Catálogo de publicaciones - revistas

<jats:p>Diurnal metabolic changes in circadian clock neurons are coupled to changes in potassium channel activity.</jats:p>

<jats:title>Take Another Cap</jats:title> <jats:p> Selective cytosolic protein degradation is mediated primarily by the proteasome, which is comprised of a core peptidase and a regulatory cap. Current dogma holds that the 20 <jats:italic>S</jats:italic> core peptidase of the proteasome functions exclusively with the 19 <jats:italic>S</jats:italic> regulatory particle in eukaryotes, with PAN in archaea, and with Mpa in mycobacteria. <jats:bold>Barthelme and Sauer</jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="843" related-article-type="in-this-issue" vol="337" xlink:href="10.1126/science.1224352">843</jats:related-article> , published online 26 July 2012; see the Perspective by <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6096" page="813" related-article-type="in-this-issue" vol="337" xlink:href="10.1126/science.1227301"> <jats:bold>Matouschek and Finley</jats:bold> </jats:related-article> ) now suggest that another type of proteasome can assemble in archaea consisting of the double-ring AAA+ protein, Cdc48, in complex with the 20 <jats:italic>S</jats:italic> core protease. </jats:p>

<jats:title>Biology Made Me Do It</jats:title> <jats:p> Introducing evidence of a biological basis of dysfunctional behavior might induce a judge to impose a lighter sentence upon defendants on the grounds that their innate biology lessened personal responsibility for their actions. On the other hand, it might also plausibly lead to a longer sentence on the grounds that this biological predisposition would imply a higher risk of future criminal acts. <jats:bold> Aspinwall <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="846" related-article-type="in-this-issue" vol="337" xlink:href="10.1126/science.1219569">846</jats:related-article> ) analyzed sentencing opinions from a nationwide group of judges in the United States of a scenario closely modeled on a real-life case. Varying two factors—whether evidence for a biological basis was presented and whether it was offered by the defense or by the prosecution—revealed an overall lessening of sentences when biology was invoked. </jats:p>

<jats:title>How to Make a Place Cell</jats:title> <jats:p> Hippocampal place cells have been studied for more than 40 years, yet the mechanisms underlying their remarkable spatial tuning are still not established. Using whole-cell patch-clamp recordings in freely moving rats, <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="849" related-article-type="in-this-issue" vol="337" xlink:href="10.1126/science.1221489">849</jats:related-article> ) changed the baseline membrane potential in hippocampal pyramidal neurons. Place fields arose spontaneously in otherwise silent pyramidal cells after depolarization when the membrane voltage reached a threshold. Place cells in the hippocampus and grid cells in the entorhinal cortex are thought to provide the framework for spatial navigation in an animal. However, it is still unclear how the hexagonal symmetry that is so prominent in grid cells emerges. While recording from the entorhinal cortex and in the pre- and parasubiculum during spatial behavior in the rat, <jats:bold> Krupic <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="853" related-article-type="in-this-issue" vol="337" xlink:href="10.1126/science.1222403">853</jats:related-article> ) discovered that many forms of spatial periodicity exist in neurons in these structures. The grid cells seem to reflect a subset of this larger set, generated by self-organized dynamics. </jats:p>

<jats:title>How to Make a Place Cell</jats:title> <jats:p> Hippocampal place cells have been studied for more than 40 years, yet the mechanisms underlying their remarkable spatial tuning are still not established. Using whole-cell patch-clamp recordings in freely moving rats, <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="849" related-article-type="in-this-issue" vol="337" xlink:href="10.1126/science.1221489">849</jats:related-article> ) changed the baseline membrane potential in hippocampal pyramidal neurons. Place fields arose spontaneously in otherwise silent pyramidal cells after depolarization when the membrane voltage reached a threshold. Place cells in the hippocampus and grid cells in the entorhinal cortex are thought to provide the framework for spatial navigation in an animal. However, it is still unclear how the hexagonal symmetry that is so prominent in grid cells emerges. While recording from the entorhinal cortex and in the pre- and parasubiculum during spatial behavior in the rat, <jats:bold> Krupic <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="853" related-article-type="in-this-issue" vol="337" xlink:href="10.1126/science.1222403">853</jats:related-article> ) discovered that many forms of spatial periodicity exist in neurons in these structures. The grid cells seem to reflect a subset of this larger set, generated by self-organized dynamics. </jats:p>

<jats:title>All TOGether Now</jats:title> <jats:p> αβ-Tubulin is the polymerizing subunit of microtubules, which are dynamic polymers that have essential roles in cell division and intracellular organization. TOG domains are αβ-tubulin binding modules that occur in the evolutionarily conserved Stu2p/XMAP215 family of proteins and promote microtubule elongation. <jats:bold> Ayaz <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="857" related-article-type="in-this-issue" vol="337" xlink:href="10.1126/science.1221698">857</jats:related-article> ) used crystallographic and biochemical experiments to reveal that the TOG1 domain interacts with guanosine triphosphate–bound αβ-tubulin in a conformation-selective manner, binding preferentially to a “curved,” microtubule-incompatible conformation. The binding mode apparently excludes analogous binding of a second TOG domain to the same heterodimer and may help to ensure polarized growth of microtubules. </jats:p>

<jats:title>Truthful Embellishments</jats:title> <jats:p> Exaggerated ornaments such as beetle horns, deer antlers, and extreme tail lengths in birds are typically assumed to be subject to sexual selection because they signal the quality of an individual's breeding status—but how? <jats:bold> Emlen <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="860" related-article-type="in-this-issue" vol="337" xlink:href="10.1126/science.1224286">860</jats:related-article> , published online 26 July) present a general mechanistic model for the evolution of exaggerated traits, proposing that sensitivity to the insulin response pathway can explain variation among individuals. The exaggerated size of such ornaments and their increased variability between individuals are a result of sexual selection for traits that are honest signals of the fitness of the individual. </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 citizens' roles in protecting species, biological evidence in courts, sequestration of the U.S. research budget, and more.</jats:p>

<jats:p>A materials scientist turned visual artist illuminates the microscopic processes happening all around us.</jats:p>