Catálogo de publicaciones - revistas

<jats:title>Conquering Rice Sterility</jats:title> <jats:p> The hybrid sterility occurring among rice species has long been a puzzle and hampers progress in breeding crops with improved performance and yield characteristics. <jats:bold> Yang <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="1336" related-article-type="in-this-issue" vol="337" xlink:href="10.1126/science.1223702">1336</jats:related-article> ) have identified three linked genes encoding a killer, a partner, and a protector protein. The killer and partner work together to kill female gametes not carrying the functional protector, resulting in preferential transmission of gametes carrying the functional protector, which also causes segregation distortion in the progeny. This explanation for how reproductive isolation is maintained among species of rice, and perhaps other organisms, also offers approaches for boosting yields by intersubspecific heterosis. </jats:p>

<jats:title>Dissecting SNARE Zippering</jats:title> <jats:p> The SNARE complex is critical for vesicle fusion, notably during release of neurotransmitters at synapses. Understanding the biophysics of SNARE assembly has been the object of several structural studies, and yet much remains to be understood about the mechanisms. Now, <jats:bold> Gao <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="1340" related-article-type="in-this-issue" vol="337" xlink:href="10.1126/science.1224492">1340</jats:related-article> , published online 16 August; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6100" page="1300" related-article-type="in-this-issue" vol="337" xlink:href="10.1126/science.1228654">Rizo</jats:related-article> </jats:bold> ) describe the results of cell-free experiments using optical tweezers to elucidate assembly and disassembly of the SNARE complex. Direct observations of SNARE intermediates revealed multiple steps of the assembly process, along with the associated energetics and kinetics. Applying forces similar to those occurring during fusion, an intermediate was stabilized, and the derived mechanism indicates how neurotransmitter release may be regulated. </jats:p>

<jats:title>Influenza Antibodies, Part B</jats:title> <jats:p> With its ability to reassort in animal hosts like pigs and birds, and to cause pandemics, influenza A viruses are often in the spotlight. However, a substantial portion of the annual flu burden is also the result of influenza B virus, which is a single influenza type that is characterized by two antigenically and genetically distinct lineages. <jats:bold> Dreyfus <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="1343" related-article-type="in-this-issue" vol="337" xlink:href="10.1126/science.1222908">1343</jats:related-article> , published online 9 August) identify three monoclonal human antibodies that are able to protect against lethal infection with both lineages of influenza B virus in mice. Two antibodies, which bind to distinct regions of the viral hemagluttinin (HA) molecule, neutralize multiple strains from both lineages of influenza B virus, whereas the third antibody binds to the stem region of HA and is able to neutralize both influenza A and B strains. The structural data from these antibodies bound to HA, together with already known antibodies targeting influenza A, may provide clues for designing a universal vaccine to protect against both influenza virus types. </jats:p>

<jats:title>Dynamic Assembly</jats:title> <jats:p> Structural characterization of protein complexes has yielded significant insight into biological function; however, most structural techniques require stable, homogenous samples. This presents a challenge in characterizing transient signaling complexes. <jats:bold> Herzog <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="1348" related-article-type="in-this-issue" vol="337" xlink:href="10.1126/science.1221483">1348</jats:related-article> ) used chemical cross-linking and mass spectroscopy (XL-MS) to characterize the modular and dynamic interaction network involving phosphatase 2A (PP2A), which interacts with tens of regulatory and adaptor proteins in diverse signaling pathways. They found 176 interprotein and 569 intraprotein distance restraints that delineated the topology of the network. The study establishes the importance of XL-MS in the suite of structural methods used to characterize dynamic assemblies. </jats:p>

<jats:title>Infectious Phenotype</jats:title> <jats:p> The pathogenic yeast <jats:italic>Candida albicans</jats:italic> needs to adopt a filamentous form to invade tissues. The distantly related yeast species <jats:italic>Saccharomyces cerevisiae</jats:italic> also takes on a filamentous form for nutrient foraging. Comparing genome-wide deletion libraries between the two species, <jats:bold> Ryan <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="1353" related-article-type="in-this-issue" vol="337" xlink:href="10.1126/science.1224339">1353</jats:related-article> ) identified genes involved in three different filamentous yeast phenotypes and found unique genes for each of these phenotypes. However, in addition, core genes, including a previously unknown conserved regulator, appear to have homologous roles in regulating filamentous growth in these distantly related yeast species. </jats:p>

<jats:title>A Critical Period for Glia</jats:title> <jats:p> The brain develops in fits and starts—while one system is completed, another system may still be under construction. Such transient states are known as critical periods, and during these specific aspects of brain development may become more sensitive to outside agents than they would be later. <jats:bold> Makinodan <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="1357" related-article-type="in-this-issue" vol="337" xlink:href="10.1126/science.1220845">1357</jats:related-article> ) observed the effect of environmental conditions on the brains of mice bioengineered to develop fluorescent oligodendrocytes. The mice were exposed to a variety of social conditions during rearing, ranging from isolation to a normal laboratory cage setting, or to settings enriched with extra buddies and a steady rotation of new play toys. The results show that social isolation leaves a developmental trace that persists into adulthood. Specifically, they found that oligodendrocytes, which produce the myelin that insulates neurons, were underdeveloped, suggesting that there may be a critical period that governs development of these glial oligodendrocyte cells. </jats:p>

<jats:title>Intergenerational Transposable Shutdown</jats:title> <jats:p> Transposable elements (TEs) are a potential threat, especially to the germline genome. In many eukaryotes, TEs are shut down by DNA methylation and/or small-RNA–mediated silencing. Therefore, it seems counterintuitive that results obtained by <jats:bold> Ibarra <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="1360" related-article-type="in-this-issue" vol="337" xlink:href="10.1126/science.1224839">1360</jats:related-article> ) on <jats:italic>Arabidopsis</jats:italic> showed that in the cells of this plant's sexual apparatus, many small TEs are demethylated by DEMETER (DME) DNA glycosylase and become activated. But it turns out that activation of the TEs triggers the formation of small-interfering RNAs, which in these experiments were seen to travel from the surrounding cells to the egg. Thus, activation of TEs in the companion cells “immunizes” the gametes via the interfering RNAs that shutdown the TEs in the gametes permanently. </jats:p>

<jats:p>The show includes grandma killer whales, who invented the Higgs, do-it-yourself lab equipment, and more.</jats:p>

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