Catálogo de publicaciones - revistas

<jats:title>Dusty Origins</jats:title> <jats:p> The formation of cirrus clouds begins with the production of ice nuclei, on which water vapor then condenses. <jats:bold> Cziczo <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="6138" page="1320" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1234145">1320</jats:related-article> , published online 9 May) determined the kinds of particles on which cirrus ice crystals form by sublimating samples collected by research aircraft and analyzing the chemical and physical properties of the residual seeds. Most of the seed particles were either mineral dust or metallic. </jats:p>

<jats:title>Holding Your Breath</jats:title> <jats:p> Hemoglobin and myoglobin are widely responsible for oxygen transport and storage (see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6138" page="1293" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1240631">Rezende</jats:related-article> </jats:bold> ). The ability of diving mammals to obtain enough oxygen to support extended dives and foraging is largely dependent on muscle myoglobin (Mb) content. <jats:bold> Mirceta <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/340/6138/1234192.full">1303</jats:ext-link> ) found that in mammalian lineages with an aquatic or semiaquatic lifestyle, Mb net charge increases, which may represent an adaptation to inhibit self-association of Mb at high intracellular concentrations. Epistasis results from nonadditive genetic interactions and can affect phenotypic evolution. <jats:bold> Natarajan <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="6138" page="1324" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1236862">1324</jats:related-article> ) found that epistatic interactions were able to explain the increased hemoglobin oxygen-binding affinity observed in deer mice populations at high altitude. In mammals, the offloading of oxygen from hemoglobin is facilitated by a reduction in the blood's pH, driven by metabolically produced CO <jats:sub>2</jats:sub> . However, in fish, a reduction in blood pH reduces oxygen carrying capacity of hemoglobin. <jats:bold> Rummer <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="6138" page="1327" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1233692">1327</jats:related-article> ) implanted fiber optic oxygen sensors within the muscles of rainbow trout and found that elevated CO <jats:sub>2</jats:sub> levels in the water led to acidosis and elevated oxygen tensions. </jats:p>

<jats:title>Holding Your Breath</jats:title> <jats:p> Hemoglobin and myoglobin are widely responsible for oxygen transport and storage (see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6138" page="1293" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1240631">Rezende</jats:related-article> </jats:bold> ). The ability of diving mammals to obtain enough oxygen to support extended dives and foraging is largely dependent on muscle myoglobin (Mb) content. <jats:bold> Mirceta <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/340/6138/1234192.full">1303</jats:ext-link> ) found that in mammalian lineages with an aquatic or semiaquatic lifestyle, Mb net charge increases, which may represent an adaptation to inhibit self-association of Mb at high intracellular concentrations. Epistasis results from nonadditive genetic interactions and can affect phenotypic evolution. <jats:bold> Natarajan <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="6138" page="1324" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1236862">1324</jats:related-article> ) found that epistatic interactions were able to explain the increased hemoglobin oxygen-binding affinity observed in deer mice populations at high altitude. In mammals, the offloading of oxygen from hemoglobin is facilitated by a reduction in the blood's pH, driven by metabolically produced CO <jats:sub>2</jats:sub> . However, in fish, a reduction in blood pH reduces oxygen carrying capacity of hemoglobin. <jats:bold> Rummer <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="6138" page="1327" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1233692">1327</jats:related-article> ) implanted fiber optic oxygen sensors within the muscles of rainbow trout and found that elevated CO <jats:sub>2</jats:sub> levels in the water led to acidosis and elevated oxygen tensions. </jats:p>

<jats:title>Methylation and Methuselah?</jats:title> <jats:p> Hutchinson-Gilford progeria syndrome (HGPS) and other prelamin A–associated progeroid disorders arise when farnesylated and methylated forms of prelamin A accumulate at the nuclear envelope. <jats:bold> Ibrahim <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="6138" page="1330" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1238880">1330</jats:related-article> , published online 16 May; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6138" page="1299" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1240843">Johnson</jats:related-article> </jats:bold> ) show that reducing the activity of the isoprenylcysteine carboxyl methyltransferase (ICMT) mislocalizes prelamin A, triggers prelamin A–dependent AKT-mTOR signaling, and eliminates disease phenotypes in 30-week-old progeria model mice. Reduced ICMT expression increased the proliferation and delayed the premature senescence of progeria model mouse fibroblasts and cells from children with HGPS. </jats:p>

