Catálogo de publicaciones - revistas

<jats:title>Small But Perfectly Formed</jats:title> <jats:p> The imaginal discs of <jats:italic>Drosophila</jats:italic> represent defined larval tissues that give rise to the subsequent adult appendages. These tissues regenerate in response to damage. When the imaginal discs are injured or show tumor growth, they signal to the rest of the larval animal to slow down growth and delay morphogenesis. <jats:bold> Garelli <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="579" related-article-type="in-this-issue" vol="336" xlink:href="10.1126/science.1216735">579</jats:related-article> ) and <jats:bold> Colombani <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="582" related-article-type="in-this-issue" vol="336" xlink:href="10.1126/science.1216689">582</jats:related-article> ) now show that an insulin-like peptide, termed Dilp8, is secreted into the hemolymph (insect “blood”) and participates in the communication between growing organs and the endocrine system to adjust the growth program and maturation time. This collaboration ensures that adults attain the normal size and maintain appropriate proportions and symmetry. </jats:p>

<jats:title>Hooking Up in Water Striders</jats:title> <jats:p> The male water strider <jats:italic>Rheumatobates rileyi</jats:italic> has an extensively modified antenna that is used for forced copulations with females. <jats:bold> Khila <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="585" related-article-type="in-this-issue" vol="336" xlink:href="10.1126/science.1217258">585</jats:related-article> ) describe several microscopic antenna attributes that make the antenna fit perfectly with the female head when the male grasps the female. The features depend upon the expression of the gene <jats:italic>distal-less</jats:italic> ( <jats:italic>dll</jats:italic> ) during antenna development. Reducing the expression of <jats:italic>dll</jats:italic> compromised male grasping traits, while female antennae were unaffected. </jats:p>

<jats:title>Give It Time</jats:title> <jats:p> Experimental ecological studies in recent years have provided a great deal of insight into how species diversify and influence ecosystem properties, but in most cases the experiments have been relatively brief (up to ∼5 years). <jats:bold> Reich <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="589" related-article-type="in-this-issue" vol="336" xlink:href="10.1126/science.1217909">589</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="6081" page="552" related-article-type="in-this-issue" vol="336" xlink:href="10.1126/science.1222102">Cardinale</jats:related-article> </jats:bold> ) performed two 13- and 15-year grassland experiments and found that the effects of plant species richness on community-level processes like biomass production tend to be saturating at early stages but that those impacts grow stronger and more linear as experiments run longer. Stronger influences through time were largely driven by increasing amounts of “complementarity” among species, and these trends were correlated with greater expression of functional diversity in multispecies assemblages. Thus, the effects of diversity grow stronger through time as species gain more and more opportunity to vary in their use of the limiting biological resources in their environment, which emphasizes the functional importance of maintaining diversity in ecosystems. </jats:p>

<jats:title>Not Broken Until Repaired</jats:title> <jats:p> Humans, and indeed most eukaryotes, have linear chromosomes with two DNA ends, known as telomeres. Cells have evolved sophisticated systems to repair broken chromosomes, which specifically recognize DNA ends as damage. Telomeres are protected from these repair systems, which would otherwise wreak havoc in the cell, causing genome aberrations that, ironically, can lead to cancer. To understand all the possible threats to telomeres <jats:bold>Sfeir and de Lange</jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="593" related-article-type="in-this-issue" vol="336" xlink:href="10.1126/science.1218498">593</jats:related-article> ) mutated components of the mouse shelterin protein complex, which forms a protective cap over the telomere ends, rendering telomeres completely devoid of the complex (and packaged only in nucleosomal chromatin). These “naked” telomeres were vulnerable to six DNA repair–related pathways: classical and alternative nonhomologous end joining; ATM and ATR signaling pathways; homology directed recombination; and unmitigated DNA resection. </jats:p>

