Catálogo de publicaciones - revistas

<jats:title>Crystal nuclei beaten to the punch</jats:title> <jats:p> Amorphous nanoparticles often dissolve more rapidly than their crystalline counterparts, which can be useful in applications such as drug delivery. Amstad <jats:italic>et al.</jats:italic> made amorphous nanoparticles from organic and inorganic compounds—even table salt—using droplets of dissolved compounds created with a microfluidic nebulator. The solvent evaporates fast enough that nanoparticles form before crystal nuclei can develop. The small particle size inhibits crystallization for periods of months </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="6251" page="956" related-article-type="in-this-issue" vol="349" xlink:href="10.1126/science.aac9582">956</jats:related-article> </jats:p>

<jats:title>Iron plays matchmaker to pair up olefins</jats:title> <jats:p> In theory, shining the right wavelength of light onto carbon-carbon double bonds should pair them up into four-membered cyclobutane rings. In practice, however, this route can prove finicky and inefficient, particularly if the necessary wavelength lies deep in the ultraviolet region. Hoyt <jats:italic>et al.</jats:italic> report an iron catalyst that coaxes a wide variety of simple olefins into such rings without the need for photoexcitation (see the Perspective by Smith and Baran). Systematic optimization of the ligand coordinated to iron effectively eliminated competing pathways to alternative products. </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="6251" page="960" related-article-type="in-this-issue" vol="349" xlink:href="10.1126/science.aac7440">960</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6251" page="925" related-article-type="in-this-issue" vol="349" xlink:href="10.1126/science.aac9883">925</jats:related-article> </jats:p>

<jats:title>A third option leads to poor mates</jats:title> <jats:p>A “decoy” effect decreases rational decision-making in humans. Irrational decisions in this case are a result of a choice between two options being affected by the introduction of a suboptimal third choice. Lea and Ryan show that tungara frogs are also subject to a decoy effect, choosing a male with a less appealing call when presented with a third, inferior calling male. These results suggest that the choice of mates by animals may be context dependent. It appears that rational choice may not always drive sexual selection.</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="6251" page="964" related-article-type="in-this-issue" vol="349" xlink:href="10.1126/science.aab2012">964</jats:related-article> </jats:p>

<jats:p>Life history theory attempts to explain why species differ in offspring number and quality, growth rate, and parental effort. I show that unappreciated interactions of these traits in response to age-related mortality risk challenge traditional perspectives and explain life history evolution in songbirds. Counter to a long-standing paradigm, tropical songbirds grow at similar overall rates to temperate species but grow wings relatively faster. These growth tactics are favored by predation risk, both in and after leaving the nest, and are facilitated by greater provisioning of individual offspring by parents. Increased provisioning of individual offspring depends on partitioning effort among fewer young because of constraints on effort from adult and nest mortality. These growth and provisioning responses to mortality risk finally explain the conundrum of small clutch sizes of tropical birds.</jats:p>

<jats:title>Cosmopolitan plant root symbionts</jats:title> <jats:p> The aboveground lives of plants are only sustainable because of the symbiotic soil fungi that encase their roots. These fungi swap nutrients with plants, defend them from attack, and help them withstand abrupt environmental changes. Out of necessity, fungal symbionts in the soil would appear to be restricted and local to certain plant species. Davison <jats:italic>et al.</jats:italic> , however, discovered that some taxa are globally distributed. How these underground fungi have dispersed so widely remains a mystery; perhaps human farmers have had something to do with it. </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="6251" page="970" related-article-type="in-this-issue" vol="349" xlink:href="10.1126/science.aab1161">970</jats:related-article> </jats:p>

<jats:title>Axon paths in developing spinal cords</jats:title> <jats:p> Sensory neurons entering the spinal cord take different paths as inputs for pain and proprioception diverge. Working with chick and mouse embryos, Guy <jats:italic>et al.</jats:italic> found that glycerophospholipids produced by radial glial cells guide these neural fibers, or axons, in the developing spinal cord. A soluble glycerophospholipid released by the cells provided an inhibitory signal to the pain-sensitive axons, keeping them on their own unique 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="6251" page="974" related-article-type="in-this-issue" vol="349" xlink:href="10.1126/science.aab3516">974</jats:related-article> </jats:p>

<jats:title>Matching DNA three bases at a time</jats:title> <jats:p> The exchange of genetic information between DNA strands is vital for accurate DNA repair and effective meiotic cell division. Using single-molecule methods and molecular dynamics simulations, Lee <jats:italic>et al.</jats:italic> show that members of the family of recombinase enzymes responsible for these strand exchange reactions search for and recognize matching DNA strands three bases at a time. A single mismatch abolishes triplet recognition, except for the meiosis-specific recombinase. This enzyme can stabilize a partially mismatched triplet, reflecting the partial homology of the DNA substrates in meiosis. </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="6251" page="977" related-article-type="in-this-issue" vol="349" xlink:href="10.1126/science.aab2666">977</jats:related-article> </jats:p>

<jats:title>A giant disruption of the heart</jats:title> <jats:p> Certain forms of heart failure originate from genetic mutations. Understanding how the culprit mutant proteins alter normal heart function could lead to more effective treatments. One candidate is the giant protein tintin, which is mutated in a subset of patients with dilated cardiomyopathy. Through a combination of patient-derived stem cells, tissue engineering, and gene editing, Hinson <jats:italic>et al.</jats:italic> found that disease-associated titin mutations disrupt the function of the contractile unit in heart muscle. As a result, the heart does not respond properly to mechanical and other forms of stress. </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="6251" page="982" related-article-type="in-this-issue" vol="349" xlink:href="10.1126/science.aaa5458">982</jats:related-article> </jats:p>

<jats:title>Engineering cell population behavior</jats:title> <jats:p> Attaining the full promise of synthetic biology will require designing population-level behaviors of multiple interacting cell types. As a start, Chen et al. engineered two strains of the bacterium <jats:italic>Escherichia coli</jats:italic> to produce signaling molecules that regulate transcription in the complementary strain (see the Perspective by Teague and Weiss). The signaling circuit was successfully designed to produce feedback loops that produce synchronous oscillations in transcription between the two strains. A mathematical model helped determine how to modulate the oscillations and control their robustness to perturbations. </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="6251" page="986" related-article-type="in-this-issue" vol="349" xlink:href="10.1126/science.aaa3794">986</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6251" page="924" related-article-type="in-this-issue" vol="349" xlink:href="10.1126/science.aad0876">924</jats:related-article> </jats:p>

<jats:title>Gut microbes make T cells keep the peace</jats:title> <jats:p> Our guts harbor trillions of microbial inhabitants, some of which regulate the types of immune cells that are present in the gut. For instance, <jats:italic>Clostridium</jats:italic> species of bacteria induce a type of T cell that promotes tolerance between the host and its microbial contents. Ohnmacht <jats:italic>et al.</jats:italic> and Sefik <jats:italic>et al.</jats:italic> characterized a population of gut regulatory T cells in mice, which required gut microbiota to survive. Multiple bacterial species of the microbiota could induce transcription factor–expressing regulatory T cells that helped maintain immune homeostasis. Mice engineered to lack these transcription factors exhibited enhanced susceptibility to colonic inflammation and had elevated amounts of proinflammatory molecules associated with allergies (see the Perspective by Hegazy and Powrie). </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue pp. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6251" page="989" related-article-type="in-this-issue" vol="349" xlink:href="10.1126/science.aac4263">989</jats:related-article> and <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6251" page="993" related-article-type="in-this-issue" vol="349" xlink:href="10.1126/science.aaa9420">993</jats:related-article> </jats:p>