Catálogo de publicaciones - revistas

<jats:title>Stick to the Bush</jats:title> <jats:p> Can the underlying genetic changes driving the divergence of populations into new species be predicted or repeated? <jats:bold> Soria-Carrasco <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6185" page="738" related-article-type="in-this-issue" vol="344" xlink:href="10.1126/science.1252136">738</jats:related-article> ) investigated the genetic changes observed after one generation when stick insect ( <jats:italic>Timema cristinae</jats:italic> ) populations were transplanted from their preferred host plants to alternative hosts. Diverged genetic regions were relatively small, with most loci showing divergence in a single population pair. However, the number of loci showing parallel divergence was greater than expected by chance. Thus, selection can drive parallel phenotypic evolution via parallel genetic changes. </jats:p>

<jats:title>Fundamentals of Bone Formation</jats:title> <jats:p> In vitro models can help guide research for tissue engineering or drug delivery, but the extent to which results from in vitro experiments may mimic in vivo ones will depend on the robustness of the model. For complex tissues like the extracellular matrix or bone, this means matching the chemical organization of the tissue at both the atomic scale and the structural level. <jats:bold> Chow <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6185" page="742" related-article-type="in-this-issue" vol="344" xlink:href="10.1126/science.1248167">742</jats:related-article> ) used nuclear magnetic resonance (NMR) spectroscopy to analyze a sample on both these length scales. First an isotope-enriched mouse was produced to enhance the NMR signal. Samples from these mice were then used to study the extracellular matrix of developing bone and the calcification front during fetal bone growth. </jats:p>

<jats:title>Hunters and Farmers</jats:title> <jats:p> The Neolithic period in Europe saw the transition from a hunter-gatherer lifestyle to farming. Previous genetic analyses have suggested that hunter-gatherers were replaced by immigrant farmers. <jats:bold> Skoglund <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6185" page="747" related-article-type="in-this-issue" vol="344" xlink:href="10.1126/science.1253448">747</jats:related-article> , published online 24 April) sequenced one Mesolithic and nine Neolithic Swedish individuals to examine the transition from hunter-gatherers to farmers. Substantial genetic differentiation was observed between hunter-gatherers and farmers: There was lower genetic diversity within the hunter-gatherers and gene flow from the hunter-gatherers into the farmers but not vice versa. </jats:p>

<jats:title>American Beauty</jats:title> <jats:p> Modern Native American ancestry traces back to an East Asian migration across Beringia. However, some Native American skeletons from the late Pleistocene show phenotypic characteristics more similar to other, more geographically distant, human populations. <jats:bold> Chatters <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6185" page="750" related-article-type="in-this-issue" vol="344" xlink:href="10.1126/science.1252619">750</jats:related-article> ) describe a skeleton with a Paleoamerican phenotype from the eastern Yucatan, dating to approximately 12 to 13 thousand years ago, with a relatively common extant Native American mitochondrial DNA haplotype. The Paleoamerican phenotype may thus have evolved independently among Native American populations. </jats:p>

<jats:title>Scents and Sperm</jats:title> <jats:p> Once sperm enter the female reproductive tract, they have an arduous task to find an egg at a distant, often concealed, location. <jats:bold> McKnight <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6185" page="754" related-article-type="in-this-issue" vol="344" xlink:href="10.1126/science.1250598">754</jats:related-article> ) show that <jats:italic>Caenorhabditis elegans</jats:italic> make this task more or less difficult, depending on pheromones in the external environment. Pheromones perceived by female sensory neurons modulate the synthesis of ovarian prostaglandins, which provide sperm positional information. Thus, environmental cues can indirectly impact sperm function even when the sperm themselves are not directly exposed. </jats:p>

<jats:title>Virus-Enhanced Sulfur Oxidation</jats:title> <jats:p> How do microbial viruses affect subsurface microbial communities? <jats:bold> Anantharaman <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6185" page="757" related-article-type="in-this-issue" vol="344" xlink:href="10.1126/science.1252229">757</jats:related-article> , published online 1 May) investigated the interactions between ubiquitous marine lithotrophs found at hydrothermal vents and their viruses. The genes for sulfur oxidation in viruses that infect abundant marine chemosynthetic sulfur-oxidizing bacteria enhanced sulfur oxidation, thereby influencing the biogeochemical sulfur cycle. </jats:p>

<jats:title>Signaling Dynamics</jats:title> <jats:p> The signaling pathways that activate the transcription factor NF-κB are key regulatory pathways in cells of the immune system, and their dynamic properties are still being elucidated. In B cells, analysis of single-cell responses has shown that the stimulation of the B cell receptor causes a “digital” all-or-none response of cells to a stimulus. <jats:bold> Shinohara <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6185" page="760" related-article-type="in-this-issue" vol="344" xlink:href="10.1126/science.1250020">760</jats:related-article> ) used a combination of mathematical modeling and experiments to show that this property of the system results from the presence of a positive feedback loop among the signaling components activated in response to the receptor. Studies in cells expressing mutated signaling components resolved key phosphorylation events that provide the threshold responses observed and identified potential molecular modifications that might modify the threshold or other aspects of the dynamic response. </jats:p>

<jats:p>Editors: Bradley Duerstock, Clark Shingledecker</jats:p> <jats:p>From College to Careers: Fostering Inclusion of Persons with Disabilities in STEM is the product of a collaborative project initiated to examine current issues and explore future directions for improving the academic success and career entry rate of postsecondary students with disabilities (SWDs) in science, technology, engineering and mathematics (STEM) fields. This publication contains chapters prepared by four groups of invited authors who shared their pertinent research findings, expert knowledge and views on key topics pertinent to this topic.</jats:p> <jats:p> This booklet brought to you by the <jats:italic>Science</jats:italic> /AAAS Custom Publishing Office. </jats:p> <jats:p>DOI: 10.1126/science.opms.sb0002</jats:p>

<jats:p>On this week's show: Avoiding quantum back-action effects and a roundup of stories from our daily news site.</jats:p>

<jats:p>Editors: Bradley Duerstock, Clark Shingledecker</jats:p> <jats:p>From College to Careers: Fostering Inclusion of Persons with Disabilities in STEM is the product of a collaborative project initiated to examine current issues and explore future directions for improving the academic success and career entry rate of postsecondary students with disabilities (SWDs) in science, technology, engineering and mathematics (STEM) fields. This publication contains chapters prepared by four groups of invited authors who shared their pertinent research findings, expert knowledge and views on key topics pertinent to this topic.</jats:p> <jats:p> This booklet brought to you by the <jats:italic>Science</jats:italic> /AAAS Custom Publishing Office. </jats:p> <jats:p>DOI: 10.1126/science.opms.sb0002</jats:p>