Catálogo de publicaciones - revistas

<jats:title>Watching Organic Reactions</jats:title> <jats:p> Single-molecule studies can overcome the difficulty of inferring the various outcomes of reactions in ensemble measurements. <jats:bold> De Oteyza <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="6139" page="1434" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1238187">1434</jats:related-article> , published online 30 May; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6139" page="1417" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1239961">Giessibl</jats:related-article> </jats:bold> ) used a variation of noncontact atomic force microscopy in which the imaging tip was derivatized with a single CO molecule to obtain subnanometer-resolution images of conjugated organic molecules undergoing reaction on a silver surface. Different thermally induced cyclization reactions of oligo- (phenylene-1,2-ethynylenes) were observed. </jats:p>

<jats:title>The Equations Underlying Cities</jats:title> <jats:p> Cities are complex systems of which functioning depends upon many social, economic, and environmental factors. <jats:bold>Bettencourt</jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6139" page="1438" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1235823">1438</jats:related-article> ; see the cover; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6139" page="1418" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1239870">Batty</jats:related-article> </jats:bold> ) developed a theory to explain the quantitative relationships observed between various aspects of cities and population size or land area. </jats:p>

<jats:title>Feather Features</jats:title> <jats:p> Diversification of feather pigment patterns is essential for avian speciation and adaptation. Yet the identity of feather pigment progenitor cells and the cellular and molecular basis for feather pigment pattern formation is poorly understood. <jats:bold> Lin <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="6139" page="1442" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1230374">1442</jats:related-article> , published online 25 April) report that, compared to the localized pigment cell niche in hair, a more dispersed circular topology of the feather pigment progenitor niche loosens spatial constraints and allows for more freedom in patterning possibilities. Multiple cellular mechanisms are co-opted and choreographed in this multidimensional space to create patterns. </jats:p>

<jats:title>Lord of the Ring Canal</jats:title> <jats:p> In <jats:italic>Drosophila</jats:italic> , some cells maintain direct cytoplasmic connections with their siblings by intercellular bridges known as ring canals that arise from mitotic cleavage furrows. In ovarian follicle cells and imaginal discs, <jats:bold>McLean and Cooley</jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6139" page="1445" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1234887">1445</jats:related-article> , published online 23 May) found that ring canals allowed diffusion of cytoplasmic proteins between cells and across mitotic clone boundaries, which may suggest a role in compensating for transcriptional variation between cells. </jats:p>

<jats:title>Coherence in Photosynthesis</jats:title> <jats:p> It is unclear how energy absorbed by pigments in antenna proteins is transferred to the central site of chemical catalysis during photosynthesis. <jats:bold> Hildner <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="6139" page="1448" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1235820">1448</jats:related-article> ) observed coherence—prolonged persistence of a quantum mechanical phase relationship—at the single-molecule level in light-harvesting complexes from purple bacteria. The results bolster conclusions from past ensemble measurements that coherence plays a pivotal role in photosynthetic energy transfer. <jats:bold> Hayes <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="6139" page="1431" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1233828">1431</jats:related-article> , published online 18 April) examined a series of small molecules comprised of bridged chromophores that also manifest prolonged coherence. </jats:p>

<jats:title>Parkin Enhanced?</jats:title> <jats:p> Inactivation of parkin, an E3 ubiquitin ligase, is responsible for a familial form of Parkinson's disease and may be involved in sporadic forms as well. <jats:bold> Trempe <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="6139" page="1451" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1237908">1451</jats:related-article> , published online 9 May) present the crystal structure of full-length parkin in an autoinhibited configuration. Guided by the structure, mutations were designed that activated parkin both in vitro and in cells. Because parkin is neuroprotective, the structure provides a framework for enhancing parkin function as a therapeutic strategy in Parkinson's disease. </jats:p>

<jats:title> GPR15 Gets T <jats:sub>regs</jats:sub> to Guard the Gut </jats:title> <jats:p> The large intestine is the site that is typically most inflamed in Crohn's disease and ulcerative colitis, which are thought to result when the immune system is not able to keep the peace with trillions of resident gut microbes. The immune system does this by recruiting specific cell populations, like regulatory T cells (T <jats:sub>regs</jats:sub> ), to the gut. <jats:bold> Kim <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="6139" page="1456" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1237013">1456</jats:related-article> , published online 9 May) now suggest that the orphan G protein–coupled receptor GPR15 is expressed by T <jats:sub>regs</jats:sub> and required for T <jats:sub>reg</jats:sub> homing to the large intestine in mice. </jats:p>

<jats:title>Influencing Influenza</jats:title> <jats:p> Currently, there is anxiety that the avian H5N1 influenza virus will reassort with the highly transmissible and epidemic H1N1 subtype to trigger a virulent human pandemic. <jats:bold> Y. 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="6139" page="1459" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1229455">1459</jats:related-article> , published online 2 May) used reverse genetics to make all possible reassortants between a virulent bird H5N1 with genes from a human pandemic H1N1. Virulence was tested in mice and transmissibility was tested between guinea pigs, which have both avian- and human-like airway influenza virus receptors. To assess what is happening to the receptor-ligand interactions as a result of these mutations, <jats:bold> W. 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="6139" page="1463" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1236787">1463</jats:related-article> , published online 2 May) probed the structure of both wild-type and mutant hemagglutinin of H5 in complex with analogs of the avian and human receptor types. Certain mutations in the receptor-binding site changed binding affinity. </jats:p>

<jats:title>Influencing Influenza</jats:title> <jats:p> Currently, there is anxiety that the avian H5N1 influenza virus will reassort with the highly transmissible and epidemic H1N1 subtype to trigger a virulent human pandemic. <jats:bold> Y. 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="6139" page="1459" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1229455">1459</jats:related-article> , published online 2 May) used reverse genetics to make all possible reassortants between a virulent bird H5N1 with genes from a human pandemic H1N1. Virulence was tested in mice and transmissibility was tested between guinea pigs, which have both avian- and human-like airway influenza virus receptors. To assess what is happening to the receptor-ligand interactions as a result of these mutations, <jats:bold> W. 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="6139" page="1463" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1236787">1463</jats:related-article> , published online 2 May) probed the structure of both wild-type and mutant hemagglutinin of H5 in complex with analogs of the avian and human receptor types. Certain mutations in the receptor-binding site changed binding affinity. </jats:p>

<jats:title>Genetic College</jats:title> <jats:p> Many genomic elements in humans are associated with behavior, including educational attainment. In a genome-wide association study including more than 100,000 samples, <jats:bold> Rietveld <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="6139" page="1467" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1235488">1467</jats:related-article> , published online 30 May; see the Perspective by <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6139" page="1416" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1240684"> <jats:bold>Flint and Munafò</jats:bold> </jats:related-article> ) looked for genes related to educational attainment in Caucasians. Small genetic effects at three loci appeared to impact educational attainment. </jats:p>