Catálogo de publicaciones - revistas

<jats:title>Tweaking Dopamine Reception</jats:title> <jats:p> Dopamine modulates many cognitive and emotional functions of the human brain by activating G protein–coupled receptors. Antipsychotic drugs that block two of the receptor subtypes are used to treat schizophrenia but have multiple side effects. <jats:bold> Chien <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1091" related-article-type="in-this-issue" vol="330" xlink:href="10.1126/science.1197410">1091</jats:related-article> ; see the Research Article by <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6007" page="1066" related-article-type="in-this-issue" vol="330" xlink:href="10.1126/science.1194396"> <jats:bold> Wu <jats:italic>et al.</jats:italic> </jats:bold> </jats:related-article> ) resolved the crystal structure of one receptor in complex with a small-molecule inhibitor at 3.15 angstrom resolution. Homology modeling with other receptor subtypes might be a promising route to reveal potential structural differences that can be exploited in the design of selective therapeutic inhibitors having fewer side effects. </jats:p>

<jats:title>Germinal Center Survival</jats:title> <jats:p> The humoral immune response, which comprises antibodies secreted by B lymphocytes, is critical for protection against pathogens. In response to infection, B lymphocytes proliferate and differentiate into antibody-producing effector cells. After an infection clears, a small number of cells persist as memory B cells; however, the survival signals that regulate effector and memory B lymphocyte generation are not well understood. To probe this question, <jats:bold> Vikstrom <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1095" related-article-type="in-this-issue" vol="330" xlink:href="10.1126/science.1191793">1095</jats:related-article> , published online 7 October) deleted prosurvival genes in activated, antigen-specific B cells during a T lymphocyte–dependent immune response in mice. They found that a specific programmed cell death inhibitor, known as Mcl1, was required for the formation of germinal-center B cells (an effector cell population) and memory B cells but not for their maintenance. Dysregulation of the B cell responses mediated by Mcl1 may be a trigger for lymphomagenesis. </jats:p>

<jats:title>Theory of Growth Control</jats:title> <jats:p> Although quantitative studies of growth in bacterial cultures have been made for over 50 years, the relationship between cell proliferation and gene expression has not been clear. <jats:bold> Scott <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1099" related-article-type="in-this-issue" vol="330" xlink:href="10.1126/science.1192588">1099</jats:related-article> ; see the Perspective by <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6007" page="1058" related-article-type="in-this-issue" vol="330" xlink:href="10.1126/science.1199353"> <jats:bold>Lerman and Palsson</jats:bold> </jats:related-article> ) have revealed that mass per cell exponentially increased with linear increases in growth rate and that ribosome abundance increased linearly with growth rate depending on the rate of translation. Hence, the systems properties of the biological processes involved in growth can be derived without any molecular understanding of their basis and can be used to establish fundamental properties for the design of biotechnological procedures. </jats:p>

<jats:title>Turncoat Aphids</jats:title> <jats:p> Aphid color has consequences for the fate of the wearer: Coccinellid beetles prefer to eat red ones and parasitoid wasps attack green ones. What might happen if aphids could change color and outwit their predators? <jats:bold> Tsuchida <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1102" related-article-type="in-this-issue" vol="330" xlink:href="10.1126/science.1195463">1102</jats:related-article> ) have found that a subpopulation of the pea aphid can do this, but not without help from a previously unknown species of bacterium that lives intimately with the aphid as an endosymbiont and makes red aphids turn green. The bacterium interferes with host pigment biosynthesis—itself borrowed from fungi long ago in evolution—to stimulate blue-green pigment production as the aphid larva matures, turning the red nymph into a green adult. The ecological consequences of this about-turn of color have yet to be tested, but other studies have shown a variety of effects on aphid behavior mediated by endosymbionts in response to adaptation to different food plants, temperature tolerance, and predator avoidance. </jats:p>

<jats:title>Piggybacking on Cancer Genes</jats:title> <jats:p> Transposons are mobile segments of DNA that can insert in or near important genes to cause mutations that disrupt gene function. <jats:bold> Rad <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1104" related-article-type="in-this-issue" vol="330" xlink:href="10.1126/science.1193004">1104</jats:related-article> , published online 14 October) adapted a mutagenic transposon called Piggybac, originally derived from a moth, into a tool for discovery of cancer-causing genes in mice. Mobilization of Piggybac in mice was associated with the development of leukemias and solid tumors. In many instances the causative mutations, which were identified by mapping the Piggybac integration sites, were within genes not previously implicated in cancer. </jats:p>

<jats:title>Wiping Out Memories</jats:title> <jats:p> Inhibition of fear responses can be unexpectedly reversed even when a subject is perfectly safe. This can lead to inappropriate reactions to a fear-associated trigger, such as a bright light or loud noise. This type of reaction appears to underpin posttraumatic stress disorder, but there is little understanding of when training to inhibit fear may fail or succeed. Using a combination of electrophysiology and behavioral training in mice, <jats:bold>Clem and Huganir</jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1108" related-article-type="in-this-issue" vol="330" xlink:href="10.1126/science.1195298">1108</jats:related-article> , published online 28 October) observed that fear conditioning increased synaptic transmission by calcium-permeable AMPA receptors into the part of the brain that controls emotional responses (the amygdala). This effect lasted for about a week, during which the fearful memories could be erased if the animals were trained to reduce conditioned fear responses. Postmortem brain slices showed that the fear-induced synaptic changes also reversed, except in transgenic mice with a mutant subunit of the AMPA receptor. </jats:p>

<jats:title>Orientation Columns</jats:title> <jats:p> In the brain's visual cortex, certain neurons respond to vertical lines and others to horizontal lines, with a range in between. Such orientation of neurons tends to be organized in columns reflecting similar responses, and the columns are organized in pinwheels representing the range of responses. <jats:bold> Kaschube <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1113" related-article-type="in-this-issue" vol="330" xlink:href="10.1126/science.1194869">1113</jats:related-article> , published online 4 November; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1059" related-article-type="in-this-issue" vol="330" xlink:href="10.1126/science.1198857">Miller</jats:related-article> </jats:bold> ) looked at the organization of orientation columns in diverse placental mammals and discovered a similarity of organizational principles. </jats:p>

<jats:p>The show includes science in Russia, animal genome plasticity, linking uncertainty with nonlocality in quantum mechanics, and more.</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> This issue of <jats:italic>Science</jats:italic> includes the program of the 2011 AAAS Annual Meeting. The theme of the AAAS Annual Meeting in Washington, D.C., 17 to 21 February 2011, is "Science Without Borders." </jats:p> <jats:p> A <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://www.sciencemag.org/cgi/reprint/330/6007/1118.pdf">PDF</jats:ext-link> of the program as it appears in this issue is available here; for more information on the meeting (including registration forms and information on accommodations), please visit <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="www.aaas.org/meetings/">www.aaas.org/meetings/</jats:ext-link> . </jats:p>