Catálogo de publicaciones - revistas

<jats:title>Practice makes perfect — or does it?</jats:title> <jats:p> How do we learn from past errors? Herzfeld <jats:italic>et al.</jats:italic> found that when we practice a movement, the human brain has a memory for errors that is then used to learn faster in new conditions. This memory for error exists in parallel with motor memory's two traditional forms: memory of actions and memory of external perturbations. They also proposed a mathematical model for learning from errors. This model explained previous experimental results and predicted other major findings that they later verified experimentally. </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="6202" page="1349" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1253138">1349</jats:related-article> </jats:p>

<jats:title>Top-down rather than bottom-up change</jats:title> <jats:p> The Larsen-B Ice Shelf in Antarctica collapsed in 2002 because of a regional increase in surface temperature. This finding, reported by Rebesco <jats:italic>et al.</jats:italic> , will surprise many who supposed that the shelf's disintegration probably occurred because of thinning of the ice shelf and the resulting loss of support by the sea floor beneath it. The authors mapped the sea floor beneath the ice shelf before it fell apart, which revealed that the modern ice sheet grounding line was established around 12,000 years ago and has since remained unchanged. If the ice shelf did not collapse because of thinning from below, then it must have been caused by warming from above. </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="6202" page="1354" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1256697">1354</jats:related-article> </jats:p>

<jats:title>Origin of fish pigment cell for pattern</jats:title> <jats:p> Zebrafish stripes arise from the interactions of pigment cells: black melanophores, iridescent iridophores, and yellow-orange xanthophores. Melanophores and iridophores develop from nerve-associated stem cells, but the origin of xanthophores is unclear. Two studies now reveal that adult xanthophores originate from xanthophores in embryonic and larval fish, when they proliferate to cover the skin before the arrival of black and silver cells in a striped arrangement. Mahalwar <jats:italic>et al.</jats:italic> show that xanthophores change their final shape and color depending on their location. In black cells, xanthophores appear faint and stellate, but in silver cells, they are bright and compact. Precise superposition creates the blue and golden colors. McMenamin <jats:italic>et al.</jats:italic> observe the loss of pigment in embryonic xanthophores and the later reappearance in the adult. They show that redifferentiation depends on the thyroid hormone that also limits melanophore population expansion. </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="6202" page="1362" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1254837">1362</jats:related-article> and p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6202" page="1358" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1256251">1358</jats:related-article> </jats:p>

<jats:title>Origin of fish pigment cell for pattern</jats:title> <jats:p> Zebrafish stripes arise from the interactions of pigment cells: black melanophores, iridescent iridophores, and yellow-orange xanthophores. Melanophores and iridophores develop from nerve-associated stem cells, but the origin of xanthophores is unclear. Two studies now reveal that adult xanthophores originate from xanthophores in embryonic and larval fish, when they proliferate to cover the skin before the arrival of black and silver cells in a striped arrangement. Mahalwar <jats:italic>et al.</jats:italic> show that xanthophores change their final shape and color depending on their location. In black cells, xanthophores appear faint and stellate, but in silver cells, they are bright and compact. Precise superposition creates the blue and golden colors. McMenamin <jats:italic>et al.</jats:italic> observe the loss of pigment in embryonic xanthophores and the later reappearance in the adult. They show that redifferentiation depends on the thyroid hormone that also limits melanophore population expansion. </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="6202" page="1362" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1254837">1362</jats:related-article> and p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6202" page="1358" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1256251">1358</jats:related-article> </jats:p>

<jats:title>Origin of the spine lies in a worm</jats:title> <jats:p> The notochord, the developmental backbone precursor, defines chordates—the group of animals to which humans belong. The origin of the notochord remains mysterious. Lauri <jats:italic>et al.</jats:italic> report the identification of a longitudinal muscle in an annelid worm that displays striking similarities to the notochord regarding position, developmental origin, and expression profile. Similar muscles, termed axochords, are found in various invertebrate phyla. These data suggest that the last common ancestor of bilaterians already possessed contractile midline tissue that, via stiffening, developed into a cartilaginous rod in the chordate line. </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="6202" page="1365" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1253396">1365</jats:related-article> </jats:p>

<jats:title>Evolution of Ebola virus over time</jats:title> <jats:p> The high rate of mortality in the current Ebola epidemic has made it difficult for researchers to collect samples of the virus and study its evolution. Gire <jats:italic>et al.</jats:italic> describe Ebola epidemiology on the basis of 99 whole-genome sequences, including samples from 78 affected individuals. The authors analyzed changes in the viral sequence and conclude that the current outbreak probably resulted from the spread of the virus from central Africa in the past decade. The outbreak started from a single transmission event from an unknown animal reservoir into the human population. Two viral lineages from Guinea then spread from person to person into Sierra Leone. </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="6202" page="1369" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1259657">1369</jats:related-article> </jats:p>

<jats:p>On this week's show: Engineering global health and a news roundup.</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>Academic researchers are increasingly venturing out of the laboratory and into unfamiliar professional territory. The draw might be a multidisciplinary project, industry collaboration, or consulting. The new field might be government, law, or even the military. To ease interactions with colleagues in other fields with different work environments, seven researchers share what they've learned about productive, professional cross-disciplinary relationships.</jats:p>