Catálogo de publicaciones - revistas

<jats:title>Outfoxing Immune Excess</jats:title> <jats:p> Immune responses are kept in check by Foxp3-expressing CD4 <jats:sup>+</jats:sup> -regulatory T cells (T <jats:sub>regs</jats:sub> ) through a variety of mechanisms. Expression of specific transcription factors directs T <jats:sub>reg</jats:sub> responses into distinct T helper cell lineages; however, the transcription factors that regulate particular helper lineages have not been completely characterized. <jats:bold> Chaudhry <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="986" related-article-type="in-this-issue" vol="326" xlink:href="10.1126/science.1172702">986</jats:related-article> , published online 1 October) show that the transcription factor Stat3, that is required for the initial differentiation of T <jats:sub>H</jats:sub> 17-effector T cells, is also required for T <jats:sub>reg</jats:sub> cell-mediated suppression of T <jats:sub>H</jats:sub> 17-mediated immune responses. Mice carrying a T <jats:sub>reg</jats:sub> cellspecific deletion in Stat3 succumb to an intestinal inflammatory disease driven by uncontrolled T <jats:sub>H</jats:sub> 17 responses. Thus, different classes of immune responses can result from the expression of helper lineage–specific transcription factors. </jats:p>

<jats:title>BubR1 Broadens Its Remit</jats:title> <jats:p> During mitosis in mammalian somatic cells, BubR1 is indispensable for spindle assembly checkpoint signaling and for establishing contacts between chromosomes and spindle microtubules. <jats:bold> Homer <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="991" related-article-type="in-this-issue" vol="326" xlink:href="10.1126/science.1175326">991</jats:related-article> ) found that in mouse oocytes during meiosis I, BubR1 was not only required to sustain prophase I arrest but also for promoting the completion of meiosis I. Both effects converge on the Cdh1 coactivator of the multimeric ubiquitin ligase, known as the anaphase-promoting complex, and both functions are required for the production of fertilizable eggs. </jats:p>

<jats:title>Life Histories to Suit</jats:title> <jats:p> Nematode worms can profoundly manipulate their life histories in several ways. For example, <jats:italic>Caenorhabditis elegans</jats:italic> has two genders: males and hermaphrodites. Some clues for the evolution of this peculiar mating system have been revealed by <jats:bold> Baldi <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="1002" related-article-type="in-this-issue" vol="326" xlink:href="10.1126/science.1176013">1002</jats:related-article> ), who turned females of a related species, <jats:italic>Caenorhabditis remanei</jats:italic> , into hermaphrodites by modifying a gene involved in making sperm and another gene required for activating the spermatids. In most animals, the germ line is fully established during adulthood and a reproductive period is determined, at least in part, by aging of the germ line and the viability of oocytes. The reproductive longevity of hermaphrodite <jats:italic>C. elegans</jats:italic> can be increased at least 15-fold by starvation. <jats:bold>Angelo and Van Gilst</jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="954" related-article-type="in-this-issue" vol="326" xlink:href="10.1126/science.1178343">954</jats:related-article> , published online 27 August; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="5955" page="944" related-article-type="in-this-issue" vol="326" xlink:href="10.1126/science.1183272">Ogawa and Sommer</jats:related-article> </jats:bold> ) found that in starved worms, the germline component of the reproductive system is actively killed, with the exception of a small set of preserved stem cells. When the worms are able to feed again, these cells regenerate into an entirely new and functional germ line. But this is not all. <jats:bold> Kim <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="994" related-article-type="in-this-issue" vol="326" xlink:href="10.1126/science.1176331">994</jats:related-article> , published online 1 October; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="5955" page="944" related-article-type="in-this-issue" vol="326" xlink:href="10.1126/science.1183272"> <jats:bold>Ogawa and Sommer</jats:bold> </jats:related-article> </jats:bold> ) show that subsets of the complex mixture of structurally related molecules in dauer pheromone act via distinct G protein–coupled receptors either to initiate longterm effects on development and physiology by modulating the neuroendocrine axis, or to trigger short-term acute effects on behavior by altering neuronal responses. </jats:p>

