Catálogo de publicaciones - revistas

<jats:title>Making Roots</jats:title> <jats:p> A tiny bunch of stem cells generates the bulk and diversity of plant roots. These cells are found at the root meristem and are themselves regulated by signaling inputs from a variety of sources. In <jats:italic>Arabidopsis</jats:italic> , <jats:bold> Matsuzaki <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="1065" related-article-type="in-this-issue" vol="329" xlink:href="10.1126/science.1191132">1065</jats:related-article> ) have identified a family of peptide factors that regulate these root stem cells. These peptides, known as root meristem growth factors, carry the post-translational modification, tyrosine sulfation, and are essential for maintaining the root stem cell niche. </jats:p>

<jats:title>Ant Variation</jats:title> <jats:p> Ants of the same genotype can exhibit numerous phenotypic forms and develop multiple functional castes within a colony. <jats:bold> Bonasio <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="1068" related-article-type="in-this-issue" vol="329" xlink:href="10.1126/science.1192428">1068</jats:related-article> ) sequenced the genomes of two ant species exhibiting differences in caste development— <jats:italic>Camponotus floridanus</jats:italic> and <jats:italic>Harpegnathos saltator</jats:italic> —and used the sequences to compare gene expression and identify differences in epigenetic gene regulation that lead to the phenotypic differences. Ants may offer a model system for studying the role of epigenetics in behavior and development. </jats:p>

<jats:title>Human Adenovirus Structures</jats:title> <jats:p> Human adenoviruses may be a common cause of acute infections in humans, but they can also be used as vectors for vaccine and therapeutic gene transfer. Rational engineering of safe adenovirus vectors has been hampered by a lack of high-resolution structural information. Two papers now describe the structure of human adenovirus using complementary techniques. <jats:bold> Reddy <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="1071" related-article-type="in-this-issue" vol="329" xlink:href="10.1126/science.1187292">1071</jats:related-article> ; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="5995" page="1026" related-article-type="in-this-issue" vol="329" xlink:href="10.1126/science.1194922">Harrison</jats:related-article> </jats:bold> ) have determined the crystal structure at 3.5 angstrom resolution, while <jats:bold> Liu <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="1038" related-article-type="in-this-issue" vol="329" xlink:href="10.1126/science.1187433">1038</jats:related-article> ; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="5995" page="1026" related-article-type="in-this-issue" vol="329" xlink:href="10.1126/science.1194922">Harrison</jats:related-article> </jats:bold> ) solved the structure to 3.6 angstrom resolution by electron microscopy. Together the structures provide insights into viral assembly, stabilization, and cell entry mechanisms. </jats:p>

<jats:title>Plants' Modified SOS Call</jats:title> <jats:p> Plants have several ways of defending themselves against insect attack. The release of distinctive volatile chemicals betrays the location of herbivores to their predators, but volatile production can be slow and the pests may escape. Compounds known as green leaf volatiles are released immediately after damage, and <jats:bold>Allmann and Baldwin</jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1075" related-article-type="in-this-issue" vol="329" xlink:href="10.1126/science.1191634">1075</jats:related-article> ) have found that, when attacked by tobacco hornworm ( <jats:italic>Manduca sexta</jats:italic> ) caterpillars, <jats:italic>Nicotiana attenuata</jats:italic> plants emit a compound that, when combined with an oral secretion from the caterpillar, is transformed into an attractant for the generalist hemipteran predator <jats:italic>Geocoris pallidens</jats:italic> , which preys on the hornworm eggs and young larvae. Thus, insect feeding activity can begin the process of plant defense before other protective volatiles are synthesized and emitted. </jats:p>

<jats:title>Environment Matters</jats:title> <jats:p> Stem cells isolated from muscle can be used for muscle regeneration, but only if the stem cells are fresh. Under standard cell culture conditions in the laboratory, muscle stem cells fail to proliferate efficiently and lose their regenerative capacity. <jats:bold> Gilbert <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="1078" related-article-type="in-this-issue" vol="329" xlink:href="10.1126/science.1191035">1078</jats:related-article> , published online 15 July; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="5995" page="1024" related-article-type="in-this-issue" vol="329" xlink:href="10.1126/science.1194919">Bhatia</jats:related-article> </jats:bold> ) built an in vitro–culture system that resembles the physical characteristics in which muscle stem cells normally reside: a squishy elastic bed (rather than the hard slab of a plastic culture flask). Laminin tethered to hydrogels was used to generate substrates of varying elasticity. When cultured on these substrates, muscle stem cells remained undifferentiated and were able to support muscle regeneration when transplanted back into mice. </jats:p>

<jats:title>Two Heads Are Better Than One</jats:title> <jats:p> When two people peer into the distance and try to figure out if a faint number is a three or an eight, classical signal detection theory states that the joint decision can only be as good as that of the person with higher visual acuity. <jats:bold> Bahrami <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="1081" related-article-type="in-this-issue" vol="329" xlink:href="10.1126/science.1185718">1081</jats:related-article> ; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="5995" page="1022" related-article-type="in-this-issue" vol="329" xlink:href="10.1126/science.1194920">Ernst</jats:related-article> </jats:bold> ) propose that a discussion not only of what each person perceives but also of the degree of confidence in those assignments can improve the overall sensitivity of the decision. Using a traditional contrast-detection task, they showed that, when the individuals did not differ too much in their powers of visual discrimination, collective decision-making significantly improved sensitivity. The model offered here formalizes debates held since the Enlightenment about whether collective thinking can outperform that of elite individuals. </jats:p>

<jats:title>Intracellular pH and Lipid Metabolism</jats:title> <jats:p> Intracellular pH regulates metabolism by poorly understood mechanisms, but biosensors are likely to be important in this process. <jats:bold> Young <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="1085" related-article-type="in-this-issue" vol="329" xlink:href="10.1126/science.1191026">1085</jats:related-article> ) took a systems-biology approach in yeast to identify in excess of 200 genes that regulate phospholipid metabolism. They found that the signaling lipid, phosphatidic acid, appeared to act as a cytosolic biosensor via the pH-dependent binding of protein effectors to phosphatidic acid. This pH-dependent mechanism directly affects gene expression and is involved in a pathway in which nutrient availability regulates phospholipid metabolism to control production of membranes. </jats:p>

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

<jats:p>The show includes ant genomics, archaeological research using satellite images, multiple planets transiting a Sun-like star, and more.</jats:p>