Catálogo de publicaciones - revistas

<jats:title>Be-Deviled Cancer</jats:title> <jats:p> Recently, a deadly transmissible cancer has emerged in Tasmanian devils, the largest existing marsupial carnivore. This disease, devil facial tumor disease (DFTD), leads to the growth of large facial tumors that frequently metastasize to internal organs. DFTD is thought to be transmitted by biting, and leads to death of affected animals within months, usually by obstructing the animals' ability to feed. Consequently, in the last 10 years Tasmanian devil numbers have dropped by about 60%. There are no genetic tests, vaccines, or treatments available for this disease, and without intervention, models predict that DFTD could cause extinction of Tasmanian devils in the wild within 50 years. Several lines of evidence suggest that DFTD is transmitted as a clonal allograft, whereby the cancer cells themselves are the agents of tumor transmission. <jats:bold> Murchison <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="84" related-article-type="in-this-issue" vol="327" xlink:href="10.1126/science.1180616">84</jats:related-article> ) examined this hypothesis in detail by genotyping 25 tumor-host pairs from around Tasmania at 14 microsatellite loci and at a variable mitochondrial polymorphism. DFTD tumors were indeed found to be genetically distinct from their hosts and almost completely genetically identical to one another, supporting the idea of transmission by allograft. </jats:p>

<jats:title>Modifying Protein Modification</jats:title> <jats:p> Alpha-dystroglycan (α-DG) is a cell-surface receptor that anchors the basal lamina to the sarcolemma by binding proteins containing laminin-G domains. This binding is essential for protecting muscle from contraction-induced injury, and defective binding is thought to cause a subclass of congenital muscular dystrophy (CMD) in humans. Mutations in six (putative) glycosyltransferase genes have been identified in patients with CMD, suggesting that glycosylation of α-DG may confer the ability to bind laminin. Despite extensive efforts for over 20 years, the actual laminin-binding moiety has remained unclear. Now, <jats:bold> Yoshida-Moriguchi <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="88" related-article-type="in-this-issue" vol="327" xlink:href="10.1126/science.1180512">88</jats:related-article> ) have identified a phosphorylated <jats:italic>O</jats:italic> -mannosyl glycan on α-DG. This modification occurred in the Golgi via an unidentified kinase and was required for the maturation of α-DG into its laminin-binding form. </jats:p>

<jats:title>Evolution in Action</jats:title> <jats:p> Rates of evolution in gene and genome sequences have been estimated, but these estimates are subject to error because many of the steps of evolution over the ages are not directly measurable or are hidden under subsequent changes. <jats:bold> Ossowski <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="92" related-article-type="in-this-issue" vol="327" xlink:href="10.1126/science.1180677">92</jats:related-article> ) now provide a more accurate measurement of how often spontaneous mutations arise in a nuclear genome. Mutations arising over 30 generations were compared by sequencing DNA from individual <jats:italic>Arabidopsis thaliana</jats:italic> plants. UV- and deamination-induced mutagenesis appeared to bias the type of mutations found. </jats:p>

<jats:title>Flowery Regulator</jats:title> <jats:p> Control of gene transcription is multilayered, depending on transcription factors, epigenetic mechanisms, and interactions with small RNA molecules. <jats:bold> Liu <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="94" related-article-type="in-this-issue" vol="327" xlink:href="10.1126/science.1180278">94</jats:related-article> , published online 3 December) have now found that for the <jats:italic>FLOWERING LOCUS C</jats:italic> ( <jats:italic>FLC</jats:italic> ) gene of the plant <jats:italic>Arabidopsis</jats:italic> , a backwards transcript of the gene conspires with 3′ RNA-processing tools and histone demethylation to regulate the transcription of the protein-coding gene. The 3′-processing events require the antisense, not the sense, RNA transcript. It is then the sense transcript that, in the end, regulates onset of flowering. </jats:p>

<jats:title>Consciousness and Reproducibility</jats:title> <jats:p> What exactly does it mean for neural information to reach subjective awareness? Previous work has suggested that the intensity and the duration of activation in brain areas that encode the contents of perception determine whether or not the information contributes directly to subjective experience. Now <jats:bold> Schurger <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="97" related-article-type="in-this-issue" vol="327" xlink:href="10.1126/science.1180029">97</jats:related-article> , published online 12 November; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="5961" page="43" related-article-type="in-this-issue" vol="327" xlink:href="10.1126/science.1184242">Schwarzkopf and Rees</jats:related-article> </jats:bold> ) describe a third property that distinguishes conscious from nonconscious neural encoding reproducibility. Spatiotemporal patterns of brain activity were recorded while subjects performed a simple visual category-discrimination task. Activation patterns corresponding to conscious information were more reproducible—i.e., more reliable, across different presentations of the same stimulus category, compared to nonconscious activation patterns coding for the same perception. </jats:p>

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<jats:p>The show includes masquerading caterpillars, an influential Russian astrophysicist, cancer in Tasmanian devils, and more.</jats:p>