A New Design Strategy for Observing Lithium Oxide Growth-Evolution Interactions Using Geometric Catalyst Positioning

Understanding the catalyzed formation and evolution of lithium-oxide products in Li–O₂ batteries is central to the development of next-generation energy storage technology. Catalytic sites, while effective in lowering reaction barriers, often become deactivated when placed on the surface of an oxygen electrode due to passivation by solid products. Here we investigate a mechanism for alleviating catalyst deactivation by dispersing Pd catalytic sites away from the oxygen electrode surface in a well-structured anodic aluminum oxide (AAO) porous membrane interlayer. We observe the cross-sectional product growth and evolution in Li–O₂ cells by characterizing products that grow from the electrode surface. Morphological and structural details of the products in both catalyzed and uncatalyzed cells are investigated independently from the influence of the oxygen electrode. We find that the geometric decoration of catalysts far from the conductive electrode surface significantly improves the reaction reversibility by chemically facilitating the oxidation reaction through local coordination with PdO surfaces. The influence of the catalyst position on product composition is further verified by ex situ X-ray photoelectron spectroscopy and Raman spectroscopy in addition to morphological studies

Three New Difunctional Electrocatalysts Built from Polyoxometalates and Cu–Tpy Units: Experimental and Theoretical Study

Three new organic–inorganic compounds based on polyoxometalates, [(CuCltpy)2(Cu2Cl2(tpy)2)(α-SiW12O40)]·5H2O (1), [Cu4(tpy)4(H2O)4(α-P2W18O62)]·4H2O (2), and [Cu(tpy)(Mo3O10)]·H2O (3) (tpy = 4′-(pyrrol-3-yl)-2,2′:6′,2″-terpyridine), were facilely isolated by hydrothermal technique. X-ray diffraction analysis shows that compound 1 with three-dimensional (3D) supramolecular structure is featured by α-SiW12 clusters, {Cu2Cl2/tpy} dimers, and {CuCl/tpy} monomers. Compound 2 with zero-dimensional (0D) discrete structure is constructed from α-P2W18 clusters and four Cu/tpy units. The one-dimensional (1D) infinite chain of 3 is stemmed from [Mo3O10]2– units and Cu/tpy motifs. Furthermore, we explored the bifunctional electrocatalytic activities of these three compounds for reduction and oxidation. The results show that the [Mo3O10]2–-type hybrid displays better difunctional electrocatalytic activities than heteropolyacids toward both reduction and oxidation. Significantly, the molecular electrostatic potential and the frontier molecular orbital were achieved by density functional theory calculations to analyze the electronic structure of three compounds. The natural bond orbital analysis was also carried out to interpret electron charge distribution

Spontaneous Cell Competition in Immortalized Mammalian Cell Lines

<div><p>Cell competition is a form of cell-cell interaction by which cells compare relative levels of fitness, resulting in the active elimination of less-fit cells, “losers,” by more-fit cells, “winners.” Here, we show that in three routinely-used mammalian cell lines – U2OS, 3T3, and MDCK cells – sub-clones arise stochastically that exhibit context-dependent competitive behavior. Specifically, cell death is elicited when winner and loser sub-clones are cultured together but not alone. Cell competition and elimination in these cell lines is caspase-dependent and requires cell-cell contact but does not require <i>de novo</i> RNA synthesis. Moreover, we show that the phenomenon involves differences in cellular metabolism. Hence, our study demonstrates that cell competition is a common feature of immortalized mammalian cells in vitro and implicates cellular metabolism as a mechanism by which cells sense relative levels of “fitness.”</p></div

Additional file 1 of Circ_005077 accelerates myocardial lipotoxicity induced by high-fat diet via CyPA/p47PHOX mediated ferroptosis

Supplementary Material

U2OS cell “fitness” is context-dependent.

