Catálogo de publicaciones - revistas

<jats:title> Keeping <jats:italic>Z</jats:italic> -olefins intact with iridium </jats:title> <jats:p> Transition metal catalysis offers a versatile means of modifying carbon centers adjacent to carbon-carbon double bonds. However, in the course of these reactions, the double bond tends to get weakened, allowing its substituents to swivel back and forth. Thus, if two large groups start out on the same side of the bond axis (a geometry known as a <jats:italic>Z</jats:italic> -olefin), they end up on opposite sides in the product. Jiang <jats:italic>et al.</jats:italic> report a chiral iridium catalyst that prevents this swiveling just long enough to substitute the adjacent carbon enantioselectively (see the Perspective by Malcolmson). </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article issue="6527" page="380" related-article-type="in-this-issue" vol="371">380</jats:related-article> ; see also p. <jats:related-article issue="6527" page="345" related-article-type="in-this-issue" vol="371">345</jats:related-article> </jats:p>

<jats:title>From offense to defense</jats:title> <jats:p> Venom in snakes is largely used to subdue and/or kill prey, and most venoms have clear actions that facilitate death or paralysis. In one group of snakes, however, venom has evolved and shifted from predation to protection. Specifically, in three different lineages of “spitting” snakes, venom is used to deter predators. Kazandjian <jats:italic>et al.</jats:italic> show that similar adaptions have occurred within these lineages that transform cytotoxic components into a mixture that acts on mammalian sensory neurons and causes pain. The authors argue that increased predation on these lineages led to similar shifts in venom function. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article issue="6527" page="386" related-article-type="in-this-issue" vol="371">386</jats:related-article> </jats:p>

<jats:title>Opening charge transport pathways</jats:title> <jats:p> In perovskite solar cells, the insulating nature of passivation layers needed to boost open-circuit voltage also increases the series resistance of the cell and limits the fill factor. Most improvements in power conversion efficiency have come from higher open-circuit voltage, with most fill factor improvements reported for very small-area cells. Peng <jats:italic>et al.</jats:italic> used a nanostructured titanium oxide electron transport layer to boost the fill factor of larger-area cells (1 square centimeter) to 0.84 by creating local regions with high conductivity. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article issue="6527" page="390" related-article-type="in-this-issue" vol="371">390</jats:related-article> </jats:p>

<jats:title>Enhancer-gene interactions drive split</jats:title> <jats:p> In many species across the animal kingdom, male and female phenotypes differ. One such example is the wing spot seen in male <jats:italic>Drosophila biarmipes</jats:italic> flies but not the female flies. Galouzis and Prud'homme investigate the X-linked <jats:italic>yellow</jats:italic> gene and its enhancer. Investigating the genetics of the trait, they found evidence that the male-specific phenotype is caused by a trans interaction between the enhancer and gene that silences the gene when it is present in only one copy in the male (which only has a single X chromosome) versus the two copies found in the female. This gene thus appears to be regulated by differing genomic interactions in male and female flies and is an example of the phenomenon known as transvection. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article issue="6527" page="396" related-article-type="in-this-issue" vol="371">396</jats:related-article> </jats:p>

<jats:title> <jats:italic>Salmonella</jats:italic> profits from immunometabolism </jats:title> <jats:p> Extensive metabolic rewiring occurs in various immune cells during the course of infection. Whether these changes can be exploited by intracellular pathogens remains an open question. Rosenberg <jats:italic>et al.</jats:italic> report that infection with <jats:italic>Salmonella enterica</jats:italic> serovar Typhimurium ( <jats:italic>S.</jats:italic> Tm) induces the accumulation of the metabolite succinate in macrophages (see the Perspective by Lynch and Lesser). This key intermediate in the citric acid cycle activates virulence genes in <jats:italic>S.</jats:italic> Tm, leading to microbial resistance. Moreover, the active transport of succinate through the C4-dicarboxylate transporter DcuB is required for <jats:italic>S.</jats:italic> Tm virulence and survival within macrophages. Sensing of citric acid cycle intermediates may more generally serve as a cue to initiate the resistance programs of intracellular 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="6527" page="400" related-article-type="in-this-issue" vol="371" xlink:href="10.1126/science.aba8026">400</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6527" page="344" related-article-type="in-this-issue" vol="371" xlink:href="10.1126/science.abf8414">344</jats:related-article> </jats:p>

