Catálogo de publicaciones - revistas

<jats:title>Sweet bystander becomes a villain</jats:title> <jats:p> Patients with pancreatic cancer often have elevated blood levels of CA19-9, a carbohydrate antigen present on many proteins. CA19-9 is thus commonly used as a biomarker for diagnosing and monitoring disease progression. In a study of mice, Engle <jats:italic>et al.</jats:italic> found that CA19-9 may be more than an innocent bystander that marks the presence of pancreatic disease; it may play a causal role in disease (see the Perspective by Halbrook and Crawford). Transgenic mice expressing the human enzymes that add CA19-9 to proteins developed severe pancreatitis that could be reversed by treatment with CA19-9 antibodies. When the transgenic mice also harbored a <jats:italic>Kras</jats:italic> oncogene, they went on to develop pancreatic cancer. These unexpected observations suggest new avenues for the treatment of pancreatic disease. </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="6446" page="1156" related-article-type="in-this-issue" vol="364" xlink:href="10.1126/science.aaw3145">1156</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6446" page="1132" related-article-type="in-this-issue" vol="364" xlink:href="10.1126/science.aax9341">1132</jats:related-article> </jats:p>

<jats:title>Improving precision with quantum amplification</jats:title> <jats:p> Quantum mechanically, an object can be described by a pair of noncommuting observables, typically by its position and momentum. The precision to which these observables can be measured is limited by unavoidable quantum fluctuations. However, the method of “squeezing” allows the fluctuations to be manipulated, while preserving the Heisenberg uncertainty relation. This allows improved measurement precision for one observable at the expense of increased fluctuations in the other. Burd <jats:italic>et al.</jats:italic> now show that an additional displacement of a trapped atom results in amplification of the squeezing and a further improvement in the precision with which the displacement can be determined (see the Perspective by Schleier-Smith). This technique should be useful for a number of applications in metrology. </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="6446" page="1163" related-article-type="in-this-issue" vol="364" xlink:href="10.1126/science.aaw2884">1163</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6446" page="1137" related-article-type="in-this-issue" vol="364" xlink:href="10.1126/science.aax0143">1137</jats:related-article> </jats:p>

<jats:title>Light teaches (co)enzymes new tricks</jats:title> <jats:p> Light is widely used in organic synthesis to excite electrons in a substrate or catalyst, opening up reactive pathways to a desired product. Biology uses light sparingly in this way, but coenzymes such as flavin can be driven to excited states by light. Biegasiewicz <jats:italic>et al.</jats:italic> investigated this reactivity and found a suite of flavoenzymes that catalyze asymmetric radical cyclization when exposed to light. “Ene”-reductases, when reduced and illuminated, converted starting materials containing an α-chloroamide and an alkene into five-, six-, seven-, or eight-membered lactams. Different enzymes furnished different stereochemistry in the products, likely because of changes in active-site pocket geometry. </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="6446" page="1166" related-article-type="in-this-issue" vol="364" xlink:href="10.1126/science.aaw1143">1166</jats:related-article> </jats:p>

<jats:title>A metal-free route to PET probes</jats:title> <jats:p> Positron emission tomography (PET) is a widely used imaging technique for medical diagnostics and pharmaceutical development. As the name implies, it requires tracers that emit positrons, typically through labeling with fluorine or carbon radioisotopes. W. Chen <jats:italic>et al.</jats:italic> devised a versatile technique to incorporate radioactive fluoride into aromatic rings. The metal-free photochemical method directly substitutes aryl carbon-hydrogen bonds with [ <jats:sup>18</jats:sup> F]fluoride and so is particularly well suited to late-stage transformation of complex molecules into tracers. </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="6446" page="1170" related-article-type="in-this-issue" vol="364" xlink:href="10.1126/science.aav7019">1170</jats:related-article> </jats:p>

<jats:title>Mobile particles in colloidal crystals</jats:title> <jats:p> The crystallization of nanoparticles can be controlled by functionalizing them with DNA strands that direct assembly through hybridization. The design rules for interactions between pairs of particles resemble those for ionic compounds. Inspired by molecular dynamics simulations, Girard <jats:italic>et al.</jats:italic> show that larger particles (∼10 nanometers in diameter) that have mutual repulsive interactions can form a stable lattice only if much smaller conjugate particles (∼1.5 nanometers in diameter) are present. These smaller particles are mobile and diffuse through the lattice, so the bonding interaction resembles the classical picture of electrons in metals. </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="6446" page="1174" related-article-type="in-this-issue" vol="364" xlink:href="10.1126/science.aaw8237">1174</jats:related-article> </jats:p>

<jats:title>Context shapes anticommensal immunity</jats:title> <jats:p> The gut bacterium <jats:italic>Akkermansia muciniphila</jats:italic> is associated with protection from obesity, enhanced wound healing, and augmented antitumor responses. Ansaldo <jats:italic>et al.</jats:italic> found that this microbe induces antigen-specific immunoglobulin G1 (IgG1) antibodies generated by B cells with CD4 <jats:sup>+</jats:sup> T cell help. This is in contrast to most anticommensal responses, which involve the T cell–independent production of IgA antibodies. In a gnotobiotic setting in which all components of the microbiome are defined, <jats:italic>A. muciniphila</jats:italic> –specific T cells expanded only when <jats:italic>A. muciniphila</jats:italic> was present. The T cells primarily displayed a phenotype associated with B cell help. However, in mice with a conventional gut microbiota, other proinflammatory <jats:italic>A. muciniphila</jats:italic> –specific T cell populations also expanded. Thus, anti– <jats:italic>A. muciniphila</jats:italic> immunity is context dependent, which may explain the variable immune responses to this microbe reported in patients. </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="6446" page="1179" related-article-type="in-this-issue" vol="364" xlink:href="10.1126/science.aaw7479">1179</jats:related-article> </jats:p>

<jats:title>Keeping the gate open</jats:title> <jats:p> Cystic fibrosis is a progressive disease that affects lung function and is often fatal. It is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR). One class of mutants impairs ion conductance, and the drug ivacaftor acts by increasing the ion flux. Liu <jats:italic>et al.</jats:italic> describe high-resolution structures of CFTR bound to ivacaftor and to an investigational drug GLPG1837 that also potentiates ion flow. The two drugs bind at the same site in the transmembrane region. This site coincides with a hinge involved in channel gating, suggesting that the drugs may stabilize the open conformation of the channel. </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="6446" page="1184" related-article-type="in-this-issue" vol="364" xlink:href="10.1126/science.aaw7611">1184</jats:related-article> </jats:p>

<jats:title>Little fish make a big contribution</jats:title> <jats:p> Coral reefs represent one of the most biodiverse and rich ecosystems. Such richness conjures up images of coral heads and large colorful reef fishes. Brandl <jats:italic>et al.</jats:italic> show, however, that one of the most striking and important parts of the reef ecosystem is almost never seen (see the Perspective by Riginos and Leis). Small cryptobenthic fish, like blennies, make up nearly 40% of reef fish biodiversity. Furthermore, the majority of cryptobenthic fish larvae settle locally, rather than being widely dispersed, and have rapid turnover rates. Such high diversity and densities could thus provide the biomass base for larger, better-known reef fish. </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="6446" page="1189" related-article-type="in-this-issue" vol="364" xlink:href="10.1126/science.aav3384">1189</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6446" page="1128" related-article-type="in-this-issue" vol="364" xlink:href="10.1126/science.aax8961">1128</jats:related-article> </jats:p>