Catálogo de publicaciones - revistas

<jats:title>Graphene-based biosensors</jats:title> <jats:p> The mid-infrared (mid-IR) range is particularly well suited for biosensing because it encompasses the molecular vibrations that identify the biochemical building blocks of life, such as proteins, lipids, and DNA. However, the resulting optical signal is extremely weak and often requires complex techniques to enhance the biological detection. Rodrigo <jats:italic>et al.</jats:italic> present a graphene-based biosensor that they dynamically tuned over a broad spectral range through electrical gating. The authors selectively probed protein molecules at different mid-IR frequencies using a single device. </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="6244" page="165" related-article-type="in-this-issue" vol="349" xlink:href="10.1126/science.aab2051">165</jats:related-article> </jats:p>

<jats:title>Black hole out of kilter with theory</jats:title> <jats:p> It is believed that black holes and their host galaxies coevolve, with the feedback from the black hole inducing star formation. Such a scenario requires certain timing and mass constraints for the black hole and the star-forming gas. Trakhtenbrot <jats:italic>et al.</jats:italic> looked at high–red shift galaxies, when the universe was only about 2 billion years old. They found a black hole that developed to maturity much earlier than would be expected and was about 10% of the total galactic mass—much more than expected. Moreover, star formation continued after it would have been expected to stop. </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="6244" page="168" related-article-type="in-this-issue" vol="349" xlink:href="10.1126/science.aaa4506">168</jats:related-article> </jats:p>

<jats:title>Laid-back bamboo eater</jats:title> <jats:p> Pandas are members of the order Carnivora but are entirely herbivorous, living almost exclusively on bamboo. Unlike most other herbivorous species, however, their digestive tract has not evolved the long twists and turns that facilitate the slower digestion necessary for cellulose-rich plants. Nie <jats:italic>et al.</jats:italic> measured energy expenditure in both wild and captive pandas, which was extremely low, relative to other mammals. The pandas' thyroid hormone levels are also a fraction of the mammalian norm. </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="6244" page="171" related-article-type="in-this-issue" vol="349" xlink:href="10.1126/science.aab2413">171</jats:related-article> </jats:p>

<jats:title>Continental global water filter</jats:title> <jats:p> Mobile surface waters and soil waters are relatively disconnected on a global scale. Water on land is eventually lost by surface runoff into the oceans or is ultimately sent back to the atmosphere through evapotranspiration processes. Good <jats:italic>et al.</jats:italic> determined that 65% of continental water evaporation is from soils, which includes water taken up and transpired by plants (see the Perspective by Brooks). Although just a small fraction of global surface waters pass through soils, individual stream ecosystems may be affected by water quality changes in nearby soils. </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="6244" page="175" related-article-type="in-this-issue" vol="349" xlink:href="10.1126/science.aaa5931">175</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6244" page="138" related-article-type="in-this-issue" vol="349" xlink:href="10.1126/science.aac4742">138</jats:related-article> </jats:p>

<jats:title>Bucking the trend</jats:title> <jats:p> Responses to climate change have been observed across many species. There is a general trend for species to shift their ranges poleward or up in elevation. Not all species, however, can make such shifts, and these species might experience more rapid declines. Kerr <jats:italic>et al.</jats:italic> looked at data on bumblebees across North America and Europe over the past 110 years. Bumblebees have not shifted northward and are experiencing shrinking distributions in the southern ends of their range. Such failures to shift may be because of their origins in a cooler climate, and suggest an elevated susceptibility to rapid climate change. </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="6244" page="177" related-article-type="in-this-issue" vol="349" xlink:href="10.1126/science.aaa7031">177</jats:related-article> </jats:p>

<jats:title>Memory storage in neural networks</jats:title> <jats:p>Neuronal networks can store and retrieve discrete memories, but often fail to retrieve stored sequences. This is because error decreases over time for a static attractor, but builds up drastically over time if patterns are not trained to retrieve themselves but to retrieve the next item in a sequence. Pfeiffer and Foster studied brain activity in awake but immobile rats. Recording simultaneously from a large number of place cells in the hippocampal formation, they found that internally generated sequences alternated between periods of hovering in place while being strengthened, and periods of abrupt transition to a new place.</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="6244" page="180" related-article-type="in-this-issue" vol="349" xlink:href="10.1126/science.aaa9633">180</jats:related-article> </jats:p>

