional functional boundaries that are necessary to identify and shape specific learning in the striatum. </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="6477" page="549" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aaz5751">549</jats:related-article> </jats:p>

<jats:title>A cool way to use isotopes</jats:title> <jats:p> Thermal management of electronics requires materials that can efficiently remove heat. Several promising materials have been found recently, but diamond remains the bulk material with the highest thermal conductivity. Chen <jats:italic>et al.</jats:italic> found that isotopically pure cubic boron nitride has an ultrahigh thermal conductivity, 75% that of diamond. Using only boron-11 or boron-10 allows the crystal vibrations that carry heat to move more efficiently through the material. This property could be exploited for better regulating the temperature of high-power 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="6477" page="555" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aaz6149">555</jats:related-article> </jats:p>

<jats:title>Convergent coupling</jats:title> <jats:p> Metal-catalyzed coupling of two flat aromatic rings is one of the most versatile and widely applied chemical reactions. Efforts to extend this protocol to alkyl-alkyl coupling are complicated by the prospect of forming two different three-dimensional configurations at each carbon center, corresponding to four possible products. Huo <jats:italic>et al.</jats:italic> now report that a chiral nickel catalyst can convergently link two mirror-image pairs of alkyl reactants into just one product (see the Perspective by Xu and Watson). The specific reaction couples propargylic halides to zinc-activated aliphatic amides. </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="6477" page="559" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aaz3855">559</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6477" page="509" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aba4222">509</jats:related-article> </jats:p>

<jats:title>Speedy crystallography</jats:title> <jats:p> Electron backscatter diffraction is one standard technique for determining crystal structure, typically of materials or geological samples. However, this method requires structural guesses and user input that are often time consuming or incorrect. Kaufmann <jats:italic>et al.</jats:italic> developed a general methodology using a convolutional neural network that automatically determines the crystal structure quickly and with high accuracy. After the network is exposed to a training set, it can identify the crystal structure without any additional input most of the time, providing a method for eliminating some of the guesswork from crystal structure determination. </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="6477" page="564" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aay3062">564</jats:related-article> </jats:p>

<jats:title>African schizophrenia genetic variants</jats:title> <jats:p> The genetics of schizophrenia have predominately been studied in populations of European and Asian descent. However, studies in Africans, who host the greatest degree of human genetic diversity, have lagged. Examining the exomes of more than 1800 Xhosa individuals from South Africa, about half of which have been diagnosed with schizophrenia, Gulsuner <jats:italic>et al.</jats:italic> identified both rare and common genetic variants associated with the disease. They found that the genetic architecture of schizophrenia in Africans generally reflects that of Europeans but that the greater genetic variation in Africa provides more power to detect relationships of genes to phenotypes. </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="6477" page="569" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aay8833">569</jats:related-article> </jats:p>

<jats:title>Inducing immune bee genes</jats:title> <jats:p> Honey bees are prone to parasitism by the <jats:italic>Varroa</jats:italic> mite, which is a vector for several bee pathogens. However, honey bees are also host to the symbiotic gut bacterium <jats:italic>Snodgrassella alvi.</jats:italic> Leonard <jats:italic>et al.</jats:italic> engineered <jats:italic>S. alvi</jats:italic> to produce double-stranded RNA (dsRNA)—a stimulus for insect RNA interference defense responses—from a plasmid containing two inverted promoters tagged with a fluorescent label (see the Perspective by Paxton). This dsRNA module can be targeted to interfere with specific bee genes as well as crucial viral and mite genes. The authors found that gene expression could be blocked for at least 15 days as the symbionts established in the bees' guts and continuously expressed the dsRNA constructs. <jats:italic>S. alvi</jats:italic> with specifically targeted plasmids not only suppressed infection with deformed wing virus but also effectively reduced <jats:italic>Varroa</jats:italic> mite survival. </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="6477" page="573" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aax9039">573</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6477" page="504" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aba6135">504</jats:related-article> </jats:p>

<jats:title>Pulsar timing detects frame dragging</jats:title> <jats:p> Frame dragging is a predicted phenomenon in general relativity, whereby a rotating mass drags the surrounding spacetime around with it. Venkatraman Krishnan <jats:italic>et al.</jats:italic> analyzed timing observations of PSR J1141-6545, a young pulsar in a binary orbit with a white dwarf. Modeling the arrival times of the radio pulses showed a long-term drift in the orbital parameters. After considering possible contributions to this drift, they concluded that it is dominated by frame dragging (the Lense-Thirring effect) of the rapidly spinning white dwarf. These observations verify a prediction of general relativity and provide constraints on the evolutionary history of the binary system. </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="6477" page="577" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aax7007">577</jats:related-article> </jats:p>