Catálogo de publicaciones - revistas

<jats:title>Going to Mars</jats:title> <jats:p> The Mars Science Laboratory spacecraft containing the Curiosity rover, was launched from Earth in November 2011 and arrived at Gale crater on Mars in August 2012. <jats:bold> Zeitlin <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="6136" page="1080" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1235989">1080</jats:related-article> ) report measurements of the energetic particle radiation environment inside the spacecraft during its cruise to Mars, confirming the hazard likely to be posed by this radiation to astronauts on a future potential trip to Mars. <jats:bold> Williams <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="6136" page="1068" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1237317">1068</jats:related-article> , see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6136" page="1055" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1239343">Jerolmack</jats:related-article> </jats:bold> ) report the detection of sedimentary conglomerates (pebbles mixed with sand and turned to rock) at Gale crater. The rounding of the rocks suggests abrasion of the pebbles as they were transported by flowing water several kilometers or more from their source. </jats:p>

<jats:title>Choice in Changing Environments</jats:title> <jats:p> Animals, including humans, generally tend to judge the world on relative, rather than absolute, terms. For example, the value of a particular object or reward is generally determined based on comparison to other rewards we have received in the past or to those that others have received. Such contrast effects can have negative or positive impacts on our behavior. <jats:bold> McNamara <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="6136" page="1084" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1230599">1084</jats:related-article> ) used an optimality model to show that contrast effects could evolve as an adaptive response to environmental instability and unpredictability. </jats:p>

<jats:title>The Birds and the Seeds</jats:title> <jats:p> When species are lost from ecosystems through local extinction, the pattern of ecological interactions changes. <jats:bold> Galetti <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="6136" page="1086" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1233774">1086</jats:related-article> ) show how the loss of large fruit-eating birds from tropical forest fragments in Brazil affects the reduction of seed size in a palm species. A data set was compiled that consisted of &gt;9000 seeds measured in 22 populations over a large area of Atlantic rainforest, including seven areas where large-seed dispersers (toucans, cracids, and large cotingas) were extinct and 15 areas where they are still common. </jats:p>

<jats:title>It's an Ant's Life</jats:title> <jats:p> Eusocial insects live in highly organized societies where groups of individuals carry out specific tasks; for example, caring for the eggs, cleaning the nest, or foraging, which might suggest the presence of an advanced form of organization, similar to what might be expected from more cognitively advanced species. <jats:bold> Mersch <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="6136" page="1090" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1234316">1090</jats:related-article> , published online 18 April) tracked individual ant movements and interactions to show that their precise social organization results from temporal changes in the spatial location of workers. As they aged, ants largely progressed from being nurses located near the queen, to nest cleaners who move throughout the colony, and finally to foragers moving in and out at the colony edges. </jats:p>

<jats:title>Multiple Inputs to Flowering</jats:title> <jats:p> Perennial plants need to cycle through an extended vegetative phase, in a process known as vernalization, before they initiate flowering. <jats:bold> Bergonzi <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="6136" page="1094" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1234116">1094</jats:related-article> ) and <jats:bold> Zhou <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="6136" page="1097" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1234340">1097</jats:related-article> ) studied how molecular signals translate environmental information—such as exposure to a winter season or changes in daylength and physiological information, such as age of the plant—into signals that promote flowering. In both <jats:italic>Arabis alpina</jats:italic> and <jats:italic>Cardamine flexuosa</jats:italic> , age and vernalization pathways are integrated through the regulation of microRNAs miR156 and miR172. </jats:p>

<jats:title>Multiple Inputs to Flowering</jats:title> <jats:p> Perennial plants need to cycle through an extended vegetative phase, in a process known as vernalization, before they initiate flowering. <jats:bold> Bergonzi <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="6136" page="1094" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1234116">1094</jats:related-article> ) and <jats:bold> Zhou <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="6136" page="1097" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1234340">1097</jats:related-article> ) studied how molecular signals translate environmental information—such as exposure to a winter season or changes in daylength and physiological information, such as age of the plant—into signals that promote flowering. In both <jats:italic>Arabis alpina</jats:italic> and <jats:italic>Cardamine flexuosa</jats:italic> , age and vernalization pathways are integrated through the regulation of microRNAs miR156 and miR172. </jats:p>

