Catálogo de publicaciones - revistas

<jats:title>Transcription machinery remains steadfast</jats:title> <jats:p> Eukaryotic transcription of mRNA is a multistep process mediated by RNA polymerase II (Pol II). Pol II combines with several other factors to form an elongation complex that promotes transcription elongation. Ehara <jats:italic>et al.</jats:italic> determined the high-resolution structure of the elongation complex by means of x-ray crystallography and cryo-electron microscopy (see the Perspective by Fouqueau and Werner). Multiple elongation factors are distributed on a wide surface of Pol II and establish an RNA exit path and DNA entry or exit tunnels, which facilitate nascent transcript transfer and DNA unwinding or rewinding. The Pol II elongation complex thus adopts a stable architecture suitable for processive transcription. </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="6354" page="921" related-article-type="in-this-issue" vol="357" xlink:href="10.1126/science.aan8552">921</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6354" page="871" related-article-type="in-this-issue" vol="357" xlink:href="10.1126/science.aao4754">871</jats:related-article> </jats:p>

<jats:title>How microtubules organize in embryos</jats:title> <jats:p> Cell functions ranging from cell division to morphogenesis rely on microtubules, with microtubule-organizing centers serving as anchoring sites for their outgrowth. Although the centrosome organizes the microtubule cytoskeleton in most animal cells, this organelle is absent in early development. Using live-cell imaging, Zenker <jats:italic>et al.</jats:italic> found that the cells of the early mouse embryo are connected by stable microtubule bridges to direct the growth of microtubules within them. Microtubules emanating from the bridges help to guide transport of key proteins, including E-cadherin, to the cell membrane to control cell polarization during early development. </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="6354" page="925" related-article-type="in-this-issue" vol="357" xlink:href="10.1126/science.aam9335">925</jats:related-article> </jats:p>

<jats:title>How a hydrogenase protects its active site</jats:title> <jats:p> Hydrogen-metabolizing organisms use an [NiFe]-hydrogenase to catalyze hydrogen oxidation. One type of [NiFe]-hydrogenase, the NAD <jats:sup>+</jats:sup> -reducing soluble [NiFe]-hydrogenase (SH), couples reduction of NAD <jats:sup>+</jats:sup> to the oxidation of hydrogen. Shomura <jats:italic>et al.</jats:italic> solved the structure of SH from an H <jats:sub>2</jats:sub> -oxidizing bacterium in both the air-oxidized and the active reduced state. In the reduced state, the NiFe catalytic center in SH has the same ligand coordination as in other [NiFe]-hydrogenases. However, the air-oxidized active site has an unusual coordination geometry that would prevent O <jats:sub>2</jats:sub> from accessing the site and so may protect against irreversible oxidation. </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="6354" page="928" related-article-type="in-this-issue" vol="357" xlink:href="10.1126/science.aan4497">928</jats:related-article> </jats:p>

<jats:title>Trisomic animals lose third chromosome</jats:title> <jats:p> Generally, when a third sex chromosome is added to the normal two in mammals (XX for female and XY for male), developmental defects result. Mice that are trisomic for the sex chromosomes are infertile. Hirota <jats:italic>et al.</jats:italic> demonstrate that reprogramming cells from sterile mice with chromosome trisomies XXY or XYY generates XY stem cells. Sperm generated from these XY stem cells could give rise to healthy, fertile offspring. Reprogramming also promoted loss of the extra chromosome in cells from patients with Klinefelter (XXY) or Down (trisomy 21) syndrome. </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="6354" page="932" related-article-type="in-this-issue" vol="357" xlink:href="10.1126/science.aam9046">932</jats:related-article> </jats:p>

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

<jats:p>The genomics era has had a profound impact on life science research, leading to significant developments such as the use of expression quantitative trait loci (eQTLs), which link polymorphisms in single genes to quantifiable changes in gene expression associated with specific diseases. As the end products and biological effectors of gene expression, proteins are crucial for improving our understanding of human biology, developing new and better drugs, and advancing precision medicine. Proteomics technologies have lagged behind their genomics counterparts, but recent breakthroughs are now combining these methods in powerful ways. The journey to clinical utility, however, remains challenging. Association of a protein biomarker with any given disease process, for example, needs to be assessed in terms of disease-independent, confounding factors that may modulate protein expression levels among different individuals. Moreover, understanding whether an associated protein is causally involved in (or merely reflects) a disease process is extremely valuable information for identifying new drug targets. Our panelists will discuss how multi-omics and epidemiological approaches are accelerating important advances in the use of protein biomarkers for clinical research and pharmaceutical development.</jats:p>