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Nuclear speckles are nuclear membraneless organelles in higher eukaryotic cells playing a vital role in gene expression. Using an in situ reverse transcription–based sequencing method, we study nuclear speckle–associated human transcripts. Our data indicate the existence of three gene groups whose transcripts demonstrate different speckle localization properties: stably enriched in nuclear speckles, transiently enriched in speckles at the pre–messenger RNA stage, and not enriched. We find that stably enriched transcripts contain inefficiently excised introns and that disruption of nuclear speckles specifically affects splicing of speckle-enriched transcripts. We further reveal RNA sequence features contributing to transcript speckle localization, indicating a tight interplay between transcript speckle enrichment, genome organization, and splicing efficiency. Collectively, our data highlight a role of nuclear speckles in both co- and posttranscriptional splicing regulation. Last, we show that genes with stably enriched transcripts are over-represented among genes with heat shock–up-regulated intron retention, hinting at a connection between speckle localization and cellular stress response. 

Four new donor-acceptor-acceptor' (D-A-A')-configured donors, CPNT, DCPNT, CPNBT, and DCPNBT equipped with naphtho[1,2-c:5,6-c']bis([1,2,5]-thiadiazole) (NT) or naphtho[2,3-c][1,2,5]thiadiazole (NBT) as the central acceptor (A) unit bridging triarylamine donor (D) and cyano or dicyanovinylene acceptor (A'), were synthesized and characterized. All molecules exhibit bathochromic absorption shifts as compared to those of the benzothiadiazole (BT)-based analogues owing to improved electron-withdrawing and quinoidal character of NT and NBT cores that lead to stronger intramolecular charge transfer. Favorable energy level alignments with C70 , together with the good thermal stability and the antiparallel dimeric packing render CPNT and DCPNT suitable donors for vacuum-processed organic photovoltaics (OPV)s. OPVs based on DCPNT : C70 active layers displayed the best power conversion efficiency (PCE)=8.3%, along with an open circuit voltage of 0.92 V, a short circuit current of 14.5 mA cm-2 and a fill factor of 62% under 1 sun intensity, simulated AM1.5G illumination. Importantly, continuous light-soaking with AM 1.5G illumination has verified the durability of the devices based on CPNT:C70 and DCPNT : C70 as the active blends. The devices were examined for their feasibility of indoor light harvesting under 500 lux illumination by a TLD-840 fluorescent lamp, giving PCE=12.8% and 12.6%, respectively. These results indicate that the NT-based D-A-A'-type donors CPNT and DCPNT are potential candidates for high-stability vacuum-processed OPVs suitable for indoor energy harvesting.