<jats:title>A better way to explain neuronal activity</jats:title> <jats:p> A brain region called the lateral intraparietal (LIP) area is involved in primate decision-making. The dominant model to explain neuronal firing in LIP assumes that neurons slowly accumulate sensory evidence in favor of one choice or another. Latimer <jats:italic>et al.</jats:italic> hypothesized that neurons instead exhibit rapid steps or jumps in their firing rate, reflecting discrete changes in the animal's decision state. They recorded from LIP neurons in macaque monkeys performing a motion-discrimination task. LIP spike trains in most cells involved discrete stepping dynamics rather than slow evidence integration dynamics. </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="6244" page="184" related-article-type="in-this-issue" vol="349" xlink:href="10.1126/science.aaa4056">184</jats:related-article> </jats:p>

<jats:title>Structure of a sterol sensor</jats:title> <jats:p> The aberrant accumulation of sterols contributes to heart attack and stroke. Two proteins embedded in the membrane of the endoplasmic reticulum, Insig-1 and Insig-2, are key players in the cellular pathway that regulates cellular sterol levels. Ren <jats:italic>et al.</jats:italic> report the structure of a mycobacterial homolog of Insig. The structure, together with biochemical experiments, suggests how Insig interacts with other components of the sterol regulatory 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="6244" page="187" related-article-type="in-this-issue" vol="349" xlink:href="10.1126/science.aab1091">187</jats:related-article> </jats:p>

<jats:title>Steps in the right direction</jats:title> <jats:p> HIV-1 mutates rapidly, making it difficult to design a vaccine that will protect people against all of the virus' iterations. A potential successful vaccine design might protect by eliciting broadly neutralizing antibodies (bNAbs), which target specific regions on HIV-1's trimeric envelope glycoprotein (Env) (see the Perspective by Mascola). Jardine <jats:italic>et al.</jats:italic> used mice engineered to express germline-reverted heavy chains of a particular bNAb and immunized them with an Env-based immunogen designed to bind to precursors of that bNAb. Sanders <jats:italic>et al.</jats:italic> compared rabbits and monkeys immunized with Env trimers that adopt a nativelike conformation. In both cases, immunized animals produced antibodies that shared similarities with bNAbs. Boosting these animals with other immunogens may drive these antibodies to further mutate into the longsought bNAbs. Chen <jats:italic>et al.</jats:italic> report that retaining the cytoplasmic domain of Env proteins may be important to attract bNAbs. Removing the cytoplasmic domain may distract the immune response and instead generate antibodies that target epitopes on Env that would not lead to protection. </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="6244" page="139" related-article-type="in-this-issue" vol="349" xlink:href="10.1126/science.aac7800">139</jats:related-article> , <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" related-article-type="in-this-issue" xlink:href="10.1126/science.aac4223">10.1126/science.aac4223</jats:related-article> , p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6244" page="156" related-article-type="in-this-issue" vol="349" xlink:href="10.1126/science.aac5894">156</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6244" page="191" related-article-type="in-this-issue" vol="349" xlink:href="10.1126/science.aaa9804">191</jats:related-article> </jats:p>

<jats:title>A coat of many components</jats:title> <jats:p> The formation of coated trafficking vesicles is among the most fundamental of cellular processes. COP1 transport vesicles are involved in retrograde membrane trafficking in the Golgi apparatus and endoplasmic reticulum. Dodonova <jats:italic>et al.</jats:italic> applied cryo–electron tomography to determine the structure of the COPI coat in its fully assembled form on budded vesicles (see the Perspective by Noble and Stagg). They combined structural data with cross-linking mass spectrometry to generate a complete molecular model. The model suggests a mechanism of coat assembly in which coat proteins cluster via flexible interactions instead of forming a protein cage on the membrane. </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="6244" page="195" related-article-type="in-this-issue" vol="349" xlink:href="10.1126/science.aab1121">195</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6244" page="142" related-article-type="in-this-issue" vol="349" xlink:href="10.1126/science.aac6537">142</jats:related-article> </jats:p>