Catálogo de publicaciones - revistas

<jats:title>Biodiversity protects grassland stability</jats:title> <jats:p> How biodiversity interacts with ecosystem stability and productivity is key to understanding the impacts of environmental changes on ecosystem functions. In a series of decade-long experiments in temperate grassland, Hautier <jats:italic>et al.</jats:italic> manipulated nitrogen, water, carbon dioxide, herbivory, and fire. In all cases, plant species diversity was important for preserving ecosystem function during environmental change. Hence, the preservation and restoration of biodiversity buffer ecosystems against anthropogenic assault. </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="6232" page="336" related-article-type="in-this-issue" vol="348" xlink:href="10.1126/science.aaa1788">336</jats:related-article> </jats:p>

<jats:title>Stem cells can sort mitochondria by age</jats:title> <jats:p> The renewal of tissues in aging organisms requires stem cells, which have the unusual ability to divide asymmetrically into one daughter cell that retains stem cell properties and another that differentiates into a particular tissue type. Katajisto <jats:italic>et al.</jats:italic> used photoactivated marker proteins to monitor the age of cell organelles in stemlike cells from human breast tissue and their distribution into daughter cells. Most organelles were evenly distributed, but daughter cells that maintained stem-cell properties received more newly produced mitochondria and fewer old ones. </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="6232" page="340" related-article-type="in-this-issue" vol="348" xlink:href="10.1126/science.1260384">340</jats:related-article> </jats:p>

<jats:title>Engineering superenzyme function</jats:title> <jats:p> Understanding how protein domains and subunits operate is critical for engineering novel functions into proteins. Arslan <jats:italic>et al.</jats:italic> introduced intramolecular crosslinks between two domains of the <jats:italic>Escherichia coli</jats:italic> helicase Rep, which unwinds DNA. By inserting linkers of different lengths, the domains can be held either “open” or “closed.” The closed conformation activates the helicase, but it can also generate super-helicases capable of unzipping long stretches of DNA at high speed and with considerable force. Comstock <jats:italic>et al.</jats:italic> used optical tweezers and fluorescence microscopy to simultaneously measure the structure and function of the bacterial helicase UvrD. They monitored its DNA winding and unwinding activity and its shape during these activities. The motor domain also has a “closed” conformation during DNA unwinding and switches to a reversed “open” conformation during the zipping-up interaction. </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="6232" page="344" related-article-type="in-this-issue" vol="348" xlink:href="10.1126/science.aaa0445">344</jats:related-article> and p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6232" page="352" related-article-type="in-this-issue" vol="348" xlink:href="10.1126/science.aaa0130">352</jats:related-article> </jats:p>

<jats:title>Progress toward fixing a broken back?</jats:title> <jats:p> Axon regeneration after a spinal cord injury requires interference with neuronal mechanisms to promote axon extension and early suppression of scar formation. Microtubule stabilization could provide, in principle, a basis for such intervention. Ruschel <jats:italic>et al.</jats:italic> used animal models of spinal cord injury, time-lapse imaging in vivo, primary neuronal cultures, and behavioral studies to tackle this challenge (see the Perspective by Tran and Silver). They showed that epothilone B, a U.S. Food and Drug Administration–approved microtubule-stabilizing drug that can cross the blood-brain barrier, does promote functional axon regeneration, even after injury. </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="6232" page="347" related-article-type="in-this-issue" vol="348" xlink:href="10.1126/science.aaa2958">347</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6232" page="285" related-article-type="in-this-issue" vol="348" xlink:href="10.1126/science.aab1615">285</jats:related-article> </jats:p>

<jats:title>Engineering superenzyme function</jats:title> <jats:p> Understanding how protein domains and subunits operate is critical for engineering novel functions into proteins. Arslan <jats:italic>et al.</jats:italic> introduced intramolecular crosslinks between two domains of the <jats:italic>Escherichia coli</jats:italic> helicase Rep, which unwinds DNA. By inserting linkers of different lengths, the domains can be held either “open” or “closed.” The closed conformation activates the helicase, but it can also generate super-helicases capable of unzipping long stretches of DNA at high speed and with considerable force. Comstock <jats:italic>et al.</jats:italic> used optical tweezers and fluorescence microscopy to simultaneously measure the structure and function of the bacterial helicase UvrD. They monitored its DNA winding and unwinding activity and its shape during these activities. The motor domain also has a “closed” conformation during DNA unwinding and switches to a reversed “open” conformation during the zipping-up interaction. </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="6232" page="344" related-article-type="in-this-issue" vol="348" xlink:href="10.1126/science.aaa0445">344</jats:related-article> and p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6232" page="352" related-article-type="in-this-issue" vol="348" xlink:href="10.1126/science.aaa0130">352</jats:related-article> </jats:p>

<jats:p> New proteomics tools enable researchers to dive deeply into signaling networks, allowing them to tease out interactions among key molecules. But this comes with a new challenge of increased complexity. Can cell signaling scientists balance the bewildering complexity that comes with the discovery power of proteomics technology? <jats:list list-type="bullet"> <jats:list-item> <jats:p> <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://www.sciencemag.org/site/products/lst_20150417.xhtml">Read the Feature (Full-Text HTML)</jats:ext-link> </jats:p> </jats:list-item> <jats:list-item> <jats:p> <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://www.sciencemag.org/site/products/lst_20150417.pdf">Read the Feature (PDF)</jats:ext-link> </jats:p> </jats:list-item> <jats:list-item> <jats:p> <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://www.sciencemag.org/site/products/lst_20150417_np.pdf">Read New Products (PDF)</jats:ext-link> </jats:p> </jats:list-item> </jats:list> </jats:p>

<jats:p>On this week's show: The human-dog bond, a roundup of daily news stories.</jats:p>

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