<jats:title>Too Much or Too Little</jats:title> <jats:p> An important task of the nervous system is to distribute information appropriately throughout the brain. The olfactory and gustatory systems of <jats:italic>Drosophila</jats:italic> provide good models for understanding these processes and the underlying mechanisms (see the Perspective by <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6138" page="1295" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1240139"> <jats:bold>Su and Carlson</jats:bold> </jats:related-article> ). <jats:bold> Lin <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="6138" page="1338" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1236693">1338</jats:related-article> ) mapped out the circuit that detects carbon dioxide (CO <jats:sub>2</jats:sub> ), an important environmental and communication signal for fruit flies. Two distinct classes of projection neurons mediate avoidance of high and low concentrations of CO <jats:sub>2</jats:sub> , while a third class, comprising inhibitory neurons, shuts down the low-concentration pathway at high concentrations. In contrast to other basic taste qualities, salt is innately attractive at low concentrations, but aversive at high concentrations. The mechanisms underlying salt detection are poorly understood in any species mainly because of a lack of specific molecular tools. <jats:bold> Zhang <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="6138" page="1334" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1234133">1334</jats:related-article> ) discovered that <jats:italic>Drosophila</jats:italic> uses two types of gustatory receptor neurons to distinguish between high and low concentrations of salt. One type is activated maximally by low salt and induces attractive feeding behavior. The other class of receptors is activated primarily by high salt and leads to avoidance behavior. </jats:p>

<jats:title>Too Much or Too Little</jats:title> <jats:p> An important task of the nervous system is to distribute information appropriately throughout the brain. The olfactory and gustatory systems of <jats:italic>Drosophila</jats:italic> provide good models for understanding these processes and the underlying mechanisms (see the Perspective by <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6138" page="1295" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1240139"> <jats:bold>Su and Carlson</jats:bold> </jats:related-article> ). <jats:bold> Lin <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="6138" page="1338" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1236693">1338</jats:related-article> ) mapped out the circuit that detects carbon dioxide (CO <jats:sub>2</jats:sub> ), an important environmental and communication signal for fruit flies. Two distinct classes of projection neurons mediate avoidance of high and low concentrations of CO <jats:sub>2</jats:sub> , while a third class, comprising inhibitory neurons, shuts down the low-concentration pathway at high concentrations. In contrast to other basic taste qualities, salt is innately attractive at low concentrations, but aversive at high concentrations. The mechanisms underlying salt detection are poorly understood in any species mainly because of a lack of specific molecular tools. <jats:bold> Zhang <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="6138" page="1334" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1234133">1334</jats:related-article> ) discovered that <jats:italic>Drosophila</jats:italic> uses two types of gustatory receptor neurons to distinguish between high and low concentrations of salt. One type is activated maximally by low salt and induces attractive feeding behavior. The other class of receptors is activated primarily by high salt and leads to avoidance behavior. </jats:p>

<jats:title>A Sense of Place</jats:title> <jats:p> Hippocampal place cells are believed to be mainly governed by visual and self-motion cues. However, the contribution of sensory cues such as smells, sounds, and textures, etc., is difficult to eliminate. In virtual reality, these cues will not provide any information about the animals' position. <jats:bold> Ravassard <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="6138" page="1342" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1232655">1342</jats:related-article> , published online 2 May) developed a virtual-reality system as immersive and close to the real world as possible and compared place cells in rats running in this apparatus and in the real world. Twice as many neurons were active in a real-world situation compared to virtual reality. While place cells in the real world encoded position, place cells in a virtual world encoded distance. </jats:p>

<jats:title>Choosing Water</jats:title> <jats:p> Aquaporins are proteins that facilitate transport of water across biological membranes. They must be selective for water, without binding it so tightly as to impede transport, and they must prevent proton transfer by rapid exchange between hydrogen-bonded water molecules. <jats:bold> Kosinska Eriksson <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="6138" page="1346" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1234306">1346</jats:related-article> ; see the Perspective by <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6138" page="1294" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1239270"> <jats:bold>Abramson and Vartanian</jats:bold> </jats:related-article> ) describe the subangstrom resolution structure of yeast aquaporin, which allows assignment of side-chain conformations and shows that the H-bond geometry of water molecules prevents proton conductance without compromising water transport. </jats:p>

<jats:p>As genome sequencers churn out terabytes of new data daily, researchers are increasingly turning to an information-handling strategy already favored by internet companies: cloud computing.</jats:p>

<jats:p>A weekly roundup of information on newly offered instrumentation, apparatus, and laboratory materials of potential interest to researchers.</jats:p>