Characterization of SARS-CoV-2 nucleocapsid protein reveals multiple functional consequences of the C-terminal domain

Nucleocapsid (N) encoded by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) plays key roles in the replication cycle and is a critical serological marker. Here, we characterize essential biochemical properties of N and describe the utility of these insights in serological studies. We define N domains important for oligomerization and RNA binding and show that N oligomerization provides a high-affinity RNA-binding platform. We also map the RNA-binding interface, showing protection in the N-terminal domain and linker region. In addition, phosphorylation causes reduction of RNA binding and redistribution of N from liquid droplets to loose coils, showing how N-RNA accessibility and assembly may be regulated by phosphorylation. Finally, we find that the C-terminal domain of N is the most immunogenic, based on antibody binding to patient samples. Together, we provide a biochemical description of SARS-CoV-2 N and highlight the value of using N domains as highly specific and sensitive diagnostic markers

Distinct macrophage populations and phenotypes associated with IL-4 mediated immunomodulation at the host implant interface

Macrophage populations and gene expression of the host response were studied under the effects of IL-4 released from eluting implants.</p

Expanding and optimizing 3D bioprinting capabilities using complementary network bioinks

A major challenge in 3D bioprinting is the limited number of bioinks that fulfill the physiochemical requirements of printing, while also providing a desirable environment for encapsulated cells.Here, we address this limitation by temporarily stabilizing bioinks with a complementary thermo-reversible gelatin network. This strategy enablesthe effective printing of biomaterials that would typically not meet printing requirements, with instrument parameters and structural output largely independent of the base biomaterial. This approach is demonstrated across a library of photo-crosslinkable bioinks derived from natural and synthetic polymers, including gelatin, hyaluronic acid, chondroitin sulfate, dextran, alginate, chitosan, heparin,and poly(ethylene glycol). A range of complex and heterogeneous structures are printed, including soft hydrogel constructs supporting the 3D culture of astrocytes. This highly generalizable methodology expands the palette of available bioinks, allowing the biofabrication of constructs optimized to meet the biological requirements of cell culture and tissue engineering

Domain-specific biochemical and serological characterization of SARS-CoV-2 nucleocapsid protein

Nucleocapsid proteins are essential for SARS-CoV-2 life cycle. Here, we describe protocols to gather domain-specific insights about essential properties of nucleocapsids. These assays include dynamic light scattering to characterize oligomerization, fluorescence polarization to quantify RNA binding, hydrogen-deuterium exchange mass spectrometry to map RNA binding regions, negative-stain electron microscopy to visualize oligomeric species, interferon reporter assay to evaluate interferon signaling modulation, and a serology assay to reveal insights for improved sensitivity and specificity. These assays are broadly applicable to RNA-encapsidated nucleocapsids. For complete details on the use and execution of this protocol, please refer to Wu et al. (2021)

Les complications chirurgicales de la néphrectomie chez le donneur vivant

La transplantation rénale est considérée actuellement comme le meilleur traitement de l'insuffisance rénale chronique, surtout à partir de donneur vivant. Nous rapportons les complications chirurgicales à partir de 38 néphrectomies chez 38 donneurs vivants durant une période de 14 ans dans notre département. L'âge moyen de nos donneurs était de 30 ans avec des extrêmes entre de 18 et 58 ans avec une légère prédominance féminine (55,2%). L'abord chirurgical était réalisé par une lombotomie postérolatérale sur la 11e côte avec résection de celle-ci. Le rein gauche était prélevé chez 34 donneurs (90%). Les complications chirurgicales étaient notées chez 39,4% des donneurs: une plaie de la veine cave inférieure (2,6%), un cas dû au lâchage d'un clamp de l'artère rénale (2,6%), quatre cas de plaie pleurale (10,5%), un cas de pneumothorax (2,6%), un cas de pleurésie (2,6%), trois cas d'infection urinaire (7,8%), trois cas de suppuration pariétale (7,8%) et 12 cas de douleur persistante au niveau de l'incision (2,6%). Nous n'avons déploré aucun décès. Nous concluons que la morbidité de la néphrectomie chez le donneur vivant reste très négligeable par rapport à ses avantages pour le receveur