<jats:title>Blood Pressure Gauge</jats:title> <jats:p> Endothelial cells line blood vessels and, by interacting with smooth muscle, can help to control blood flow. <jats:bold> Sonkusare <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="597" related-article-type="in-this-issue" vol="336" xlink:href="10.1126/science.1216283">597</jats:related-article> ; see the Perspective by <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6081" page="546" related-article-type="in-this-issue" vol="336" xlink:href="10.1126/science.1222540"> <jats:bold> Lederer <jats:italic>et al.</jats:italic> </jats:bold> </jats:related-article> ) describe how signaling in endothelial cells controls contraction of surrounding smooth muscle cells, which provides an important mechanism for control of blood pressure. A calcium-sensitive fluorescent protein was expressed in endothelial cells of mouse arteries to image small changes in calcium concentration that appear to represent opening of single TRPV4 ion channels and consequent influx of calcium into the cell. Clustering of the channels allowed cooperative activation of a handful of channels, which appeared to produce a sufficient calcium signal to open another set of calcium-sensitive potassium channels. The resulting depolarization of the endothelial cells then passes an electrical connection to smooth muscle cells through gap junctions. </jats:p>

<jats:title>Metabolic Networking</jats:title> <jats:p> Understanding complex biological networks, such as those underlying cellular metabolism, requires evaluation not only of the network connections but also the flux through the various biochemical pathways. <jats:bold> Schuetz <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="601" related-article-type="in-this-issue" vol="336" xlink:href="10.1126/science.1216882">601</jats:related-article> ) explored the evolutionary constraints that appear to be most critical for the metabolic network in the bacteria <jats:italic>Escherichia coli</jats:italic> using a combination of experimental tests of reaction flux under various conditions along with mathematical modeling. As a pathway evolves, there are likely to be competing objectives that must be satisfied. Key objectives for the bacterium were strong performance under a given environmental condition, balanced by a requirement for adaptability—minimizing the adjustments required to respond to changed conditions. </jats:p>

<jats:title>Gene Expression by Remote Control</jats:title> <jats:p> Techniques that allow remote, noninvasive activation of specific genes in specific tissues could one day be applied to regulate expression of therapeutic proteins in a clinical setting. In a proof-of-concept study, <jats:bold> Stanley <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="604" related-article-type="in-this-issue" vol="336" xlink:href="10.1126/science.1216753">604</jats:related-article> ) showed that heating of iron oxide nanoparticles by radiowaves can remotely activate insulin gene expression in cultured cells and in a mouse model. Heating of membrane-targeted nanoparticles induced opening of a temperature-sensitive membrane channel in the cells and triggered calcium entry. The intracellular calcium signal in turn stimulated expression of an engineered insulin gene, leading to the synthesis and release of insulin. In experiments with mice bearing tumors that expressed the engineered insulin gene, exposure to radiowaves promoted secretion of insulin from the tumors and lowered blood glucose levels in the animals. </jats:p>

<jats:title>Blooming Succession</jats:title> <jats:p> Algal blooms in the ocean will trigger a succession of microbial predators and scavengers. <jats:bold> Teeling <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="6081" page="608" related-article-type="in-this-issue" vol="336" xlink:href="10.1126/science.1218344">608</jats:related-article> ) used a combination of microscopy, metagenomics, and metaproteomics to analyze samples from a North Sea diatom bloom over time. Distinct steps of polysaccharide degradation and carbohydrate uptake could be assigned to clades of Flavobacteria and Gammaproteobacteria, which differ profoundly in their transporter profiles and their uptake systems for phosphorus. The phytoplankton/bacterioplankton coupling in coastal marine systems is of crucial importance for global carbon cycling. Bacterioplankton clade succession following phytoplankton blooms may be predictable enough that it can be included in models of global carbon cycling. </jats:p>

<jats:p>Emotionally healthy older adults show a reduced responsiveness to regret when performing a sequential decision task.</jats:p>

<jats:p>The show includes remotely controlled gene expression, evidence for water on ancient Mars, nanopore sequencing advances, and more.</jats:p>