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<jats:p>Editors’ selections from the current scientific literature</jats:p>

<jats:title>Pumping macrocycles onto surfaces</jats:title> <jats:p> Numerous chemical processes, ranging from water purification to catalysis, involve sorption of small molecules onto surfaces. Typically, spontaneous attractive interactions favor the binding event. Feng <jats:italic>et al</jats:italic> . report a mechanisorption process that requires redox manipulations to pump macrocycles from bulk solution onto axles immobilized on a metal-organic framework. The resulting rotaxanes store energy through nonequilibrium charge concentration in their mechanical bonds. Ultimately, the technique could also prove useful for actively partitioning compounds with particular functionality between surface and bulk environments. —JSY </jats:p>

<jats:title>Rare variants and blood LDL cholesterol</jats:title> <jats:p> A current goal in genomics is to identify genetic variation associated with actionable traits of clinical concern. Through exome sequencing of an Old Order Amish population, Montasser <jats:italic>et al</jats:italic> . identified a genetic variant that results in an amino acid change in the beta-1,4-galactosyltransferase 1 protein and is correlated with lower levels of cardiovascular disease. Investigation of the mutant protein showed that it affects genes associated with low-density lipoprotein cholesterol (LDL-C), and mice engineered to express the mutant protein exhibited a 38% decrease in blood LDL-C levels. This study suggests that such genomic sequencing and analysis can link genotype to phenotype and identify potentially clinically actionable pathways to treat disease. —LMZ </jats:p>

<jats:title>Reversing the chain</jats:title> <jats:p> The mitochondrial electron transport chain is a major part of cellular metabolism and plays key roles in both cellular respiration and the synthesis of critical metabolites. Typically, electrons flow through the electron transport chain in a specific direction, ending up with oxygen as the terminal electron acceptor. Spinelli <jats:italic>et al</jats:italic> . characterized an alternative path of electron flow through the transport chain, ending with fumarate as the electron acceptor (see the Perspective by Baksh and Finley). This pathway operates under conditions of limited oxygen availability, and the authors have confirmed its activity in vivo in a mouse model, observing that the propensity to use this pathway varied between organs. —YN </jats:p>

<jats:title>Synthesizing topological order</jats:title> <jats:p> Topologically ordered matter exhibits long-range quantum entanglement. However, measuring this entanglement in real materials is extremely tricky. Now, two groups take a different approach and turn to synthetic systems to engineer the topological order of the so-called toric code type (see the Perspective by Bartlett). Satzinger <jats:italic>et al</jats:italic> . used a quantum processor to study the ground state and excitations of the toric code. Semeghini <jats:italic>et al</jats:italic> . detected signatures of a toric code–type quantum spin liquid in a two-dimensional array of Rydberg atoms held in optical tweezers. —JS </jats:p>

<jats:title>Synthesizing topological order</jats:title> <jats:p> Topologically ordered matter exhibits long-range quantum entanglement. However, measuring this entanglement in real materials is extremely tricky. Now, two groups take a different approach and turn to synthetic systems to engineer the topological order of the so-called toric code type (see the Perspective by Bartlett). Satzinger <jats:italic>et al</jats:italic> . used a quantum processor to study the ground state and excitations of the toric code. Semeghini <jats:italic>et al</jats:italic> . detected signatures of a toric code–type quantum spin liquid in a two-dimensional array of Rydberg atoms held in optical tweezers. —JS </jats:p>

<jats:title>Dyed roots reveal inner complexity</jats:title> <jats:p> Plant roots do so much more than just hold a plant up. As a site for air storage during flooding, mycorrhizal symbiosis, or carbohydrate storage, the more complex root can tap more complicated functions. Taking advantage of a dye that stains less the deeper it penetrates the tissue, Ortiz-Ramírez <jats:italic>et al</jats:italic> . applied fluorescence-activated cell sorting to the complex cell layers of the maize root. RNA sequencing applied to the single-cell pools defined a developmental map and showed that the mobile transcription factor SHORT-ROOT travels through multiple cell layers and directs this grass root’s anatomical complexity. —PJH </jats:p>

<jats:title>Maturation for survival</jats:title> <jats:p> Although cells with defects in DNA replication usually die under stress conditions, some cells acquire new mutations and survive. Sun <jats:italic>et al</jats:italic> . identified an error-prone, stress-induced Okazaki fragment maturation pathway that induces tandem duplications and enables the survival of cells that have defects in removing the 5′ RNA-DNA flap during DNA replication. In these cells, stress conditions activate DUN1 signaling and induce conversion of the 5′ flap to a 3′ flap that can form secondary structures and be extended and ligated to the downstream DNA fragment, generating alternative duplication mutations similar to the ones in human cancers. The revealed information is analogous to the mechanism in cancer cell evolution and drug resistance. —DJ </jats:p>

<jats:title>Radical substitution</jats:title> <jats:p> Nucleophilic substitution is a venerable reaction in organic chemistry. Typically, an incoming ion delivers two electrons to a carbon center while a departing ion takes two electrons away with it. The one-electron analog, homolytic substitution, is more rarely used, in part because the incoming neutral radicals can self-couple instead of bonding to the intended target. Liu <jats:italic>et al</jats:italic> . report that an iron porphyrin catalyst can direct homolytic substitution between primary and tertiary carbon radicals by selectively activating the primary partners. —JSY </jats:p>

<jats:title>Optomechanical upconversion</jats:title> <jats:p> Molecules have rich signatures in their spectra at infrared wavelengths and are typically accessed with dedicated spectroscopic instrumentation. Chen <jats:italic>et al</jats:italic> . and Xomalis <jats:italic>et al</jats:italic> . report optomechanical frequency upconversion from the mid-infrared to the visible domain using molecular vibrations coupled to a plasmonic nanocavity at ambient conditions (see the Perspective by Gordon). Using different nanoantenna designs, one with a nanoparticle-on-resonator and the other with nanoparticle-in-groove, both approaches show the ability to upconvert the mid-infrared vibrations of the molecules in the nanocavity to visible light wavelengths. The effect could be used to simplify infrared spectroscopy, possibly with single-molecule sensitivity. —ISO </jats:p>