Catálogo de publicaciones - revistas

<jats:p>The balanced expression of two transcription factors controls the development of a subset of T cells that support B cell maturation.</jats:p>

<jats:p>Observations indicate that attempts to limit climate warming by reducing incoming shortwave radiation risk major precipitation changes.</jats:p>

<jats:p>A new focus of the most recoverable gas hydrate deposits is shortening the timeline for the future production of natural gas from this vast resource.</jats:p>

<jats:p>Several dog breeds owe their short legs to a gene duplication event based on reverse transcription of RNA.</jats:p>

<jats:title>Discussing Polymerization Dynamics</jats:title> <jats:p> Actin and tubulin represent the major components of microfilaments and microtubules, which are responsible for the cytoskeletal framework of cells. Together with their recently discovered bacterial counterparts, the mechanisms of assembly and disassembly of polymers of these proteins are fundamental to our understanding of cytoplasmic organization and motility. <jats:bold>Kueh and Mitchison</jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="960" related-article-type="in-this-issue" vol="325" xlink:href="10.1126/science.1168823">960</jats:related-article> ) review mechanisms of cytoskeleton polymerization dynamics and discuss the relative importance of structural plasticity in regulating polymerization. </jats:p>

<jats:p>Several species of deep-sea polychaete worms have been discovered that have a bizarre predator distraction mechanism.</jats:p>

<jats:p>A rare form of lung cancer in children is associated with mutational disruption of an enzyme that generates small noncoding RNAs.</jats:p>

<jats:title>Protein Synthesis Initiation Complex</jats:title> <jats:p> The final step in the initiation phase of protein synthesis is the formation of the first peptide bond, which requires initiator transfer RNA (tRNA) to be bound at the ribosomal P site. Elongation factor P (EF-P) is a protein conserved in all eubacteria that stimulates this initial bond formation. Insight into how this is achieved comes from a structure of <jats:italic>Thermus thermophilus</jats:italic> 70 <jats:italic>S</jats:italic> ribosome bound to EF-P, initiator tRNA, and a short piece of messenger RNA presented by <jats:bold> Blaha <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="966" related-article-type="in-this-issue" vol="325" xlink:href="10.1126/science.1175800">966</jats:related-article> ). EF-P binds between the P and E sites and facilitates proper positioning of initiator tRNA in the P site. A similar mechanism is likely to apply to structurally homologous initiation factors in archea and eukarya. </jats:p>

<jats:title>Toward Detecting Dark Matter Signals</jats:title> <jats:p> Dark matter, whose presence has been inferred indirectly through its gravitational effects on luminous matter, is thought to hold galaxies together and may form most of the matter in the universe. Although its nature is still unknown, theoretical models predict that when certain dark matter particles collide, they annihilate, producing gamma rays. Using a numerical simulation of a galaxy the size of the Milky Way, <jats:bold> Kuhlen <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="970" related-article-type="in-this-issue" vol="325" xlink:href="10.1126/science.1174881">970</jats:related-article> , published online 16 July) investigated the potential signals from dark matter in our galaxy, for the case in which the annihilation rate is boosted by an attractive force between incident dark matter particles. If this enhancement effect is valid, hundreds of dark matter clumps in our galaxy should be detected by the Fermi Gamma-ray Space Telescope. </jats:p>

<jats:title>Saturated Magnetism in Photoexcited Nanocrystals</jats:title> <jats:p> Switching the magnetic state of semiconductors with either an electric field or by light absorption is a key requirement for spintronics, in which devices are based on electronic spin state rather than charge. In semiconductor nanoparticles doped with magnetic ions, excitons can form a spin state, a magnetic polaron, but often the effect is limited to low temperatures (below 30 kelvin) and does not saturate in the absence of an applied magnetic field. <jats:bold> Beaulac <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="973" related-article-type="in-this-issue" vol="325" xlink:href="10.1126/science.1174419">973</jats:related-article> ) report the synthesis of Mn-doped CdSe nanocrystals in which the quantum confinement effects lead to long exciton lifetimes. Photoexcitation results in exchange fields that can exceed 30 Tesla at low temperatures and that persist even up to room temperature in the absence of an applied magnetic field. </jats:p>