Dynamics of RNA localization to nuclear speckles are connected to splicing efficiency.

Nuclear speckles, a type of membraneless nuclear organelle in higher eukaryotic cells, play a vital role in gene expression regulation. Using the reverse transcription-based RNA-binding protein binding sites sequencing (ARTR-seq) method, we study human transcripts associated with nuclear speckles. We identify three gene groups whose transcripts demonstrate different speckle localization properties and dynamics: stably enriched in nuclear speckles, transiently enriched in speckles at the pre-mRNA stage, and not enriched in speckles. Specifically, we find that stably-enriched transcripts contain inefficiently spliced introns. We show that nuclear speckles specifically facilitate splicing of speckle-enriched transcripts. We further reveal RNA sequence features contributing to transcript speckle localization, underscoring a tight interplay between genome organization, RNA cis-elements, and transcript speckle enrichment, and connecting transcript speckle localization with splicing efficiency. Finally, we show that speckles can act as hubs for the regulated retention of introns during cellular stress. Collectively, our data highlight a role of nuclear speckles in both co- and post-transcriptional splicing regulation.

Theoretical calculations and photoluminescence properties of Sr4Al14O25:Mn4+ red phosphors doped with Li.

The absence of high-efficiency oxide red phosphors restricts the development of high-performance solid-state lighting. In this work, a series of Li+ doped Sr4Al14O25:Mn4+ (SAO-Li+) red phosphors were prepared. Theoretical calculation results indicate that Li+ is inclined to occupy the gap 2 position. The low concentration Li+ gap doping has almost no influence on the Sr4Al14O25 structure, and a 0.4 mol Li+-doped sample exhibits a pure phase with regular morphology. With increasing Li+ doping content, the luminescence intensities of phosphors increase first and then decrease. 0.4 mol is found to be the optimal concentration. The fluorescence lifetime continues to decrease with the increase in the Li+ doping content and a mutation occurs at 0.5 mol Li+. Phosphor doping with Li+ can improve the thermal quenching resistance. The WLED device encapsulated with SAO-0.4Li and YAG:Ce3+ phosphors prepared showed a correlated color temperature of 4667 K, a color rendering index of 82, and a light efficiency of 137.34 lm W-1 at a driving current of 20 mA. The above results indicate that the use of a SAO-0.4Li+ phosphor is expected for application in warm WLEDs.