<jats:title>Sexual Blotch</jats:title> <jats:p> Sexual conflicts may provide selection pressures that facilitate invasion of new genetic sex determiners. <jats:bold> Roberts <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="998" related-article-type="in-this-issue" vol="326" xlink:href="10.1126/science.1174705">998</jats:related-article> , published online 1 October) describe data obtained from several species of sexually dimorphic cichlid fishes found in Lake Malawi that support this model. An orangeblotch color pattern has evolved among the females of rock-dwelling species because it provides effective camouflage against the algae-coated rocks. Blotched males (OB) are rare, possibly because the trait interferes with the normal male color pattern of blue stripes that are important cues for mate selection. The pigmentation pattern that creates this conflict between natural selection in females and sexual selection in males is caused by mutation in the <jats:italic>cis</jats:italic> -regulatory region of the <jats:italic>Pax7</jats:italic> gene and is tightly linked to a dominant female sex determiner. When bred in the lab, the OB males inherit the intact maternal OB haplotype and their OB-carrying chromosome determines female sex in the offspring; the males seem to be sex-reversed by another mechanism. </jats:p>

<jats:title>Life Histories to Suit</jats:title> <jats:p> Nematode worms can profoundly manipulate their life histories in several ways. For example, <jats:italic>Caenorhabditis elegans</jats:italic> has two genders: males and hermaphrodites. Some clues for the evolution of this peculiar mating system have been revealed by <jats:bold> Baldi <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="1002" related-article-type="in-this-issue" vol="326" xlink:href="10.1126/science.1176013">1002</jats:related-article> ), who turned females of a related species, <jats:italic>Caenorhabditis remanei</jats:italic> , into hermaphrodites by modifying a gene involved in making sperm and another gene required for activating the spermatids. In most animals, the germ line is fully established during adulthood and a reproductive period is determined, at least in part, by aging of the germ line and the viability of oocytes. The reproductive longevity of hermaphrodite <jats:italic>C. elegans</jats:italic> can be increased at least 15-fold by starvation. <jats:bold>Angelo and Van Gilst</jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="954" related-article-type="in-this-issue" vol="326" xlink:href="10.1126/science.1178343">954</jats:related-article> , published online 27 August; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="5955" page="944" related-article-type="in-this-issue" vol="326" xlink:href="10.1126/science.1183272">Ogawa and Sommer</jats:related-article> </jats:bold> ) found that in starved worms, the germline component of the reproductive system is actively killed, with the exception of a small set of preserved stem cells. When the worms are able to feed again, these cells regenerate into an entirely new and functional germ line. But this is not all. <jats:bold> Kim <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="994" related-article-type="in-this-issue" vol="326" xlink:href="10.1126/science.1176331">994</jats:related-article> , published online 1 October; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="5955" page="944" related-article-type="in-this-issue" vol="326" xlink:href="10.1126/science.1183272"> <jats:bold>Ogawa and Sommer</jats:bold> </jats:related-article> </jats:bold> ) show that subsets of the complex mixture of structurally related molecules in dauer pheromone act via distinct G protein–coupled receptors either to initiate longterm effects on development and physiology by modulating the neuroendocrine axis, or to trigger short-term acute effects on behavior by altering neuronal responses. </jats:p>

<jats:title>Sleep and Alzheimer's Disease</jats:title> <jats:p> Accumulation of amyloid-β (Aβ) in the brain is thought to be the initiating event in the pathogenesis of Alzheimer's disease (AD). Aβ is a peptide secreted in a soluble monomeric form predominantly by neurons and its aggregation into toxic forms is concentration dependent. Synaptic activity regulates the release of Aβ in vivo. However, how physiological and environmental processes are involved in regulation of Aβ levels is not understood. <jats:bold> Kang <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="1005" related-article-type="in-this-issue" vol="326" xlink:href="10.1126/science.1180962">1005</jats:related-article> , published online 24 September), by performing sleep-wake studies in freely behaving animals concomitant with in vivo microdialysis, found that brain interstitial fluid levels of Aβ were significantly correlated with wakefulness and negatively correlated with sleep. Furthermore, relatively short-term (3 weeks) sleep deprivation markedly accelerated amyloid plaque deposition in amyloid precursor protein transgenic mice. Thus, sleep-wake behavior is linked to Aβ levels and abnormal sleep may be linked to AD pathogenesis. </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>The show includes climate change predictions, creating hermaphroditic worms, and more.</jats:p>