The role of SARS-CoV-2 N protein in diagnosis and vaccination in the context of emerging variants: present status and prospects

Despite many countries rapidly revising their strategies to prevent contagions, the number of people infected with Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to surge. The emergent variants that can evade the immune response significantly affect the effectiveness of mainstream vaccines and diagnostic products based on the original spike protein. Therefore, it is essential to focus on the highly conserved nature of the nucleocapsid protein as a potential target in the field of vaccines and diagnostics. In this regard, our review initially discusses the structure, function, and mechanism of action of N protein. Based on this discussion, we summarize the relevant research on the in-depth development and application of diagnostic methods and vaccines based on N protein, such as serology and nucleic acid detection. Such valuable information can aid in designing more efficient diagnostic and vaccine tools that could help end the SARS-CoV-2 pandemic

Effects of extreme drought on plant nutrient uptake and resorption in rhizomatous vs bunch grass dominated grasslands

Both the dominance and the mass ratio hypotheses predict that plant internal nutrient cycling in ecosystems is determined by the dominant species within plant communities. We tested this hypothesis under conditions of extreme drought by assessing plant nutrient (N, P and K) uptake and resorption in response to experimentally imposed precipitation reductions in two semiarid grasslands of northern China. These two communities shared similar environmental conditions, but had different dominant species-one was dominated by a rhizomatous grass (Leymus chinensis) and the other by a bunchgrass (Stipa grandis). Results showed that responses of N to drought differed between the two communities with drought decreasing green leaf N concentration and resorption in the community dominated by the rhizomatous grass, but not in the bunchgrass-dominated community. In contrast, negative effects of drought on green leaf P and K concentrations and their resorption efficiencies were consistent across the two communities. Additionally, in each community, the effects of extreme drought on soil N, P and K supply did not change synchronously with that on green leaf N, P and K concentrations, and senesced leaf N, P and K concentrations showed no response to extreme drought. Consistent with the dominance/mass ratio hypothesis, our findings suggest that differences in dominant species and their growth form (i.e., rhizomatous vs bunch grass) play an important nutrient-specific role in mediating plant internal nutrient cycling across communities within a single region

Exogenous P compounds differentially interacted with N availability to regulate enzymatic activities in a meadow steppe

Increased inputs of ecosystem nitrogen (N) and phosphorus (P) may affect the activity of soil enzymes that play essential roles in the metabolization of carbon (C), N and P for microbial growth. However, the associations between soil enzymatic activities and N and P availability remain poorly understood. We conducted a study in a meadow steppe to elucidate the effects of the addition of N, as ammonium nitrate (NH₄NO₃3), and two forms of P with contrasting solubility, comprising monopotassium phosphate (KH₂PO₄) and the less soluble triple superphosphate (Ca(H₂PO₄)₂, on activity of β-glucosidase (BG), N-acetyl-glucosaminidase (NAG) and acid and alkaline phosphomonoesterases (PMEs). In general, there was a positive effect of N on BG, NAG and alkaline PME activity as a result of enhanced soil N availability, plant-microbe nutrient competition and plant P uptake. Addition of KH₂2PO₄ increased activity of BG, NAG and alkaline PME, but had no impact on acid PME activity. Addition of Ca(H₂PO₄)2 increased NAG activity, but only increased activity of BG and alkaline PME with the addition of N. Concentration of soil available P and microbial biomass P increased with added P, particularly KH₂PO₄. These results provide the first evidence for the N- and P-mediated stimulation of microbial activity depending on the chemical form of added P in this ecosystem. Relationships between activity of BG and NAG, and between that of NAG and PME, were allometric, indicating disproportionate changes in activity of these soil enzymes. This further suggests shifts in microbial acquisition of C, N and P along with increases in availability of N and P that may potentially affect plant productivity. We conclude that scenarios of global environmental change, in which ecosystem availability of N and P is affected, may result in variable activity responses among soil enzymes, and the chemical form of P input should be considered as an important factor influencing meadow steppe grassland ecosystem function

Effects of extreme drought on plant nutrient uptake and resorption in rhizomatous vs bunch grass dominated grasslands

Both the dominance and the mass ratio hypotheses predict that plant internal nutrient cycling in ecosystems is determined by the dominant species within plant communities. We tested this hypothesis under conditions of extreme drought by assessing plant nutrient (N, P and K) uptake and resorption in response to experimentally imposed precipitation reductions in two semiarid grasslands of northern China. These two communities shared similar environmental conditions, but had different dominant species-one was dominated by a rhizomatous grass (Leymus chinensis) and the other by a bunchgrass (Stipa grandis). Results showed that responses of N to drought differed between the two communities with drought decreasing green leaf N concentration and resorption in the community dominated by the rhizomatous grass, but not in the bunchgrass-dominated community. In contrast, negative effects of drought on green leaf P and K concentrations and their resorption efficiencies were consistent across the two communities. Additionally, in each community, the effects of extreme drought on soil N, P and K supply did not change synchronously with that on green leaf N, P and K concentrations, and senesced leaf N, P and K concentrations showed no response to extreme drought. Consistent with the dominance/mass ratio hypothesis, our findings suggest that differences in dominant species and their growth form (i.e., rhizomatous vs bunch grass) play an important nutrient-specific role in mediating plant internal nutrient cycling across communities within a single region

Fractal Inorganic-Organic Interfaces in Hybrid Membranes for Efficient Proton Transport

International audienceA facile method for preparing highly conductive hybrid organic-inorganic membranes is reported. These membranes are synthesized using an electrospinning process with a sol-gel-based solution containing PVDF-HFP (polyvinylidenefluoride-hexafluoropropylene), functionalized or not functionalized silicon alkoxides, and additives. Proton conduction measurements highlight that these hybrid membranes exhibit conductivity value of 101 mS/cm at 120 degrees C under 80% RH (relative humidity), comparable to the best Nafion measured under the same conditions. These membranes have a proton conductivity-humidity variation close to Nafion and a modulus value higher than that for Nafion above 80 degrees C. Their proton conductivity value is about 15 mS/cm under 50% RH, and it constitutes one of the highest values reported. These interesting properties are related to the microstructure of the electrospun membranes that have been characterized using field emission scanning electron microscopy (FE-SEM) and small angle neutron scattering (SANS). The electrospun membranes are made composed of a bundle of fibers surrounded by a functionalized silica network. The bundle of fibers corresponds to the assembly of small polymer fibers surrounded by small anisotropic functionalized silica domains. Coupling the reactive chemistry of the sol-gel-based process with electrospinning allows the design of hybrid membranes with fractal hydrophobic/hydrophilic interfaces exhibiting different length scales