Structures of the promoter-bound respiratory syncytial virus polymerase.

The respiratory syncytial virus (RSV) polymerase is a multifunctional RNA-dependent RNA polymerase composed of the large (L) protein and the phosphoprotein (P). It transcribes the RNA genome into ten viral mRNAs and replicates full-length viral genomic and antigenomic RNAs1. The RSV polymerase initiates RNA synthesis by binding to the conserved 3'-terminal RNA promoters of the genome or antigenome2. However, the lack of a structure of the RSV polymerase bound to the RNA promoter has impeded the mechanistic understanding of RSV RNA synthesis. Here we report cryogenic electron microscopy structures of the RSV polymerase bound to its genomic and antigenomic viral RNA promoters, representing two of the first structures of an RNA-dependent RNA polymerase in complex with its RNA promoters in non-segmented negative-sense RNA viruses. The overall structures of the promoter-bound RSV polymerases are similar to that of the unbound (apo) polymerase. Our structures illustrate the interactions between the RSV polymerase and the RNA promoters and provide the structural basis for the initiation of RNA synthesis at positions 1 and 3 of the RSV promoters. These structures offer a deeper understanding of the pre-initiation state of the RSV polymerase and could aid in antiviral research against RSV.

Characterisation of bond between cement paste and steel fibres with different surface roughness using SEM.

The performance of cementitious composites reinforced with fibres or/and bars depends on the bond strength between inclusion and cementitious matrix. The nature of formation of fibre-matrix bond is crucial for enhancing the reliability and utilisation of reinforced composites. The research provides a review on the recently published result about the changes in the microstructure of cement matrix surrounding steel fibres with different surface roughness, using a scanning electron microscope (SEM) coupled with k-means clustering algorithm for image segmentation. The debonding pattern of the fibre-matrix bond after the tensile loading cycles was discussed by observing the amount of adhered cement paste to the pulled out fibre surface with SEM. Therefore, analysis of SEM images enabled to explain the connection between the micro-scale properties of cement paste and fibre after application of cyclic loading.

In Vitro Primer-Based RNA Elongation and Promoter Fine Mapping of the Respiratory Syncytial Virus.

Respiratory syncytial virus (RSV) is a nonsegmented negative-sense (NNS) RNA virus and shares a similar RNA synthesis strategy with other members of NNS RNA viruses, such as measles, rabies virus, and Ebola virus. RSV RNA synthesis is catalyzed by a multifunctional RNA-dependent RNA polymerase (RdRP), which is composed of a large (L) protein that catalyzes three distinct enzymatic functions and an essential coenzyme phosphoprotein (P). Here, we successfully prepared highly pure, full-length, wild-type and mutant RSV polymerase (L-P) complexes. We demonstrated that the RSV polymerase could carry out both de novo and primer-based RNA synthesis. We defined the minimal length of the RNA template for in vitro de novo RNA synthesis using the purified RSV polymerase as 8 nucleotides (nt), shorter than previously reported. We showed that the RSV polymerase catalyzed primer-dependent RNA elongation with different lengths of primers on both short (10-nt) and long (25-nt) RNA templates. We compared the sequence specificity of different viral promoters and identified positions 3, 5, and 8 of the promoter sequence as essential to the in vitro RSV polymerase activity, consistent with the results previously mapped with the in vivo minigenome assay. Overall, these findings agree well with those of previous biochemical studies and extend our understanding of the promoter sequence and the mechanism of RSV RNA synthesis.IMPORTANCE As a major human pathogen, RSV affects 3.4 million children worldwide annually. However, no effective antivirals or vaccines are available. An in-depth mechanistic understanding of the RSV RNA synthesis machinery remains a high priority among the NNS RNA viruses. There is a strong public health need for research on this virus, due to major fundamental gaps in our understanding of NNS RNA virus replication. As the key enzyme executing transcription and replication of the virus, the RSV RdRP is a logical target for novel antiviral drugs. Therefore, exploring the primer-dependent RNA elongation extends our mechanistic understanding of the RSV RNA synthesis. Further fine mapping of the promoter sequence paves the way to better understand the function and structure of the RSV polymerase.

Sustaining transformations: changing marine governance, environmental meaning, and 'left behind' Brexit narratives on the Yorkshire East Coast.

Transformations to sustainability are frequently framed as key to blue growth, but they often engender complex consequences for communities. This article illustrates the role of environmental meaning in these processes through the lens of the Brexit vote on the Yorkshire East Coast. Based on discursive institutionalist analysis of narrative materials from semi-formal interviews conducted in 2017 alongside textual documentation from media, policy, and regional archives, I trace connections between transforming marine governance regimes, environmental meaning, and the British relationship with the EU from the Cod Wars to today. The transformation towards ecosystem-based management in British maritime governance post UNCLOS III left local communities feeling 'left behind' not only economically but also in terms of marginalised local meanings of place, labour, and environment. The Brexit vote, in this context, shows the multivalence of transformational processes and the importance of considering environmental meaning as part of their just execution.

Direct CO2 Capture by Alkali-Dissolved Cellulose and Sequestration in Building Materials and Artificial Reef Structures.

Current carbon capture and utilization (CCU) technologies require high energy input and costly catalysts. Here, an effective pathway is offered that addresses climate action by atmospheric CO2 sequestration. Industrially relevant highly reactive alkali cellulose solutions are used as CO2 absorption media. The latter lead to mineralized cellulose materials (MCM) at a tailorable cellulose-to-mineral ratio, forming organic-inorganic viscous systems (viscosity from 102 to 107  mPa s and storage modulus from 10 to 105  Pa). CO2 absorption and conversion into calcium carbonate and associated minerals translate to maximum absorption of 6.5 gCO2 gcellulose -1 , tracking inversely with cellulose loading. Cellulose lean gels are easily converted into dry powders, shown as a functional component of ceramic glazes and cementitious composites. Meanwhile, cellulose-rich gels are moldable and extrudable, yielding stone-like structures tested as artificial substrates for coral reef restoration. Life Cycle Assessment (LCA) suggests new CCU opportunities for building materials, as demonstrated in underwater deployment for coral reef ecosystem restoration.

Cryo-EM structure of the respiratory syncytial virus RNA polymerase.

The respiratory syncytial virus (RSV) RNA polymerase, constituted of a 250 kDa large (L) protein and tetrameric phosphoprotein (P), catalyzes three distinct enzymatic activities - nucleotide polymerization, cap addition, and cap methylation. How RSV L and P coordinate these activities is poorly understood. Here, we present a 3.67 Å cryo-EM structure of the RSV polymerase (L:P) complex. The structure reveals that the RNA dependent RNA polymerase (RdRp) and capping (Cap) domains of L interact with the oligomerization domain (POD) and C-terminal domain (PCTD) of a tetramer of P. The density of the methyltransferase (MT) domain of L and the N-terminal domain of P (PNTD) is missing. Further analysis and comparison with other RNA polymerases at different stages suggest the structure we obtained is likely to be at an elongation-compatible stage. Together, these data provide enriched insights into the interrelationship, the inhibitors, and the evolutionary implications of the RSV polymerase.