Catálogo de publicaciones - revistas

<jats:title>Unmasking supercooled water transitions</jats:title> <jats:p> The unusual thermodynamic properties of water suggest that when supercooled, a second critical point should exist between two liquid phases that differ in density. Pure water crystallizes before such conditions can be reached. Woutersen <jats:italic>et al.</jats:italic> studied hydrazinium trifluoroacetate solutions that have similar hydrogen bonding to that of water. They observed a liquid-liquid transition near 190 K by using infrared spectroscopy and calorimetry. The liquid states were analogous to the predicted high- and low-density amorphous phases of water. </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="6380" page="1127" related-article-type="in-this-issue" vol="359" xlink:href="10.1126/science.aao7049">1127</jats:related-article> </jats:p>

<jats:title>Coherent strained superlattices</jats:title> <jats:p> Two-dimensional superlattices represent the atomic-thickness limit of heterostructures that enable technologies such as strain-engineered multiferroics and quantum-cascade lasers. Xie <jats:italic>et al.</jats:italic> were able to produce monolayer superlattices of transition metal dichalcogenides (WS <jats:sub>2</jats:sub> and WSe <jats:sub>2</jats:sub> ) with full lattice coherence, despite a 4% lattice mismatch. They used a modulated metal-organic chemical vapor deposition process that precisely controlled each precursor. Furthermore, the authors could strain-engineer the optical properties of the superlattices to observe out-of-plane rippling. </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="6380" page="1131" related-article-type="in-this-issue" vol="359" xlink:href="10.1126/science.aao5360">1131</jats:related-article> </jats:p>

<jats:title>Starving ocean productivity</jats:title> <jats:p> Projected increases in greenhouse gas emissions could suppress marine biological productivity for a thousand years or more. As the climate warms, westerly winds in the Southern Hemisphere will strengthen and shift poleward, surface waters will warm, and sea ice will disappear. Moore <jats:italic>et al.</jats:italic> suggest that one effect of these changes will be a dramatic decrease in marine biological productivity (see the Perspective by Laufkötter and Gruber). This decrease will result from a global-scale redistribution of nutrients, with a net transfer to the deep ocean. By 2300, this could drive declines in fisheries yields by more than 20% globally and by nearly 60% in the North Atlantic. </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="6380" page="1139" related-article-type="in-this-issue" vol="359" xlink:href="10.1126/science.aao6379">1139</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6380" page="1103" related-article-type="in-this-issue" vol="359" xlink:href="10.1126/science.aat0795">1103</jats:related-article> </jats:p>

<jats:title>The mechanisms behind grid cell changes</jats:title> <jats:p> When grid cells were first discovered in the brain, the grids were considered to have rigid coordinates beyond the borders of the testing environments. However, recent findings suggest that the grid cell pattern can be altered easily by changing the space of the enclosure. But how? Krupic <jats:italic>et al.</jats:italic> discovered that local changes in the geometry of the environment shifted individual neighboring grid fields, while more distant fields remained unchanged. Thus, changes to the grid structure are localized. Stable landmarks continue to exert an effect on most grid cells, whereas the ones close to changed borders are modified. </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="6380" page="1143" related-article-type="in-this-issue" vol="359" xlink:href="10.1126/science.aao4960">1143</jats:related-article> </jats:p>

<jats:title>Lies spread faster than the truth</jats:title><jats:p>There is worldwide concern over false news and the possibility that it can influence political, economic, and social well-being. To understand how false news spreads, Vosoughi<jats:italic>et al.</jats:italic>used a data set of rumor cascades on Twitter from 2006 to 2017. About 126,000 rumors were spread by ∼3 million people. False news reached more people than the truth; the top 1% of false news cascades diffused to between 1000 and 100,000 people, whereas the truth rarely diffused to more than 1000 people. Falsehood also diffused faster than the truth. The degree of novelty and the emotional reactions of recipients may be responsible for the differences observed.</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="6380" page="1146" related-article-type="in-this-issue" vol="359" xlink:href="10.1126/science.aap9559">1146</jats:related-article></jats:p>

