Catálogo de publicaciones - revistas

<jats:title>Translational Rearrangements</jats:title> <jats:p> Conformational changes in the ribosome are required to translocate messenger RNA and transfer RNA (tRNA) during protein biosynthesis. For example, after peptide bond formation, rotation of the large and small subunits results in a hybrid state of tRNA binding—tRNAs are bound respectively in the aminoacyl-tRNA (A) and peptidyl-tRNA (P) sites in the small subunit, but in the P and exit-tRNA (E) sites on the large subunit. <jats:bold> Zhang <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="1014" related-article-type="in-this-issue" vol="325" xlink:href="10.1126/science.1175275">1014</jats:related-article> ) now describe x-ray structures of the intact <jats:italic>Escherichia coli</jats:italic> ribosome, either in the apo form or with one or two anticodon stem-loop tRNA mimics bound, which show intermediate states of intersubunit rotation. The structures provide insight into how the interface between the large and small subunits rearranges in discrete steps to reach the hybrid state. </jats:p>

<jats:title>Making Memories Last</jats:title> <jats:p> How can memory traces persist over days or weeks, despite the short-lived nature and rapid turnover of their molecular substrates? It has recently been reported that, in order to persist, an otherwise rapidly forgotten long-term memory requires BDNF (brain-derived neurotrophic factor) expression in the hippocampus 12 hours post training. <jats:bold> Rossato <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="1017" related-article-type="in-this-issue" vol="325" xlink:href="10.1126/science.1172545">1017</jats:related-article> ) now show that this mechanism is gated into action by activation of the ventral tegmental area acting upon dopamine D1 receptors in the hippocampus. Time-limited <jats:italic>N</jats:italic> -methyl- <jats:sc>d</jats:sc> -aspartate receptor–dependent activity in the ventral tegmental area–hippocampal circuitry underlies the delayed increase in BDNF levels in the hippocampus 12 hours after inhibitory avoidance, a hippocampus-dependent form of learning. </jats:p>

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<jats:p>The show includes optimizing the distribution of influenza vaccines, archaeology in China, bioluminescent deep-sea worms, and more.</jats:p>