Catálogo de publicaciones - revistas

<jats:title>An unconventional route to protection</jats:title><jats:p>One promising approach toward an HIV-1 vaccine involves infecting people with cytomegalovirus engineered to express proteins from HIV-1. This approach, which works by eliciting virus-killing CD8<jats:sup>+</jats:sup>T cells, provides robust protection in nonhuman primate models. Hansen<jats:italic>et al.</jats:italic>have found out why this approach is so effective. Normally, peptide antigens presented by major histocompatibility complex-1a (MHC-Ia) activate CD8<jats:sup>+</jats:sup>T cells. In vaccinated monkeys, however, CD8<jats:sup>+</jats:sup>T cells reacted to peptide antigens presented by MHC-E molecules instead. Moreover, MHC-E could present a much wider range of peptides than MHC-Ia.</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="6274" page="714" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aac9475">714</jats:related-article></jats:p>

<jats:title>Quantitative analysis of epigenetic memory</jats:title> <jats:p> To explore quantitative and dynamic properties of transcriptional regulation by epigenetic modifications, Bintu <jats:italic>et al.</jats:italic> monitored a transcriptional reporter gene carried on a human artificial chromosome in Chinese hamster ovary cells (see the Perspective by Keung and Khalil). They measured effects of DNA methylation and histone modifications by methylation or deacetylation in single cells using time-lapse microscopy. Silencing was an all-or-none, stochastic event, so graded adjustments to transcription occurred from changes in the proportion of cells that responded. Furthermore, the duration of recruitment of the chromatin regulators determined the fraction of cells that were silenced. Thus, distinct modifiers can produce different characteristics of epigenetic memory. </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="6274" page="720" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aab2956">720</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6274" page="661" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aaf1647">661</jats:related-article> </jats:p>

<jats:title>The SAGA of removing nucleosomal ubiquitin</jats:title> <jats:p> Covalent modifications of histones play a critical role in gene regulation. The addition of the small protein ubiquitin to histone H2B in nucleosomes is a mark of actively transcribed chromatin. Morgan <jats:italic>et al.</jats:italic> determined the crystal structure of a nucleosome bound by a module of the SAGA protein complex that removes ubiquitin from histone H2B (see the Perspective by Workman). The structure suggests that the deubiquitinating module can remove ubiquitin at multiple points during the transcription cycle. </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="6274" page="725" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aac5681">725</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6274" page="667" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aaf1495">667</jats:related-article> </jats:p>

<jats:title>Controlling supplies for DNA and RNA synthesis</jats:title> <jats:p> The mTORC1 protein kinase complex regulates anabolic metabolism and coordinates cellular signals that promote growth with availability of required precursor metabolites. Signaling through mTORC1 controls pyrimidine synthesis. Ben-Sahra <jats:italic>et al.</jats:italic> found that mTORC1 also functions by a different mechanism to regulate purine biosynthesis, thus generating precursors for the synthesis of RNA and DNA (see the Perspective by Ma and Jones). Signaling by mTORC1 caused accumulation of the transcription factor ATF4, which enhances production of the enzyme methylenetetrahydrofolate dehydrogenase 2, thus leading to increased production of the purine nucleotides needed for cell growth. </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="6274" page="728" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aad0489">728</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6274" page="670" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aaf1929">670</jats:related-article> </jats:p>

<jats:title>Spatial control of cellular enzymes</jats:title> <jats:p> Purine is a building block of DNA and also a component of ATP that is used as an energy source in the cell. Enzymes involved in purine biosynthesis organize into dynamic bodies called purinosomes. French <jats:italic>et al.</jats:italic> found that purinosomes colocalize with mitochondria, organelles that generate ATP (see the Perspective by Ma and Jones). Dysregulation of mitochondria caused an increase in the number of purinosomes. This suggests a synergy, with the purinosomes supplying the purine required for ATP production and in turn using ATP in the biosynthetic pathway. A master regulator of cellular metabolism, mTOR, appears to mediate the association of purinosomes and mitochondria. This could make purine and ATP synthesis responsive to changes in the metabolic needs of the cell. </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="6274" page="733" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aac6054">733</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6274" page="670" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aaf1929">670</jats:related-article> </jats:p>

<jats:title>The legacy of human-Neandertal interbreeding</jats:title> <jats:p> Non-African humans are estimated to have inherited on average 1.5 to 4% of their genomes from Neandertals. However, how this genetic legacy affects human traits is unknown. Simonti <jats:italic>et al.</jats:italic> combined genotyping data with electronic health records. Individual Neandertal alleles were correlated with clinically relevant phenotypes in individuals of European descent. These archaic genetic variants were associated with medical conditions affecting the skin, the blood, and the risk of depression. </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="6274" page="737" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aad2149">737</jats:related-article> </jats:p>

<jats:p> The 2016 Gordon Research Conference schedule was published on pages 742 to 770 of this issue of the print version of <jats:italic>Science</jats:italic> . The current schedule can also be found online at <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://www.grc.org/">www.grc.org/</jats:ext-link> . </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>graded for easy DNA sequencing is a minor annoyance. They simply prepare another, better sample from the abundant source material they have on hand in cultured cells, laboratory animals, or a freezer full of tissues. But what if the only available specimen is an arsenic-preserved pelt from 150 years ago, a pile of mummified dung found in a cave, or a single formalin-fixed pathology slide? As sequencing technology steadily improves, such irremediably difficult samples have gradually begun yielding usable sequences.</jats:p>