Catálogo de publicaciones - revistas

<jats:title>Beyond adaptive immunity</jats:title> <jats:p> Prokaryotic CRISPR-Cas systems defend bacterial cells from phage and plasmid infection. Strecker <jats:italic>et al.</jats:italic> characterized a CRISPR-Cas system that functions beyond adaptive immunity (see the Perspective by Hou and Zhang). Type V-K CRISPR-Cas from cyanobacteria was associated with a Tn7-like transposon and a natural nuclease–deficient effector Cas12k. Cas12k directed the insertion of Tn7-like transposons into target sites via RNA-guided Tn7 transposition. This system was reprogrammed to efficiently and specifically insert DNA both in vitro and into the <jats:italic>Escherichia coli</jats:italic> genome. </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="6448" page="48" related-article-type="in-this-issue" vol="365" xlink:href="10.1126/science.aax9181">48</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6448" page="25" related-article-type="in-this-issue" vol="365" xlink:href="10.1126/science.aay2056">25</jats:related-article> </jats:p>

<jats:title>ER-phagy keeps cells healthy</jats:title> <jats:p> In eukaryotic cells, about one-third of all proteins are targeted to the endoplasmic reticulum (ER), which serves as a hub for secretory protein traffic and quality control. Cui <jats:italic>et al.</jats:italic> studied a protein known as Lst1 in yeast and SEC24C in mammalian cells that is involved in loading secretory cargo into vesicles that are delivered to the Golgi complex. In response to stress caused by starvation or misfolded aggregate-prone secretory proteins, Lst1 acted to promote an additional function—ER-phagy. Together with autophagy receptors on the ER, Lst1 targeted ER domains for degradation to avert protein aggregation, thus preserving cellular health. </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="6448" page="53" related-article-type="in-this-issue" vol="365" xlink:href="10.1126/science.aau9263">53</jats:related-article> </jats:p>

<jats:title>Refilling the proton pump</jats:title> <jats:p> Proteins are dynamic. Rearrangements of side chains, secondary structure, and entire domains gate functional transitions on time scales ranging from picoseconds to milliseconds. Weinert <jats:italic>et al.</jats:italic> used time-resolved serial crystallography to study large conformational changes in the proton pump bacteriorhodopsin that allow for redistribution of protons during the pumping cycle. They adapted methods used for x-ray free electron lasers to synchrotron x-ray sources. Large loop movements and a chain of water molecules were central to regenerating the starting state of bacteriorhodopsin. </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="6448" page="61" related-article-type="in-this-issue" vol="365" xlink:href="10.1126/science.aaw8634">61</jats:related-article> </jats:p>

<jats:title>Oxygen sensing across kingdoms</jats:title> <jats:p> The ability to sense and respond to changes in oxygen levels is critical for most forms of life. To date, mechanistic studies of this process in mammals have focused on the oxygen-sensitive stability of a transcription factor called hypoxia-inducible factor. Masson <jats:italic>et al.</jats:italic> discovered an enzymatic oxygen sensor in humans that is functionally identical to plant cysteine oxidases, enzymes that control responses to hypoxia in plants. The human and plant enzymes convert the N-terminal cysteine in substrate proteins to cysteine sulfinic acid, a modification that ultimately targets the proteins for degradation. Oxygen sensing is impaired in many human diseases, and further study of the human enzyme could help in the development of strategies for therapeutic intervention. </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="6448" page="65" related-article-type="in-this-issue" vol="365" xlink:href="10.1126/science.aaw0112">65</jats:related-article> </jats:p>

<jats:title>Honesty and selfishness across cultures</jats:title> <jats:p> Rationalist approaches to economics assume that people value their own interests over the interests of strangers. Cohn <jats:italic>et al.</jats:italic> wanted to examine the trade-off between material self-interest and more altruistic behaviors (see the Perspective by Shalvi). They distributed more than 17,000 wallets containing various sums of money in 355 cities across 40 countries. In contrast to what rationalist theories of economics predict, citizens were more likely to return wallets that contained more money. The findings also reveal a high level of civic honesty across nations. </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="6448" page="70" related-article-type="in-this-issue" vol="365" xlink:href="10.1126/science.aau8712">70</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6448" page="29" related-article-type="in-this-issue" vol="365" xlink:href="10.1126/science.aax5034">29</jats:related-article> </jats:p>

<jats:title>Smaller but more ductile</jats:title> <jats:p> Poor ductility is one limiting factor in widespread use of strong but lightweight magnesium alloys in cars, trains, and planes. The usual way to try to circumvent this poor ductility is by adding other elements, which can be costly. Liu <jats:italic>et al.</jats:italic> show that very small samples of pure magnesium are much more ductile than previously believed (see the Perspective by Proust). The small samples suppress the deformation twinning that causes fractures in larger samples. Avoiding this mechanism should allow development of high-ductility magnesium and other metal alloys. </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="6448" page="73" related-article-type="in-this-issue" vol="365" xlink:href="10.1126/science.aaw2843">73</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6448" page="30" related-article-type="in-this-issue" vol="365" xlink:href="10.1126/science.aax9732">30</jats:related-article> </jats:p>

<jats:p>The restoration of trees remains among the most effective strategies for climate change mitigation. We mapped the global potential tree coverage to show that 4.4 billion hectares of canopy cover could exist under the current climate. Excluding existing trees and agricultural and urban areas, we found that there is room for an extra 0.9 billion hectares of canopy cover, which could store 205 gigatonnes of carbon in areas that would naturally support woodlands and forests. This highlights global tree restoration as one of the most effective carbon drawdown solutions to date. However, climate change will alter this potential tree coverage. We estimate that if we cannot deviate from the current trajectory, the global potential canopy cover may shrink by ~223 million hectares by 2050, with the vast majority of losses occurring in the tropics. Our results highlight the opportunity of climate change mitigation through global tree restoration but also the urgent need for action.</jats:p>

<jats:title>A panoramic view of photodissociation</jats:title> <jats:p> As light pulses get shorter in time, they correspondingly get broader in frequency. Kobayashi <jats:italic>et al.</jats:italic> take advantage of both properties of attosecond pulses to elucidate iodine monobromide (IBr) photodissociation by detecting ultrafast bromine and iodine spectral shifts simultaneously. A preliminary burst of light weakens the I–Br bond. Then, as the atoms fly apart, they reach a configuration where the bond vibration can couple ground and excited electronic states. The broadband probe pulse reveals rapid changes in each atom's electronic structure at this juncture. </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="6448" page="79" related-article-type="in-this-issue" vol="365" xlink:href="10.1126/science.aax0076">79</jats:related-article> </jats:p>

<jats:title>The biggest bloom</jats:title> <jats:p> Floating mats of <jats:italic>Sargassum</jats:italic> seaweed in the center of the North Atlantic were first reported by Christopher Columbus in the 15th century. These mats, although abundant, have until recently been limited and discontinuous. However, Wang <jats:italic>et al.</jats:italic> report that, since 2011, the mats have increased in density and aerial extent to generate a 8850-kilometer-long belt that extends from West Africa to the Caribbean Sea and Gulf of Mexico (see the Perspective by Gower and King). This represents the world's largest macroalgal bloom. Such recurrent blooms may become the new normal. </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="6448" page="83" related-article-type="in-this-issue" vol="365" xlink:href="10.1126/science.aaw7912">83</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6448" page="27" related-article-type="in-this-issue" vol="365" xlink:href="10.1126/science.aay0989">27</jats:related-article> </jats:p>