Catálogo de publicaciones - revistas

<jats:title>Making RNA in the prebiotic world</jats:title> <jats:p> The RNA World hypothesis posits that RNA was one of the first self-replicating molecules leading to the origin of life. The nucleotide bases of RNA—A, U, C, and G—are chemically complex, and it has been unclear how the large purine bases A and G might have arisen on prebiotic Earth. Becker <jats:italic>et al.</jats:italic> show that the A and G bases can be synthesized easily and in high yield from prebiotically reasonable precursors, lending further support to the RNA World hypothesis. </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="6287" page="833" related-article-type="in-this-issue" vol="352" xlink:href="10.1126/science.aad2808">833</jats:related-article> </jats:p>

<jats:title>Epistasis and mutational fitness landscape</jats:title> <jats:p> A fitness landscape of a gene defines the molecular potential of evolution. This can help us understand the current state of evolution as well as predict unrealized potential. Using deep sequencing to examine mutations in nonessential genes that affect the growth of yeast strains, two studies have generated fitness landscapes and measured the effect of epistatic interactions (see the Perspective by He and Liu). Li <jats:italic>et al.</jats:italic> generated a library of mutants in a transfer RNA gene, including all single and many double and multiple mutants. The RNA secondary structure was generally predictive of bases under selection. Similarly, Puchta <jats:italic>et al.</jats:italic> assessed a small nucleolar RNA gene for the fitness effects of individual mutations, which correlated with evolutionary conservation and structural stability. Both studies suggest that epistasis—the combined functional effect—for double substitutions is more often negative than positive. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue pp. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6287" page="837" related-article-type="in-this-issue" vol="352" xlink:href="10.1126/science.aae0568">837</jats:related-article> and <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6287" page="840" related-article-type="in-this-issue" vol="352" xlink:href="10.1126/science.aaf0965">840</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6287" page="769" related-article-type="in-this-issue" vol="352" xlink:href="10.1126/science.aaf7543">769</jats:related-article> </jats:p>

<jats:title>Epistasis and mutational fitness landscape</jats:title> <jats:p> A fitness landscape of a gene defines the molecular potential of evolution. This can help us understand the current state of evolution as well as predict unrealized potential. Using deep sequencing to examine mutations in nonessential genes that affect the growth of yeast strains, two studies have generated fitness landscapes and measured the effect of epistatic interactions (see the Perspective by He and Liu). Li <jats:italic>et al.</jats:italic> generated a library of mutants in a transfer RNA gene, including all single and many double and multiple mutants. The RNA secondary structure was generally predictive of bases under selection. Similarly, Puchta <jats:italic>et al.</jats:italic> assessed a small nucleolar RNA gene for the fitness effects of individual mutations, which correlated with evolutionary conservation and structural stability. Both studies suggest that epistasis—the combined functional effect—for double substitutions is more often negative than positive. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue pp. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6287" page="837" related-article-type="in-this-issue" vol="352" xlink:href="10.1126/science.aae0568">837</jats:related-article> and <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6287" page="840" related-article-type="in-this-issue" vol="352" xlink:href="10.1126/science.aaf0965">840</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6287" page="769" related-article-type="in-this-issue" vol="352" xlink:href="10.1126/science.aaf7543">769</jats:related-article> </jats:p>

<jats:title>An oncohistone deranges inhibitory chromatin</jats:title> <jats:p> Missense mutations (that change one amino acid for another) in histone H3 can produce a so-called oncohistone and are found in a number of pediatric cancers. For example, the lysine-36–to-methionine (K36M) mutation is seen in almost all chondroblastomas. Lu <jats:italic>et al.</jats:italic> show that K36M mutant histones are oncogenic, and they inhibit the normal methylation of this same residue in wild-type H3 histones. The mutant histones also interfere with the normal development of bone-related cells and the deposition of inhibitory chromatin marks. </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="6287" page="844" related-article-type="in-this-issue" vol="352" xlink:href="10.1126/science.aac7272">844</jats:related-article> </jats:p>

<jats:p>From van Leeuwenhoek to the new millennium, microscopy was governed by one seemingly unbreakable principle: The ability to resolve two objects is constrained by the wavelength of the light used to view them. But in 2000, researchers showed this so-called diffraction limit could be broken, unveiling over the next decade an alphabet soup of superresolution techniques from GSDIM and PALM to SIM, STED, and STORM. The resulting images are both beautiful and revealing, documenting biological phenomena and structures that researchers never even knew they were missing.</jats:p>

<jats:p>A weekly roundup of information on newly offered instrumentation, apparatus, and laboratory materials of potential interest to researchers.</jats:p>