Catálogo de publicaciones - revistas

<jats:title>Watching nucleation pathways in calcite</jats:title> <jats:p> The initial stage of crystallization, the formation of nuclei, is a critical process, but because of the length and time scales involved, is hard to observe. Nielsen <jats:italic>et al.</jats:italic> explored the crystallization of calcium carbonate, a well-studied material but one with multiple nucleation theories. Different calcium and carbonate solutions were mixed inside a fluid cell and imaged using a liquid cell inside a transmission electron microscope. Competing pathways operated during nucleation, with both the direct association of ions into nuclei from solution and the transformation of amorphous calcium carbonate into and between different crystalline polymorphs. </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="6201" page="1158" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1254051">1158</jats:related-article> </jats:p>

<jats:title>Surprise found by γ-ray metal detector</jats:title> <jats:p> Astronomers commonly use type-Ia supernovae as standard distance measurement tools, though the physics of these bright sources are not fully understood. One product of the thermonuclear explosion is <jats:sup>56</jats:sup> Ni, which probably lies at the heart of the supernova cloud. Diehl <jats:italic>et al.</jats:italic> detected the gamma-ray emission from <jats:sup>56</jats:sup> Ni in SN2014J much earlier than expected, only about 20 days after the initial explosion. This early exposure suggests both an asymmetric event and the production of <jats:sup>56</jats:sup> Ni farther out in the ejecta than predicted. These sources will help astronomers measure distances far beyond where supernovae have been studied. </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="6201" page="1162" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1254738">1162</jats:related-article> </jats:p>

<jats:title>The earthquake that rocked northern Chile</jats:title> <jats:p> Subduction zones often produce the largest earthquakes on Earth. A magnitude 8.2 earthquake (Iquique) occurred in one such zone off the coast of northern Chile on 1 April 2014, in a seismic gap that had not experienced a large earthquake since the 9.0 one in 1877. Ruiz <jats:italic>et al.</jats:italic> analyzed continuous GPS data to monitor the movement of plates over time in this region, including before and after major earthquakes. The most recent large quake was preceded by an extended series of smaller earthquakes and creeping westward movement of the coastline. </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="6201" page="1165" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1256074">1165</jats:related-article> </jats:p>

<jats:title>Cofactors linked to nutrient limitation</jats:title> <jats:p> Microbes require inventive ways to acquire scarce nutrients from the environment. Enzymes that catalyze the acquisition of phosphorus from dissolved organic matter, for example, rely on complex metal cofactors in the active site. Yong <jats:italic>et al.</jats:italic> determined the crystal structure of the PhoX alkaline phosphatase from <jats:italic>Pseudomonas fluorescens</jats:italic> (see the Perspective by Moore). The metal centers arrange themselves in a triangular structure of two iron atoms and one calcium atom, bridged together by an oxide ion. The presence of iron, which itself is a trace nutrient in most environments, suggests that it limits phosphorus acquisition. </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="6201" page="1170" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1254237">1170</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6201" page="1120" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1258133">1120</jats:related-article> </jats:p>

<jats:title>Protein markers of cyanobacterial stress</jats:title> <jats:p> Nutrients including iron, nitrogen, and phosphorus limit primary productivity in the oceans. Determining how abundant cyanobacteria such as <jats:italic>Prochlorococcus</jats:italic> adapt to nutrient stress across marine settings requires accurate molecular assays. Saito <jats:italic>et al.</jats:italic> developed a proteomic and metaproteomic approach capable of targeting specific metabolic biomarkers from mixed communities in seawater (see the Perspective by Moore). <jats:italic>Prochlorococcus</jats:italic> proteins are indicative of a major limiting nutrient across a wide transect in the Pacific Ocean; however, they also show that the limitation of multiple nutrients at overlapping biomes is an additional source of stress. </jats:p> <jats:p> Science, this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6201" page="1173" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1256450">1173</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6201" page="1120" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1258133">1120</jats:related-article> </jats:p>

<jats:title>Old and older, cold and colder</jats:title> <jats:p> Greenland surface air temperatures changed dramatically during the last deglaciation. The exact amount is unknown, which makes it difficult to understand what caused those changes. Buizert <jats:italic>et al.</jats:italic> report temperature reconstructions for the period from 19,000 to 10,000 years before the present from three different locations in Greenland and interpret them with a climate model (see the Perspective by Sime). They provide the broad geographic pattern of temperature variability and infer the mechanisms of the changes and their seasonality, which differ in important ways from the traditional view. </jats:p> <jats:p> Science, this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6201" page="1177" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1254961">1177</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6201" page="1116" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1257842">1116</jats:related-article> </jats:p>

<jats:title>Coffee, tea, and chocolate converge</jats:title> <jats:p> Caffeine has evolved multiple times among plant species, but no one knows whether these events involved similar genes. Denoeud <jats:italic>et al.</jats:italic> sequenced the <jats:italic>Coffea canephora</jats:italic> (coffee) genome and identified a conserved gene order (see the Perspective by Zamir). Although this species underwent fewer genome duplications than related species, the relevant caffeine genes experienced tandem duplications that expanded their numbers within this species. Scientists have seen similar but independent expansions in distantly related species of tea and cacao, suggesting that caffeine might have played an adaptive role in coffee evolution. </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="6201" page="1181" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1255274">1181</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6201" page="1124" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1258941">1124</jats:related-article> </jats:p>

<jats:title>Genome editing corrects a muscle disease</jats:title> <jats:p> Patients with Duchenne muscular dystrophy find their muscles growing progressively weaker. Studies identified <jats:italic>dystrophin</jats:italic> as the culprit gene, which galvanized research into gene-targeted therapies. Long <jats:italic>et al.</jats:italic> apply genome editing to “correct” the disease-causing mutation in mice genetically destined to develop the disease. This germline editing strategy kept muscles from degenerating, even in mice harboring only a small percentage of corrected cells. Although not feasible for humans, this proof of concept sets the stage for applying genome editing to specific cell types involved in the disease. </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="6201" page="1184" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1254445">1184</jats:related-article> </jats:p>

<jats:title>Caught in the act of making protein</jats:title> <jats:p> The ribosome is a large RNA-protein complex that converts the genetic code stored in messenger RNA (mRNA) into proteins. Zhou <jats:italic>et al.</jats:italic> have determined the structure of a bacterial ribosome caught in the act of decoding an mRNA. Transfer RNAs (tRNAs) decipher the genetic code in the mRNA to ensure that the ribosome uses the correct amino acids. The structure shows tRNAs in the process of being moved between successive protein-building binding pockets as the ribosome reads the mRNA like a piece of old-fashion computer tape. </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="6201" page="1188" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1255030">1188</jats:related-article> </jats:p>

<jats:title>Dipeptide repeat peptides on the attack</jats:title> <jats:p> Certain neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS), are associated with expanded dipeptides translated from RNA transcripts of disease-associated genes (see the Perspective by West and Gitler). Kwon <jats:italic>et al.</jats:italic> show that the peptides encoded by the expanded repeats in the C9orf72 gene interfere with the way cells make RNA and kill cells. These effects may account for how this genetic form of ALS causes disease. Working in <jats:italic>Drosophila</jats:italic> , Mizielinska <jats:italic>et al.</jats:italic> aimed to distinguish between the effects of repeat-containing RNAs and the dipeptide repeat peptides that they encode. The findings provide evidence that dipeptide repeat proteins can cause toxicity directly. </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="6201" page="1139" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1254917">1139</jats:related-article> and p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6201" page="1192" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1256800">1192</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6201" page="1118" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1259461">1118</jats:related-article> </jats:p>