Catálogo de publicaciones - revistas

<jats:title>Smaller but more thermally stable</jats:title> <jats:p> Synthesizing metals with extremely small (nanoscale) grain sizes makes for much stronger materials. However, very small–grained materials start to coarsen at relatively low temperatures, wiping out their most desirable properties. Zhou <jats:italic>et al.</jats:italic> discovered a way to avoid this problem by mechanically grinding copper and nickel at liquid nitrogen temperatures. The processing method creates low-angle grain boundaries between the nanograins, which promotes thermal stability. </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="6388" page="526" related-article-type="in-this-issue" vol="360" xlink:href="10.1126/science.aar6941">526</jats:related-article> </jats:p>

<jats:title>Loss of touch receptors leads to itch</jats:title> <jats:p> Itch in response to light touch of the skin is an aging-associated problem. This phenomenon is called alloknesis and can become a major medical condition associated with dry skin. Feng <jats:italic>et al.</jats:italic> discovered that loss or dysfunction of Merkel cells causes scratching in mice (see the Perspective by Lewis and Grandl). Reduction of Merkel cell numbers results in reduced firing patterns and frequencies and changes the activation thresholds of slowly adapting afferent nerve fibers. Like hair cells, Merkel cells are lost with age. A painful scratch will temporarily alleviate itch because it induces enough activity through the remaining Merkel cells. </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="6388" page="530" related-article-type="in-this-issue" vol="360" xlink:href="10.1126/science.aar5703">530</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6388" page="492" related-article-type="in-this-issue" vol="360" xlink:href="10.1126/science.aat5617">492</jats:related-article> </jats:p>

<jats:title>Multiple, diverse, and complex</jats:title> <jats:p> Calcium currents characterize the developing pollen tube in the small mustard plant <jats:italic>Arabidopsis</jats:italic> and correlate with growth at the tip of the pollen tube. This system constitutes a practical model for screening for Ca <jats:sup>2+</jats:sup> -signaling mechanisms in plants. Wudick <jats:italic>et al.</jats:italic> analyzed multiple variants of glutamate receptor–like (GLR) channels and discovered that some work alone and others work in pairs or trios. Subcellular localization of GLRs is a complex response to CORNICHON sorting proteins, which leave some GLRs at the plasma membrane and ferry others to internal calcium reservoirs. The calcium current at the tip of the growing pollen tube apparently integrates multiple intracellular currents. </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="6388" page="533" related-article-type="in-this-issue" vol="360" xlink:href="10.1126/science.aar6464">533</jats:related-article> </jats:p>

<jats:title>Setting conscious perception alight</jats:title> <jats:p> What are the neuronal mechanisms that enable conscious perception? Why do some images remain subliminal? Van Vugt <jats:italic>et al.</jats:italic> trained monkeys to detect low-contrast images and compared neuronal activity in brain areas V1, V4, and the dorsolateral prefrontal cortex. Some stimuli made it into consciousness, and others were subliminal depending on their propagation, which can be variable for weak stimuli (see the Perspective by Mashour). Strongly propagated stimuli initiated a state in the higher brain areas called “ignition” that caused information about a brief stimulus to become sustained and broadcasted back through recurrent interactions between many brain areas. </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="6388" page="537" related-article-type="in-this-issue" vol="360" xlink:href="10.1126/science.aar7186">537</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6388" page="493" related-article-type="in-this-issue" vol="360" xlink:href="10.1126/science.aat5616">493</jats:related-article> </jats:p>

<jats:title>How to build a better morphogen gradient</jats:title> <jats:p> To translate insights in developmental biology into medical applications, techniques are needed to ensure correct cell localization. Morphogen gradients allow precise and highly reproducible pattern formation during development. Through in vitro experiments and modeling, Li <jats:italic>et al.</jats:italic> tested the effects of unusual properties of Hedgehog (HH) signaling. The HH morphogen's receptor, Patched (PTCH), sends an inhibitory signal when no ligand is bound, which is relieved by ligand binding. PTCH also regulates spatial distribution of the signal by sequestering the HH ligand. Furthermore, signaling through the receptor promotes synthesis of more inhibitory receptor. These characteristics help speed gradient formation and explain the robustness of the system to changes in the rate of morphogen production. </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="6388" page="543" related-article-type="in-this-issue" vol="360" xlink:href="10.1126/science.aao0645">543</jats:related-article> </jats:p>

<jats:title>Relationships among North Africans</jats:title> <jats:p> The general view is that Eurasians mostly descend from a single group of humans that dispersed outside of sub-Saharan Africa around 50,000 to 100,000 years ago. Present-day North Africans share a majority of their ancestry with present-day Near Easterners, but not with sub-Saharan Africans. To investigate this conundrum, Van de Loosdrecht <jats:italic>et al.</jats:italic> sequenced high-quality DNA obtained from bone samples of seven individuals from Taforalt in eastern Morocco dating from the Later Stone Age, about 15,000 years ago. The Taforalt individuals were found to be most closely related to populations from the Near East (Natufians), with a third of their ancestry from sub-Saharan Africa. No evidence was found for introgression with western Europeans, despite attribution to the Iberomaurusian culture. None of the present-day or ancient Holocene African groups are a good proxy for the sub-Saharan genetic component. </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="6388" page="548" related-article-type="in-this-issue" vol="360" xlink:href="10.1126/science.aar8380">548</jats:related-article> </jats:p>

<jats:title>Staying attached through division</jats:title> <jats:p>When a cell prepares to divide, it copies its DNA into pairs of each chromosome, called chromatids. Microtubules attach to the chromosome pairs through protein complexes called kinetochores. During cell division, microtubule depolymerization pulls the chromatids apart. Jenni and Harrison describe the structure of an essential component of the yeast kinetochore, the DASH/Dam1c complex, that forms a ring around a microtubule. The structure shows how the DASH/Dam1c ring interacts with the microtubule and kinetochore components so that the kinetochore can track to the end of the microtubule through cycles of growth and shrinkage.</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="6388" page="552" related-article-type="in-this-issue" vol="360" xlink:href="10.1126/science.aar6436">552</jats:related-article> </jats:p>

<jats:title> Complement is a CD8 <jats:sup>+</jats:sup> T cell metabolic rheostat </jats:title> <jats:p> Systemic lupus erythematosus (SLE) is associated with deficiencies in the complement protein C1q. Although C1q plays a role in the clearance of apoptotic cells, there are several redundant clearance pathways. Disruption of one pathway does not lead to an autoimmune defect. In a chronic graft-versus-host disease model of SLE, Ling <jats:italic>et al.</jats:italic> show that C1q dampens CD8 <jats:sup>+</jats:sup> T cell responses to self-antigens. C1q modulates metabolism through the mitochondrial cell-surface protein p32/gC1qR. The lack of C1q during a viral infection also enhances CD8 <jats:sup>+</jats:sup> T cell responses. Thus, C1q plays a role as a “metabolic rheostat” for effector CD8 <jats:sup>+</jats:sup> T cells. </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="6388" page="558" related-article-type="in-this-issue" vol="360" xlink:href="10.1126/science.aao4555">558</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>