Catálogo de publicaciones - revistas

<jats:title>Cropland Acidification in China</jats:title> <jats:p> China is experiencing increasing problems with acid rain, groundwater pollution, and nitrous oxide emissions. Rapid development of industry and transportation has accelerated nitrate (N) emissions to the atmosphere. Consequently, soil degradation, water shortage, and pollution, in addition to atmospheric quality decline are becoming major public concerns across China. Since the 1990s, China has become both the largest consumer of chemical N fertilizers and the highest cereal producer in the world, which has consequences for arable soil acidification. <jats:bold> Guo <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1008" related-article-type="in-this-issue" vol="327" xlink:href="10.1126/science.1182570">1008</jats:related-article> , published online 11 February) present a meta-analysis of a regional acidification phenomenon in Chinese arable soils that is largely associated with higher N fertilization and higher crop production. Such large-scale soil acidification is likely to threaten the sustainability of agriculture and affect the biogeochemical cycles of nutrients and also toxic elements in soils. </jats:p>

<jats:title> Killing <jats:italic>Pseudomonas</jats:italic> </jats:title> <jats:p> Gram-negative <jats:italic>Pseudomonas</jats:italic> bacteria are opportunistic pathogens, and drug-resistant strains present a serious health problem. <jats:bold> Srinivas <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1010" related-article-type="in-this-issue" vol="327" xlink:href="10.1126/science.1182749">1010</jats:related-article> ) synthesized a family of peptidomimetic antibiotics that is active only against <jats:italic>Pseudomonas</jats:italic> . These antibiotics do not lyse the cell membrane, but instead target an essential outer membrane protein, LptD, which plays a role in the assembly of lipopolysaccharide in the outer cell membrane. Activity in a mouse infection model suggests that the antibiotics might have therapeutic potential. In addition, LptD is widely distributed in gram-negative bacteria and so its validation as a target has the potential to drive development of antibiotics with a broader spectrum of activity against gram-negative pathogens. </jats:p>

<jats:title>Examining the Backbone</jats:title> <jats:p> Determination of tertiary protein structures by nuclear magnetic resonance (NMR) currently relies heavily on side-chain NMR data. The assignment of side-chain atoms is challenging. In addition, proteins larger than 15 kilodaltons (kD) must be deuterated to improve resolution and this eliminates the possibility of measuring long-range interproton distance constraints. Now <jats:bold> Raman <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1014" related-article-type="in-this-issue" vol="327" xlink:href="10.1126/science.1183649">1014</jats:related-article> , published online 4 February) use backbone-only NMR data—chemical shifts, residual dipolar coupling, and backbone amide proton distances—available from highly deuterated proteins to guide conformational searching in the Rosetta structure prediction protocol. Using this new protocol, they were able to generate accurate structures for proteins of up to 25 kD. </jats:p>

<jats:title>Predictable Travel Routines</jats:title> <jats:p> While people rarely perceive their actions to be random, current models of human activity are fundamentally stochastic. Processes that rely on human mobility patterns, like the prediction of new epidemics, traffic engineering, or city planning, could benefit from highly accurate predictive models. To investigate the predictability of human dynamics, <jats:bold> Song <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1018" related-article-type="in-this-issue" vol="327" xlink:href="10.1126/science.1177170">1018</jats:related-article> ) used the recorded trajectories of millions of mobile phone users, collected by mobile phone companies and anonymized for research purposes. They hypothesized that given the wide range of travel patterns that different users follow, there would be significant differences between their predictability as well: Users who travel less should be easier to predict than those who are constantly on the road. Surprisingly, there was 93% predictability across the whole user base, and individuals' predictability did not in general fall significantly below 80%. </jats:p>

<jats:p>The show includes Predicting human mobility, possible prebiotic sugar formation, and the 2009 Visualizaton Challenge..</jats:p>

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