<p>(A) Aspect of U2OS G1, R1, and YFP co-cultures in fluorescence microscopy. Cells were plated at a 1:1 ratio as indicated (R1:G1 or R1:YFP) and allowed to grow for 1, 3 or 6 days. (B) Cp3-IF apoptosis quantification. R1 cells behave as “winners” in R1:YFP cultures but as “losers” in the presence of G1 cells, indicating that R1 cells assume “winner” or “loser” status depending on the properties of their co-culture partners. *: p<0.001 by Student’s <i>t</i>-test.</p

U2OS cell competition interactions are short-ranged.

<p>(A) Schematic representation of U2OS transwell cultures, Cells shared culture medium but were separated by a 0.8 μm Durapore membrane. (B) Cp3-IF analysis of apoptosis in transwell cultures. Wt cells induce apoptosis in YFP cells in the insert but not in YFP cells separated by the transwell. (C) Spot-seeding of YFP and H2B-mCherry expressing clone R1. Mixed YFP:R1 spots surrounded by pure YFP cell populations were divided in “inner” (I), “border” (B), and “outer” (O) zones as represented. (D) Time-lapse microscopy tracking of YFP cell fates during 72-hour spot cultures. The number of cell layers separating each YFP cell from its nearest R1 neighbor was recorded, and YFP “B” cells were grouped accordingly: for instance, a YFP cell is labeled “B3” if it comes within 3 cell layers of the nearest R1 cell, while a”B0” YFP cell comes to lie adjacent to an R1 cell at any time during the observation period. The data summarizes the fate of cells present at the beginning of each experiment and their immediate progeny, followed over 72 hours. The percentage of followed cells that underwent cell division is shown at the top; cell death is shown at the middle, and net population size change at the bottom. Increased apoptosis is observed only in inner YFP cells and “B0” border cells that come in direct contact with R1 cells. Data in panel D was derived from 3 independent experiments (Supplemental Movie S1-3), comprising over 5,000 cells counted. *: p<0.05, **: p<0.01 by Student’s <i>t</i>-test; #:p<0.05, ##:p<0.01 by paired <i>t</i>-test.</p

Cell death is triggered by a cell competition-like interaction in clonally-derived mammalian cell lines.

<p>(A) Cell counts showing YFP (“loser” cells) cells first expand, then decline, in the presence of Wt (“winner”) cells but grow unimpeded when cultured alone. Time is measured from cell seeding (t = 0). (B) Cleaved caspase-3 (Cp3) immuno-fluorescence (IF) (red) of U2OS cultures showing increased apoptosis in co-cultured YFP cells (green). Arrows indicate Cp3+ apoptotic YFP cells. Wt cells are counterstained with Hoescht 33342 (blue). (C) Quantification of apoptosis on immune-stained cultures; x-axis, time in days (d) Note that the baseline level of apoptosis increases with cell density by day 6 under all culture conditions. (D) Quantification of cell proliferation in 72-hour U2Os cultures by phospho-histone H3 (PH3) immunofluorescence. (E) Cp3 IF of 72-hour U2OS cultures treated with the caspase-3 inhibitor Z-VAD-FMK. YFP cell counts per microscope field are shown at the bottom. Inhibition of apoptosis by Z-VAD-FM K prevents YFP elimination from Wt:YFP co-cultures. (F) P-H3 IF of U2OS cells cultured for 72 hours in presence of the Cyclin D1 inhibitor purvalanol A as indicated. Quantification of apoptosis is shown below. Purvalanol A treatment inhibits proliferation (top) and rescues YFP elimination (bottom). Images were taken at 100X magnification. Error bars in this and all subsequent figures reflect mean ± SD. *: p<0.05, **: p<0.01 and ***: p<0.001 by Student’s <i>t</i>-test.</p

Differences in energy metabolism drive cell competition in mammalian cells.