<jats:title>Limiting mTORC1</jats:title> <jats:p> The mTORC1 protein kinase complex has important functions linking metabolism to cell growth and its functions are disrupted in common diseases, including cancer and diabetes. <jats:bold> Bar-Peled <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="6136" page="1100" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1232044">1100</jats:related-article> ; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6136" page="1056" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1240315">Shaw</jats:related-article> </jats:bold> ) discovered regulatory components that help turn down signaling by mTORC1 when cells are deprived of amino acids. Two complexes of proteins, GATOR1 and GATOR2, have opposite effects on activity and cellular localization of mTORC1. Components of the GATOR1 complex negatively regulate mTORC1 and appear to function as tumor supressors. Cancers with loss of GATOR1 function may be particularly amenable to therapeutic strategies that limit activity of mTORC1. </jats:p>

<jats:title>Vitamin E Out</jats:title> <jats:p> Familial vitamin E deficiency is caused by mutations in the α-tocopherol transfer protein (α-TTP) gene. <jats:bold> Kono <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="6136" page="1106" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1233508">1106</jats:related-article> , published online 18 April; see the Perspective by <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6136" page="1051" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1239800"> <jats:bold>Mesmin and Antonny</jats:bold> </jats:related-article> ) studied natural mutations in α-TTP. α-TTP bound phosphatidylinositol polyphosphates (PIPs), especially PI(4,5)P2, and a disease-related missense mutation abolished PIP binding but not α-tocopherol binding. The x-ray crystal structure of the α-TTP–PIP complex suggested that PIP binding opens the lid of the α-tocopherol–binding pocket to facilitate the release of α-tocopherol. Thus, PIP binding to α-TTP at the target membrane may facilitate the release of α-tocopherol in the hydrophobic pocket of α-TTP to the lipid bilayer of the target membrane, providing a mechanism for the transfer of lipids from the lipid-transfer protein to the target membrane. </jats:p>

<jats:title>Kinetochore Targeting</jats:title> <jats:p> Chromosomes must be segregated accurately during cell division. This is facilitated by the attachment of mitotic spindle microtubules to the kinetochore at the chromosomal centromere. The centromere is marked with the histone H3 variant CenH3 (CENP-A in human), and CENP-C forms part of the inner kinetochore. <jats:bold> Kato <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="6136" page="1110" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1235532">1110</jats:related-article> ) used structural biology, biochemistry, and mutagenesis to show that CENP-C recognizes CENP-A chromatin via several different interactions. The CENP-C "central domain" makes close contact with the acidic patch of histones H2A/H2B, and the highly conserved "CENP-C motif" senses both the acidic patch and recognizes the hydrophobicity of the otherwise nonconserved CenH3 tail, supporting a conserved mechanism of centromere targeting by the kinetochore. </jats:p>

<jats:title>Building Better Vaccines</jats:title> <jats:p> Vaccines are one of the most effective tools to protect against infectious diseases. Unfortunately, vaccines for diseases with the highest global health burdens, such as HIV, malaria, and tuberculosis, are not yet available. <jats:bold> Koff <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://www.sciencemag.org/content/340/6136/1064.full">1064</jats:ext-link> ) review the latest advances in vaccine development and why these particular diseases remain such a challenge. Respiratory syncytial virus (RSV) is a serious cause of morbidity and mortality in infants and young children worldwide. Although a prophylactic antibody is available for children at high risk, a vaccine is much needed. As a potential step toward this goal, <jats:bold> McLellan <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="6136" page="1113" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1234914">1113</jats:related-article> , published online 25 April) solved the cocrystal structure of a neutralizing antibody (D25) bound to the prefusion F protein of RSV. Knowledge of the structure of the prefusion protein should help to guide vaccine design and the development of additional therapeutics. </jats:p>