Catálogo de publicaciones - revistas

<jats:title>Baboons inform on human gut microbiota</jats:title> <jats:p> Commensal bacteria are found throughout an organism, but it is not known whether associations between gut bacteria and their host are heritable. Grieneisen <jats:italic>et al.</jats:italic> examined changes in the microbiomes of 585 wild baboons from fecal samples collected over 14 years (see the Perspective by Cortes-Ortiz and Amato). Almost all microbiome traits tested demonstrated some level of statistically significant heritability. Most heritability values were low but varied over time correlating with the age of the host. Baboons live in an environment similar to that postulated for early humans and have a microbiome similar to that of humans. Thus, this heritability of the microbiome may reflect similar genetic determinants in humans, for which similar datasets are not available. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , aba5483, this issue p. <jats:related-article issue="6551" page="181" related-article-type="in-this-issue" vol="373">181</jats:related-article> ; see also abj5287, p. <jats:related-article issue="6551" page="159" related-article-type="in-this-issue" vol="373">159</jats:related-article> </jats:p>

<jats:title>Ice goes bendy</jats:title> <jats:p> One well known characteristic of ice is that it fractures instead of bending when strained. This characteristic is caused by the inevitable defects introduced into the ice structure during solidification. Xu <jats:italic>et al.</jats:italic> show that very thin, carefully grown ice microfibers can bend a lot, up to about 11%, and still remain elastic (see the Perspective by Schulson). This value is reasonably close to theoretical limits previously estimated. The fibers are also super clear, allowing for efficient light transmission. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , abh3754, this issue p. <jats:related-article issue="6551" page="187" related-article-type="in-this-issue" vol="373">187</jats:related-article> ; see also abj4441, p. <jats:related-article issue="6551" page="158" related-article-type="in-this-issue" vol="373">158</jats:related-article> </jats:p>

<jats:title>Vegetal fractals</jats:title> <jats:p> Cauliflower, along with dahlias and daisies, develop as phyllotactic spirals. Azpeitia <jats:italic>et al</jats:italic> . combined modeling with experimental investigation to clarify the gene-regulatory network that sets up a multitude of undeveloped flowers to form a cauliflower curd. Irrepressible inflorescence identity genes in the context of dysfunctional meristems and slow internode elongation results in piles of incomplete flowers. If meristem size drifts during organogenesis, then the conical structures of the Romanesco form emerge in fractal formation. —PJH </jats:p>

<jats:title>Modified clay minerals on Mars</jats:title> <jats:p> Sedimentary rocks exposed in Gale crater on Mars contain extensive clay minerals. Bristow <jats:italic>et al.</jats:italic> analyzed drill samples collected by the Curiosity rover as it climbed up sedimentary layers in the crater. They found evidence of past reactions with liquid water and sulfate brines, which could have percolated through the clay from an overlying sulfate deposit. Similar sulfate deposits are widespread across the planet and represent some of the last sedimentary rocks to form before the planet lost its surface liquid water, so the results inform our understanding of the geologic processes that occurred as Mars dried out. </jats:p> <jats:p> Science, abg5449, this issue p. <jats:related-article issue="6551" page="198" related-article-type="in-this-issue" vol="373">198</jats:related-article> </jats:p>

<jats:title>The limits of channel offset</jats:title> <jats:p> The offset of stream channels across a strike-slip fault offer a record of long-term slip rates. The process itself is an interesting case of landscape evolution because the streams will spill straight across the fault at some point and reset the offset. Dascher-Cousineau <jats:italic>et al.</jats:italic> developed a model for this process that they validated using observations from the Carrizo Plain in California. The model leverages transitions from active to abandoned stream channels to determine when and how drainage networks in these regions reorganize and allow quantification of both slip and bedload transport. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , abf2320, this issue p. <jats:related-article issue="6551" page="204" related-article-type="in-this-issue" vol="373">204</jats:related-article> </jats:p>