<jats:title>Microbial modulation of diabetes</jats:title> <jats:p> Short-chain fatty acids (SCFAs) are produced by various human gut microbes. SCFAs act as an energy source to the colonic epithelium and are also sensed by host signaling pathways that modulate appetite and inflammation. Deficiency of gut SCFAs is associated with type 2 diabetes. Zhao <jats:italic>et al.</jats:italic> found that adopting a high-fiber diet promoted the growth of SCFA-producing organisms in diabetic humans. The high-fiber diet induced changes in the entire gut microbe community and correlated with elevated levels of glucagon-like peptide-1, a decline in acetylated hemoglobin levels, and improved blood-glucose regulation. </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="6380" page="1151" related-article-type="in-this-issue" vol="359" xlink:href="10.1126/science.aao5774">1151</jats:related-article> </jats:p>

<jats:title>Bacterial involvement in autoimmunity</jats:title> <jats:p> The composition of the commensal microbiota is known to influence autoimmune disease development and persistence. Manfredo Vieira <jats:italic>et al.</jats:italic> identified a gut microbe, <jats:italic>Enterococcus gallinarum</jats:italic> , that translocates from the gut into the organs of mice with a genetic predisposition to lupus-like autoimmunity (see the Perspective by Citi). Molecular signatures of gut barrier disintegration and pathogenic T helper cells were evident in the gut, liver, and lymphoid organs during colonization with the pathobiont. The ensuing pathology could be reversed by vancomycin treatment and by vaccination against <jats:italic>E. gallinarum</jats:italic> . The same bug was also found in liver biopsies of autoimmune patients, but not in healthy controls. </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="6380" page="1156" related-article-type="in-this-issue" vol="359" xlink:href="10.1126/science.aar7201">1156</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6380" page="1097" related-article-type="in-this-issue" vol="359" xlink:href="10.1126/science.aat0835">1097</jats:related-article> </jats:p>

<jats:title>Overcoming a barrier to IBD</jats:title> <jats:p> Inflammatory bowel disease (IBD) is a group of disorders linked to inflammation of the gastrointestinal tract. Colitis is a type of IBD that affects the inner lining of the colon and has been linked to a gene known as <jats:italic>C1orf106</jats:italic> . Mohanan <jats:italic>et al.</jats:italic> found that <jats:italic>C1orf106</jats:italic> encodes a protein that stabilizes the integrity of epithelial junctions and enhances barrier defense (see the Perspective by Citi). IBD-associated mutations in <jats:italic>C1orf106</jats:italic> lead to greater cytohesin-1 protein levels, changes in E-cadherin localization, and enhanced susceptibility to intestinal pathogens. Modulation of C1orf106 may thus hold promise for treating colitis and other IBDs. </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="6380" page="1161" related-article-type="in-this-issue" vol="359" xlink:href="10.1126/science.aan0814">1161</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6380" page="1097" related-article-type="in-this-issue" vol="359" xlink:href="10.1126/science.aat0835">1097</jats:related-article> </jats:p>

<jats:title>Hemimethylation drives chromatin assembly</jats:title> <jats:p>Cytosine DNA methylation is a heritable and essential epigenetic mark. During DNA replication, cytosines on mother strands remain methylated, but those on daughter strands are initially unmethylated. These hemimethylated sites are rapidly methylated to maintain faithful methylation patterns. Xu and Corces mapped genome-wide strand-specific DNA methylation sites on nascent chromatin, confirming such maintenance in the vast majority of the DNA methylome (see the Perspective by Sharif and Koseki). However, they also identified a small fraction of sites that were stably hemimethylated and showed their inheritance at CTCF (CCCTC-binding factor)/cohesin binding sites. These inherited hemimethylation sites were required for CTCF and cohesin to establish proper chromatin interactions.</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="6380" page="1166" related-article-type="in-this-issue" vol="359" xlink:href="10.1126/science.aan5480">1166</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6380" page="1102" related-article-type="in-this-issue" vol="359" xlink:href="10.1126/science.aat0789">1102</jats:related-article> </jats:p>