Catálogo de publicaciones - revistas

<jats:title>Making small actuators more effective</jats:title> <jats:p> Liquid-crystal molecules orient locally in response to external fields. When long-chain liquid-crystalline molecules are crosslinked together, changes in local orientation can lead to significant volume changes. Ware <jats:italic>et al.</jats:italic> made efficient microactuators that can change their shape from flat to three-dimensional structures (see the Perspective by Verduzco). By patterning volume elements so that each has a different preferred alignment for the liquid-crystalline molecules, they could fine-tune the volume changes. </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="6225" page="982" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.1261019">982</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6225" page="949" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.aaa6579">949</jats:related-article> </jats:p>

<jats:title>Mating plugs promote malaria parasites</jats:title> <jats:p> Males of some of the malaria-transmitting mosquitoes “plug” females after copulation to stop interloping males from mating. The mating plug also delivers a steroid hormone into the female uterus. This hormone pulse promotes egg production and stimulates egg laying. It also curbs the mosquitoes' immune responses, which allows parasites such as malaria to develop unhindered. Mitchell <jats:italic>et al.</jats:italic> discovered that plugs are a recent evolutionary acquisition (see the Perspective by Alonzo). South American anopheline mosquitoes lack these plugs altogether, whereas African and Indian species have complex plugs replete with hormones. It is unlikely to be a coincidence that the most elaborate mosquito plugs are also found in regions where malaria transmission rates are highest. </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="6225" page="985" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.1259435">985</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6225" page="948" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.aaa6495">948</jats:related-article> </jats:p>

<jats:title>Is the end of the warming hiatus nigh?</jats:title> <jats:p> Which recent climate changes have been forced by greenhouse gas emissions, and which have been natural fluctuations of the climate system? Steinman <jats:italic>et al.</jats:italic> combined observational data and a large collection of climate models to assess the Northern Hemisphere climate over the past 150 years (see the Perspective by Booth). At various points in time, the Pacific Decadal Oscillation and the Atlantic Multidecadal Oscillation have played particularly large roles in producing temperature trends. Their effects have combined to cause the apparent pause in warming at the beginning of the 21st century, known as the warming “hiatus.” This pause is projected to end in the near future as temperatures resume their upward climb. </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="6225" page="988" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.1257856">988</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6225" page="952" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.aaa4840">952</jats:related-article> </jats:p>

<jats:title>Bypassing a plant's defense for pest defense</jats:title> <jats:p> Colorado potato beetles can skeletonize the leaves on a potato plant, devastating crop yields. Insecticides are increasingly useless as the beetle evolves resistance. Zhang <jats:italic>et al.</jats:italic> used RNA interference to take down this beetle (see the Perspective by Whyard). Success required shifting production of the double-stranded RNA to the plastids to evade the plant's own RNA management mechanisms. The insect's own RNA interference mechanisms then inactivated two everyday genes that the beetle can't do without. </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="6225" page="991" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.1261680">991</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6225" page="950" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.aaa7722">950</jats:related-article> </jats:p>

<jats:title>Channeling Ebola virus entry into the cell</jats:title> <jats:p> The current outbreak of Ebola virus in West Africa highlights the need for antiviral therapies. One strategy would be to block the Ebola virus's ability to enter host cells. Cells engulf Ebola virus particles, which then traffic into the cell in structures called endosomes. Sakurai <jats:italic>et al.</jats:italic> now report that the Ebola virus requires calcium channels called two-pore channels (TPCs) in endosomal membranes for successful entry (see the Perspective by Falzarano and Feldmann). The Ebola virus could not enter cells lacking TPCs or cells treated with a TPC inhibitor. Blocking TPCs therapeutically allowed 50% of mice to survive an ordinarily lethal Ebola virus infection. </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="6225" page="995" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.1258758">995</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6225" page="947" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.aaa8121">947</jats:related-article> </jats:p>

<jats:title>Early wheat movement into Britain</jats:title> <jats:p> The transition into the New Stone Age, or Neolithic period, in Great Britain and Europe was characterized by a change from hunter-gatherers to farmers. However, the early stages of this transition are not well understood. Smith <jats:italic>et al.</jats:italic> studied archaeological remains at an 8000-year-old site that has been underwater ever since the Neolithic (see the Perspective by Larson). The finds include evidence of wheat (or a relative of wheat) 2000 years before the first documented farmers in Britain. It seems that trade may have preceded the adoption of farming. </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="6225" page="998" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.1261278">998</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6225" page="945" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.aaa6113">945</jats:related-article> </jats:p>

<jats:title>mRNA modification regulates pluripotency</jats:title> <jats:p> When stem cells progress from an embryonic pluripotent state toward a particular lineage, molecular switches dismantle the transcription factor network that keeps the cell pluripotent. Geula <jats:italic>et al.</jats:italic> now show that N6-methyladenosine (m6A), a messenger RNA (mRNA) modification present on transcripts of pluripotency factors, drives this transition. Methylation destabilized mRNA transcripts and limited their translation efficiency, which promoted the timely decay of naïve pluripotency. This m6A methylation was also critical for mammalian 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="6225" page="1002" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.1261417">1002</jats:related-article> </jats:p>

<jats:title>The downstream effects of false promotion</jats:title> <jats:p> Special DNA sequences at the ends of chromosomes, called telomeres, are replenished by a dedicated enzyme called telomerase. A subset of human tumors harbors mutations in the promoter region of the TERT gene, which codes for a subunit of telomerase. Borah <jats:italic>et al.</jats:italic> explored the downstream effects of TERT promoter mutations in cells derived from urothelial (urinary tract) cancers. The mutations were associated with aberrantly high levels of TERT mRNA, TERT protein and telomerase activity, and longer telomeres. A small study of clinical samples suggested that high levels of TERT mRNA may be a marker of more aggressive urothelial cancers. </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="6225" page="1006" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.1260200">1006</jats:related-article> </jats:p>

<jats:title>Uncaging promoter and enhancer dynamics</jats:title> <jats:p> In order to understand cellular differentiation, it is important to understand the timing of the regulation of gene expression. Arner <jats:italic>et al.</jats:italic> used cap analysis of gene expression (CAGE) to analyze gene enhancer and promoter activities in a number of human and mouse cell types. The RNA of enhancers was transcribed first, followed by that of transcription factors, and finally by genes that are not transcription factors. </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="6225" page="1010" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.1259418">1010</jats:related-article> </jats:p>

<jats:title>Losing and then regaining flagella</jats:title> <jats:p> The ability to adapt to changes in the function of gene regulators, as opposed to structural genes, is a crucial aspect of evolutionary change. Taylor <jats:italic>et al.</jats:italic> mutated a central regulator for the formation of flagella in the bacterium <jats:italic>Pseudomonas fluorescens</jats:italic> . They then put the mutated flagella-free bacteria under strong selection pressure to regain mobility. The mutated bacteria regained the lost flagella, and motility, within 4 days. Two stereotypical mutations diverted an evolutionarily related regulator that normally controls nitrogen uptake to control flagella biosynthesis. The mutations increased the levels of the co-opted regulator, then altered its specificity for the flagella pathway. </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="6225" page="1014" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.1259145">1014</jats:related-article> </jats:p>