Catálogo de publicaciones - revistas

<jats:title>Still Living in Their Mother's House</jats:title> <jats:p> Dispersal, movement away from an organism's natal site, is a critical stage in the development of a juvenile into an adult and several drivers of this process have been proposed. A classic hypothesis put forward by Hamilton and May argues that individuals disperse away from kin in order to avoid competing with similar phenotypes. Many species have been shown to follow this pattern, and it is generally accepted that most organisms disperse well away from the sites where they were born. However, not all species follow this pattern and some display a distinct tendency to remain within their mother's home range. <jats:bold>Hoogland</jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6124" page="1205" related-article-type="in-this-issue" vol="339" xlink:href="10.1126/science.1231689">1205</jats:related-article> ) studied populations of three species of prairie dogs over more than three decades and found that the presence of close kin in these highly social rodents actually led young animals to remain on their natal site, whereas dispersal away from it occurred almost exclusively when close female kin were absent. This suggests that sociality may in fact result in individuals remaining with their close kin in order to benefit from cooperation and that longer-distance dispersal may instead occur when the opportunity for cooperation does not exist. </jats:p>

<jats:title>Hot, Toxic Eukaryote</jats:title> <jats:p> Unusually, the single-celled eukaryote red alga, <jats:italic>Galdieria sulphuraria</jats:italic> , can thrive in hot, acidic springs. This organism is endowed with extraordinary metabolic talents and can consume a variety of strange carbohydrates, as well as turn on photosynthesis when the food runs out. <jats:bold> Schönknecht <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6124" page="1207" related-article-type="in-this-issue" vol="339" xlink:href="10.1126/science.1231707">1207</jats:related-article> ; see the Perspective by <jats:bold>Rocha</jats:bold> ) discerned from phylogenetic analysis of its genome that during its evolution, <jats:italic>G. sulphuraria</jats:italic> appears to have commandeered at least 75 bacterial and archaeal genes by horizontal gene transfer and then applied gene expansion to boost its metabolic repertoire. </jats:p>

<jats:title>Antibiotic Mechanisms Revisited</jats:title> <jats:p> Several recent studies have suggested that bactericidal antibiotics kill cells by a common mechanism involving reactive oxygen species (ROS). Two groups tested this hypothesis using diverse experiments, with both finding that quinolone, lactam, and aminoglycoside antibiotics had similar efficacy for killing in the presence or absence of oxygen (or nitrate). <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" issue="6124" page="1210" related-article-type="in-this-issue" vol="339" xlink:href="10.1126/science.1232751">1210</jats:related-article> ) saw no increase in hydrogen peroxide production in antibiotic-exposed cells and found no association between antibiotic exposure and the expected symptoms of oxidative damage, such as the breakdown of iron-sulfur clusters in enzymes or of hydroxyl radical injuries to DNA. Similarly, <jats:bold> Keren <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6124" page="1213" related-article-type="in-this-issue" vol="339" xlink:href="10.1126/science.1232688">1213</jats:related-article> ) found no correlation between the production of ROS, inferred from hydroxyphenyl fluorescein dye measurements, and bacterial survival, nor was there any significant protective effect engendered by thiourea. The results do not support a common mode of action for bactericidal antibiotics mediated by ROS. </jats:p>

<jats:title>Antibiotic Mechanisms Revisited</jats:title> <jats:p> Several recent studies have suggested that bactericidal antibiotics kill cells by a common mechanism involving reactive oxygen species (ROS). Two groups tested this hypothesis using diverse experiments, with both finding that quinolone, lactam, and aminoglycoside antibiotics had similar efficacy for killing in the presence or absence of oxygen (or nitrate). <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" issue="6124" page="1210" related-article-type="in-this-issue" vol="339" xlink:href="10.1126/science.1232751">1210</jats:related-article> ) saw no increase in hydrogen peroxide production in antibiotic-exposed cells and found no association between antibiotic exposure and the expected symptoms of oxidative damage, such as the breakdown of iron-sulfur clusters in enzymes or of hydroxyl radical injuries to DNA. Similarly, <jats:bold> Keren <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6124" page="1213" related-article-type="in-this-issue" vol="339" xlink:href="10.1126/science.1232688">1213</jats:related-article> ) found no correlation between the production of ROS, inferred from hydroxyphenyl fluorescein dye measurements, and bacterial survival, nor was there any significant protective effect engendered by thiourea. The results do not support a common mode of action for bactericidal antibiotics mediated by ROS. </jats:p>