<jats:title>Shear selectivity</jats:title> <jats:p> Chemical reactions typically proceed by distributing energy statistically among all accessible molecular vibrations. Liu <jats:italic>et al.</jats:italic> report that external shear forces can sometimes pry open strained carbon rings without dissipating energy into adjacent bond rotations. Through careful design and synthesis of polymer-embedded cyclobutyl rings, the authors showed that certain relative substituent geometries are preserved when sonication induces ring opening. Accompanying simulations support the instigation of “flyby” trajectories that channel energy narrowly to cleave the cyclic sigma bonds and then rapidly form acyclic pi bonds. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , abi7609, this issue p. <jats:related-article issue="6551" page="208" related-article-type="in-this-issue" vol="373">208</jats:related-article> </jats:p>

<jats:title>Looking for magnetic clues</jats:title> <jats:p> Thin films of the neodymium nickelate NdNiO <jats:sub>2</jats:sub> doped with strontium have recently been found to be superconducting. This materials class bears structural and electronic similarities to the famed cuprate superconductors, but how far the analogy goes remains unclear. Lu <jats:italic>et al.</jats:italic> used resonant inelastic x-ray scattering to look for magnetism, which exists in the cuprates, in Nd <jats:sub>1-x</jats:sub> Sr <jats:sub>x</jats:sub> NiO <jats:sub>2</jats:sub> films (see the Perspective by Benckiser). The authors observed magnetic modes in the undoped compound that had a doping evolution consistent with the behavior of a doped Mott insulator. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , abd7726, this issue p. <jats:related-article issue="6551" page="213" related-article-type="in-this-issue" vol="373">213</jats:related-article> ; see also abi6855, p. <jats:related-article issue="6551" page="157" related-article-type="in-this-issue" vol="373">157</jats:related-article> </jats:p>

<jats:title>Hitting the limits on propene synthesis</jats:title> <jats:p> The greater abundance of propane from shale gas has spurred efforts to use it as a propylene feedstock. Direct dehydrogenation catalysts consisting of platinum–tin alloy nanoparticles supported on alumina often must run with hydrogen dilution to avoid carbon buildup and excess tin to avoid alloy segregation. Motagamwala <jats:italic>et al.</jats:italic> report that platinum–tin nanoparticles interact more weakly with a silica support and the metals thus do not segregate. The use of undiluted reactants allowed the reaction to run near the thermodynamically limit of about 67% conversion with a selectivity to propylene of more than 99%. This catalyst also does not build up carbon and could run up to 30 hours without deactivation. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , abg7894, this issue p. <jats:related-article issue="6551" page="217" related-article-type="in-this-issue" vol="373">217</jats:related-article> </jats:p>

<jats:title>Keeping warm when small</jats:title> <jats:p> Several mammal species live in cold-water environments, enabled by adaptations such as blubber and large size. A notable exception to this rule is the sea otter, a species that is orders of magnitude smaller and skinnier than the others. It is known that the sea otter's unusually thick fur helps, but Wright <jats:italic>et al.</jats:italic> show that they are also internally warmed by thermogenic leak from skeletal muscle, a process that elevates their metabolic rate three times above that expected for their size. This mechanism is present even in infants with immature muscles, providing these animals with internal warmth from birth. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , abf4557, this issue p. <jats:related-article issue="6551" page="223" related-article-type="in-this-issue" vol="373">223</jats:related-article> </jats:p>

<jats:title>From savory to sweet</jats:title> <jats:p> Seeing a bird eat nectar from a flower is a common sight in our world. The ability to detect sugars, however, is not ancestral in the bird lineage, where most species were carnivorous. Toda <jats:italic>et al.</jats:italic> looked at receptors within the largest group of birds, the passerines or songbirds, and found that the emergence of sweet detection involved a single shift in a receptor for umami (see the Perspective by Barker). This ancient change facilitated sugar detection not just in nectar feeding birds, but also across the songbird group, and in a way that was different from, though convergent with, that in hummingbirds. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , abf6505, this issue p. <jats:related-article issue="6551" page="226" related-article-type="in-this-issue" vol="373">226</jats:related-article> ; see also abj6746, p. <jats:related-article issue="6551" page="154" related-article-type="in-this-issue" vol="373">154</jats:related-article> </jats:p>