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<jats:title>An E-Z boron swivel</jats:title> <jats:p> Compounds with carbon-carbon double bonds can form two distinct isomers, depending on whether the heaviest substituents on both carbons lie on the same side (labeled Z) or diagonally across from each other (labeled E). Molloy <jats:italic>et al.</jats:italic> present a convenient method to reorient double bonds that bear boron and carbonyl substituents. When they are diagonally opposed, both substituents stay in plane, and the double bond is easily swiveled by photosensitization. However, once on the same side as the carbonyl, the boron rotates out of plane and further sensitization is inhibited. </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="6501" page="302" related-article-type="in-this-issue" vol="369" xlink:href="10.1126/science.abb7235">302</jats:related-article> </jats:p>

<jats:title>Molecule-molecule forward scattering</jats:title> <jats:p> The classical picture of nonreactive inelastic scattering implies that a considerable transfer of translational to rotational energy should be accompanied by backward scattering. Using cross–molecular beam scattering combined with velocity map imaging, Sun <jats:italic>et al.</jats:italic> provide evidence of an unusual pair-correlated channel in the collision of carbon monoxide (CO) molecules, specifically <jats:sup>13</jats:sup> CO with <jats:sup>12</jats:sup> CO, both initially in the ground rotational state. These two molecules were scattered into the forward direction, both finally in the high rotational states. The experimental work is supported by quasiclassical trajectory simulations that exhibit unexpected molecular dance moves and suggest that similar effects could be expected for other molecule-molecule scattering systems. </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="6501" page="307" related-article-type="in-this-issue" vol="369" xlink:href="10.1126/science.aan2729">307</jats:related-article> </jats:p>

<jats:title>Separating organics without distillation</jats:title> <jats:p> Hydrocarbon distillation is a widespread and energy-intensive process. Membranes might offer an alternative approach, but few can survive immersion in organic solvents nor are they able to extract relatively small molecules. Thompson <jats:italic>et al.</jats:italic> developed a series of polymers of intrinsic microporosity that they used for membrane-based separations of organic compounds in an organic solvent (see the Perspective by Brennecke and Freeman). The new membrane has a molecular weight cutoff of 253 daltons, far lower than existing ones closer to 600 daltons. The polymers were used to separate light shale crude oil and succeeded in fractionation of molecular weights of about 170 daltons. </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="6501" page="310" related-article-type="in-this-issue" vol="369" xlink:href="10.1126/science.aba9806">310</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6501" page="254" related-article-type="in-this-issue" vol="369" xlink:href="10.1126/science.abd1307">254</jats:related-article> </jats:p>

<jats:title>CORONAVIRUS</jats:title> <jats:p> In some quarters, it is hoped that increased humidity and higher temperatures over the Northern Hemisphere in the summer will snuff out the 2020 severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. In reality, the situation is likely to be more complicated than that. Baker <jats:italic>et al.</jats:italic> used a climate-dependent epidemic model to simulate the SARS-CoV-2 pandemic, testing different scenarios of climate dependence based on known coronavirus biology. Levels of susceptibility among the population remain the driving factor for the pandemic, and without effective control measures, the pandemic will persist in the coming months, causing severe outbreaks even in humid climates. Summer will not substantially limit pandemic growth. </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="6501" page="315" related-article-type="in-this-issue" vol="369" xlink:href="10.1126/science.abc2535">315</jats:related-article> </jats:p>

<jats:title>Prenatal antibodies are polyreactive</jats:title> <jats:p> Extensive immunoglobulin gene rearrangements allow humans to recognize a diversity of potential pathogens. This antibody repertoire is more restricted during early life to prevent the generation of autoreactive B cells, though tolerance does not appear to be complete. Chen <jats:italic>et al.</jats:italic> examined the reactivities of antibodies cloned from individual human fetal B cells residing in the liver, bone marrow, and spleen. They observed the accumulation of autoreactive and polyreactive B cells, which were frequently cross-reactive to commensals in the absence of any somatic hypermutation. The generation of these reactive B cells before they are ever exposed to microbes may promote later beneficial commensal- host interactions and/or augmented host defense during the first weeks of life. </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="6501" page="320" related-article-type="in-this-issue" vol="369" xlink:href="10.1126/science.aay9733">320</jats:related-article> </jats:p>

<jats:title>Programmed aging in yeast cells</jats:title> <jats:p> Following the fate of individual yeast cells has revealed aging to be more of a programmable decision process rather than a simple accumulation of deleterious events. Li <jats:italic>et al.</jats:italic> combined single-cell studies and mathematical modeling to show that yeast cells showed two different forms of aging: one with less ribosomal DNA silencing, in which nucleoli were degraded, and another with less heme accumulation and hemedependent transcription, in which mitochondria were more affected. Overexpression of the lysine deacetylase Sir2, which contributes to ribosomal DNA silencing, led to a third cell-aging fate in which the average life span was extended. If other cells age in similar ways, then this study may provide new ways to consider dynamics of aging and strategies to extend the health span. </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="6501" page="325" related-article-type="in-this-issue" vol="369" xlink:href="10.1126/science.aax9552">325</jats:related-article> </jats:p>

<jats:title>SARS-CoV-2 spike protein, elaborated</jats:title> <jats:p> Vaccine development for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is focused on the trimeric spike protein that initiates infection. Each protomer in the trimeric spike has 22 glycosylation sites. How these sites are glycosylated may affect which cells the virus can infect and could shield some epitopes from antibody neutralization. Watanabe <jats:italic>et al.</jats:italic> expressed and purified recombinant glycosylated spike trimers, proteolysed them to yield glycopeptides containing a single glycan, and determined the composition of the glycan sites by mass spectrometry. The analysis provides a benchmark that can be used to measure antigen quality as vaccines and antibody tests are developed. </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="6501" page="330" related-article-type="in-this-issue" vol="369" xlink:href="10.1126/science.abb9983">330</jats:related-article> </jats:p>

<jats:title>Compact defense system in bacteriophages</jats:title> <jats:p> The CRISPR-Cas system, naturally found in many prokaryotes, is widely used for genome editing. CRISPR arrays in the bacterial genome, derived from the genome of invading viruses, are used to generate a CRISPR RNA that guides the Cas enzyme to destroy repeat viral invaders. Recently, an unexpectedly compact CRISPR-Cas system was identified in huge bacteriophages. Pausch <jats:italic>et al</jats:italic> . show that even though this system lacks commonly found accessory proteins, it is functional. In addition to a CRISPR array, the only component of the system is an enzyme called CasF, which uses the same active site to process transcripts of the CRISPR arrays into CRISPR RNA and to destroy foreign nucleic acids. This system, which is active in human and plant cells, provides a hypercompact addition to the genome-editing toolbox. </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="6501" page="333" related-article-type="in-this-issue" vol="369" xlink:href="10.1126/science.abb1400">333</jats:related-article> </jats:p>

<jats:p>Biomarkers for neurological diseases used to be few and far between, but better technology is making it easier for researchers to track brain health by measuring molecules. This means less invasive testing, earlier diagnosis, faster drug development, and—hopefully—more effective treatments.</jats:p>