No abstract

Pseudouridine (Ψ) is the most abundant post-transcriptional RNA modification, yet little is known about its prevalence, mechanism and function in mRNA. Here, we performed quantitative MS analysis and show that Ψ is much more prevalent (Ψ/U ratio ∼0.2-0.6%) in mammalian mRNA than previously believed. We developed N3-CMC-enriched pseudouridine sequencing (CeU-Seq), a selective chemical labeling and pulldown method, to identify 2,084 Ψ sites within 1,929 human transcripts, of which four (in ribosomal RNA and EEF1A1 mRNA) are biochemically verified. We show that hPUS1, a known Ψ synthase, acts on human mRNA; under stress, CeU-Seq demonstrates inducible and stress-specific mRNA pseudouridylation. Applying CeU-Seq to the mouse transcriptome revealed conserved and tissue-specific pseudouridylation. Collectively, our approaches allow comprehensive analysis of transcriptome-wide pseudouridylation and provide tools for functional studies of Ψ-mediated epigenetic regulation.

Newborn microglia rapidly replenish the whole brain after selective elimination of most microglia (>99%) in adult mice. Previous studies reported that repopulated microglia were largely derived from microglial progenitor cells expressing nestin in the brain. However, the origin of these repopulated microglia has been hotly debated. In this study, we investigated the origin of repopulated microglia by a series of fate-mapping approaches. We first excluded the blood origin of repopulated microglia via parabiosis. With different transgenic mouse lines, we then demonstrated that all repopulated microglia were derived from the proliferation of the few surviving microglia (<1%). Despite a transient pattern of nestin expression in newly forming microglia, none of repopulated microglia were derived from nestin-positive non-microglial cells. In summary, we conclude that repopulated microglia are solely derived from residual microglia rather than de novo progenitors, suggesting the absence of microglial progenitor cells in the adult brain.

High-energy-density, green, safe batteries are highly desirable for meeting the rapidly growing needs of portable electronics. The incomplete oxidation of sugars mediated by one or a few enzymes in enzymatic fuel cells suffers from low energy densities and slow reaction rates. Here we show that nearly 24 electrons per glucose unit of maltodextrin can be produced through a synthetic catabolic pathway that comprises 13 enzymes in an air-breathing enzymatic fuel cell. This enzymatic fuel cell is based on non-immobilized enzymes that exhibit a maximum power output of 0.8 mW cm À 2 and a maximum current density of 6 mA cm À 2 , which are far higher than the values for systems based on immobilized enzymes. Enzymatic fuel cells containing a 15% (wt/v) maltodextrin solution have an energy-storage density of 596 Ah kg À 1 , which is one order of magnitude higher than that of lithium-ion batteries. Sugar-powered biobatteries could serve as next-generation green power sources, particularly for portable electronics.