<p>(A) Quantification of apoptosis (Cp3 immunofluorescence) in U2OS cultures grown for 72 hours under normoxic (21% O₂) or hypoxic (1.5% O₂) conditions. Hypoxia inhibits cell competition-induced elimination of YFP and R1 cells in Wt:YFP and Wt:R1 co-cultures. (B) Quantification of Cp3 immunofluorescence in U2OS R1 cells expressing a nonsense (NSC, non-silencing control) shRNA or shRNAs directed against the Hif1a transcription factor. Hif1a knockdown in loser cells does not affect cell competition. qPCR analysis of Hif1a in shRNA-expressing YFP cells is shown on the right. (C) Quantification of Cp3 immunofluorescence in U2OS cultures grown for 72 hours in medium containing standard (4 mM) and reduced (0.4 mM) Glutamin (Gln) concentrations. Withholding Gln arrests cell competition in U2OS cells. (D) Quantification of Cp3 immunofluorescence in U2OS cultures treated with a mitochondrial uncoupling agent (carbonyl cyanide m-chlorophenyl hydrazine, CCCP). Uncoupling respiration from oxidative phosphorylation blocks competition-induced elimination of R1 and YFP cells, indicating that competition is driven by differences in the activity of ATP-generating pathways. (E) Luciferase analysis of intracellular ATP levels in monocultured U2OS cell. YFP, but not R1 cells, display reduced ATP levels in when compared to Wt cells. Hypoxia increases ATP levels YFP cells, suggesting that reduced ATP levels may reflect or underlie YFP cell fitness.*: p<0.001, by one-way ANOVA.</p

Cell competition in U2OS cells is mediated by post-transcriptional mechanism.

<p>(A) Microarray RNA analysis experimental design. Cells were grown in mono- or co-cultures for 48h as indicated and sorted by flow cytometry before RNA extraction. (B) Venn diagram distribution of RNAs displaying >2-fold expression change across indicated sample groups. Only six transcripts were found to be differentially expressed in mono-cultured and competing YFP cells, while no transcription changes were observed in response to competition in Wt and R1 cells. (C) Immuno-staining of metabolite-labeled nascent RNA and protein chains in Wt U2OS cells treated with actinomycin D or cycloheximide for 24 hours. Ethynil-uridine (EU) and homopropargyl-glycin (HGP) were added to label nascent RNA and peptide chains 2 h before staining. Complete inhibition of transcription and translation was obtained with actinomycin D and cycloheximide, respectively. (D) Cp3-IF of Wt:YFP 72-hour cultures grown in presence or absence of actinomycin D- and cycloheximide. Cycloheximide completely abolished Wt-induced YFP apoptosis. Actinomycin D treatment resulted in a partial rescue to a degree consistent with its inhibition of cell division (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0132437#pone.0132437.s010" target="_blank">S10 Fig</a>). *”p<0.05, **: p<0.01 by Student’s <i>t</i>-test.</p

Characterization of a Prenyltransferase for Iso-A82775C Biosynthesis and Generation of New Congeners of Chloropestolides

Chloropupukeananin and chloropestolides are novel metabolites of the plant endophyte <i>Pestalotiopsis fici</i>, showing antimicrobial, antitumor, and anti-HIV activities. Their highly complex and unique skeletons were generated from the coisolated pestheic acid (<b>1</b>) and iso-A82775C (<b>10</b>) based on our previous studies. Here, we identified the biosynthetic gene cluster <i>iac</i> of <b>10</b> and characterized an <i>iacE</i> encoded prenyltransferase. Deletion of <i>iacE</i> abolished iso-A82775C production, accumulated the prenyl group-lacking siccayne (<b>2</b>), and generated four new chloropestolides (<b>3</b>–<b>6</b>). Compounds <b>5</b> and <b>6</b> showed antibacterial effects against <i>Staphylococcus aureus</i> and <i>Bacillus subtilis</i>, and <b>5</b> was also cytotoxic to human tumor cell lines HeLa, MCF-7, and SW480. These results provided the first genetic and biochemical insights into the biosynthesis of natural prenylepoxycyclohexanes and demonstrated the feasibility for generation of diversified congeners by manipulating the biosynthetic genes of <b>10</b>