生命科学最新文献

Long-lasting protective immunity against sarbecoviruses is hampered by the dominance of elicited antibodies to variable parts of the Spike protein, allowing ongoing viral escape and evolution. We investigated Modified Vaccinia Ankara (MVA) vaccine candidates expressing the SARS-CoV-1 or SARS-CoV-2 Spike for their ability to induce antibodies targeting different epitopes on the SARS-CoV-2 Receptor Binding Domain (RBD), including those with wide variant conservation. We also explored the capacity of these different Spike proteins to induce broad cross-reactive or cross-neutralizing B cells against multiple variants. This revealed that the SARS-CoV-1 Spike induced distinct patterns of epitope dominance compared to the traditional SARS-CoV-2 Spike antigens. Following immune imprinting by previous exposure to ancestral SARS-CoV-2 Spike, the epitope dominance patterns induced by SARS-CoV-1 and SARS-CoV-2 vaccines still differed, with most of the germinal center response consisting of de novo recruited B cells. In addition to the de novo response, B cells with germline cross-reactivity to both antigens further increased their binding toward the most recently immunized antigen. Interestingly, we found that, while SARS-CoV-2 vaccinated animals were extremely capable of mounting an antigen-specific germinal center and plasmablast response to a booster immunization with SARS-CoV-1, SARS-CoV-2 boosters were less capable of inducing SARS-CoV-2 specific B cells following prior SARS-CoV-1 vaccination. These findings have broad implications for the implementation of vaccine strategies against emerging coronavirus variants and potential future coronavirus spillover events. The implications stemming from a fundamental directionality of immune imprinting and epitope dominance may have wider implications for noncoronavirus antigens.

Small nucleolar RNAs (snoRNAs) contribute to ribosome biogenesis and modulate various aspects of plant growth and development. Given that osmotic stress downregulates numerous genes associated with ribosome biogenesis in roots, we hypothesize that snoRNAs might function in modulating plant responses to osmotic and drought stresses. To prove this hypothesis, we assessed the role of a C/D-box snoRNA, namely the HIDDEN TREASURE 2 (HID2), in Arabidopsis thaliana responses to drought using both loss-of-function and overexpression approaches. Under drought conditions, the Arabidopsis hid2 mutant displayed a significantly higher survival rate than both wild-type (WT) and HID2-complemented plants, while HID2-overexpressing plants showed a lower survival rate than WT. A series of physiological assays indicated that the hid2 mutant maintained a slower rate of water loss and more intact cell membranes than WT plants under drought, which supported their drought-tolerant phenotype. Comparative leaf transcriptome and proteome analyses revealed that processes related to wax biosynthesis, senescence, and anthocyanin accumulation were differentially regulated between hid2 and WT plants under water-deficit conditions. Consistently, the hid2 mutant accumulated higher amounts of wax and anthocyanins and exhibited delayed leaf senescence relative to WT plants under drought. Additionally, the hid2 mutant showed improved ability to increase sensitivity to abscisic acid (ABA), scavenge reactive oxygen species (ROS), and extended root hairs. Overall, these findings demonstrate HID2's role as a negative modulator in Arabidopsis drought tolerance by negatively affecting cell membrane stability, wax and anthocyanin biosynthesis, senescence, ROS-scavenging capacity, ABA responsiveness, and root hair formation.

This study, from the perspective of a Medical Immunology student, sought to explore and investigate the implementation of the Academic Tutor System in the teaching of Medical Immunology. The characteristics and challenges of studying Medical Immunology, as well as the limitations of conventional teaching models in this discipline, are analyzed. Additionally, the concept and theory of the Academic Tutor System and its application in the learning process of medical students are introduced in this study. Moreover, the specific implementation methods of the Academic Tutor System in Medical Immunology teaching are described, including implementation plan for the Academic Tutor System, implementation process for the Academic Tutor System and practical case analysis. Based on the findings of this study, it is concluded that the application of the Academic Tutor System benefits students' academic performance, enhances their research capabilities, and improves their overall comprehensive qualities. The vast majority of students support the implementation of the Academic Tutor System.

Davidia involucrata, a deciduous and endangered “living fossil” tree species, is native to mountainous regions in south-central and southwestern China. Despite the fact that drought stress severely constrains the conservation and utilization of D. involucrata resources, effective strategies for improving drought tolerance in this endangered species are still largely unexplored. This study aimed to examine the impact of exogenously applied glycine betaine (GB) on the tolerance to drought stress in D. involucrata. The results revealed that pre-treatment with 25 mM GB effectively alleviated drought-induced damage of D. involucrata seedlings. GB application significantly mitigated growth inhibition and concurrently enhanced chlorophyll accumulation in D. involucrata seedlings subjected to drought. Exogenous GB protected the photosynthetic electron transport system, maintained structural stability of the reaction center, and up-regulated the expression of photosystem II (PSII) subunit genes (DiPsbA, DiPsbP) as well as Calvin cycle-related genes (DiRbcL, DiRbcS, DiFBPase, DiSBPase), leading to improved photosynthetic capacity under drought stress. Furthermore, GB-mediated drought tolerance could also involve increased accumulation of soluble sugars, including glucose, fructose, and sucrose. Finally, we reveal that GB application can substantially enhance antioxidant enzyme activities and preserve ROS equilibrium under drought condition. Overall, this study demonstrated for the first time that exogenous GB plays a positive role during drought stress response in D. involucrata seedlings.

Plants rely on NLRs (nucleotide-binding leucine-rich repeat receptors) to recognise effector proteins secreted by pathogens into plant cells and to deliver disease resistance. Plant NLRs are broadly characterised by their N-terminal domains, which include the TIR (Toll/interleukin-1 receptor) and the CC (coiled-coil) domains. Effector recognition triggers NLR oligomerisation into complexes termed resistosomes, which initiate immune signalling. Some NLRs function as singletons that detect pathogens and activate immune responses, while there are NLRs that only recognise effectors and thereby require helper NLRs or genetically linked ‘paired’ NLRs to execute immune signalling. Recent studies have enhanced our understanding of the molecular mechanisms of different classes of NLRs, as well as how downstream proteins are recruited to signal upon effector recognition. In this review, we discuss the current knowledge of the NLR activation mechanisms, based on findings from recent structural and functional studies. We also highlight the remaining unknowns in the field and discuss current and potential future applications for enhancing plant immunity by engineering plant NLRs.