RNA Polymerase II Pausing Downstream of Core Histone Genes Is Different from Genes Producing Polyadenylated Transcripts

Recent genome-wide chromatin immunoprecipitation coupled high throughput sequencing (ChIP-seq) analyses performed in various eukaryotic organisms, analysed RNA Polymerase II (Pol II) pausing around the transcription start sites of genes. In this study we have further investigated genome-wide binding of Pol II downstream of the 3′ end of the annotated genes (EAGs) by ChIP-seq in human cells. At almost all expressed genes we observed Pol II occupancy downstream of the EAGs suggesting that Pol II pausing 3′ from the transcription units is a rather common phenomenon. Downstream of EAGs Pol II transcripts can also be detected by global run-on and sequencing, suggesting the presence of functionally active Pol II. Based on Pol II occupancy downstream of EAGs we could distinguish distinct clusters of Pol II pause patterns. On core histone genes, coding for non-polyadenylated transcripts, Pol II occupancy is quickly dropping after the EAG. In contrast, on genes, whose transcripts undergo polyA tail addition [poly(A)+], Pol II occupancy downstream of the EAGs can be detected up to 4–6 kb. Inhibition of polyadenylation significantly increased Pol II occupancy downstream of EAGs at poly(A)+ genes, but not at the EAGs of core histone genes. The differential genome-wide Pol II occupancy profiles 3′ of the EAGs have also been confirmed in mouse embryonic stem (mES) cells, indicating that Pol II pauses genome-wide downstream of the EAGs in mammalian cells. Moreover, in mES cells the sharp drop of Pol II signal at the EAG of core histone genes seems to be independent of the phosphorylation status of the C-terminal domain of the large subunit of Pol II. Thus, our study uncovers a potential link between different mRNA 3′ end processing mechanisms and consequent Pol II transcription termination processes

A robust binary supramolecular organic framework (SOF) with high CO2 adsorption and selectivity

A robust binary hydrogen-bonded supramolecular organic framework (SOF-7) has been synthesized by solvothermal reaction of 1,4-bis-(4-(3,5-dicyano-2,6 dipyridyl)dihydropyridyl)benzene (1) and 5,5’-bis-(azanediyl)-oxalyl-diisophthalic acid (2). Single crystal X-ray diffraction analysis shows that SOF-7 comprises 2 and 1,4-bis-(4-(3,5-dicyano-2,6-dipyridyl)pyridyl)benzene (3), the latter formed in situ from the oxidative dehydrogenation of 1. SOF-7 shows a three-dimensional four-fold interpenetrat-ed structure with complementary O−H···N hydrogen bonds to form channels that are decorated with cyano- and amide-groups. SOF-7 exhibits excellent thermal stability and sol-vent and moisture durability, as well as permanent porosity. The activated desolvated material SOF-7a shows high CO2 sorption capacity and selectivity compared with other po-rous organic materials assembled solely through hydrogen bonding

Effective Approach for Increasing the Heteroatom Doping Levels of Porous Carbons for Superior CO₂ Capture and Separation Performance

Development of efficient sorbents for carbon dioxide (CO₂) capture from flue gas or its removal from natural gas and landfill gas is very important for environmental protection. A new series of heteroatom-doped porous carbon was synthesized directly from pyrazole/KOH by thermolysis. The resulting pyrazole-derived carbons (PYDCs) are highly doped with nitrogen (14.9–15.5 wt %) as a result of the high nitrogen-to-carbon ratio in pyrazole (43 wt %) and also have a high oxygen content (16.4–18.4 wt %). PYDCs have a high surface area (SA_BET = 1266–2013 m² g^–1), high CO₂ <i>Q</i>_st (33.2–37.1 kJ mol^–1), and a combination of mesoporous and microporous pores. PYDCs exhibit significantly high CO₂ uptakes that reach 2.15 and 6.06 mmol g^–1 at 0.15 and 1 bar, respectively, at 298 K. At 273 K, the CO₂ uptake improves to 3.7 and 8.59 mmol g^–1 at 0.15 and 1 bar, respectively. The reported porous carbons also show significantly high adsorption selectivity for CO₂/N₂ (128) and CO₂/CH₄ (13.4) according to ideal adsorbed solution theory calculations at 298 K. Gas breakthrough studies of CO₂/N₂ (10:90) at 298 K showed that PYDCs display excellent separation properties. The ability to tailor the physical properties of PYDCs as well as their chemical composition provides an effective strategy for designing efficient CO₂ sorbents