Cell-Type-Specific Complement Expression in the Healthy and Diseased Retina

Complement dysregulation is a feature of many retinal diseases, yet mechanistic understanding at the cellular level is limited. Given this knowledge gap about which retinal cells express complement, we performed single-cell RNA sequencing on similar to 92,000 mouse retinal cells and validated our results in five major purified retinal cell types. We found evidence for a distributed cell-type-specific complement expression across 11 cell types. Notably, Muller cells are the major contributor of complement activators c1s, c3, c4, and cfb. Retinal pigment epithelium (RPE) mainly expresses cfh and the terminal complement components, whereas cfi and cfp transcripts are most abundant in neurons. Aging enhances c1s, cfb, cfp, and cfi expression, while cfh expression decreases. Transient retinal ischemia increases complement expression in microglia, Muller cells, and RPE. In summary, we report a unique complement expression signature for murine retinal cell types suggesting a well-orchestrated regulation of local complement expression in the retinal microenvironment

Iron-Catalyzed Ring-Closing C−O/C−O Metathesis of Aliphatic Ethers

ISSN:1433-7851ISSN:1521-3773ISSN:0570-083

The Cyclohexadienyl-Leaving-Group Approach toward Donor-Stabilized Silylium Ions

The cyclohexa-2,5-dien-1-yl group is established as a leaving group at silicon as an alternative to the Bartlett–Condon–Schneider silicon-to-carbon hydride transfer and the allyl-leaving-group approach to generate silylium ions. Hydride abstraction from the skipped diene unit employing trityl tetrakis­(penta­fluoro­phenyl)­borate (<b>1</b>, [Ph₃C]⁺[B­(C₆F₅)₄]⁻) yields the silicon cation along with benzene. Our investigations reveal that the presence of an internal or external donor group is mandatory to allow for the formation of intra- or intermolecularly stabilized silylium ions. If not, degradation of the precursor is observed as a result of the reaction of the allylic silane units with the released silylium ion. It is also shown that such allylic silanes do form remarkably stable alkyl-substituted carbenium ions when reacted stoichiometrically with benzene-stabilized silylium ions

The Cyclohexadienyl-Leaving-Group Approach toward Donor-Stabilized Silylium Ions

The cyclohexa-2,5-dien-1-yl group is established as a leaving group at silicon as an alternative to the Bartlett–Condon–Schneider silicon-to-carbon hydride transfer and the allyl-leaving-group approach to generate silylium ions. Hydride abstraction from the skipped diene unit employing trityl tetrakis­(penta­fluoro­phenyl)­borate (<b>1</b>, [Ph₃C]⁺[B­(C₆F₅)₄]⁻) yields the silicon cation along with benzene. Our investigations reveal that the presence of an internal or external donor group is mandatory to allow for the formation of intra- or intermolecularly stabilized silylium ions. If not, degradation of the precursor is observed as a result of the reaction of the allylic silane units with the released silylium ion. It is also shown that such allylic silanes do form remarkably stable alkyl-substituted carbenium ions when reacted stoichiometrically with benzene-stabilized silylium ions

An Anionic Dinuclear Ruthenium Dihydrogen Complex of Relevance for Alkyne gem-Hydrogenation

During an investigation into the fate of ruthenium precatalysts used for light-driven alkyne gem-hydrogenation reactions with formation of Grubbs-type ruthenium catalysts, it was found that the reaction of [(IPr)(eta(6)-cymene)RuCl2] with H-2 under UV-irradiation affords an anionic dinuclear sigma-dihydrogen complex, which is thermally surprisingly robust. Not only are anionic sigma-complexes in general exceedingly rare, but the newly formed species seems to be the first example lacking any structural attributes able to counterbalance the negative charge and, in so doing, prevent oxidative insertion of the metal centers into the ligated H-2 from occurring.ISSN:1433-7851ISSN:1521-3773ISSN:0570-083