Catálogo de publicaciones - revistas

<jats:p>Cognitive processes require working memory (WM) that involves a brief period of memory retention known as the delay period. Elevated delay-period activity in the medial prefrontal cortex (mPFC) has been observed, but its functional role in WM tasks remains unclear. We optogenetically suppressed or enhanced activity of pyramidal neurons in mouse mPFC during the delay period. Behavioral performance was impaired during the learning phase but not after the mice were well trained. Delay-period mPFC activity appeared to be more important in memory retention than in inhibitory control, decision-making, or motor selection. Furthermore, endogenous delay-period mPFC activity showed more prominent modulation that correlated with memory retention and behavioral performance. Thus, properly regulated mPFC delay-period activity is critical for information retention during learning of a WM task.</jats:p>

<jats:title>Making adjustments for a new neighborhood</jats:title> <jats:p> Competition between species drives the acquisition of diversity. Stuart <jats:italic>et al.</jats:italic> introduced a non-native anole lizard to natural experimental islands. In response, the original inhabitants adopted higher perches in the trees, where the larger invader was at a disadvantage. Within about 3 years—or 20 generations—the shift led to inherited morphological changes in the native lizards, including their growing larger toepads. </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="6208" page="463" related-article-type="in-this-issue" vol="346" xlink:href="10.1126/science.1257008">463</jats:related-article> </jats:p>

<jats:title>Mountain dwellers of the Pleistocene</jats:title> <jats:p> Humans colonized the inhospitable high Andes at least 11.5 thousand years ago. Rademaker <jats:italic>et al.</jats:italic> unearthed evidence of hunter-gatherer occupation at heights of almost 4500 m in Peru in two open-air sites. The sites contained more than 750 tools, including likely spearheads and scrapers. A nearby rockshelter with sooted ceilings and floor detritus may have been a campsite. The sites were probably used seasonally for hunting vicuña and other high-altitude prey. </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="6208" page="466" related-article-type="in-this-issue" vol="346" xlink:href="10.1126/science.1258260">466</jats:related-article> </jats:p>

<jats:title>Sex determination driven by community cooperation</jats:title> <jats:p> An optimized ratio of male and females in a sexually reproducing population helps to generate the genetic diversity useful to a species in a changing world. Tanaka <jats:italic>et al.</jats:italic> studied a fern in which the sex ratio is adjusted not by individual identity, but by signaling between individual plants (see the Perspective by Sun). Early-maturing individual ferns express some of the biosynthetic genes needed to make a precursor of the plant hormone gibberellin, which they secrete into the environment. Younger ferns, which express the enzymes needed to finalize synthesis of gibberellin, take up the signal and in response develop the organs that produce male gametes. </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="6208" page="469" related-article-type="in-this-issue" vol="346" xlink:href="10.1126/science.1259923">469</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6208" page="423" related-article-type="in-this-issue" vol="346" xlink:href="10.1126/science.1260948">423</jats:related-article> </jats:p>

<jats:title>Flu mimics damaged proteins during entry</jats:title> <jats:p> Viruses are master manipulators. The early stages of how flu viruses enter cells are very well understood, but Banerjee <jats:italic>et al.</jats:italic> describe a new wrinkle (see the Perspective by Rajsbaum and García-Sastre). It seems that the virus carries with it into the cell ubiquitin: a molecule involved in marking proteins for destruction. The virus then exploits host cell machinery involved in recognizing and dealing with damaged proteins to uncoat its own RNA genome, ready to continue its path toward successful infection. </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="6208" page="473" related-article-type="in-this-issue" vol="346" xlink:href="10.1126/science.1257037">473</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6208" page="427" related-article-type="in-this-issue" vol="346" xlink:href="10.1126/science.1261509">427</jats:related-article> </jats:p>

<jats:title>How to stop after copying the genome</jats:title> <jats:p> Replication is highly regulated: Failure to copy any part of the genome or copying parts of it more than once can cause genome instability with potentially disastrous consequences. Maric <jats:italic>et al.</jats:italic> and Priego Moreno <jats:italic>et al.</jats:italic> show that the DNA replication machinery, which stably encircles DNA during the duplication process, is actively disassembled once replication is complete (see the Perspective by Bell). The protein ring encircling the DNA is covalently modified, which allows it to be opened and the whole replication complex to be removed from DNA by a special disassembly complex. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" related-article-type="in-this-issue" xlink:href="10.1126/science.1253596">10.1126/science.1253596</jats:related-article> , p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6208" page="477" related-article-type="in-this-issue" vol="346" xlink:href="10.1126/science.1253585">477</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6208" page="418" related-article-type="in-this-issue" vol="346" xlink:href="10.1126/science.1261245">418</jats:related-article> </jats:p>

<jats:title>Building with alphahelical coiled coils</jats:title> <jats:p> Understanding how proteins fold into well-defined three-dimensional structures has been a longstanding challenge. Increased understanding has led to increased success at designing proteins that mimic existing protein folds. This raises the possibility of custom design of proteins with structures not seen in nature. Thomson <jats:italic>et al.</jats:italic> describe the design of channelcontaining α-helical barrels, and Huang <jats:italic>et al.</jats:italic> designed hyperstable helical bundles. Both groups used rational and computational design to make new protein structures based on α-helical coiled coils but took different routes to reach different target structures. </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="6208" page="485" related-article-type="in-this-issue" vol="346" xlink:href="10.1126/science.1257452">485</jats:related-article> , p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6208" page="481" related-article-type="in-this-issue" vol="346" xlink:href="10.1126/science.1257481">481</jats:related-article> </jats:p>

<jats:title>Building with alphahelical coiled coils</jats:title> <jats:p> Understanding how proteins fold into well-defined three-dimensional structures has been a longstanding challenge. Increased understanding has led to increased success at designing proteins that mimic existing protein folds. This raises the possibility of custom design of proteins with structures not seen in nature. Thomson <jats:italic>et al.</jats:italic> describe the design of channelcontaining α-helical barrels, and Huang <jats:italic>et al.</jats:italic> designed hyperstable helical bundles. Both groups used rational and computational design to make new protein structures based on α-helical coiled coils but took different routes to reach different target structures. </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="6208" page="485" related-article-type="in-this-issue" vol="346" xlink:href="10.1126/science.1257452">485</jats:related-article> , p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6208" page="481" related-article-type="in-this-issue" vol="346" xlink:href="10.1126/science.1257481">481</jats:related-article> </jats:p>

<jats:p>On this week's show: The earliest high-altitude humans.</jats:p>

<jats:p>Over the past 10 years, light sheet microscopy (or selective plane illumination microscopy, SPIM) has transformed the microscopy field, offering a faster, less phototoxic technique than conventional methods that can create true 3-D images. Ideal for observing living organisms and the cellular dynamics of biological systems, this method uses a unique illumination approach to achieve high penetration depths, fast imaging speeds, and subcellular-level resolution. Because a specimen is illuminated with a sheet of light rather than a focused laser beam, only regions directly exposed to light will fluoresce—creating minimal photo-induced tissue damage. In this webinar, the speakers will discuss their own uses of light sheet microscopy and provide insight into its different applications, including open source SPIM and the dynamic behavior of subcellular components within live specimens.</jats:p>