<jats:title>A metabolic circuit in T cell immunity</jats:title> <jats:p> Naïve T cells are metabolically reprogrammed when they differentiate into T effector (T <jats:sub>eff</jats:sub> ) cells, transitioning from a reliance on mitochondrial oxidative phosphorylation to aerobic glycolysis. Xu <jats:italic>et al.</jats:italic> found that lactate dehydrogenase A (LDHA), a glycolytic enzyme that converts pyruvate to lactate, is a key player in this process. T <jats:sub>eff</jats:sub> cells that differentiate in mice infected with the bacterium <jats:italic>Listeria monocytogenes</jats:italic> turned on LDHA through phosphoinositide 3-kinase (PI3K) signaling. By promoting adenosine triphosphate (ATP) production, LDHA in turn facilitated PI3K-dependent inactivation of the transcription factor Foxo1 needed for effective T <jats:sub>eff</jats:sub> cell responses. Thus, glycolytic ATP acts like a rheostat that both gauges and regulates PI3K-dependent signaling. This type of positive feedback circuit may also provide a mechanistic explanation for the Warburg effect observed in cancer cells. </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="6527" page="405" related-article-type="in-this-issue" vol="371" xlink:href="10.1126/science.abb2683">405</jats:related-article> </jats:p>

<jats:title>Cuticular pheromone circadian regulation</jats:title> <jats:p> Several species of anopheline mosquitoes are important malaria vectors in Africa. Male mosquitoes show species-specific swarming behaviors at certain times of the day to attract females for mating. Wang <jats:italic>et al.</jats:italic> found that transcriptional patterns of metabolic and immune function genes apparently showed a diurnal rhythm that correlated with the physiological demands of mating flight swarming (see the Perspective by Manoukis). By altering temperature and light regimes and by knocking out the master genes <jats:italic>period</jats:italic> and <jats:italic>timeless</jats:italic> for circadian clock regulation, the authors disrupted mating flight behavior in a combination of cage experiments and enclosed field conditions. Knocking out the rhythmically expressed desaturase enzyme reduced cuticular hydrocarbon pheromone production and limited mating success. These key interacting components of the diurnal regulation of mosquito mating behavior are potential targets for alternative malaria control strategies. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article issue="6527" page="411" related-article-type="in-this-issue" vol="371">411</jats:related-article> ; see also p. <jats:related-article issue="6527" page="340" related-article-type="in-this-issue" vol="371">340</jats:related-article> </jats:p>

<jats:title>Yeast switches for glucose and galactose</jats:title> <jats:p> Some organisms can switch metabolic pathways depending on their environment. One such example is yeast, which can transition between the sugars glucose and galactose as carbon sources. Boocock <jats:italic>et al.</jats:italic> show that this ability has undergone selection, resulting in the maintenance of two incompatible metabolic pathways in a select set of yeast strains within a single species. A phylogenetic analysis supports that these different pathways are mediated by three genes that differ between strains within and among yeast species and likely have been maintained over 10 million to 20 million years. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article issue="6527" page="415" related-article-type="in-this-issue" vol="371">415</jats:related-article> </jats:p>

<jats:p> This issue of <jats:italic>Science</jats:italic> includes the program of the 2021 AAAS Annual Meeting. The theme of the AAAS Annual Meeting is <jats:italic>Understanding Dynamic Ecosystems</jats:italic> . The 2021 Annual Meeting will convene entirely online, February 8-11, with pre-recorded videos available starting on January 18. </jats:p> <jats:p> A <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="https://science.sciencemag.org/content/sci/371/6527/421.full.pdf">PDF</jats:ext-link> of the program as it appears in this issue is available here; for more information on the meeting (including registration forms and information on accommodations), please visit <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="www.aaas.org/meetings/">www.aaas.org/meetings/</jats:ext-link> . </jats:p>

<jats:p>A weekly roundup of information on newly offered instrumentation, apparatus, and laboratory materials of potential interest to researchers.</jats:p>