Catálogo de publicaciones - revistas

<jats:title>Starvation and Autophagy</jats:title> <jats:p> Starvation stimulates withdrawal from the cell cycle, as well as stimulating autophagy. Are these two events connected? <jats:bold> Lee <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="225" related-article-type="in-this-issue" vol="336" xlink:href="10.1126/science.1218395">225</jats:related-article> ) show a direct and nutrient-sensitive interaction between the tumor suppressor p53 and the essential autophagy gene Atg7. Further, in the absence of Atg7, the p53-dependent induction of the cyclin-dependent kinase inhibitor p21 is inhibited. This leads to Atg7-deficient cells being unable to properly withdraw from the cell cycle under starved conditions. While Atg7 deletion leads to an impairment of p53-mediated cell-cycle arrest, the Atg7-deficient cells hyperactivate p53-mediated cell-death pathways. The physiological importance of this hyperactivation is underscored by the observation that genetic blocking of p53-mediated cell death significantly extended neonatal survival of mice in which Atg7 had been deleted. </jats:p>

<jats:title>Open and Shut Case</jats:title> <jats:p> Voltage-sensing domains (VSDs) control the activity of voltage-gated ion channels to regulate the ion flow that underlies nerve conduction. Structural and biophysical studies have provided insight into voltage gating; however, understanding has been hindered by the lack of a crystal structure of a fully closed state. Starting from a structure of an open conducting state, a voltage-gated K <jats:sup>+</jats:sup> channel, <jats:bold> Jensen <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="229" related-article-type="in-this-issue" vol="336" xlink:href="10.1126/science.1216533">229</jats:related-article> ) used all-atom molecular dynamics simulations to show the conformational changes involved in switching to the closed, nonconducting state. Additional simulations revealed the major steps of channel activation. The computational determination of a closed state may guide development of drugs to treat channelopathies associated with this resting state. </jats:p>

<jats:title>Translation Block</jats:title> <jats:p> MicroRNAs (miRNAs) are small, noncoding RNA genes that are found in the genomes of most eukaryotes, where they play an important role in the regulation of gene expression. Although whether gene activity is repressed by blocking translation of messenger RNA (mRNA) targets, or by promoting their deadenylation and then degradation, has been open to debate. <jats:bold> Bazzini <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="233" related-article-type="in-this-issue" vol="336" xlink:href="10.1126/science.1215704">233</jats:related-article> , published online 15 March) and <jats:bold> Djuranovic <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="237" related-article-type="in-this-issue" vol="336" xlink:href="10.1126/science.1215691">237</jats:related-article> ) looked at early points in the repression reaction in the zebrafish embryo or in Drosophila tissue culture cells, respectively, and found that translation was blocked before target mRNAs were significantly deadenylated and degraded. Thus, miRNAs appear to interfere with the initiation step of translation. </jats:p>

<jats:title>Translation Block</jats:title> <jats:p> MicroRNAs (miRNAs) are small, noncoding RNA genes that are found in the genomes of most eukaryotes, where they play an important role in the regulation of gene expression. Although whether gene activity is repressed by blocking translation of messenger RNA (mRNA) targets, or by promoting their deadenylation and then degradation, has been open to debate. <jats:bold> Bazzini <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="233" related-article-type="in-this-issue" vol="336" xlink:href="10.1126/science.1215704">233</jats:related-article> , published online 15 March) and <jats:bold> Djuranovic <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="237" related-article-type="in-this-issue" vol="336" xlink:href="10.1126/science.1215691">237</jats:related-article> ) looked at early points in the repression reaction in the zebrafish embryo or in Drosophila tissue culture cells, respectively, and found that translation was blocked before target mRNAs were significantly deadenylated and degraded. Thus, miRNAs appear to interfere with the initiation step of translation. </jats:p>

<jats:title>Disrupting Drug Memories</jats:title> <jats:p> In drug recovery programs, conditioned responses to drug cues can be inhibited by extinction protocols. However, extinguished behavioral responses can return after renewed exposure to the drug itself, or to drug-associated paraphernalia, and sometimes these responses reemerge spontaneously. Attempts have been made to disrupt cue-memory reconsolidation or to strengthen extinction learning, but these efforts have often relied on pharmacological agents that either are not approved for human use or cause problematic side effects. <jats:bold> Xue <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="241" related-article-type="in-this-issue" vol="336" xlink:href="10.1126/science.1215070">241</jats:related-article> ; see the Perspective by <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6078" page="167" related-article-type="in-this-issue" vol="336" xlink:href="10.1126/science.1221691"> <jats:bold>Milton and Everitt</jats:bold> </jats:related-article> ) have tried to circumvent the limitations of pharmacological approaches in daily retrieval trials conducted in rats within the short timeframe of the “reconsolidation window” before the extinction sessions reduced drug-induced reinstatement, spontaneous recovery, and renewal of drug seeking. When translated to heroin-addicted humans, similar retrieval trials before extinction sessions impaired cue-induced heroin craving up to 6 months later. This retrieval-extinction procedure is thus a promising non-pharmacological treatment for addiction. </jats:p>

<jats:title>Monkey See, Monkey Read</jats:title> <jats:p> An orthographic object such as a set of letters, and the ability to recognize such sets as words, is a key component of reading. The ability to develop these skills has often been attributed to the prior acquisition of a complex language. For example, we learn how letters sound and thus recognize when a particular letter makes up part of a word. However, orthographic processing is also a visual process, because we learn to recognize words as discrete objects, and the ability to read may thus be related to an ability to recognize and classify objects. <jats:bold> Grainger <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="245" related-article-type="in-this-issue" vol="336" xlink:href="10.1126/science.1218152">245</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="6078" page="168" related-article-type="in-this-issue" vol="336" xlink:href="10.1126/science.1221402">Platt and Adams</jats:related-article> </jats:bold> ) tested orthographic skills in baboons. Captive, but freely ranging, baboons were trained to distinguish real English words from combinations of similar letters that are not words, and they were able to distinguish real words with remarkable accuracy. Thus, a basic ability to recognize words as objects does not require complex linguistic understanding. </jats:p>

<jats:p>Japanese academic reforms over the last decade have encouraged entrepreneurship and technology transfer from universities to industry. These reforms are now yielding results. Science and business leaders hope these changes push Japan into the next phase of innovation development, with increased flexibility and transparency, a more global focus, and more national and international collaboration. Japanese scientists are ready. After delays caused by the March 2011 triple disaster of earthquake, tsunami, and nuclear power plant failure, the lights are on again in Japanese research laboratories. Although recovery and reconstruction are priorities, the long-term goals of developing sustainable energy sources and solving the health challenges of an aging population continue to be major focus areas.</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 quantitative modeling in biology, women in academia, virtual animals, and more.</jats:p>