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

<jats:p>Polycomb repressive complex 2 (PRC2) silences genes through trimethylation of histone H3K27. PRC2 associates with numerous precursor messenger RNAs (pre-mRNAs) and long noncoding RNAs (lncRNAs) with a binding preference for G-quadruplex RNA. In this work, we present a 3.3-Å-resolution cryo–electron microscopy structure of PRC2 bound to a G-quadruplex RNA. Notably, RNA mediates the dimerization of PRC2 by binding both protomers and inducing a protein interface composed of two copies of the catalytic subunit EZH2, thereby blocking nucleosome DNA interaction and histone H3 tail accessibility. Furthermore, an RNA-binding loop of EZH2 facilitates the handoff between RNA and DNA, another activity implicated in PRC2 regulation by RNA. We identified a gain-of-function mutation in this loop that activates PRC2 in zebrafish. Our results reveal mechanisms for RNA-mediated regulation of a chromatin-modifying enzyme.</jats:p>

<jats:p>An estimated 23 million people live on floodplains affected by potentially dangerous concentrations of toxic waste derived from past and present metal mining activity. We analyzed the global dimensions of this hazard, particularly in regard to lead, zinc, copper, and arsenic, using a georeferenced global database detailing all known metal mining sites and intact and failed tailings storage facilities. We then used process-based and empirically tested modeling to produce a global assessment of metal mining contamination in river systems and the numbers of human populations and livestock exposed. Worldwide, metal mines affect 479,200 kilometers of river channels and 164,000 square kilometers of floodplains. The number of people exposed to contamination sourced from long-term discharge of mining waste into rivers is almost 50 times greater than the number directly affected by tailings dam failures.</jats:p>

<jats:p> Photoisomerization of azobenzenes from their stable <jats:italic>E</jats:italic> isomer to the metastable <jats:italic>Z</jats:italic> state is the basis of numerous applications of these molecules. However, this reaction typically requires ultraviolet light, which limits applicability. In this study, we introduce disequilibration by sensitization under confinement (DESC), a supramolecular approach to induce the <jats:italic>E</jats:italic> -to- <jats:italic>Z</jats:italic> isomerization by using light of a desired color, including red. DESC relies on a combination of a macrocyclic host and a photosensitizer, which act together to selectively bind and sensitize <jats:italic>E</jats:italic> -azobenzenes for isomerization. The <jats:italic>Z</jats:italic> isomer lacks strong affinity for and is expelled from the host, which can then convert additional <jats:italic>E-</jats:italic> azobenzenes to the <jats:italic>Z</jats:italic> state. In this way, the host–photosensitizer complex converts photon energy into chemical energy in the form of out-of-equilibrium photostationary states, including ones that cannot be accessed through direct photoexcitation. </jats:p>

<jats:p>Although some lineages of animals and plants have made impressive adaptive radiations when provided with ecological opportunity, the propensities to radiate vary profoundly among lineages for unknown reasons. In Africa’s Lake Victoria region, one cichlid lineage radiated in every lake, with the largest radiation taking place in a lake less than 16,000 years old. We show that all of its ecological guilds evolved in situ. Cycles of lineage fusion through admixture and lineage fission through speciation characterize the history of the radiation. It was jump-started when several swamp-dwelling refugial populations, each of which were of older hybrid descent, met in the newly forming lake, where they fused into a single population, resuspending old admixture variation. Each population contributed a different set of ancient alleles from which a new adaptive radiation assembled in record time, involving additional fusion-fission cycles. We argue that repeated fusion-fission cycles in the history of a lineage make adaptive radiation fast and predictable.</jats:p>

<jats:p> A fundamental goal in evolutionary biology is to understand the genetic architecture of adaptive traits. Using whole-genome data of 3955 of Darwin’s finches on the Galápagos Island of Daphne Major, we identified six loci of large effect that explain 45% of the variation in the highly heritable beak size of <jats:italic>Geospiza fortis,</jats:italic> a key ecological trait. The major locus is a supergene comprising four genes. Abrupt changes in allele frequencies at the loci accompanied a strong change in beak size caused by natural selection during a drought. A gradual change in <jats:italic>Geospiza scandens</jats:italic> occurred across 30 years as a result of introgressive hybridization with <jats:italic>G. fortis</jats:italic> . This study shows how a few loci with large effect on a fitness-related trait contribute to the genetic potential for rapid adaptive radiation. </jats:p>

<jats:p> S <jats:italic>cience</jats:italic> is fortunate that so many authors seek to publish with us. We shoulder enormous responsibility from both our outsized influence on research across many fields and from the journal's impact on the careers of scientists who publish in our pages. Although there can be some cynicism about the role of highly selective “glam journals,” we understand why we are part of conversations that sometimes center around “CNS” ( <jats:italic>Cell</jats:italic> , <jats:italic>Nature</jats:italic> , <jats:italic>Science</jats:italic> ) periodicals. All three have considerable importance and prominence in the scientific community. But there is a major difference that often gets lost. Whereas <jats:italic>Cell</jats:italic> and <jats:italic>Nature</jats:italic> generate revenue for their parent for-profit companies, Elsevier and Springer Nature, <jats:italic>Science</jats:italic> is published by a nonprofit organization, the American Association for the Advancement of Science (AAAS), and produces no revenue for shareholders. We don't get the word out about this distinction frequently or overtly enough. It's an important contrast because decisions that we make at <jats:italic>Science</jats:italic> and AAAS are driven by putting scientists ahead of profit. </jats:p>

<jats:p>Bennu’s rocks could reveal origin of organic molecules and Solar System evolution</jats:p>