Catálogo de publicaciones - revistas

<jats:title>Severing to build microtubules</jats:title> <jats:p> Microtubules are essential intracellular polymers, built from tubulin subunits, that establish cell shape, move organelles, and segregate chromosomes during cell division. Vemu <jats:italic>et al.</jats:italic> show that microtubule-severing enzymes extract tubulin subunits along the microtubule shaft. This nanoscale damage is repaired by the incorporation of free tubulin, which stabilizes the microtubule against depolymerization. When extraction outpaces repair, microtubules are severed, emerging with stabilized ends composed of fresh tubulin. The severed microtubules act as templates for new microtubule growth, leading to amplification of microtubule number and mass. Thus, seemingly paradoxically, severing enzymes can increase microtubule mass in processes such as neurogenesis and mitotic spindle assembly. </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" related-article-type="in-this-issue" xlink:href="10.1126/science.aau1504">eaau1504</jats:related-article> </jats:p>

<jats:title>Developing the bloodbrain barrier</jats:title> <jats:p> During development, signals need to be dynamically integrated by endothelial cells, neurons, and glia to achieve functional neuro-glia-vascular units in the central nervous system. During cortical development, neuronal Dab1 and ApoER2 receptors respond to a guidance cue called reelin. Studying mice, Segarra <jats:italic>et al.</jats:italic> found that Dab1 and ApoER2 are also expressed in endothelial cells (see the Perspective by Thomas). The integration of reelin signaling in endothelial cells and neurons facilitates the communication between vessels, glia, and neurons that is necessary for the correct positioning of neurons during cortical development. This integration is also important for correct communication at the neurovascular unit required for blood-brain barrier integrity in the mature brain. </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" related-article-type="in-this-issue" xlink:href="10.1126/science.aao2861">eaao2861</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6404" page="754" related-article-type="in-this-issue" vol="361" xlink:href="10.1126/science.aau7155">754</jats:related-article> </jats:p>

<jats:p> Amoroso <jats:italic>et al</jats:italic> . demonstrate the power of our data by estimating the high-resolution trawling footprint on seafloor habitat. Yet we argue that a coarser grid is required to understand full ecosystem impacts. Vessel tracking data allow us to estimate the footprint of human activities across a variety of scales, and the proper scale depends on the specific impact being investigated. </jats:p>

<jats:p>Rigorous economic analysis has long been recognized as essential for sound, defensible decision-making by government agencies whose regulations affect human health and the environment. The acting administrator (since July 2018) of the U.S. Environmental Protection Agency (EPA) has emphasized the importance of transparency and public trust. These laudable goals are enhanced by external scientific review of the EPA's analytical procedures. Yet, in June 2018, the EPA's Science Advisory Board (SAB) eliminated its Environmental Economics Advisory Committee (EEAC). The agency should be calling for more—not less—external advice on economics, given the Trump administration's promotion of economic analyses that push the boundaries of well-established best practices. The pattern is clear: When environmental regulations are expected to provide substantial public benefits, assumptions are made to substantially diminish their valuations.</jats:p>

<jats:p>A roundup of weekly science policy and related news.</jats:p>

<jats:p>With miniaturized guidance and propulsion systems, tiny craft aim for destinations beyond Earth.</jats:p>

<jats:p>Woman had a Neanderthal mother and a Denisovan father.</jats:p>

<jats:p>Seafloor cores suggest thickening ice sheets triggered near-collapse of Atlantic currents</jats:p>

<jats:p>Long-acting treatments now in clinical trials may work as preventives, too.</jats:p>