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The spatial localization of charge carriers to promote the formation of bound excitons and concomitantly enhance radiative recombination has long been a goal for luminescent semiconductors. Zero‐dimensional materials structurally impose carrier localization and result in the formation of localized Frenkel excitons. Now the fully inorganic, perovskite‐derived zero‐dimensional SnII material Cs4SnBr6 is presented that exhibits room‐temperature broad‐band photoluminescence centered at 540 nm with a quantum yield (QY) of 15±5 %. A series of analogous compositions following the general formula Cs4−xAxSn(Br1−yIy)6 (A=Rb, K; x≤1, y≤1) can be prepared. The emission of these materials ranges from 500 nm to 620 nm with the possibility to compositionally tune the Stokes shift and the self‐trapped exciton emission bands.

The engineering of transgenic crops resistant to the broad-spectrum herbicide glyphosate has greatly improved agricultural efficiency worldwide. Glyphosate-based herbicides, such as Roundup, target the shikimate pathway enzyme 5-enolpyruvylshikimate 3-phosphate (EPSP) synthase, the functionality of which is absolutely required for the survival of plants. Roundup Ready plants carry the gene coding for a glyphosate-insensitive form of this enzyme, obtained from Agrobacterium sp. strain CP4. Once incorporated into the plant genome, the gene product, CP4 EPSP synthase, confers crop resistance to glyphosate. Although widely used, the molecular basis for this glyphosate-resistance has remained obscure. We generated a synthetic gene coding for CP4 EPSP synthase and characterized the enzyme using kinetics and crystallography. The CP4 enzyme has unexpected kinetic and structural properties that render it unique among the known EPSP synthases. Glyphosate binds to the CP4 EPSP synthase in a condensed, noninhibitory conformation. Glyphosate sensitivity can be restored through a single-site mutation in the active site (Ala-100 -Gly), allowing glyphosate to bind in its extended, inhibitory conformation.conformational change ͉ crystal structure ͉ genetic modification ͉ mutation T he broad-spectrum herbicide glyphosate, the active ingredient of Roundup, inhibits 5-enolpyruvylshikimate-3-phosphate (EPSP) synthase (EC 2.5.1.19), the enzyme catalyzing the penultimate step of the shikimate pathway toward the biosynthesis of aromatic amino acids. Roundup Ready crop lines contain a gene derived from Agrobacterium sp. strain CP4, encoding a glyphosate-tolerant enzyme, the so-called CP4 EPSP synthase (1, 2). Expression of CP4 EPSP synthase results in glyphosate-tolerant crops, enabling more effective weed control by allowing postemergent herbicide application. The substantial advantages of glyphosate-tolerant crops have resulted in rapid adoption: 87% of soybeans, 61% of cotton, and 26% of corn planted in the United States in 2005 were glyphosate-tolerant varieties (3). However, lingering concerns about the potential health and environmental effects of genetically modified organisms have limited the acceptance of such seed lines and food products, particularly in Europe and Japan.EPSP synthase catalyzes the transfer of the enolpyruvyl moiety of phosphoenolpyruvate (PEP) to the 5-hydroxyl of shikimate-3-phosphate (S3P) (Fig. 1A). Beginning in the early 1980s, researchers sought to identify glyphosate-insensitive EPSP synthases that could be introduced into crops to provide herbicide resistance. A number of promising enzymes were identified through selective evolution, site-directed mutagenesis, and microbial screens (4-7). However, an increased tolerance for glyphosate in EPSP synthase was often accompanied by a concomitant decrease in the enzyme's affinity for PEP, resulting in decreased catalytic efficiency. More favorable kinetic characteristics were observed in some enzymes with substitutions including Pro-101-Ser and Thr-97-Ile (nu...

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Adaptive thermogenesis is an energy-demanding process that is mediated by cold-activated beige and brown adipocytes, and it entails increased uptake of carbohydrates, as well as lipoprotein-derived triglycerides and cholesterol, into these thermogenic cells. Here we report that cold exposure in mice triggers a metabolic program that orchestrates lipoprotein processing in brown adipose tissue (BAT) and hepatic conversion of cholesterol to bile acids via the alternative synthesis pathway. This process is dependent on hepatic induction of cytochrome P450, family 7, subfamily b, polypeptide 1 (CYP7B1) and results in increased plasma levels, as well as fecal excretion, of bile acids that is accompanied by distinct changes in gut microbiota and increased heat production. Genetic and pharmacological interventions that targeted the synthesis and biliary excretion of bile acids prevented the rise in fecal bile acid excretion, changed the bacterial composition of the gut and modulated thermogenic responses. These results identify bile acids as important metabolic effectors under conditions of sustained BAT activation and highlight the relevance of cholesterol metabolism by the host for diet-induced changes of the gut microbiota and energy metabolism.