<jats:title>It's a SIRT</jats:title> <jats:p> Intense attention has focused on the SIRT1 deacetylase as a possible target for anti-aging drugs. But unexpected complications in assays of SIRT1 activity have made it unclear whether compounds thought to be sirtuin-activating compounds (STACs) are really direct regulators of the enzyme. Further exploration of these effects by <jats:bold> Hubbard <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6124" page="1216" related-article-type="in-this-issue" vol="339" xlink:href="10.1126/science.1231097">1216</jats:related-article> ; see the Perspective by <jats:bold>Yuan and Marmorstein</jats:bold> ) revealed that interaction of SIRT1 with certain substrates allows activation of SIRT1 by STACs and identified critical amino acids in SIRT1 required for these effects. Mouse myoblasts reconstituted with SIRT1 mutated at this amino acid lost their responsiveness to STACs. </jats:p>

<jats:title> On the Origin of Tumor T <jats:sub>regs</jats:sub> </jats:title> <jats:p> The tumor microenvironment is often seeded with regulatory T cells (T <jats:sub>regs</jats:sub> ), which inhibit antitumor immunity. Using mice with genetically driven prostate cancer, <jats:bold> Malchow <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6124" page="1219" related-article-type="in-this-issue" vol="339" xlink:href="10.1126/science.1233913">1219</jats:related-article> ; see the Perspective by <jats:bold>Joshi and Jacks</jats:bold> ) found a population of T <jats:sub>regs</jats:sub> that were enriched in the prostate of tumor-bearing mice. Surprisingly, these cells were also present in female mice and were found to be specific, not for a tumor-specific antigen, but rather for an antigen normally expressed in the prostate. Prostate antigen–specific T <jats:sub>regs</jats:sub> arose in the thymus and their selection was dependent on Aire, a protein that drives the expression of tissue-specific antigens in the thymus. Thus, T <jats:sub>regs</jats:sub> that seed tumors likely arise in the thymus, are not necessarily tumor-specific, and are recruited and/or expand in an organ when a tumor arises. </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>Listen to stories on quantum spintronics, the behavioral economics of retirement savings, the changing practice of oceanography, and more.</jats:p>

<jats:sec> <jats:title>Background</jats:title> <jats:p>Metamaterials (MMs) are smartly engineered structures with rationally designed, nanostructured building blocks that allow us to build devices with distinct responses to light, acoustic waves, and heat flows that are not attainable with naturally available materials.</jats:p> </jats:sec> <jats:sec> <jats:title>Advances</jats:title> <jats:p>The latest developments have shown that optical metasurfaces comprising a class of optical MMs with a reduced dimensionality can exhibit exceptional abilities for controlling the flow of light; achieve the anomalously large photonic density of states; and, similar to their bulk analog, provide superresolution imaging. Such a planar photonics technology is expected to facilitate new physics and enhanced functionality for devices that are distinctly different from those observed in their three-dimensional MM counterparts. As a result, this technology will enable new applications in imaging, sensing, data storage, quantum information processing, and light harvesting.</jats:p> </jats:sec> <jats:sec> <jats:title>Outlook</jats:title> <jats:p>The recent progress in optical metasurfaces can address the major issues hampering the full-scale development of MM technology, such as high loss, cost-ineffective fabrication, and challenging integration. The studies of new, low-loss, tunable plasmonic materials—such as transparent conducting oxides and intermetallics—that can be used as building blocks for metasurfaces will complement the exploration of smart designs and advanced switching capabilities. This progress in metasurface design and realization will lead to novel functionalities and improved performance and may result in the development of new types of ultrathin metasurface designs with unparalleled properties, including increased operational bandwidths and reduced losses. These new designs would also be compatible with planar, low-cost manufacturing. In turn, these advances will lead to ultrathin devices with unprecedented functionalities, ranging from dynamic spatial light modulation to pulse shaping and from subwavelength imaging or sensing to novel quantum optics devices.</jats:p> </jats:sec>